Check in the pristine copy of ICU 4.6...

icu46/source/i18n/regexcmp.cpp

+//
+//  file:  regexcmp.cpp
+//
+//  Copyright (C) 2002-2010 International Business Machines Corporation and others.
+//  All Rights Reserved.
+//
+//  This file contains the ICU regular expression compiler, which is responsible
+//  for processing a regular expression pattern into the compiled form that
+//  is used by the match finding engine.
+//
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_REGULAR_EXPRESSIONS
+
+#include "unicode/ustring.h"
+#include "unicode/unistr.h"
+#include "unicode/uniset.h"
+#include "unicode/uchar.h"
+#include "unicode/uchriter.h"
+#include "unicode/parsepos.h"
+#include "unicode/parseerr.h"
+#include "unicode/regex.h"
+#include "util.h"
+#include "putilimp.h"
+#include "cmemory.h"
+#include "cstring.h"
+#include "uvectr32.h"
+#include "uvectr64.h"
+#include "uassert.h"
+#include "ucln_in.h"
+#include "uinvchar.h"
+
+#include "regeximp.h"
+#include "regexcst.h"   // Contains state table for the regex pattern parser.
+                        //   generated by a Perl script.
+#include "regexcmp.h"
+#include "regexst.h"
+#include "regextxt.h"
+
+
+
+U_NAMESPACE_BEGIN
+
+
+//------------------------------------------------------------------------------
+//
+//  Constructor.
+//
+//------------------------------------------------------------------------------
+RegexCompile::RegexCompile(RegexPattern *rxp, UErrorCode &status) :
+   fParenStack(status), fSetStack(status), fSetOpStack(status)
+{
+    // Lazy init of all shared global sets (needed for init()'s empty text)
+    RegexStaticSets::initGlobals(&status);
+
+    fStatus           = &status;
+
+    fRXPat            = rxp;
+    fScanIndex        = 0;
+    fLastChar         = -1;
+    fPeekChar         = -1;
+    fLineNum          = 1;
+    fCharNum          = 0;
+    fQuoteMode        = FALSE;
+    fInBackslashQuote = FALSE;
+    fModeFlags        = fRXPat->fFlags | 0x80000000;
+    fEOLComments      = TRUE;
+
+    fMatchOpenParen   = -1;
+    fMatchCloseParen  = -1;
+    fStringOpStart    = -1;
+
+    if (U_SUCCESS(status) && U_FAILURE(rxp->fDeferredStatus)) {
+        status = rxp->fDeferredStatus;
+    }
+}
+
+static const UChar      chAmp       = 0x26;      // '&'
+static const UChar      chDash      = 0x2d;      // '-'
+
+
+//------------------------------------------------------------------------------
+//
+//  Destructor
+//
+//------------------------------------------------------------------------------
+RegexCompile::~RegexCompile() {
+}
+
+static inline void addCategory(UnicodeSet *set, int32_t value, UErrorCode& ec) {
+    set->addAll(UnicodeSet().applyIntPropertyValue(UCHAR_GENERAL_CATEGORY_MASK, value, ec));
+}
+
+//------------------------------------------------------------------------------
+//
+//  Compile regex pattern.   The state machine for rexexp pattern parsing is here.
+//                           The state tables are hand-written in the file regexcst.txt,
+//                           and converted to the form used here by a perl
+//                           script regexcst.pl
+//
+//------------------------------------------------------------------------------
+void    RegexCompile::compile(
+                         const UnicodeString &pat,   // Source pat to be compiled.
+                         UParseError &pp,            // Error position info
+                         UErrorCode &e)              // Error Code
+{
+        fRXPat->fPatternString = new UnicodeString(pat);
+    UText patternText = UTEXT_INITIALIZER;
+    utext_openConstUnicodeString(&patternText, fRXPat->fPatternString, &e);
+    
+    if (U_SUCCESS(e)) {
+        compile(&patternText, pp, e);
+        utext_close(&patternText);
+    }
+}
+
+//
+//   compile, UText mode
+//     All the work is actually done here.
+//
+void    RegexCompile::compile(
+                         UText *pat,                 // Source pat to be compiled.
+                         UParseError &pp,            // Error position info
+                         UErrorCode &e)              // Error Code
+{
+    fStatus             = &e;
+    fParseErr           = &pp;
+    fStackPtr           = 0;
+    fStack[fStackPtr]   = 0;
+
+    if (U_FAILURE(*fStatus)) {
+        return;
+    }
+
+    // There should be no pattern stuff in the RegexPattern object.  They can not be reused.
+    U_ASSERT(fRXPat->fPattern == NULL || utext_nativeLength(fRXPat->fPattern) == 0);
+
+    // Prepare the RegexPattern object to receive the compiled pattern.
+    fRXPat->fPattern        = utext_clone(fRXPat->fPattern, pat, FALSE, TRUE, fStatus);
+    fRXPat->fStaticSets     = RegexStaticSets::gStaticSets->fPropSets;
+    fRXPat->fStaticSets8    = RegexStaticSets::gStaticSets->fPropSets8;
+
+
+    // Initialize the pattern scanning state machine
+    fPatternLength = utext_nativeLength(pat);
+    uint16_t                state = 1;
+    const RegexTableEl      *tableEl;
+    nextChar(fC);                        // Fetch the first char from the pattern string.
+
+    //
+    // Main loop for the regex pattern parsing state machine.
+    //   Runs once per state transition.
+    //   Each time through optionally performs, depending on the state table,
+    //      - an advance to the the next pattern char
+    //      - an action to be performed.
+    //      - pushing or popping a state to/from the local state return stack.
+    //   file regexcst.txt is the source for the state table.  The logic behind
+    //     recongizing the pattern syntax is there, not here.
+    //
+    for (;;) {
+        //  Bail out if anything has gone wrong.
+        //  Regex pattern parsing stops on the first error encountered.
+        if (U_FAILURE(*fStatus)) {
+            break;
+        }
+
+        U_ASSERT(state != 0);
+
+        // Find the state table element that matches the input char from the pattern, or the
+        //    class of the input character.  Start with the first table row for this
+        //    state, then linearly scan forward until we find a row that matches the
+        //    character.  The last row for each state always matches all characters, so
+        //    the search will stop there, if not before.
+        //
+        tableEl = &gRuleParseStateTable[state];
+        REGEX_SCAN_DEBUG_PRINTF(("char, line, col = (\'%c\', %d, %d)    state=%s ",
+            fC.fChar, fLineNum, fCharNum, RegexStateNames[state]));
+
+        for (;;) {    // loop through table rows belonging to this state, looking for one
+                      //   that matches the current input char.
+            REGEX_SCAN_DEBUG_PRINTF(("."));
+            if (tableEl->fCharClass < 127 && fC.fQuoted == FALSE &&   tableEl->fCharClass == fC.fChar) {
+                // Table row specified an individual character, not a set, and
+                //   the input character is not quoted, and
+                //   the input character matched it.
+                break;
+            }
+            if (tableEl->fCharClass == 255) {
+                // Table row specified default, match anything character class.
+                break;
+            }
+            if (tableEl->fCharClass == 254 && fC.fQuoted)  {
+                // Table row specified "quoted" and the char was quoted.
+                break;
+            }
+            if (tableEl->fCharClass == 253 && fC.fChar == (UChar32)-1)  {
+                // Table row specified eof and we hit eof on the input.
+                break;
+            }
+
+            if (tableEl->fCharClass >= 128 && tableEl->fCharClass < 240 &&   // Table specs a char class &&
+                fC.fQuoted == FALSE &&                                       //   char is not escaped &&
+                fC.fChar != (UChar32)-1) {                                   //   char is not EOF
+                if (RegexStaticSets::gStaticSets->fRuleSets[tableEl->fCharClass-128].contains(fC.fChar)) {
+                    // Table row specified a character class, or set of characters,
+                    //   and the current char matches it.
+                    break;
+                }
+            }
+
+            // No match on this row, advance to the next  row for this state,
+            tableEl++;
+        }
+        REGEX_SCAN_DEBUG_PRINTF(("\n"));
+
+        //
+        // We've found the row of the state table that matches the current input
+        //   character from the rules string.
+        // Perform any action specified  by this row in the state table.
+        if (doParseActions(tableEl->fAction) == FALSE) {
+            // Break out of the state machine loop if the
+            //   the action signalled some kind of error, or
+            //   the action was to exit, occurs on normal end-of-rules-input.
+            break;
+        }
+
+        if (tableEl->fPushState != 0) {
+            fStackPtr++;
+            if (fStackPtr >= kStackSize) {
+                error(U_REGEX_INTERNAL_ERROR);
+                REGEX_SCAN_DEBUG_PRINTF(("RegexCompile::parse() - state stack overflow.\n"));
+                fStackPtr--;
+            }
+            fStack[fStackPtr] = tableEl->fPushState;
+        }
+
+        //
+        //  NextChar.  This is where characters are actually fetched from the pattern.
+        //             Happens under control of the 'n' tag in the state table.
+        //
+        if (tableEl->fNextChar) {
+            nextChar(fC);
+        }
+
+        // Get the next state from the table entry, or from the
+        //   state stack if the next state was specified as "pop".
+        if (tableEl->fNextState != 255) {
+            state = tableEl->fNextState;
+        } else {
+            state = fStack[fStackPtr];
+            fStackPtr--;
+            if (fStackPtr < 0) {
+                // state stack underflow
+                // This will occur if the user pattern has mis-matched parentheses,
+                //   with extra close parens.
+                //
+                fStackPtr++;
+                error(U_REGEX_MISMATCHED_PAREN);
+            }
+        }
+
+    }
+
+    if (U_FAILURE(*fStatus)) {
+        // Bail out if the pattern had errors.
+        //   Set stack cleanup:  a successful compile would have left it empty,
+        //   but errors can leave temporary sets hanging around.
+        while (!fSetStack.empty()) {
+            delete (UnicodeSet *)fSetStack.pop();
+        }
+        return;
+    }
+
+    //
+    // The pattern has now been read and processed, and the compiled code generated.
+    //
+
+    //
+    // Compute the number of digits requried for the largest capture group number.
+    //
+    fRXPat->fMaxCaptureDigits = 1;
+    int32_t  n = 10;
+    int32_t  groupCount = fRXPat->fGroupMap->size();
+    while (n <= groupCount) {
+        fRXPat->fMaxCaptureDigits++;
+        n *= 10;
+    }
+
+    //
+    // The pattern's fFrameSize so far has accumulated the requirements for
+    //   storage for capture parentheses, counters, etc. that are encountered
+    //   in the pattern.  Add space for the two variables that are always
+    //   present in the saved state:  the input string position (int64_t) and
+    //   the position in the compiled pattern.
+    //
+    fRXPat->fFrameSize+=RESTACKFRAME_HDRCOUNT;
+
+    //
+    // Optimization pass 1: NOPs, back-references, and case-folding
+    //
+    stripNOPs();
+
+    //
+    // Get bounds for the minimum and maximum length of a string that this
+    //   pattern can match.  Used to avoid looking for matches in strings that
+    //   are too short.
+    //
+    fRXPat->fMinMatchLen = minMatchLength(3, fRXPat->fCompiledPat->size()-1);
+
+    //
+    // Optimization pass 2: match start type
+    //
+    matchStartType();
+
+    //
+    // Set up fast latin-1 range sets
+    //
+    int32_t numSets = fRXPat->fSets->size();
+    fRXPat->fSets8 = new Regex8BitSet[numSets];
+    // Null pointer check.
+    if (fRXPat->fSets8 == NULL) {
+        e = *fStatus = U_MEMORY_ALLOCATION_ERROR;
+        return;
+    }
+    int32_t i;
+    for (i=0; i<numSets; i++) {
+        UnicodeSet *s = (UnicodeSet *)fRXPat->fSets->elementAt(i);
+        fRXPat->fSets8[i].init(s);
+    }
+
+}
+
+
+
+
+
+//------------------------------------------------------------------------------
+//
+//  doParseAction        Do some action during regex pattern parsing.
+//                       Called by the parse state machine.
+//
+//                       Generation of the match engine PCode happens here, or
+//                       in functions called from the parse actions defined here.
+//
+//
+//------------------------------------------------------------------------------
+UBool RegexCompile::doParseActions(int32_t action)
+{
+    UBool   returnVal = TRUE;
+
+    switch ((Regex_PatternParseAction)action) {
+
+    case doPatStart:
+        // Start of pattern compiles to:
+        //0   SAVE   2        Fall back to position of FAIL
+        //1   jmp    3
+        //2   FAIL            Stop if we ever reach here.
+        //3   NOP             Dummy, so start of pattern looks the same as
+        //                    the start of an ( grouping.
+        //4   NOP             Resreved, will be replaced by a save if there are
+        //                    OR | operators at the top level
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_STATE_SAVE, 2), *fStatus);
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_JMP,  3), *fStatus);
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_FAIL, 0), *fStatus);
+
+        // Standard open nonCapture paren action emits the two NOPs and
+        //   sets up the paren stack frame.
+        doParseActions(doOpenNonCaptureParen);
+        break;
+
+    case doPatFinish:
+        // We've scanned to the end of the pattern
+        //  The end of pattern compiles to:
+        //        URX_END
+        //    which will stop the runtime match engine.
+        //  Encountering end of pattern also behaves like a close paren,
+        //   and forces fixups of the State Save at the beginning of the compiled pattern
+        //   and of any OR operations at the top level.
+        //
+        handleCloseParen();
+        if (fParenStack.size() > 0) {
+            // Missing close paren in pattern.
+            error(U_REGEX_MISMATCHED_PAREN);
+        }
+
+        // add the END operation to the compiled pattern.
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_END, 0), *fStatus);
+
+        // Terminate the pattern compilation state machine.
+        returnVal = FALSE;
+        break;
+
+
+
+    case doOrOperator:
+        // Scanning a '|', as in (A|B)
+        {
+            // Insert a SAVE operation at the start of the pattern section preceding
+            //   this OR at this level.  This SAVE will branch the match forward
+            //   to the right hand side of the OR in the event that the left hand
+            //   side fails to match and backtracks.  Locate the position for the
+            //   save from the location on the top of the parentheses stack.
+            int32_t savePosition = fParenStack.popi();
+            int32_t op = (int32_t)fRXPat->fCompiledPat->elementAti(savePosition);
+            U_ASSERT(URX_TYPE(op) == URX_NOP);  // original contents of reserved location
+            op = URX_BUILD(URX_STATE_SAVE, fRXPat->fCompiledPat->size()+1);
+            fRXPat->fCompiledPat->setElementAt(op, savePosition);
+
+            // Append an JMP operation into the compiled pattern.  The operand for
+            //  the JMP will eventually be the location following the ')' for the
+            //  group.  This will be patched in later, when the ')' is encountered.
+            op = URX_BUILD(URX_JMP, 0);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // Push the position of the newly added JMP op onto the parentheses stack.
+            // This registers if for fixup when this block's close paren is encountered.
+            fParenStack.push(fRXPat->fCompiledPat->size()-1, *fStatus);
+
+            // Append a NOP to the compiled pattern.  This is the slot reserved
+            //   for a SAVE in the event that there is yet another '|' following
+            //   this one.
+            fRXPat->fCompiledPat->addElement(URX_BUILD(URX_NOP, 0), *fStatus);
+            fParenStack.push(fRXPat->fCompiledPat->size()-1, *fStatus);
+        }
+        break;
+
+
+    case doOpenCaptureParen:
+        // Open Paren.
+        //   Compile to a
+        //      - NOP, which later may be replaced by a save-state if the
+        //         parenthesized group gets a * quantifier, followed by
+        //      - START_CAPTURE  n    where n is stack frame offset to the capture group variables.
+        //      - NOP, which may later be replaced by a save-state if there
+        //             is an '|' alternation within the parens.
+        //
+        //    Each capture group gets three slots in the save stack frame:
+        //         0: Capture Group start position (in input string being matched.)
+        //         1: Capture Group end position.
+        //         2: Start of Match-in-progress.
+        //    The first two locations are for a completed capture group, and are
+        //     referred to by back references and the like.
+        //    The third location stores the capture start position when an START_CAPTURE is
+        //      encountered.  This will be promoted to a completed capture when (and if) the corresponding
+        //      END_CAPTURE is encountered.
+        {
+            fRXPat->fCompiledPat->addElement(URX_BUILD(URX_NOP, 0), *fStatus);
+            int32_t  varsLoc    = fRXPat->fFrameSize;    // Reserve three slots in match stack frame.
+            fRXPat->fFrameSize += 3;
+            int32_t  cop        = URX_BUILD(URX_START_CAPTURE, varsLoc);
+            fRXPat->fCompiledPat->addElement(cop, *fStatus);
+            fRXPat->fCompiledPat->addElement(URX_BUILD(URX_NOP, 0), *fStatus);
+
+            // On the Parentheses stack, start a new frame and add the postions
+            //   of the two NOPs.  Depending on what follows in the pattern, the
+            //   NOPs may be changed to SAVE_STATE or JMP ops, with a target
+            //   address of the end of the parenthesized group.
+            fParenStack.push(fModeFlags, *fStatus);                       // Match mode state
+            fParenStack.push(capturing, *fStatus);                        // Frame type.
+            fParenStack.push(fRXPat->fCompiledPat->size()-3, *fStatus);   // The first  NOP location
+            fParenStack.push(fRXPat->fCompiledPat->size()-1, *fStatus);   // The second NOP loc
+
+            // Save the mapping from group number to stack frame variable position.
+            fRXPat->fGroupMap->addElement(varsLoc, *fStatus);
+        }
+         break;
+
+    case doOpenNonCaptureParen:
+        // Open non-caputuring (grouping only) Paren.
+        //   Compile to a
+        //      - NOP, which later may be replaced by a save-state if the
+        //         parenthesized group gets a * quantifier, followed by
+        //      - NOP, which may later be replaced by a save-state if there
+        //             is an '|' alternation within the parens.
+        {
+            fRXPat->fCompiledPat->addElement(URX_BUILD(URX_NOP, 0), *fStatus);
+            fRXPat->fCompiledPat->addElement(URX_BUILD(URX_NOP, 0), *fStatus);
+
+            // On the Parentheses stack, start a new frame and add the postions
+            //   of the two NOPs.
+            fParenStack.push(fModeFlags, *fStatus);                       // Match mode state
+            fParenStack.push(plain,      *fStatus);                       // Begin a new frame.
+            fParenStack.push(fRXPat->fCompiledPat->size()-2, *fStatus);   // The first  NOP location
+            fParenStack.push(fRXPat->fCompiledPat->size()-1, *fStatus);   // The second NOP loc
+        }
+         break;
+
+
+    case doOpenAtomicParen:
+        // Open Atomic Paren.  (?>
+        //   Compile to a
+        //      - NOP, which later may be replaced if the parenthesized group
+        //         has a quantifier, followed by
+        //      - STO_SP  save state stack position, so it can be restored at the ")"
+        //      - NOP, which may later be replaced by a save-state if there
+        //             is an '|' alternation within the parens.
+        {
+            fRXPat->fCompiledPat->addElement(URX_BUILD(URX_NOP, 0), *fStatus);
+            int32_t  varLoc    = fRXPat->fDataSize;    // Reserve a data location for saving the
+            fRXPat->fDataSize += 1;                    //  state stack ptr.
+            int32_t  stoOp     = URX_BUILD(URX_STO_SP, varLoc);
+            fRXPat->fCompiledPat->addElement(stoOp, *fStatus);
+            fRXPat->fCompiledPat->addElement(URX_BUILD(URX_NOP, 0), *fStatus);
+
+            // On the Parentheses stack, start a new frame and add the postions
+            //   of the two NOPs.  Depending on what follows in the pattern, the
+            //   NOPs may be changed to SAVE_STATE or JMP ops, with a target
+            //   address of the end of the parenthesized group.
+            fParenStack.push(fModeFlags, *fStatus);                       // Match mode state
+            fParenStack.push(atomic, *fStatus);                           // Frame type.
+            fParenStack.push(fRXPat->fCompiledPat->size()-3, *fStatus);   // The first NOP
+            fParenStack.push(fRXPat->fCompiledPat->size()-1, *fStatus);   // The second NOP
+        }
+        break;
+
+
+    case doOpenLookAhead:
+        // Positive Look-ahead   (?=  stuff  )
+        //
+        //   Note:   Addition of transparent input regions, with the need to
+        //           restore the original regions when failing out of a lookahead
+        //           block, complicated this sequence.  Some conbined opcodes
+        //           might make sense - or might not, lookahead aren't that common.
+        //
+        //      Caution:  min match length optimization knows about this
+        //               sequence; don't change without making updates there too.
+        //
+        // Compiles to
+        //    1    START_LA     dataLoc     Saves SP, Input Pos
+        //    2.   STATE_SAVE   4            on failure of lookahead, goto 4
+        //    3    JMP          6           continue ...
+        //
+        //    4.   LA_END                   Look Ahead failed.  Restore regions.
+        //    5.   BACKTRACK                and back track again.
+        //
+        //    6.   NOP              reserved for use by quantifiers on the block.
+        //                          Look-ahead can't have quantifiers, but paren stack
+        //                             compile time conventions require the slot anyhow.
+        //    7.   NOP              may be replaced if there is are '|' ops in the block.
+        //    8.     code for parenthesized stuff.
+        //    9.   LA_END
+        //
+        //  Two data slots are reserved, for saving the stack ptr and the input position.
+        {
+            int32_t dataLoc = fRXPat->fDataSize;
+            fRXPat->fDataSize += 2;
+            int32_t op = URX_BUILD(URX_LA_START, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            op = URX_BUILD(URX_STATE_SAVE, fRXPat->fCompiledPat->size()+ 2);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            op = URX_BUILD(URX_JMP, fRXPat->fCompiledPat->size()+ 3);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+            
+            op = URX_BUILD(URX_LA_END, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            op = URX_BUILD(URX_BACKTRACK, 0);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+            
+            op = URX_BUILD(URX_NOP, 0);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // On the Parentheses stack, start a new frame and add the postions
+            //   of the NOPs.
+            fParenStack.push(fModeFlags, *fStatus);                       // Match mode state
+            fParenStack.push(lookAhead, *fStatus);                        // Frame type.
+            fParenStack.push(fRXPat->fCompiledPat->size()-2, *fStatus);   // The first  NOP location
+            fParenStack.push(fRXPat->fCompiledPat->size()-1, *fStatus);   // The second NOP location
+        }
+        break;
+
+    case doOpenLookAheadNeg:
+        // Negated Lookahead.   (?! stuff )
+        // Compiles to
+        //    1.    START_LA    dataloc
+        //    2.    SAVE_STATE  7         // Fail within look-ahead block restores to this state,
+        //                                //   which continues with the match.
+        //    3.    NOP                   // Std. Open Paren sequence, for possible '|'
+        //    4.       code for parenthesized stuff.
+        //    5.    END_LA                // Cut back stack, remove saved state from step 2.
+        //    6.    BACKTRACK             // code in block succeeded, so neg. lookahead fails.
+        //    7.    END_LA                // Restore match region, in case look-ahead was using
+        //                                        an alternate (transparent) region.
+        {
+            int32_t dataLoc = fRXPat->fDataSize;
+            fRXPat->fDataSize += 2;
+            int32_t op = URX_BUILD(URX_LA_START, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            op = URX_BUILD(URX_STATE_SAVE, 0);    // dest address will be patched later.
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            op = URX_BUILD(URX_NOP, 0);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // On the Parentheses stack, start a new frame and add the postions
+            //   of the StateSave and NOP.
+            fParenStack.push(fModeFlags, *fStatus);                       // Match mode state
+            fParenStack.push(negLookAhead, *fStatus);                    // Frame type
+            fParenStack.push(fRXPat->fCompiledPat->size()-2, *fStatus);   // The STATE_SAVE location
+            fParenStack.push(fRXPat->fCompiledPat->size()-1, *fStatus);   // The second NOP location
+
+            // Instructions #5 - #7 will be added when the ')' is encountered.
+        }
+        break;
+
+    case doOpenLookBehind:
+        {
+            //   Compile a (?<= look-behind open paren.
+            //
+            //          Compiles to
+            //              0       URX_LB_START     dataLoc
+            //              1       URX_LB_CONT      dataLoc
+            //              2                        MinMatchLen
+            //              3                        MaxMatchLen
+            //              4       URX_NOP          Standard '(' boilerplate.
+            //              5       URX_NOP          Reserved slot for use with '|' ops within (block).
+            //              6         <code for LookBehind expression>
+            //              7       URX_LB_END       dataLoc    # Check match len, restore input  len
+            //              8       URX_LA_END       dataLoc    # Restore stack, input pos
+            //
+            //          Allocate a block of matcher data, to contain (when running a match)
+            //              0:    Stack ptr on entry
+            //              1:    Input Index on entry
+            //              2:    Start index of match current match attempt.
+            //              3:    Original Input String len.
+
+            // Allocate data space
+            int32_t dataLoc = fRXPat->fDataSize;
+            fRXPat->fDataSize += 4;
+
+            // Emit URX_LB_START
+            int32_t op = URX_BUILD(URX_LB_START, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // Emit URX_LB_CONT
+            op = URX_BUILD(URX_LB_CONT, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+            fRXPat->fCompiledPat->addElement(0,  *fStatus);    // MinMatchLength.  To be filled later.
+            fRXPat->fCompiledPat->addElement(0,  *fStatus);    // MaxMatchLength.  To be filled later.
+
+            // Emit the NOP
+            op = URX_BUILD(URX_NOP, 0);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // On the Parentheses stack, start a new frame and add the postions
+            //   of the URX_LB_CONT and the NOP.
+            fParenStack.push(fModeFlags, *fStatus);                       // Match mode state
+            fParenStack.push(lookBehind, *fStatus);                       // Frame type
+            fParenStack.push(fRXPat->fCompiledPat->size()-2, *fStatus);   // The first NOP location
+            fParenStack.push(fRXPat->fCompiledPat->size()-1, *fStatus);   // The 2nd   NOP location
+
+            // The final two instructions will be added when the ')' is encountered.
+        }
+
+        break;
+
+    case doOpenLookBehindNeg:
+        {
+            //   Compile a (?<! negated look-behind open paren.
+            //
+            //          Compiles to
+            //              0       URX_LB_START     dataLoc    # Save entry stack, input len
+            //              1       URX_LBN_CONT     dataLoc    # Iterate possible match positions
+            //              2                        MinMatchLen
+            //              3                        MaxMatchLen
+            //              4                        continueLoc (9)
+            //              5       URX_NOP          Standard '(' boilerplate.
+            //              6       URX_NOP          Reserved slot for use with '|' ops within (block).
+            //              7         <code for LookBehind expression>
+            //              8       URX_LBN_END      dataLoc    # Check match len, cause a FAIL
+            //              9       ...
+            //
+            //          Allocate a block of matcher data, to contain (when running a match)
+            //              0:    Stack ptr on entry
+            //              1:    Input Index on entry
+            //              2:    Start index of match current match attempt.
+            //              3:    Original Input String len.
+
+            // Allocate data space
+            int32_t dataLoc = fRXPat->fDataSize;
+            fRXPat->fDataSize += 4;
+
+            // Emit URX_LB_START
+            int32_t op = URX_BUILD(URX_LB_START, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // Emit URX_LBN_CONT
+            op = URX_BUILD(URX_LBN_CONT, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+            fRXPat->fCompiledPat->addElement(0,  *fStatus);    // MinMatchLength.  To be filled later.
+            fRXPat->fCompiledPat->addElement(0,  *fStatus);    // MaxMatchLength.  To be filled later.
+            fRXPat->fCompiledPat->addElement(0,  *fStatus);    // Continue Loc.    To be filled later.
+
+            // Emit the NOP
+            op = URX_BUILD(URX_NOP, 0);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // On the Parentheses stack, start a new frame and add the postions
+            //   of the URX_LB_CONT and the NOP.
+            fParenStack.push(fModeFlags, *fStatus);                       // Match mode state
+            fParenStack.push(lookBehindN, *fStatus);                      // Frame type
+            fParenStack.push(fRXPat->fCompiledPat->size()-2, *fStatus);   // The first NOP location
+            fParenStack.push(fRXPat->fCompiledPat->size()-1, *fStatus);   // The 2nd   NOP location
+
+            // The final two instructions will be added when the ')' is encountered.
+        }
+        break;
+
+    case doConditionalExpr:
+        // Conditionals such as (?(1)a:b)
+    case doPerlInline:
+        // Perl inline-condtionals.  (?{perl code}a|b) We're not perl, no way to do them.
+        error(U_REGEX_UNIMPLEMENTED);
+        break;
+
+
+    case doCloseParen:
+        handleCloseParen();
+        if (fParenStack.size() <= 0) {
+            //  Extra close paren, or missing open paren.
+            error(U_REGEX_MISMATCHED_PAREN);
+        }
+        break;
+
+    case doNOP:
+        break;
+
+
+    case doBadOpenParenType:
+    case doRuleError:
+        error(U_REGEX_RULE_SYNTAX);
+        break;
+
+
+    case doMismatchedParenErr:
+        error(U_REGEX_MISMATCHED_PAREN);
+        break;
+
+    case doPlus:
+        //  Normal '+'  compiles to
+        //     1.   stuff to be repeated  (already built)
+        //     2.   jmp-sav 1
+        //     3.   ...
+        //
+        //  Or, if the item to be repeated can match a zero length string,
+        //     1.   STO_INP_LOC  data-loc
+        //     2.      body of stuff to be repeated
+        //     3.   JMP_SAV_X    2
+        //     4.   ...
+
+        //
+        //  Or, if the item to be repeated is simple
+        //     1.   Item to be repeated.
+        //     2.   LOOP_SR_I    set number  (assuming repeated item is a set ref)
+        //     3.   LOOP_C       stack location
+        {
+            int32_t  topLoc = blockTopLoc(FALSE);        // location of item #1
+            int32_t  frameLoc;
+
+            // Check for simple constructs, which may get special optimized code.
+            if (topLoc == fRXPat->fCompiledPat->size() - 1) {
+                int32_t repeatedOp = (int32_t)fRXPat->fCompiledPat->elementAti(topLoc);
+
+                if (URX_TYPE(repeatedOp) == URX_SETREF) {
+                    // Emit optimized code for [char set]+
+                    int32_t loopOpI = URX_BUILD(URX_LOOP_SR_I, URX_VAL(repeatedOp));
+                    fRXPat->fCompiledPat->addElement(loopOpI, *fStatus);
+                    frameLoc = fRXPat->fFrameSize;
+                    fRXPat->fFrameSize++;
+                    int32_t loopOpC = URX_BUILD(URX_LOOP_C, frameLoc);
+                    fRXPat->fCompiledPat->addElement(loopOpC, *fStatus);
+                    break;
+                }
+
+                if (URX_TYPE(repeatedOp) == URX_DOTANY ||
+                    URX_TYPE(repeatedOp) == URX_DOTANY_ALL ||
+                    URX_TYPE(repeatedOp) == URX_DOTANY_UNIX) {
+                    // Emit Optimized code for .+ operations.
+                    int32_t loopOpI = URX_BUILD(URX_LOOP_DOT_I, 0);
+                    if (URX_TYPE(repeatedOp) == URX_DOTANY_ALL) {
+                        // URX_LOOP_DOT_I operand is a flag indicating ". matches any" mode.
+                        loopOpI |= 1;
+                    }
+                    if (fModeFlags & UREGEX_UNIX_LINES) {
+                        loopOpI |= 2;
+                    }
+                    fRXPat->fCompiledPat->addElement(loopOpI, *fStatus);
+                    frameLoc = fRXPat->fFrameSize;
+                    fRXPat->fFrameSize++;
+                    int32_t loopOpC = URX_BUILD(URX_LOOP_C, frameLoc);
+                    fRXPat->fCompiledPat->addElement(loopOpC, *fStatus);
+                    break;
+                }
+
+            }
+
+            // General case.
+
+            // Check for minimum match length of zero, which requires
+            //    extra loop-breaking code.
+            if (minMatchLength(topLoc, fRXPat->fCompiledPat->size()-1) == 0) {
+                // Zero length match is possible.
+                // Emit the code sequence that can handle it.
+                insertOp(topLoc);
+                frameLoc =  fRXPat->fFrameSize;
+                fRXPat->fFrameSize++;
+
+                int32_t op = URX_BUILD(URX_STO_INP_LOC, frameLoc);
+                fRXPat->fCompiledPat->setElementAt(op, topLoc);
+
+                op = URX_BUILD(URX_JMP_SAV_X, topLoc+1);
+                fRXPat->fCompiledPat->addElement(op, *fStatus);
+            } else {
+                // Simpler code when the repeated body must match something non-empty
+                int32_t  jmpOp  = URX_BUILD(URX_JMP_SAV, topLoc);
+                fRXPat->fCompiledPat->addElement(jmpOp, *fStatus);
+            }
+        }
+        break;
+
+    case doNGPlus:
+        //  Non-greedy '+?'  compiles to
+        //     1.   stuff to be repeated  (already built)
+        //     2.   state-save  1
+        //     3.   ...
+        {
+            int32_t topLoc      = blockTopLoc(FALSE);
+            int32_t saveStateOp = URX_BUILD(URX_STATE_SAVE, topLoc);
+            fRXPat->fCompiledPat->addElement(saveStateOp, *fStatus);
+        }
+        break;
+
+
+    case doOpt:
+        // Normal (greedy) ? quantifier.
+        //  Compiles to
+        //     1. state save 3
+        //     2.    body of optional block
+        //     3. ...
+        // Insert the state save into the compiled pattern, and we're done.
+        {
+            int32_t   saveStateLoc = blockTopLoc(TRUE);
+            int32_t   saveStateOp  = URX_BUILD(URX_STATE_SAVE, fRXPat->fCompiledPat->size());
+            fRXPat->fCompiledPat->setElementAt(saveStateOp, saveStateLoc);
+        }
+        break;
+
+    case doNGOpt:
+        // Non-greedy ?? quantifier
+        //   compiles to
+        //    1.  jmp   4
+        //    2.     body of optional block
+        //    3   jmp   5
+        //    4.  state save 2
+        //    5    ...
+        //  This code is less than ideal, with two jmps instead of one, because we can only
+        //  insert one instruction at the top of the block being iterated.
+        {
+            int32_t  jmp1_loc = blockTopLoc(TRUE);
+            int32_t  jmp2_loc = fRXPat->fCompiledPat->size();
+
+            int32_t  jmp1_op  = URX_BUILD(URX_JMP, jmp2_loc+1);
+            fRXPat->fCompiledPat->setElementAt(jmp1_op, jmp1_loc);
+
+            int32_t  jmp2_op  = URX_BUILD(URX_JMP, jmp2_loc+2);
+            fRXPat->fCompiledPat->addElement(jmp2_op, *fStatus);
+
+            int32_t  save_op  = URX_BUILD(URX_STATE_SAVE, jmp1_loc+1);
+            fRXPat->fCompiledPat->addElement(save_op, *fStatus);
+        }
+        break;
+
+
+    case doStar:
+        // Normal (greedy) * quantifier.
+        // Compiles to
+        //       1.   STATE_SAVE   4
+        //       2.      body of stuff being iterated over
+        //       3.   JMP_SAV      2
+        //       4.   ...
+        //
+        // Or, if the body is a simple [Set],
+        //       1.   LOOP_SR_I    set number
+        //       2.   LOOP_C       stack location
+        //       ...
+        //
+        // Or if this is a .*
+        //       1.   LOOP_DOT_I    (. matches all mode flag)
+        //       2.   LOOP_C        stack location
+        //
+        // Or, if the body can match a zero-length string, to inhibit infinite loops,
+        //       1.   STATE_SAVE   5
+        //       2.   STO_INP_LOC  data-loc
+        //       3.      body of stuff
+        //       4.   JMP_SAV_X    2
+        //       5.   ...
+        {
+            // location of item #1, the STATE_SAVE
+            int32_t   topLoc = blockTopLoc(FALSE);
+            int32_t   dataLoc = -1;
+
+            // Check for simple *, where the construct being repeated
+            //   compiled to single opcode, and might be optimizable.
+            if (topLoc == fRXPat->fCompiledPat->size() - 1) {
+                int32_t repeatedOp = (int32_t)fRXPat->fCompiledPat->elementAti(topLoc);
+
+                if (URX_TYPE(repeatedOp) == URX_SETREF) {
+                    // Emit optimized code for a [char set]*
+                    int32_t loopOpI = URX_BUILD(URX_LOOP_SR_I, URX_VAL(repeatedOp));
+                    fRXPat->fCompiledPat->setElementAt(loopOpI, topLoc);
+                    dataLoc = fRXPat->fFrameSize;
+                    fRXPat->fFrameSize++;
+                    int32_t loopOpC = URX_BUILD(URX_LOOP_C, dataLoc);
+                    fRXPat->fCompiledPat->addElement(loopOpC, *fStatus);
+                    break;
+                }
+
+                if (URX_TYPE(repeatedOp) == URX_DOTANY ||
+                    URX_TYPE(repeatedOp) == URX_DOTANY_ALL ||
+                    URX_TYPE(repeatedOp) == URX_DOTANY_UNIX) {
+                    // Emit Optimized code for .* operations.
+                    int32_t loopOpI = URX_BUILD(URX_LOOP_DOT_I, 0);
+                    if (URX_TYPE(repeatedOp) == URX_DOTANY_ALL) {
+                        // URX_LOOP_DOT_I operand is a flag indicating . matches any mode.
+                        loopOpI |= 1;
+                    }
+                    if ((fModeFlags & UREGEX_UNIX_LINES) != 0) {
+                        loopOpI |= 2;
+                    }
+                    fRXPat->fCompiledPat->setElementAt(loopOpI, topLoc);
+                    dataLoc = fRXPat->fFrameSize;
+                    fRXPat->fFrameSize++;
+                    int32_t loopOpC = URX_BUILD(URX_LOOP_C, dataLoc);
+                    fRXPat->fCompiledPat->addElement(loopOpC, *fStatus);
+                    break;
+                }
+            }
+
+            // Emit general case code for this *
+            // The optimizations did not apply.
+
+            int32_t   saveStateLoc = blockTopLoc(TRUE);
+            int32_t   jmpOp        = URX_BUILD(URX_JMP_SAV, saveStateLoc+1);
+
+            // Check for minimum match length of zero, which requires
+            //    extra loop-breaking code.
+            if (minMatchLength(saveStateLoc, fRXPat->fCompiledPat->size()-1) == 0) {
+                insertOp(saveStateLoc);
+                dataLoc =  fRXPat->fFrameSize;
+                fRXPat->fFrameSize++;
+
+                int32_t op = URX_BUILD(URX_STO_INP_LOC, dataLoc);
+                fRXPat->fCompiledPat->setElementAt(op, saveStateLoc+1);
+                jmpOp      = URX_BUILD(URX_JMP_SAV_X, saveStateLoc+2);
+            }
+
+            // Locate the position in the compiled pattern where the match will continue
+            //   after completing the *.   (4 or 5 in the comment above)
+            int32_t continueLoc = fRXPat->fCompiledPat->size()+1;
+
+            // Put together the save state op store it into the compiled code.
+            int32_t saveStateOp = URX_BUILD(URX_STATE_SAVE, continueLoc);
+            fRXPat->fCompiledPat->setElementAt(saveStateOp, saveStateLoc);
+
+            // Append the URX_JMP_SAV or URX_JMPX operation to the compiled pattern.
+            fRXPat->fCompiledPat->addElement(jmpOp, *fStatus);
+        }
+        break;
+
+    case doNGStar:
+        // Non-greedy *? quantifier
+        // compiles to
+        //     1.   JMP    3
+        //     2.      body of stuff being iterated over
+        //     3.   STATE_SAVE  2
+        //     4    ...
+        {
+            int32_t     jmpLoc  = blockTopLoc(TRUE);                   // loc  1.
+            int32_t     saveLoc = fRXPat->fCompiledPat->size();        // loc  3.
+            int32_t     jmpOp   = URX_BUILD(URX_JMP, saveLoc);
+            int32_t     stateSaveOp = URX_BUILD(URX_STATE_SAVE, jmpLoc+1);
+            fRXPat->fCompiledPat->setElementAt(jmpOp, jmpLoc);
+            fRXPat->fCompiledPat->addElement(stateSaveOp, *fStatus);
+        }
+        break;
+
+
+    case doIntervalInit:
+        // The '{' opening an interval quantifier was just scanned.
+        // Init the counter varaiables that will accumulate the values as the digits
+        //    are scanned.
+        fIntervalLow = 0;
+        fIntervalUpper = -1;
+        break;
+
+    case doIntevalLowerDigit:
+        // Scanned a digit from the lower value of an {lower,upper} interval
+        {
+            int32_t digitValue = u_charDigitValue(fC.fChar);
+            U_ASSERT(digitValue >= 0);
+            fIntervalLow = fIntervalLow*10 + digitValue;
+            if (fIntervalLow < 0) {
+                error(U_REGEX_NUMBER_TOO_BIG);
+            }
+        }
+        break;
+
+    case doIntervalUpperDigit:
+        // Scanned a digit from the upper value of an {lower,upper} interval
+        {
+            if (fIntervalUpper < 0) {
+                fIntervalUpper = 0;
+            }
+            int32_t digitValue = u_charDigitValue(fC.fChar);
+            U_ASSERT(digitValue >= 0);
+            fIntervalUpper = fIntervalUpper*10 + digitValue;
+            if (fIntervalUpper < 0) {
+                error(U_REGEX_NUMBER_TOO_BIG);
+            }
+        }
+        break;
+
+    case doIntervalSame:
+        // Scanned a single value interval like {27}.  Upper = Lower.
+        fIntervalUpper = fIntervalLow;
+        break;
+
+    case doInterval:
+        // Finished scanning a normal {lower,upper} interval.  Generate the code for it.
+        if (compileInlineInterval() == FALSE) {
+            compileInterval(URX_CTR_INIT, URX_CTR_LOOP);
+        }
+        break;
+
+    case doPossessiveInterval:
+        // Finished scanning a Possessive {lower,upper}+ interval.  Generate the code for it.
+        {
+            // Remember the loc for the top of the block being looped over.
+            //   (Can not reserve a slot in the compiled pattern at this time, because
+            //    compileInterval needs to reserve also, and blockTopLoc can only reserve
+            //    once per block.)
+            int32_t topLoc = blockTopLoc(FALSE);
+
+            // Produce normal looping code.
+            compileInterval(URX_CTR_INIT, URX_CTR_LOOP);
+
+            // Surround the just-emitted normal looping code with a STO_SP ... LD_SP
+            //  just as if the loop was inclosed in atomic parentheses.
+
+            // First the STO_SP before the start of the loop
+            insertOp(topLoc);
+            int32_t  varLoc    = fRXPat->fDataSize;    // Reserve a data location for saving the
+            fRXPat->fDataSize += 1;                    //  state stack ptr.
+            int32_t  op        = URX_BUILD(URX_STO_SP, varLoc);
+            fRXPat->fCompiledPat->setElementAt(op, topLoc);
+
+            int32_t loopOp = (int32_t)fRXPat->fCompiledPat->popi();
+            U_ASSERT(URX_TYPE(loopOp) == URX_CTR_LOOP && URX_VAL(loopOp) == topLoc);
+            loopOp++;     // point LoopOp after the just-inserted STO_SP
+            fRXPat->fCompiledPat->push(loopOp, *fStatus);
+
+            // Then the LD_SP after the end of the loop
+            op = URX_BUILD(URX_LD_SP, varLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+        }
+
+        break;
+
+    case doNGInterval:
+        // Finished scanning a non-greedy {lower,upper}? interval.  Generate the code for it.
+        compileInterval(URX_CTR_INIT_NG, URX_CTR_LOOP_NG);
+        break;
+
+    case doIntervalError:
+        error(U_REGEX_BAD_INTERVAL);
+        break;
+
+    case doLiteralChar:
+        // We've just scanned a "normal" character from the pattern,
+        literalChar(fC.fChar);
+        break;
+
+
+    case doEscapedLiteralChar:
+        // We've just scanned an backslashed escaped character with  no
+        //   special meaning.  It represents itself.
+        if ((fModeFlags & UREGEX_ERROR_ON_UNKNOWN_ESCAPES) != 0 &&
+            ((fC.fChar >= 0x41 && fC.fChar<= 0x5A) ||     // in [A-Z]
+            (fC.fChar >= 0x61 && fC.fChar <= 0x7a))) {   // in [a-z]
+               error(U_REGEX_BAD_ESCAPE_SEQUENCE);
+             }
+        literalChar(fC.fChar);
+        break;
+
+
+    case doDotAny:
+        // scanned a ".",  match any single character.
+        {
+            int32_t   op;
+            if (fModeFlags & UREGEX_DOTALL) {
+                op = URX_BUILD(URX_DOTANY_ALL, 0);
+            } else if (fModeFlags & UREGEX_UNIX_LINES) {
+                op = URX_BUILD(URX_DOTANY_UNIX, 0);
+            } else {
+                op = URX_BUILD(URX_DOTANY, 0);
+            }
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+        }
+        break;
+
+    case doCaret:
+        {
+            int32_t op = 0;
+            if (       (fModeFlags & UREGEX_MULTILINE) == 0 && (fModeFlags & UREGEX_UNIX_LINES) == 0) {
+                op = URX_CARET;
+            } else if ((fModeFlags & UREGEX_MULTILINE) != 0 && (fModeFlags & UREGEX_UNIX_LINES) == 0) {
+                op = URX_CARET_M;
+            } else if ((fModeFlags & UREGEX_MULTILINE) == 0 && (fModeFlags & UREGEX_UNIX_LINES) != 0) {
+                op = URX_CARET;   // Only testing true start of input. 
+            } else if ((fModeFlags & UREGEX_MULTILINE) != 0 && (fModeFlags & UREGEX_UNIX_LINES) != 0) {
+                op = URX_CARET_M_UNIX;
+            }
+            fRXPat->fCompiledPat->addElement(URX_BUILD(op, 0), *fStatus);
+        }
+        break;
+
+    case doDollar:
+        {
+            int32_t op = 0;
+            if (       (fModeFlags & UREGEX_MULTILINE) == 0 && (fModeFlags & UREGEX_UNIX_LINES) == 0) {
+                op = URX_DOLLAR;
+            } else if ((fModeFlags & UREGEX_MULTILINE) != 0 && (fModeFlags & UREGEX_UNIX_LINES) == 0) {
+                op = URX_DOLLAR_M;
+            } else if ((fModeFlags & UREGEX_MULTILINE) == 0 && (fModeFlags & UREGEX_UNIX_LINES) != 0) {
+                op = URX_DOLLAR_D;
+            } else if ((fModeFlags & UREGEX_MULTILINE) != 0 && (fModeFlags & UREGEX_UNIX_LINES) != 0) {
+                op = URX_DOLLAR_MD;
+            }
+            fRXPat->fCompiledPat->addElement(URX_BUILD(op, 0), *fStatus);
+        }
+        break;
+
+    case doBackslashA:
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_CARET, 0), *fStatus);
+        break;
+
+    case doBackslashB:
+        {
+            #if  UCONFIG_NO_BREAK_ITERATION==1
+            if (fModeFlags & UREGEX_UWORD) {
+                error(U_UNSUPPORTED_ERROR);
+            }
+            #endif
+            int32_t op = (fModeFlags & UREGEX_UWORD)? URX_BACKSLASH_BU : URX_BACKSLASH_B;
+            fRXPat->fCompiledPat->addElement(URX_BUILD(op, 1), *fStatus);
+        }
+        break;
+
+    case doBackslashb:
+        {
+            #if  UCONFIG_NO_BREAK_ITERATION==1
+            if (fModeFlags & UREGEX_UWORD) {
+                error(U_UNSUPPORTED_ERROR);
+            }
+            #endif
+            int32_t op = (fModeFlags & UREGEX_UWORD)? URX_BACKSLASH_BU : URX_BACKSLASH_B;
+            fRXPat->fCompiledPat->addElement(URX_BUILD(op, 0), *fStatus);
+        }
+        break;
+
+    case doBackslashD:
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_BACKSLASH_D, 1), *fStatus);
+        break;
+
+    case doBackslashd:
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_BACKSLASH_D, 0), *fStatus);
+        break;
+
+    case doBackslashG:
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_BACKSLASH_G, 0), *fStatus);
+        break;
+
+    case doBackslashS:
+        fRXPat->fCompiledPat->addElement(
+            URX_BUILD(URX_STAT_SETREF_N, URX_ISSPACE_SET), *fStatus);
+        break;
+
+    case doBackslashs:
+        fRXPat->fCompiledPat->addElement(
+            URX_BUILD(URX_STATIC_SETREF, URX_ISSPACE_SET), *fStatus);
+        break;
+
+    case doBackslashW:
+        fRXPat->fCompiledPat->addElement(
+            URX_BUILD(URX_STAT_SETREF_N, URX_ISWORD_SET), *fStatus);
+        break;
+
+    case doBackslashw:
+        fRXPat->fCompiledPat->addElement(
+            URX_BUILD(URX_STATIC_SETREF, URX_ISWORD_SET), *fStatus);
+        break;
+
+    case doBackslashX:
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_BACKSLASH_X, 0), *fStatus);
+        break;
+
+
+    case doBackslashZ:
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_DOLLAR, 0), *fStatus);
+        break;
+
+    case doBackslashz:
+        fRXPat->fCompiledPat->addElement(URX_BUILD(URX_BACKSLASH_Z, 0), *fStatus);
+        break;
+
+    case doEscapeError:
+        error(U_REGEX_BAD_ESCAPE_SEQUENCE);
+        break;
+
+    case doExit:
+        returnVal = FALSE;
+        break;
+
+    case doProperty:
+        {
+            UnicodeSet *theSet = scanProp();
+            compileSet(theSet);
+        }
+        break;
+
+    case doNamedChar:
+        {
+            UChar32 c = scanNamedChar();
+            literalChar(c);
+        }
+        break;
+        
+
+    case doBackRef:
+        // BackReference.  Somewhat unusual in that the front-end can not completely parse
+        //                 the regular expression, because the number of digits to be consumed
+        //                 depends on the number of capture groups that have been defined.  So
+        //                 we have to do it here instead.
+        {
+            int32_t  numCaptureGroups = fRXPat->fGroupMap->size();
+            int32_t  groupNum = 0;
+            UChar32  c        = fC.fChar;
+
+            for (;;) {
+                // Loop once per digit, for max allowed number of digits in a back reference.
+                int32_t digit = u_charDigitValue(c);
+                groupNum = groupNum * 10 + digit;
+                if (groupNum >= numCaptureGroups) {
+                    break;
+                }
+                c = peekCharLL();
+                if (RegexStaticSets::gStaticSets->fRuleDigitsAlias->contains(c) == FALSE) {
+                    break;
+                }
+                nextCharLL();
+            }
+
+            // Scan of the back reference in the source regexp is complete.  Now generate
+            //  the compiled code for it.
+            // Because capture groups can be forward-referenced by back-references,
+            //  we fill the operand with the capture group number.  At the end
+            //  of compilation, it will be changed to the variable's location.
+            U_ASSERT(groupNum > 0);
+            int32_t  op;
+            if (fModeFlags & UREGEX_CASE_INSENSITIVE) {
+                op = URX_BUILD(URX_BACKREF_I, groupNum);
+            } else {
+                op = URX_BUILD(URX_BACKREF, groupNum);
+            }
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+        }
+        break;
+
+
+    case doPossessivePlus:
+        // Possessive ++ quantifier.
+        // Compiles to
+        //       1.   STO_SP
+        //       2.      body of stuff being iterated over
+        //       3.   STATE_SAVE 5
+        //       4.   JMP        2
+        //       5.   LD_SP
+        //       6.   ...
+        //
+        //  Note:  TODO:  This is pretty inefficient.  A mass of saved state is built up
+        //                then unconditionally discarded.  Perhaps introduce a new opcode.  Ticket 6056
+        //
+        {
+            // Emit the STO_SP
+            int32_t   topLoc = blockTopLoc(TRUE);
+            int32_t   stoLoc = fRXPat->fDataSize;
+            fRXPat->fDataSize++;       // Reserve the data location for storing save stack ptr.
+            int32_t   op     = URX_BUILD(URX_STO_SP, stoLoc);
+            fRXPat->fCompiledPat->setElementAt(op, topLoc);
+
+            // Emit the STATE_SAVE
+            op = URX_BUILD(URX_STATE_SAVE, fRXPat->fCompiledPat->size()+2);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // Emit the JMP
+            op = URX_BUILD(URX_JMP, topLoc+1);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // Emit the LD_SP
+            op = URX_BUILD(URX_LD_SP, stoLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+        }
+        break;
+
+    case doPossessiveStar:
+        // Possessive *+ quantifier.
+        // Compiles to
+        //       1.   STO_SP       loc
+        //       2.   STATE_SAVE   5
+        //       3.      body of stuff being iterated over
+        //       4.   JMP          2
+        //       5.   LD_SP        loc
+        //       6    ...
+        // TODO:  do something to cut back the state stack each time through the loop.
+        {
+            // Reserve two slots at the top of the block.
+            int32_t   topLoc = blockTopLoc(TRUE);
+            insertOp(topLoc);
+
+            // emit   STO_SP     loc
+            int32_t   stoLoc = fRXPat->fDataSize;
+            fRXPat->fDataSize++;       // Reserve the data location for storing save stack ptr.
+            int32_t   op     = URX_BUILD(URX_STO_SP, stoLoc);
+            fRXPat->fCompiledPat->setElementAt(op, topLoc);
+
+            // Emit the SAVE_STATE   5
+            int32_t L7 = fRXPat->fCompiledPat->size()+1;
+            op = URX_BUILD(URX_STATE_SAVE, L7);
+            fRXPat->fCompiledPat->setElementAt(op, topLoc+1);
+
+            // Append the JMP operation.
+            op = URX_BUILD(URX_JMP, topLoc+1);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // Emit the LD_SP       loc
+            op = URX_BUILD(URX_LD_SP, stoLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+        }
+        break;
+
+    case doPossessiveOpt:
+        // Possessive  ?+ quantifier.
+        //  Compiles to
+        //     1. STO_SP      loc
+        //     2. SAVE_STATE  5
+        //     3.    body of optional block
+        //     4. LD_SP       loc
+        //     5. ...
+        //
+        {
+            // Reserve two slots at the top of the block.
+            int32_t   topLoc = blockTopLoc(TRUE);
+            insertOp(topLoc);
+
+            // Emit the STO_SP
+            int32_t   stoLoc = fRXPat->fDataSize;
+            fRXPat->fDataSize++;       // Reserve the data location for storing save stack ptr.
+            int32_t   op     = URX_BUILD(URX_STO_SP, stoLoc);
+            fRXPat->fCompiledPat->setElementAt(op, topLoc);
+
+            // Emit the SAVE_STATE
+            int32_t   continueLoc = fRXPat->fCompiledPat->size()+1;
+            op = URX_BUILD(URX_STATE_SAVE, continueLoc);
+            fRXPat->fCompiledPat->setElementAt(op, topLoc+1);
+
+            // Emit the LD_SP
+            op = URX_BUILD(URX_LD_SP, stoLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+        }
+        break;
+
+
+    case doBeginMatchMode:
+        fNewModeFlags = fModeFlags;
+        fSetModeFlag  = TRUE;
+        break;
+
+    case doMatchMode:   //  (?i)    and similar
+        {
+            int32_t  bit = 0;
+            switch (fC.fChar) {
+            case 0x69: /* 'i' */   bit = UREGEX_CASE_INSENSITIVE; break;
+            case 0x64: /* 'd' */   bit = UREGEX_UNIX_LINES;       break;
+            case 0x6d: /* 'm' */   bit = UREGEX_MULTILINE;        break;
+            case 0x73: /* 's' */   bit = UREGEX_DOTALL;           break;
+            case 0x75: /* 'u' */   bit = 0; /* Unicode casing */  break;
+            case 0x77: /* 'w' */   bit = UREGEX_UWORD;            break;
+            case 0x78: /* 'x' */   bit = UREGEX_COMMENTS;         break;
+            case 0x2d: /* '-' */   fSetModeFlag = FALSE;          break;
+            default:
+                U_ASSERT(FALSE);   // Should never happen.  Other chars are filtered out
+                                   // by the scanner.
+            }
+            if (fSetModeFlag) {
+                fNewModeFlags |= bit;
+            } else {
+                fNewModeFlags &= ~bit;
+            }
+        }
+        break;
+
+    case doSetMatchMode:
+        // We've got a (?i) or similar.  The match mode is being changed, but
+        //   the change is not scoped to a parenthesized block.
+        U_ASSERT(fNewModeFlags < 0);
+        fModeFlags = fNewModeFlags;
+
+        // Prevent any string from spanning across the change of match mode.
+        //   Otherwise the pattern "abc(?i)def" would make a single string of "abcdef"
+        fixLiterals();
+        break;
+
+
+    case doMatchModeParen:
+        // We've got a (?i: or similar.  Begin a parenthesized block, save old
+        //   mode flags so they can be restored at the close of the block.
+        //
+        //   Compile to a
+        //      - NOP, which later may be replaced by a save-state if the
+        //         parenthesized group gets a * quantifier, followed by
+        //      - NOP, which may later be replaced by a save-state if there
+        //             is an '|' alternation within the parens.
+        {
+            fRXPat->fCompiledPat->addElement(URX_BUILD(URX_NOP, 0), *fStatus);
+            fRXPat->fCompiledPat->addElement(URX_BUILD(URX_NOP, 0), *fStatus);
+
+            // On the Parentheses stack, start a new frame and add the postions
+            //   of the two NOPs (a normal non-capturing () frame, except for the
+            //   saving of the orignal mode flags.)
+            fParenStack.push(fModeFlags, *fStatus);
+            fParenStack.push(flags, *fStatus);                            // Frame Marker
+            fParenStack.push(fRXPat->fCompiledPat->size()-2, *fStatus);   // The first NOP
+            fParenStack.push(fRXPat->fCompiledPat->size()-1, *fStatus);   // The second NOP
+
+            // Set the current mode flags to the new values.
+            U_ASSERT(fNewModeFlags < 0);
+            fModeFlags = fNewModeFlags;
+        }
+        break;
+
+    case doBadModeFlag:
+        error(U_REGEX_INVALID_FLAG);
+        break;
+
+    case doSuppressComments:
+        // We have just scanned a '(?'.  We now need to prevent the character scanner from
+        // treating a '#' as a to-the-end-of-line comment.
+        //   (This Perl compatibility just gets uglier and uglier to do...)
+        fEOLComments = FALSE;
+        break;
+
+
+    case doSetAddAmp:
+        {
+          UnicodeSet *set = (UnicodeSet *)fSetStack.peek();
+          set->add(chAmp);
+        }
+        break;
+
+    case doSetAddDash:
+        {
+          UnicodeSet *set = (UnicodeSet *)fSetStack.peek();
+          set->add(chDash);
+        }
+        break;
+
+     case doSetBackslash_s:
+        {
+         UnicodeSet *set = (UnicodeSet *)fSetStack.peek();
+         set->addAll(*RegexStaticSets::gStaticSets->fPropSets[URX_ISSPACE_SET]);
+         break;
+        }
+
+     case doSetBackslash_S:
+        {
+            UnicodeSet *set = (UnicodeSet *)fSetStack.peek();
+            UnicodeSet SSet(*RegexStaticSets::gStaticSets->fPropSets[URX_ISSPACE_SET]);
+            SSet.complement();
+            set->addAll(SSet);
+            break;
+        }
+
+    case doSetBackslash_d:
+        {
+            UnicodeSet *set = (UnicodeSet *)fSetStack.peek();
+            // TODO - make a static set, ticket 6058.
+            addCategory(set, U_GC_ND_MASK, *fStatus);
+            break;
+        }
+
+    case doSetBackslash_D:
+        {
+            UnicodeSet *set = (UnicodeSet *)fSetStack.peek();
+            UnicodeSet digits;
+            // TODO - make a static set, ticket 6058.
+            digits.applyIntPropertyValue(UCHAR_GENERAL_CATEGORY_MASK, U_GC_ND_MASK, *fStatus);
+            digits.complement();
+            set->addAll(digits);
+            break;
+        }
+
+    case doSetBackslash_w:
+        {
+            UnicodeSet *set = (UnicodeSet *)fSetStack.peek();
+            set->addAll(*RegexStaticSets::gStaticSets->fPropSets[URX_ISWORD_SET]);
+            break;
+        }
+
+    case doSetBackslash_W:
+        {
+            UnicodeSet *set = (UnicodeSet *)fSetStack.peek();
+            UnicodeSet SSet(*RegexStaticSets::gStaticSets->fPropSets[URX_ISWORD_SET]);
+            SSet.complement();
+            set->addAll(SSet);
+            break;
+        }
+
+    case doSetBegin:
+        fSetStack.push(new UnicodeSet(), *fStatus);
+        fSetOpStack.push(setStart, *fStatus);
+        if ((fModeFlags & UREGEX_CASE_INSENSITIVE) != 0) {
+            fSetOpStack.push(setCaseClose, *fStatus);
+        }
+        break;
+
+    case doSetBeginDifference1:
+        //  We have scanned something like [[abc]-[
+        //  Set up a new UnicodeSet for the set beginning with the just-scanned '['
+        //  Push a Difference operator, which will cause the new set to be subtracted from what
+        //    went before once it is created.
+        setPushOp(setDifference1);
+        fSetOpStack.push(setStart, *fStatus);
+        if ((fModeFlags & UREGEX_CASE_INSENSITIVE) != 0) {
+            fSetOpStack.push(setCaseClose, *fStatus);
+        }
+        break;
+
+    case doSetBeginIntersection1:
+        //  We have scanned something like  [[abc]&[
+        //   Need both the '&' operator and the open '[' operator.
+        setPushOp(setIntersection1);
+        fSetOpStack.push(setStart, *fStatus);
+        if ((fModeFlags & UREGEX_CASE_INSENSITIVE) != 0) {
+            fSetOpStack.push(setCaseClose, *fStatus);
+        }
+        break;
+
+    case doSetBeginUnion:
+        //  We have scanned something like  [[abc][
+        //     Need to handle the union operation explicitly [[abc] | [
+        setPushOp(setUnion);
+        fSetOpStack.push(setStart, *fStatus);
+        if ((fModeFlags & UREGEX_CASE_INSENSITIVE) != 0) {
+            fSetOpStack.push(setCaseClose, *fStatus);
+        }
+        break;
+
+    case doSetDifference2:
+        // We have scanned something like [abc--
+        //   Consider this to unambiguously be a set difference operator.
+        setPushOp(setDifference2);
+        break;
+
+    case doSetEnd:
+        // Have encountered the ']' that closes a set.
+        //    Force the evaluation of any pending operations within this set,
+        //    leave the completed set on the top of the set stack.
+        setEval(setEnd);
+        U_ASSERT(fSetOpStack.peeki()==setStart);
+        fSetOpStack.popi();
+        break;
+
+    case doSetFinish:
+        {
+        // Finished a complete set expression, including all nested sets.
+        //   The close bracket has already triggered clearing out pending set operators,
+        //    the operator stack should be empty and the operand stack should have just
+        //    one entry, the result set.
+        U_ASSERT(fSetOpStack.empty());
+        UnicodeSet *theSet = (UnicodeSet *)fSetStack.pop();
+        U_ASSERT(fSetStack.empty());
+        compileSet(theSet);
+        break;
+        }
+        
+    case doSetIntersection2:
+        // Have scanned something like [abc&&
+        setPushOp(setIntersection2);
+        break;
+
+    case doSetLiteral:
+        // Union the just-scanned literal character into the set being built.
+        //    This operation is the highest precedence set operation, so we can always do
+        //    it immediately, without waiting to see what follows.  It is necessary to perform
+        //    any pending '-' or '&' operation first, because these have the same precedence
+        //    as union-ing in a literal' 
+        {
+            setEval(setUnion);
+            UnicodeSet *s = (UnicodeSet *)fSetStack.peek();
+            s->add(fC.fChar);
+            fLastSetLiteral = fC.fChar;
+            break;
+        }
+
+    case doSetLiteralEscaped:
+        // A back-slash escaped literal character was encountered.
+        // Processing is the same as with setLiteral, above, with the addition of
+        //  the optional check for errors on escaped ASCII letters.
+        {
+            if ((fModeFlags & UREGEX_ERROR_ON_UNKNOWN_ESCAPES) != 0 &&
+                ((fC.fChar >= 0x41 && fC.fChar<= 0x5A) ||     // in [A-Z]
+                 (fC.fChar >= 0x61 && fC.fChar <= 0x7a))) {   // in [a-z]
+                error(U_REGEX_BAD_ESCAPE_SEQUENCE);
+            }
+            setEval(setUnion);
+            UnicodeSet *s = (UnicodeSet *)fSetStack.peek();
+            s->add(fC.fChar);
+            fLastSetLiteral = fC.fChar;
+            break;
+        }
+
+        case doSetNamedChar:
+        // Scanning a \N{UNICODE CHARACTER NAME}
+        //  Aside from the source of the character, the processing is identical to doSetLiteral,
+        //    above.
+        {
+            UChar32  c = scanNamedChar();
+            setEval(setUnion);
+            UnicodeSet *s = (UnicodeSet *)fSetStack.peek();
+            s->add(c);
+            fLastSetLiteral = c;
+            break;
+        }
+
+    case doSetNamedRange:
+        // We have scanned literal-\N{CHAR NAME}.  Add the range to the set.
+        // The left character is already in the set, and is saved in fLastSetLiteral.
+        // The right side needs to be picked up, the scan is at the 'N'.
+        // Lower Limit > Upper limit being an error matches both Java
+        //        and ICU UnicodeSet behavior.
+        {
+            UChar32  c = scanNamedChar();
+            if (U_SUCCESS(*fStatus) && fLastSetLiteral > c) {
+                error(U_REGEX_INVALID_RANGE);
+            }
+            UnicodeSet *s = (UnicodeSet *)fSetStack.peek();
+            s->add(fLastSetLiteral, c);
+            fLastSetLiteral = c;
+            break;
+        }
+
+
+    case  doSetNegate:
+        // Scanned a '^' at the start of a set.
+        // Push the negation operator onto the set op stack.
+        // A twist for case-insensitive matching:
+        //   the case closure operation must happen _before_ negation.
+        //   But the case closure operation will already be on the stack if it's required.
+        //   This requires checking for case closure, and swapping the stack order
+        //    if it is present.
+        {
+            int32_t  tosOp = fSetOpStack.peeki();
+            if (tosOp == setCaseClose) {
+                fSetOpStack.popi();
+                fSetOpStack.push(setNegation, *fStatus);
+                fSetOpStack.push(setCaseClose, *fStatus);
+            } else {
+                fSetOpStack.push(setNegation, *fStatus);
+            }
+        }
+        break;
+
+    case doSetNoCloseError:
+        error(U_REGEX_MISSING_CLOSE_BRACKET);
+        break;
+
+    case doSetOpError:
+        error(U_REGEX_RULE_SYNTAX);   //  -- or && at the end of a set.  Illegal.
+        break;
+
+    case doSetPosixProp:
+        {
+            UnicodeSet *s = scanPosixProp();
+            if (s != NULL) {
+                UnicodeSet *tos = (UnicodeSet *)fSetStack.peek();
+                tos->addAll(*s);
+                delete s;
+            }  // else error.  scanProp() reported the error status already.
+        }
+        break;
+        
+    case doSetProp:
+        //  Scanned a \p \P within [brackets].
+        {
+            UnicodeSet *s = scanProp();
+            if (s != NULL) {
+                UnicodeSet *tos = (UnicodeSet *)fSetStack.peek();
+                tos->addAll(*s);
+                delete s;
+            }  // else error.  scanProp() reported the error status already.
+        }
+        break;
+
+
+    case doSetRange:
+        // We have scanned literal-literal.  Add the range to the set.
+        // The left character is already in the set, and is saved in fLastSetLiteral.
+        // The right side is the current character.
+        // Lower Limit > Upper limit being an error matches both Java
+        //        and ICU UnicodeSet behavior.
+        {
+        if (fLastSetLiteral > fC.fChar) {
+            error(U_REGEX_INVALID_RANGE);  
+        }
+        UnicodeSet *s = (UnicodeSet *)fSetStack.peek();
+        s->add(fLastSetLiteral, fC.fChar);
+        break;
+        }
+
+
+    default:
+        U_ASSERT(FALSE);
+        error(U_REGEX_INTERNAL_ERROR);
+        break;
+    }
+
+    if (U_FAILURE(*fStatus)) {
+        returnVal = FALSE;
+    }
+
+    return returnVal;
+}
+
+
+
+//------------------------------------------------------------------------------
+//
+//   literalChar           We've encountered a literal character from the pattern,
+//                             or an escape sequence that reduces to a character.
+//                         Add it to the string containing all literal chars/strings from
+//                             the pattern.
+//                         If we are in a pattern string already, add the new char to it.
+//                         If we aren't in a pattern string, begin one now.
+//
+//------------------------------------------------------------------------------
+void RegexCompile::literalChar(UChar32 c)  {
+    int32_t           op;            // An operation in the compiled pattern.
+    int32_t           opType;
+    int32_t           patternLoc;   // A position in the compiled pattern.
+    int32_t           stringLen;
+
+
+    // If the last thing compiled into the pattern was not a literal char,
+    //   force this new literal char to begin a new string, and not append to the previous.
+    op     = (int32_t)fRXPat->fCompiledPat->lastElementi();
+    opType = URX_TYPE(op);
+    if (!(opType == URX_STRING_LEN || opType == URX_ONECHAR || opType == URX_ONECHAR_I)) {
+        fixLiterals();
+    }
+
+    if (fStringOpStart == -1) {
+        // First char of a string in the pattern.
+        // Emit a OneChar op into the compiled pattern.
+        emitONE_CHAR(c);
+        
+        // Mark that we might actually be starting a string here
+        fStringOpStart = fRXPat->fLiteralText.length();
+        return;
+    }
+
+    op     = (int32_t)fRXPat->fCompiledPat->lastElementi();
+    opType = URX_TYPE(op);
+    U_ASSERT(opType == URX_ONECHAR || opType == URX_ONECHAR_I || opType == URX_STRING_LEN);
+
+    // If the most recently emitted op is a URX_ONECHAR,
+    if (opType == URX_ONECHAR || opType == URX_ONECHAR_I) {
+        if (U16_IS_TRAIL(c) && U16_IS_LEAD(URX_VAL(op))) {
+            // The most recently emitted op is a ONECHAR that was the first half
+            //   of a surrogate pair.  Update the ONECHAR's operand to be the
+            //   supplementary code point resulting from both halves of the pair.
+            c = U16_GET_SUPPLEMENTARY(URX_VAL(op), c);
+            op = URX_BUILD(opType, c);
+            patternLoc = fRXPat->fCompiledPat->size() - 1;
+            fRXPat->fCompiledPat->setElementAt(op, patternLoc);
+            return;
+        }
+        
+        // The most recently emitted op is a ONECHAR.
+        //  We've now received another adjacent char.  Change the ONECHAR op
+        //   to a string op.
+        fRXPat->fLiteralText.append(URX_VAL(op));
+
+        if (fModeFlags & UREGEX_CASE_INSENSITIVE) {
+            op     = URX_BUILD(URX_STRING_I, fStringOpStart);
+        } else {
+            op     = URX_BUILD(URX_STRING, fStringOpStart);
+        }
+        patternLoc = fRXPat->fCompiledPat->size() - 1;
+        fRXPat->fCompiledPat->setElementAt(op, patternLoc);
+        op         = URX_BUILD(URX_STRING_LEN, 0);
+        fRXPat->fCompiledPat->addElement(op, *fStatus);
+    }
+    
+    // We are adding onto an existing string
+    fRXPat->fLiteralText.append(c);
+    
+    // The pattern contains a URX_SRING / URX_STRING_LEN.  Update the
+    //  string length to reflect the new char we just added to the string.
+    stringLen  = fRXPat->fLiteralText.length() - fStringOpStart;
+    op         = URX_BUILD(URX_STRING_LEN, stringLen);
+    patternLoc = fRXPat->fCompiledPat->size() - 1;
+    fRXPat->fCompiledPat->setElementAt(op, patternLoc);
+}
+
+
+
+//------------------------------------------------------------------------------
+//
+//    emitONE_CHAR         emit a ONE_CHAR op into the generated code.
+//                         Choose cased or uncased version, depending on the
+//                         match mode and whether the character itself is cased.
+//
+//------------------------------------------------------------------------------
+void RegexCompile::emitONE_CHAR(UChar32  c) {
+    int32_t op;
+    if ((fModeFlags & UREGEX_CASE_INSENSITIVE) &&
+        u_hasBinaryProperty(c, UCHAR_CASE_SENSITIVE)) {
+        // We have a cased character, and are in case insensitive matching mode.
+        //c  = u_foldCase(c, U_FOLD_CASE_DEFAULT);  // !!!: handled in stripNOPs() now
+        op = URX_BUILD(URX_ONECHAR_I, c);
+    } else {
+        // Uncased char, or case sensitive match mode.
+        //  Either way, just generate a literal compare of the char.
+        op = URX_BUILD(URX_ONECHAR, c);
+    }
+    fRXPat->fCompiledPat->addElement(op, *fStatus);
+}
+
+
+//------------------------------------------------------------------------------
+//
+//    fixLiterals           When compiling something that can follow a literal
+//                          string in a pattern, we need to "fix" any preceding
+//                          string, which will cause any subsequent literals to
+//                          begin a new string, rather than appending to the
+//                          old one.
+//
+//                          Optionally, split the last char of the string off into
+//                          a single "ONE_CHAR" operation, so that quantifiers can
+//                          apply to that char alone.  Example:   abc*
+//                          The * must apply to the 'c' only.
+//
+//------------------------------------------------------------------------------
+void    RegexCompile::fixLiterals(UBool split) {
+    int32_t  stringStart = fStringOpStart;    // start index of the current literal string
+    int32_t  op;                              // An op from/for the compiled pattern.
+    int32_t  opType;                          // An opcode type from the compiled pattern.
+    int32_t  stringLastCharIdx;
+    UChar32  lastChar;
+    int32_t  stringNextToLastCharIdx;
+    UChar32  nextToLastChar;
+    int32_t  stringLen;
+
+    fStringOpStart = -1;
+    if (!split) {
+        return;
+    }
+
+    // Split:  We need to  ensure that the last item in the compiled pattern does
+    //   not refer to a literal string of more than one char.  If it does,
+    //   separate the last char from the rest of the string.
+
+    // If the last operation from the compiled pattern is not a string,
+    //   nothing needs to be done
+    op     = (int32_t)fRXPat->fCompiledPat->lastElementi();
+    opType = URX_TYPE(op);
+    if (opType != URX_STRING_LEN) {
+        return;
+    }
+    stringLen = URX_VAL(op);
+
+    //
+    // Find the position of the last code point in the string  (might be a surrogate pair)
+    //
+    stringLastCharIdx = fRXPat->fLiteralText.length();
+    stringLastCharIdx = fRXPat->fLiteralText.moveIndex32(stringLastCharIdx, -1);
+    lastChar          = fRXPat->fLiteralText.char32At(stringLastCharIdx);
+
+    // The string should always be at least two code points long, meaning that there
+    //   should be something before the last char position that we just found.
+    U_ASSERT(stringLastCharIdx > stringStart);
+    stringNextToLastCharIdx = fRXPat->fLiteralText.moveIndex32(stringLastCharIdx, -1);
+    U_ASSERT(stringNextToLastCharIdx >= stringStart);
+    nextToLastChar          = fRXPat->fLiteralText.char32At(stringNextToLastCharIdx);
+
+    if (stringNextToLastCharIdx > stringStart) {
+        // The length of string remaining after removing one char is two or more.
+        // Leave the string in the compiled pattern, shorten it by one char,
+        //   and append a URX_ONECHAR op for the last char.
+        stringLen -= (fRXPat->fLiteralText.length() - stringLastCharIdx);
+        op = URX_BUILD(URX_STRING_LEN, stringLen);
+        fRXPat->fCompiledPat->setElementAt(op, fRXPat->fCompiledPat->size() -1);
+        emitONE_CHAR(lastChar);
+    } else {
+        // The original string consisted of exactly two characters.  Replace
+        // the existing compiled URX_STRING/URX_STRING_LEN ops with a pair
+        // of URX_ONECHARs.
+        fRXPat->fCompiledPat->setSize(fRXPat->fCompiledPat->size() -2);
+        emitONE_CHAR(nextToLastChar);
+        emitONE_CHAR(lastChar);
+    }
+}
+
+
+
+
+
+
+//------------------------------------------------------------------------------
+//
+//   insertOp()             Insert a slot for a new opcode into the already
+//                          compiled pattern code.
+//
+//                          Fill the slot with a NOP.  Our caller will replace it
+//                          with what they really wanted.
+//
+//------------------------------------------------------------------------------
+void   RegexCompile::insertOp(int32_t where) {
+    UVector64 *code = fRXPat->fCompiledPat;
+    U_ASSERT(where>0 && where < code->size());
+
+    int32_t  nop = URX_BUILD(URX_NOP, 0);
+    code->insertElementAt(nop, where, *fStatus);
+
+    // Walk through the pattern, looking for any ops with targets that
+    //  were moved down by the insert.  Fix them.
+    int32_t loc;
+    for (loc=0; loc<code->size(); loc++) {
+        int32_t op = (int32_t)code->elementAti(loc);
+        int32_t opType = URX_TYPE(op);
+        int32_t opValue = URX_VAL(op);
+        if ((opType == URX_JMP         ||
+            opType == URX_JMPX         ||
+            opType == URX_STATE_SAVE   ||
+            opType == URX_CTR_LOOP     ||
+            opType == URX_CTR_LOOP_NG  ||
+            opType == URX_JMP_SAV      ||
+            opType == URX_RELOC_OPRND)    && opValue > where) {
+            // Target location for this opcode is after the insertion point and
+            //   needs to be incremented to adjust for the insertion.
+            opValue++;
+            op = URX_BUILD(opType, opValue);
+            code->setElementAt(op, loc);
+        }
+    }
+
+    // Now fix up the parentheses stack.  All positive values in it are locations in
+    //  the compiled pattern.   (Negative values are frame boundaries, and don't need fixing.)
+    for (loc=0; loc<fParenStack.size(); loc++) {
+        int32_t x = fParenStack.elementAti(loc);
+        U_ASSERT(x < code->size());
+        if (x>where) {
+            x++;
+            fParenStack.setElementAt(x, loc);
+        }
+    }
+
+    if (fMatchCloseParen > where) {
+        fMatchCloseParen++;
+    }
+    if (fMatchOpenParen > where) {
+        fMatchOpenParen++;
+    }
+}
+
+
+
+//------------------------------------------------------------------------------
+//
+//   blockTopLoc()          Find or create a location in the compiled pattern
+//                          at the start of the operation or block that has
+//                          just been compiled.  Needed when a quantifier (* or
+//                          whatever) appears, and we need to add an operation
+//                          at the start of the thing being quantified.
+//
+//                          (Parenthesized Blocks) have a slot with a NOP that
+//                          is reserved for this purpose.  .* or similar don't
+//                          and a slot needs to be added.
+//
+//       parameter reserveLoc   :  TRUE -  ensure that there is space to add an opcode
+//                                         at the returned location.
+//                                 FALSE - just return the address,
+//                                         do not reserve a location there.
+//
+//------------------------------------------------------------------------------
+int32_t   RegexCompile::blockTopLoc(UBool reserveLoc) {
+    int32_t   theLoc;
+    if (fRXPat->fCompiledPat->size() == fMatchCloseParen)
+    {
+        // The item just processed is a parenthesized block.
+        theLoc = fMatchOpenParen;   // A slot is already reserved for us.
+        U_ASSERT(theLoc > 0);
+        U_ASSERT(URX_TYPE(((uint32_t)fRXPat->fCompiledPat->elementAti(theLoc))) == URX_NOP);
+    }
+    else {
+        // Item just compiled is a single thing, a ".", or a single char, or a set reference.
+        // No slot for STATE_SAVE was pre-reserved in the compiled code.
+        // We need to make space now.
+        fixLiterals(TRUE);  // If last item was a string, separate the last char.
+        theLoc = fRXPat->fCompiledPat->size()-1;
+        if (reserveLoc) {
+            /*int32_t opAtTheLoc = fRXPat->fCompiledPat->elementAti(theLoc);*/
+            int32_t  nop = URX_BUILD(URX_NOP, 0);
+            fRXPat->fCompiledPat->insertElementAt(nop, theLoc, *fStatus);
+        }
+    }
+    return theLoc;
+}
+
+
+
+//------------------------------------------------------------------------------
+//
+//    handleCloseParen      When compiling a close paren, we need to go back
+//                          and fix up any JMP or SAVE operations within the
+//                          parenthesized block that need to target the end
+//                          of the block.  The locations of these are kept on
+//                          the paretheses stack.
+//
+//                          This function is called both when encountering a
+//                          real ) and at the end of the pattern.
+//
+//------------------------------------------------------------------------------
+void  RegexCompile::handleCloseParen() {
+    int32_t   patIdx;
+    int32_t   patOp;
+    if (fParenStack.size() <= 0) {
+        error(U_REGEX_MISMATCHED_PAREN);
+        return;
+    }
+
+    // Force any literal chars that may follow the close paren to start a new string,
+    //   and not attach to any preceding it.
+    fixLiterals(FALSE);
+
+    // Fixup any operations within the just-closed parenthesized group
+    //    that need to reference the end of the (block).
+    //    (The first one popped from the stack is an unused slot for
+    //     alternation (OR) state save, but applying the fixup to it does no harm.)
+    for (;;) {
+        patIdx = fParenStack.popi();
+        if (patIdx < 0) {
+            // value < 0 flags the start of the frame on the paren stack.
+            break;
+        }
+        U_ASSERT(patIdx>0 && patIdx <= fRXPat->fCompiledPat->size());
+        patOp = (int32_t)fRXPat->fCompiledPat->elementAti(patIdx);
+        U_ASSERT(URX_VAL(patOp) == 0);          // Branch target for JMP should not be set.
+        patOp |= fRXPat->fCompiledPat->size();  // Set it now.
+        fRXPat->fCompiledPat->setElementAt(patOp, patIdx);
+        fMatchOpenParen     = patIdx;
+    }
+
+    //  At the close of any parenthesized block, restore the match mode flags  to
+    //  the value they had at the open paren.  Saved value is
+    //  at the top of the paren stack.
+    fModeFlags = fParenStack.popi();
+    U_ASSERT(fModeFlags < 0);
+
+    // DO any additional fixups, depending on the specific kind of
+    // parentesized grouping this is
+
+    switch (patIdx) {
+    case plain:
+    case flags:
+        // No additional fixups required.
+        //   (Grouping-only parentheses)
+        break;
+    case capturing:
+        // Capturing Parentheses.
+        //   Insert a End Capture op into the pattern.
+        //   The frame offset of the variables for this cg is obtained from the
+        //       start capture op and put it into the end-capture op.
+        {
+            int32_t   captureOp = (int32_t)fRXPat->fCompiledPat->elementAti(fMatchOpenParen+1);
+            U_ASSERT(URX_TYPE(captureOp) == URX_START_CAPTURE);
+
+            int32_t   frameVarLocation = URX_VAL(captureOp);
+            int32_t   endCaptureOp = URX_BUILD(URX_END_CAPTURE, frameVarLocation);
+            fRXPat->fCompiledPat->addElement(endCaptureOp, *fStatus);
+        }
+        break;
+    case atomic:
+        // Atomic Parenthesis.
+        //   Insert a LD_SP operation to restore the state stack to the position
+        //   it was when the atomic parens were entered.
+        {
+            int32_t   stoOp = (int32_t)fRXPat->fCompiledPat->elementAti(fMatchOpenParen+1);
+            U_ASSERT(URX_TYPE(stoOp) == URX_STO_SP);
+            int32_t   stoLoc = URX_VAL(stoOp);
+            int32_t   ldOp   = URX_BUILD(URX_LD_SP, stoLoc);
+            fRXPat->fCompiledPat->addElement(ldOp, *fStatus);
+        }
+        break;
+
+    case lookAhead:
+        {
+            int32_t  startOp = (int32_t)fRXPat->fCompiledPat->elementAti(fMatchOpenParen-5);
+            U_ASSERT(URX_TYPE(startOp) == URX_LA_START);
+            int32_t dataLoc  = URX_VAL(startOp);
+            int32_t op       = URX_BUILD(URX_LA_END, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+        }
+        break;
+
+    case negLookAhead:
+        {
+            // See comment at doOpenLookAheadNeg
+            int32_t  startOp = (int32_t)fRXPat->fCompiledPat->elementAti(fMatchOpenParen-1);
+            U_ASSERT(URX_TYPE(startOp) == URX_LA_START);
+            int32_t dataLoc  = URX_VAL(startOp);
+            int32_t op       = URX_BUILD(URX_LA_END, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+            op               = URX_BUILD(URX_BACKTRACK, 0);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+            op               = URX_BUILD(URX_LA_END, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // Patch the URX_SAVE near the top of the block.
+            // The destination of the SAVE is the final LA_END that was just added.
+            int32_t saveOp   = (int32_t)fRXPat->fCompiledPat->elementAti(fMatchOpenParen);
+            U_ASSERT(URX_TYPE(saveOp) == URX_STATE_SAVE);
+            int32_t dest     = fRXPat->fCompiledPat->size()-1;
+            saveOp           = URX_BUILD(URX_STATE_SAVE, dest);
+            fRXPat->fCompiledPat->setElementAt(saveOp, fMatchOpenParen);
+        }
+        break;
+
+    case lookBehind:
+        {
+            // See comment at doOpenLookBehind.
+
+            // Append the URX_LB_END and URX_LA_END to the compiled pattern.
+            int32_t  startOp = (int32_t)fRXPat->fCompiledPat->elementAti(fMatchOpenParen-4);
+            U_ASSERT(URX_TYPE(startOp) == URX_LB_START);
+            int32_t dataLoc  = URX_VAL(startOp);
+            int32_t op       = URX_BUILD(URX_LB_END, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+                    op       = URX_BUILD(URX_LA_END, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // Determine the min and max bounds for the length of the
+            //  string that the pattern can match.
+            //  An unbounded upper limit is an error.
+            int32_t patEnd   = fRXPat->fCompiledPat->size() - 1;
+            int32_t minML    = minMatchLength(fMatchOpenParen, patEnd);
+            int32_t maxML    = maxMatchLength(fMatchOpenParen, patEnd);
+            if (maxML == INT32_MAX) {
+                error(U_REGEX_LOOK_BEHIND_LIMIT);
+                break;
+            }
+            U_ASSERT(minML <= maxML);
+
+            // Insert the min and max match len bounds into the URX_LB_CONT op that
+            //  appears at the top of the look-behind block, at location fMatchOpenParen+1
+            fRXPat->fCompiledPat->setElementAt(minML,  fMatchOpenParen-2);
+            fRXPat->fCompiledPat->setElementAt(maxML,  fMatchOpenParen-1);
+
+        }
+        break;
+
+
+
+    case lookBehindN:
+        {
+            // See comment at doOpenLookBehindNeg.
+
+            // Append the URX_LBN_END to the compiled pattern.
+            int32_t  startOp = (int32_t)fRXPat->fCompiledPat->elementAti(fMatchOpenParen-5);
+            U_ASSERT(URX_TYPE(startOp) == URX_LB_START);
+            int32_t dataLoc  = URX_VAL(startOp);
+            int32_t op       = URX_BUILD(URX_LBN_END, dataLoc);
+            fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+            // Determine the min and max bounds for the length of the
+            //  string that the pattern can match.
+            //  An unbounded upper limit is an error.
+            int32_t patEnd   = fRXPat->fCompiledPat->size() - 1;
+            int32_t minML    = minMatchLength(fMatchOpenParen, patEnd);
+            int32_t maxML    = maxMatchLength(fMatchOpenParen, patEnd);
+            if (maxML == INT32_MAX) {
+                error(U_REGEX_LOOK_BEHIND_LIMIT);
+                break;
+            }
+            U_ASSERT(minML <= maxML);
+
+            // Insert the min and max match len bounds into the URX_LB_CONT op that
+            //  appears at the top of the look-behind block, at location fMatchOpenParen+1
+            fRXPat->fCompiledPat->setElementAt(minML,  fMatchOpenParen-3);
+            fRXPat->fCompiledPat->setElementAt(maxML,  fMatchOpenParen-2);
+
+            // Insert the pattern location to continue at after a successful match
+            //  as the last operand of the URX_LBN_CONT
+            op = URX_BUILD(URX_RELOC_OPRND, fRXPat->fCompiledPat->size());
+            fRXPat->fCompiledPat->setElementAt(op,  fMatchOpenParen-1);
+        }
+        break;
+
+
+
+    default:
+        U_ASSERT(FALSE);
+    }
+
+    // remember the next location in the compiled pattern.
+    // The compilation of Quantifiers will look at this to see whether its looping
+    //   over a parenthesized block or a single item
+    fMatchCloseParen = fRXPat->fCompiledPat->size();
+}
+
+
+
+//------------------------------------------------------------------------------
+//
+//   compileSet       Compile the pattern operations for a reference to a
+//                    UnicodeSet.
+//
+//------------------------------------------------------------------------------
+void        RegexCompile::compileSet(UnicodeSet *theSet)
+{
+    if (theSet == NULL) {
+        return;
+    }
+    //  Remove any strings from the set.
+    //  There shoudn't be any, but just in case.
+    //     (Case Closure can add them; if we had a simple case closure avaialble that
+    //      ignored strings, that would be better.)
+    theSet->removeAllStrings();
+    int32_t  setSize = theSet->size();
+
+    switch (setSize) {
+    case 0:
+        {
+            // Set of no elements.   Always fails to match.
+            fRXPat->fCompiledPat->addElement(URX_BUILD(URX_BACKTRACK, 0), *fStatus);
+            delete theSet;
+        }
+        break;
+
+    case 1:
+        {
+            // The set contains only a single code point.  Put it into
+            //   the compiled pattern as a single char operation rather
+            //   than a set, and discard the set itself.
+            literalChar(theSet->charAt(0));
+            delete theSet;
+        }
+        break;
+
+    default:
+        {
+            //  The set contains two or more chars.  (the normal case)
+            //  Put it into the compiled pattern as a set.
+            int32_t setNumber = fRXPat->fSets->size();
+            fRXPat->fSets->addElement(theSet, *fStatus);
+            int32_t setOp = URX_BUILD(URX_SETREF, setNumber);
+            fRXPat->fCompiledPat->addElement(setOp, *fStatus);
+        }
+    }
+}
+
+
+//------------------------------------------------------------------------------
+//
+//   compileInterval    Generate the code for a {min, max} style interval quantifier.
+//                      Except for the specific opcodes used, the code is the same
+//                      for all three types (greedy, non-greedy, possessive) of
+//                      intervals.  The opcodes are supplied as parameters.
+//
+//                      The code for interval loops has this form:
+//                         0  CTR_INIT   counter loc (in stack frame)
+//                         1             5  patt address of CTR_LOOP at bottom of block
+//                         2             min count
+//                         3             max count   (-1 for unbounded)
+//                         4  ...        block to be iterated over
+//                         5  CTR_LOOP
+//
+//                       In
+//------------------------------------------------------------------------------
+void        RegexCompile::compileInterval(int32_t InitOp,  int32_t LoopOp)
+{
+    // The CTR_INIT op at the top of the block with the {n,m} quantifier takes
+    //   four slots in the compiled code.  Reserve them.
+    int32_t   topOfBlock = blockTopLoc(TRUE);
+    insertOp(topOfBlock);
+    insertOp(topOfBlock);
+    insertOp(topOfBlock);
+
+    // The operands for the CTR_INIT opcode include the index in the matcher data
+    //   of the counter.  Allocate it now.
+    int32_t   counterLoc = fRXPat->fFrameSize;
+    fRXPat->fFrameSize++;
+
+    int32_t   op = URX_BUILD(InitOp, counterLoc);
+    fRXPat->fCompiledPat->setElementAt(op, topOfBlock);
+
+    // The second operand of CTR_INIT is the location following the end of the loop.
+    //   Must put in as a URX_RELOC_OPRND so that the value will be adjusted if the
+    //   compilation of something later on causes the code to grow and the target
+    //   position to move.
+    int32_t loopEnd = fRXPat->fCompiledPat->size();
+    op = URX_BUILD(URX_RELOC_OPRND, loopEnd);
+    fRXPat->fCompiledPat->setElementAt(op, topOfBlock+1);
+
+    // Followed by the min and max counts.
+    fRXPat->fCompiledPat->setElementAt(fIntervalLow, topOfBlock+2);
+    fRXPat->fCompiledPat->setElementAt(fIntervalUpper, topOfBlock+3);
+
+    // Apend the CTR_LOOP op.  The operand is the location of the CTR_INIT op.
+    //   Goes at end of the block being looped over, so just append to the code so far.
+    op = URX_BUILD(LoopOp, topOfBlock);
+    fRXPat->fCompiledPat->addElement(op, *fStatus);
+
+    if ((fIntervalLow & 0xff000000) != 0 ||
+        (fIntervalUpper > 0 && (fIntervalUpper & 0xff000000) != 0)) {
+            error(U_REGEX_NUMBER_TOO_BIG);
+        }
+
+    if (fIntervalLow > fIntervalUpper && fIntervalUpper != -1) {
+        error(U_REGEX_MAX_LT_MIN);
+    }
+}
+
+
+
+UBool RegexCompile::compileInlineInterval() {
+    if (fIntervalUpper > 10 || fIntervalUpper < fIntervalLow) {
+        // Too big to inline.  Fail, which will cause looping code to be generated.
+        //   (Upper < Lower picks up unbounded upper and errors, both.)
+        return FALSE;
+    }
+
+    int32_t   topOfBlock = blockTopLoc(FALSE);
+    if (fIntervalUpper == 0) {
+        // Pathological case.  Attempt no matches, as if the block doesn't exist.
+        fRXPat->fCompiledPat->setSize(topOfBlock);
+        return TRUE;
+    }
+
+    if (topOfBlock != fRXPat->fCompiledPat->size()-1 && fIntervalUpper != 1) {
+        // The thing being repeated is not a single op, but some
+        //   more complex block.  Do it as a loop, not inlines.
+        //   Note that things "repeated" a max of once are handled as inline, because
+        //     the one copy of the code already generated is just fine.
+        return FALSE;
+    }
+
+    // Pick up the opcode that is to be repeated
+    //
+    int32_t op = (int32_t)fRXPat->fCompiledPat->elementAti(topOfBlock);
+
+    // Compute the pattern location where the inline sequence
+    //   will end, and set up the state save op that will be needed.
+    //
+    int32_t endOfSequenceLoc = fRXPat->fCompiledPat->size()-1
+                                + fIntervalUpper + (fIntervalUpper-fIntervalLow);
+    int32_t saveOp = URX_BUILD(URX_STATE_SAVE, endOfSequenceLoc);
+    if (fIntervalLow == 0) {
+        insertOp(topOfBlock);
+        fRXPat->fCompiledPat->setElementAt(saveOp, topOfBlock);
+    }
+
+
+
+    //  Loop, emitting the op for the thing being repeated each time.
+    //    Loop starts at 1 because one instance of the op already exists in the pattern,
+    //    it was put there when it was originally encountered.
+    int32_t i;
+    for (i=1; i<fIntervalUpper; i++ ) {
+        if (i == fIntervalLow) {
+            fRXPat->fCompiledPat->addElement(saveOp, *fStatus);
+        }
+        if (i > fIntervalLow) {
+            fRXPat->fCompiledPat->addElement(saveOp, *fStatus);
+        }
+        fRXPat->fCompiledPat->addElement(op, *fStatus);
+    }
+    return TRUE;
+}
+
+
+
+//------------------------------------------------------------------------------
+//
+//   matchStartType    Determine how a match can start.
+//                     Used to optimize find() operations.
+//
+//                     Operation is very similar to minMatchLength().  Walk the compiled
+//                     pattern, keeping an on-going minimum-match-length.  For any
+//                     op where the min match coming in is zero, add that ops possible
+//                     starting matches to the possible starts for the overall pattern.
+//
+//------------------------------------------------------------------------------
+void   RegexCompile::matchStartType() {
+    if (U_FAILURE(*fStatus)) {
+        return;
+    }
+
+
+    int32_t    loc;                    // Location in the pattern of the current op being processed.
+    int32_t    op;                     // The op being processed
+    int32_t    opType;                 // The opcode type of the op
+    int32_t    currentLen = 0;         // Minimum length of a match to this point (loc) in the pattern
+    int32_t    numInitialStrings = 0;  // Number of strings encountered that could match at start.
+
+    UBool      atStart = TRUE;         // True if no part of the pattern yet encountered
+                                       //   could have advanced the position in a match.
+                                       //   (Maximum match length so far == 0)
+
+    // forwardedLength is a vector holding minimum-match-length values that
+    //   are propagated forward in the pattern by JMP or STATE_SAVE operations.
+    //   It must be one longer than the pattern being checked because some  ops
+    //   will jmp to a end-of-block+1 location from within a block, and we must
+    //   count those when checking the block.
+    int32_t end = fRXPat->fCompiledPat->size();
+    UVector32  forwardedLength(end+1, *fStatus);
+    forwardedLength.setSize(end+1);
+    for (loc=3; loc<end; loc++) {
+        forwardedLength.setElementAt(INT32_MAX, loc);
+    }
+
+    for (loc = 3; loc<end; loc++) {
+        op = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+        opType = URX_TYPE(op);
+
+        // The loop is advancing linearly through the pattern.
+        // If the op we are now at was the destination of a branch in the pattern,
+        // and that path has a shorter minimum length than the current accumulated value,
+        // replace the current accumulated value.
+        if (forwardedLength.elementAti(loc) < currentLen) {
+            currentLen = forwardedLength.elementAti(loc);
+            U_ASSERT(currentLen>=0 && currentLen < INT32_MAX);
+        }
+
+        switch (opType) {
+            // Ops that don't change the total length matched
+        case URX_RESERVED_OP:
+        case URX_END:
+        case URX_FAIL:
+        case URX_STRING_LEN:
+        case URX_NOP:
+        case URX_START_CAPTURE:
+        case URX_END_CAPTURE:
+        case URX_BACKSLASH_B:
+        case URX_BACKSLASH_BU:
+        case URX_BACKSLASH_G:
+        case URX_BACKSLASH_Z:
+        case URX_DOLLAR:
+        case URX_DOLLAR_M:
+        case URX_DOLLAR_D:
+        case URX_DOLLAR_MD:
+        case URX_RELOC_OPRND:
+        case URX_STO_INP_LOC:
+        case URX_BACKREF:         // BackRef.  Must assume that it might be a zero length match
+        case URX_BACKREF_I:
+                
+        case URX_STO_SP:          // Setup for atomic or possessive blocks.  Doesn't change what can match.
+        case URX_LD_SP:
+            break;
+
+        case URX_CARET:
+            if (atStart) {
+                fRXPat->fStartType = START_START;
+            }
+            break;
+
+        case URX_CARET_M:
+        case URX_CARET_M_UNIX:
+            if (atStart) {
+                fRXPat->fStartType = START_LINE;
+            }
+            break;
+
+        case URX_ONECHAR:
+            if (currentLen == 0) {
+                // This character could appear at the start of a match.
+                //   Add it to the set of possible starting characters.
+                fRXPat->fInitialChars->add(URX_VAL(op));
+                numInitialStrings += 2;
+            }
+            currentLen++;
+            atStart = FALSE;
+            break;
+
+
+        case URX_SETREF:
+            if (currentLen == 0) {
+                int32_t  sn = URX_VAL(op);
+                U_ASSERT(sn > 0 && sn < fRXPat->fSets->size());
+                const UnicodeSet *s = (UnicodeSet *)fRXPat->fSets->elementAt(sn);
+                fRXPat->fInitialChars->addAll(*s);
+                numInitialStrings += 2;
+            }
+            currentLen++;
+            atStart = FALSE;
+            break;
+
+        case URX_LOOP_SR_I:
+            // [Set]*, like a SETREF, above, in what it can match,
+            //  but may not match at all, so currentLen is not incremented.
+            if (currentLen == 0) {
+                int32_t  sn = URX_VAL(op);
+                U_ASSERT(sn > 0 && sn < fRXPat->fSets->size());
+                const UnicodeSet *s = (UnicodeSet *)fRXPat->fSets->elementAt(sn);
+                fRXPat->fInitialChars->addAll(*s);
+                numInitialStrings += 2;
+            }
+            atStart = FALSE;
+            break;
+
+        case URX_LOOP_DOT_I:
+            if (currentLen == 0) {
+                // .* at the start of a pattern.
+                //    Any character can begin the match.
+                fRXPat->fInitialChars->clear();
+                fRXPat->fInitialChars->complement();
+                numInitialStrings += 2;
+            }
+            atStart = FALSE;
+            break;
+
+
+        case URX_STATIC_SETREF:
+            if (currentLen == 0) {
+                int32_t  sn = URX_VAL(op);
+                U_ASSERT(sn>0 && sn<URX_LAST_SET);
+                const UnicodeSet *s = fRXPat->fStaticSets[sn];
+                fRXPat->fInitialChars->addAll(*s);
+                numInitialStrings += 2;
+            }
+            currentLen++;
+            atStart = FALSE;
+            break;
+
+
+
+        case URX_STAT_SETREF_N:
+            if (currentLen == 0) {
+                int32_t  sn = URX_VAL(op);
+                const UnicodeSet *s = fRXPat->fStaticSets[sn];
+                UnicodeSet sc(*s);
+                sc.complement();
+                fRXPat->fInitialChars->addAll(sc);
+                numInitialStrings += 2;
+            }
+            currentLen++;
+            atStart = FALSE;
+            break;
+
+
+
+        case URX_BACKSLASH_D:
+            // Digit Char
+             if (currentLen == 0) {
+                 UnicodeSet s;
+                 s.applyIntPropertyValue(UCHAR_GENERAL_CATEGORY_MASK, U_GC_ND_MASK, *fStatus);
+                 if (URX_VAL(op) != 0) {
+                     s.complement();
+                 }
+                 fRXPat->fInitialChars->addAll(s);
+                 numInitialStrings += 2;
+            }
+            currentLen++;
+            atStart = FALSE;
+            break;
+
+
+        case URX_ONECHAR_I:
+            // Case Insensitive Single Character.
+            if (currentLen == 0) {
+                UChar32  c = URX_VAL(op);
+                if (u_hasBinaryProperty(c, UCHAR_CASE_SENSITIVE)) {
+                    // character may have distinct cased forms.  Add all of them
+                    //   to the set of possible starting match chars.
+                    UnicodeSet s(c, c);
+                    s.closeOver(USET_CASE_INSENSITIVE);
+                    fRXPat->fInitialChars->addAll(s);
+                } else {
+                    // Char has no case variants.  Just add it as-is to the
+                    //   set of possible starting chars.
+                    fRXPat->fInitialChars->add(c);
+                }
+                numInitialStrings += 2;
+            }
+            currentLen++;
+            atStart = FALSE;
+            break;
+
+
+        case URX_BACKSLASH_X:   // Grahpeme Cluster.  Minimum is 1, max unbounded.
+        case URX_DOTANY_ALL:    // . matches one or two.
+        case URX_DOTANY:
+        case URX_DOTANY_UNIX:
+            if (currentLen == 0) {
+                // These constructs are all bad news when they appear at the start
+                //   of a match.  Any character can begin the match.
+                fRXPat->fInitialChars->clear();
+                fRXPat->fInitialChars->complement();
+                numInitialStrings += 2;
+            }
+            currentLen++;
+            atStart = FALSE;
+            break;
+
+
+        case URX_JMPX:
+            loc++;             // Except for extra operand on URX_JMPX, same as URX_JMP.
+        case URX_JMP:
+            {
+                int32_t  jmpDest = URX_VAL(op);
+                if (jmpDest < loc) {
+                    // Loop of some kind.  Can safely ignore, the worst that will happen
+                    //  is that we understate the true minimum length
+                    currentLen = forwardedLength.elementAti(loc+1);
+
+                } else {
+                    // Forward jump.  Propagate the current min length to the target loc of the jump.
+                    U_ASSERT(jmpDest <= end+1);
+                    if (forwardedLength.elementAti(jmpDest) > currentLen) {
+                        forwardedLength.setElementAt(currentLen, jmpDest);
+                    }
+                }
+            }
+            atStart = FALSE;
+            break;
+
+        case URX_JMP_SAV:
+        case URX_JMP_SAV_X:
+            // Combo of state save to the next loc, + jmp backwards.
+            //   Net effect on min. length computation is nothing.
+            atStart = FALSE;
+            break;
+
+        case URX_BACKTRACK:
+            // Fails are kind of like a branch, except that the min length was
+            //   propagated already, by the state save.
+            currentLen = forwardedLength.elementAti(loc+1);
+            atStart = FALSE;
+            break;
+
+
+        case URX_STATE_SAVE:
+            {
+                // State Save, for forward jumps, propagate the current minimum.
+                //             of the state save.
+                int32_t  jmpDest = URX_VAL(op);
+                if (jmpDest > loc) {
+                    if (currentLen < forwardedLength.elementAti(jmpDest)) {
+                        forwardedLength.setElementAt(currentLen, jmpDest);
+                    }
+                }
+            }
+            atStart = FALSE;
+            break;
+
+
+
+
+        case URX_STRING:
+            {
+                loc++;
+                int32_t stringLenOp = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+                int32_t stringLen   = URX_VAL(stringLenOp);
+                U_ASSERT(URX_TYPE(stringLenOp) == URX_STRING_LEN);
+                U_ASSERT(stringLenOp >= 2);
+                if (currentLen == 0) {
+                    // Add the starting character of this string to the set of possible starting
+                    //   characters for this pattern.
+                    int32_t stringStartIdx = URX_VAL(op);
+                    UChar32  c = fRXPat->fLiteralText.char32At(stringStartIdx);
+                    fRXPat->fInitialChars->add(c);
+
+                    // Remember this string.  After the entire pattern has been checked,
+                    //  if nothing else is identified that can start a match, we'll use it.
+                    numInitialStrings++;
+                    fRXPat->fInitialStringIdx = stringStartIdx;
+                    fRXPat->fInitialStringLen = stringLen;
+                }
+
+                currentLen += stringLen;
+                atStart = FALSE;
+            }
+            break;
+
+        case URX_STRING_I:
+            {
+                // Case-insensitive string.  Unlike exact-match strings, we won't
+                //   attempt a string search for possible match positions.  But we
+                //   do update the set of possible starting characters.
+                loc++;
+                int32_t stringLenOp = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+                int32_t stringLen   = URX_VAL(stringLenOp);
+                U_ASSERT(URX_TYPE(stringLenOp) == URX_STRING_LEN);
+                U_ASSERT(stringLenOp >= 2);
+                if (currentLen == 0) {
+                    // Add the starting character of this string to the set of possible starting
+                    //   characters for this pattern.
+                    int32_t stringStartIdx = URX_VAL(op);
+                    UChar32  c = fRXPat->fLiteralText.char32At(stringStartIdx);
+                    UnicodeSet s(c, c);
+                    s.closeOver(USET_CASE_INSENSITIVE);
+                    fRXPat->fInitialChars->addAll(s);
+                    numInitialStrings += 2;  // Matching on an initial string not possible.
+                }
+                currentLen += stringLen;
+                atStart = FALSE;
+            }
+            break;
+
+        case URX_CTR_INIT:
+        case URX_CTR_INIT_NG:
+            {
+                // Loop Init Ops.  These don't change the min length, but they are 4 word ops
+                //   so location must be updated accordingly.
+                // Loop Init Ops.
+                //   If the min loop count == 0
+                //      move loc forwards to the end of the loop, skipping over the body.
+                //   If the min count is > 0,
+                //      continue normal processing of the body of the loop.
+                int32_t loopEndLoc   = (int32_t)fRXPat->fCompiledPat->elementAti(loc+1);
+                        loopEndLoc   = URX_VAL(loopEndLoc);
+                int32_t minLoopCount = (int32_t)fRXPat->fCompiledPat->elementAti(loc+2);
+                if (minLoopCount == 0) {
+                    // Min Loop Count of 0, treat like a forward branch and
+                    //   move the current minimum length up to the target
+                    //   (end of loop) location.
+                    U_ASSERT(loopEndLoc <= end+1);
+                    if (forwardedLength.elementAti(loopEndLoc) > currentLen) {
+                        forwardedLength.setElementAt(currentLen, loopEndLoc);
+                    }
+                }
+                loc+=3;  // Skips over operands of CTR_INIT
+            }
+            atStart = FALSE;
+            break;
+
+
+        case URX_CTR_LOOP:
+        case URX_CTR_LOOP_NG:
+            // Loop ops.
+            //  The jump is conditional, backwards only.
+            atStart = FALSE;
+            break;
+
+        case URX_LOOP_C:
+            // More loop ops.  These state-save to themselves.
+            //   don't change the minimum match
+            atStart = FALSE;
+            break;
+
+
+        case URX_LA_START:
+        case URX_LB_START:
+            {
+                // Look-around.  Scan forward until the matching look-ahead end,
+                //   without processing the look-around block.  This is overly pessimistic.
+                
+                // Keep track of the nesting depth of look-around blocks.  Boilerplate code for
+                //   lookahead contains two LA_END instructions, so count goes up by two
+                //   for each LA_START.
+                int32_t  depth = (opType == URX_LA_START? 2: 1);
+                for (;;) {
+                    loc++;
+                    op = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+                    if (URX_TYPE(op) == URX_LA_START) {
+                        depth+=2;
+                    }
+                    if (URX_TYPE(op) == URX_LB_START) {
+                        depth++;
+                    }
+                    if (URX_TYPE(op) == URX_LA_END || URX_TYPE(op)==URX_LBN_END) {
+                        depth--;
+                        if (depth == 0) {
+                            break;
+                        }
+                    }
+                    if (URX_TYPE(op) == URX_STATE_SAVE) {
+                        // Need this because neg lookahead blocks will FAIL to outside
+                        //   of the block.
+                        int32_t  jmpDest = URX_VAL(op);
+                        if (jmpDest > loc) {
+                            if (currentLen < forwardedLength.elementAti(jmpDest)) {
+                                forwardedLength.setElementAt(currentLen, jmpDest);
+                            }
+                        }
+                    }
+                    U_ASSERT(loc <= end);
+                }
+            }
+            break;
+
+        case URX_LA_END:
+        case URX_LB_CONT:
+        case URX_LB_END:
+        case URX_LBN_CONT:
+        case URX_LBN_END:
+            U_ASSERT(FALSE);     // Shouldn't get here.  These ops should be
+                                 //  consumed by the scan in URX_LA_START and LB_START
+
+            break;
+
+        default:
+            U_ASSERT(FALSE);
+            }
+
+        }
+
+
+    // We have finished walking through the ops.  Check whether some forward jump
+    //   propagated a shorter length to location end+1.
+    if (forwardedLength.elementAti(end+1) < currentLen) {
+        currentLen = forwardedLength.elementAti(end+1);
+    }
+
+
+    fRXPat->fInitialChars8->init(fRXPat->fInitialChars);
+
+
+    // Sort out what we should check for when looking for candidate match start positions.
+    // In order of preference,
+    //     1.   Start of input text buffer.
+    //     2.   A literal string.
+    //     3.   Start of line in multi-line mode.
+    //     4.   A single literal character.
+    //     5.   A character from a set of characters.
+    //
+    if (fRXPat->fStartType == START_START) {
+        // Match only at the start of an input text string.
+        //    start type is already set.  We're done.
+    } else if (numInitialStrings == 1 && fRXPat->fMinMatchLen > 0) {
+        // Match beginning only with a literal string.
+        UChar32  c = fRXPat->fLiteralText.char32At(fRXPat->fInitialStringIdx);
+        U_ASSERT(fRXPat->fInitialChars->contains(c));
+        fRXPat->fStartType   = START_STRING;
+        fRXPat->fInitialChar = c;
+    } else if (fRXPat->fStartType == START_LINE) {
+        // Match at start of line in Multi-Line mode.
+        // Nothing to do here; everything is already set.
+    } else if (fRXPat->fMinMatchLen == 0) {
+        // Zero length match possible.  We could start anywhere.
+        fRXPat->fStartType = START_NO_INFO;
+    } else if (fRXPat->fInitialChars->size() == 1) {
+        // All matches begin with the same char.
+        fRXPat->fStartType   = START_CHAR;
+        fRXPat->fInitialChar = fRXPat->fInitialChars->charAt(0);
+        U_ASSERT(fRXPat->fInitialChar != (UChar32)-1);
+    } else if (fRXPat->fInitialChars->contains((UChar32)0, (UChar32)0x10ffff) == FALSE &&
+        fRXPat->fMinMatchLen > 0) {
+        // Matches start with a set of character smaller than the set of all chars.
+        fRXPat->fStartType = START_SET;
+    } else {
+        // Matches can start with anything
+        fRXPat->fStartType = START_NO_INFO;
+    }
+
+    return;
+}
+
+
+
+//------------------------------------------------------------------------------
+//
+//   minMatchLength    Calculate the length of the shortest string that could
+//                     match the specified pattern.
+//                     Length is in 16 bit code units, not code points.
+//
+//                     The calculated length may not be exact.  The returned
+//                     value may be shorter than the actual minimum; it must
+//                     never be longer.
+//
+//                     start and end are the range of p-code operations to be
+//                     examined.  The endpoints are included in the range.
+//
+//------------------------------------------------------------------------------
+int32_t   RegexCompile::minMatchLength(int32_t start, int32_t end) {
+    if (U_FAILURE(*fStatus)) {
+        return 0;
+    }
+
+    U_ASSERT(start <= end);
+    U_ASSERT(end < fRXPat->fCompiledPat->size());
+
+
+    int32_t    loc;
+    int32_t    op;
+    int32_t    opType;
+    int32_t    currentLen = 0;
+
+
+    // forwardedLength is a vector holding minimum-match-length values that
+    //   are propagated forward in the pattern by JMP or STATE_SAVE operations.
+    //   It must be one longer than the pattern being checked because some  ops
+    //   will jmp to a end-of-block+1 location from within a block, and we must
+    //   count those when checking the block.
+    UVector32  forwardedLength(end+2, *fStatus);
+    forwardedLength.setSize(end+2);
+    for (loc=start; loc<=end+1; loc++) {
+        forwardedLength.setElementAt(INT32_MAX, loc);
+    }
+
+    for (loc = start; loc<=end; loc++) {
+        op = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+        opType = URX_TYPE(op);
+
+        // The loop is advancing linearly through the pattern.
+        // If the op we are now at was the destination of a branch in the pattern,
+        // and that path has a shorter minimum length than the current accumulated value,
+        // replace the current accumulated value.
+        // U_ASSERT(currentLen>=0 && currentLen < INT32_MAX);  // MinLength == INT32_MAX for some
+                                                               //   no-match-possible cases.
+        if (forwardedLength.elementAti(loc) < currentLen) {
+            currentLen = forwardedLength.elementAti(loc);
+            U_ASSERT(currentLen>=0 && currentLen < INT32_MAX);
+        }
+
+        switch (opType) {
+            // Ops that don't change the total length matched
+        case URX_RESERVED_OP:
+        case URX_END:
+        case URX_STRING_LEN:
+        case URX_NOP:
+        case URX_START_CAPTURE:
+        case URX_END_CAPTURE:
+        case URX_BACKSLASH_B:
+        case URX_BACKSLASH_BU:
+        case URX_BACKSLASH_G:
+        case URX_BACKSLASH_Z:
+        case URX_CARET:
+        case URX_DOLLAR:
+        case URX_DOLLAR_M:
+        case URX_DOLLAR_D:
+        case URX_DOLLAR_MD:
+        case URX_RELOC_OPRND:
+        case URX_STO_INP_LOC:
+        case URX_CARET_M:
+        case URX_CARET_M_UNIX:
+        case URX_BACKREF:         // BackRef.  Must assume that it might be a zero length match
+        case URX_BACKREF_I:
+
+        case URX_STO_SP:          // Setup for atomic or possessive blocks.  Doesn't change what can match.
+        case URX_LD_SP:
+
+        case URX_JMP_SAV:
+        case URX_JMP_SAV_X:
+            break;
+
+
+            // Ops that match a minimum of one character (one or two 16 bit code units.)
+            //
+        case URX_ONECHAR:
+        case URX_STATIC_SETREF:
+        case URX_STAT_SETREF_N:
+        case URX_SETREF:
+        case URX_BACKSLASH_D:
+        case URX_ONECHAR_I:
+        case URX_BACKSLASH_X:   // Grahpeme Cluster.  Minimum is 1, max unbounded.
+        case URX_DOTANY_ALL:    // . matches one or two.
+        case URX_DOTANY:
+        case URX_DOTANY_UNIX:
+            currentLen++;
+            break;
+
+
+        case URX_JMPX:
+            loc++;              // URX_JMPX has an extra operand, ignored here,
+                                //   otherwise processed identically to URX_JMP.
+        case URX_JMP:
+            {
+                int32_t  jmpDest = URX_VAL(op);
+                if (jmpDest < loc) {
+                    // Loop of some kind.  Can safely ignore, the worst that will happen
+                    //  is that we understate the true minimum length
+                    currentLen = forwardedLength.elementAti(loc+1);
+                } else {
+                    // Forward jump.  Propagate the current min length to the target loc of the jump.
+                    U_ASSERT(jmpDest <= end+1);
+                    if (forwardedLength.elementAti(jmpDest) > currentLen) {
+                        forwardedLength.setElementAt(currentLen, jmpDest);
+                    }
+                }
+            }
+            break;
+
+        case URX_BACKTRACK:
+            {
+                // Back-tracks are kind of like a branch, except that the min length was
+                //   propagated already, by the state save.
+                currentLen = forwardedLength.elementAti(loc+1);
+            }
+            break;
+
+
+        case URX_STATE_SAVE:
+            {
+                // State Save, for forward jumps, propagate the current minimum.
+                //             of the state save.
+                int32_t  jmpDest = URX_VAL(op);
+                if (jmpDest > loc) {
+                    if (currentLen < forwardedLength.elementAti(jmpDest)) {
+                        forwardedLength.setElementAt(currentLen, jmpDest);
+                    }
+                }
+            }
+            break;
+
+
+        case URX_STRING:
+        case URX_STRING_I:
+            {
+                loc++;
+                int32_t stringLenOp = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+                currentLen += URX_VAL(stringLenOp);
+            }
+            break;
+
+
+        case URX_CTR_INIT:
+        case URX_CTR_INIT_NG:
+            {
+                // Loop Init Ops.
+                //   If the min loop count == 0
+                //      move loc forwards to the end of the loop, skipping over the body.
+                //   If the min count is > 0,
+                //      continue normal processing of the body of the loop.
+                int32_t loopEndLoc   = (int32_t)fRXPat->fCompiledPat->elementAti(loc+1);
+                        loopEndLoc   = URX_VAL(loopEndLoc);
+                int32_t minLoopCount = (int32_t)fRXPat->fCompiledPat->elementAti(loc+2);
+                if (minLoopCount == 0) {
+                    loc = loopEndLoc;
+                } else {
+                    loc+=3;  // Skips over operands of CTR_INIT
+                }
+            }
+            break;
+
+
+        case URX_CTR_LOOP:
+        case URX_CTR_LOOP_NG:
+            // Loop ops.
+            //  The jump is conditional, backwards only.
+            break;
+
+        case URX_LOOP_SR_I:
+        case URX_LOOP_DOT_I:
+        case URX_LOOP_C:
+            // More loop ops.  These state-save to themselves.
+            //   don't change the minimum match - could match nothing at all.
+            break;
+
+
+        case URX_LA_START:
+        case URX_LB_START:
+            {
+                // Look-around.  Scan forward until the matching look-ahead end,
+                //   without processing the look-around block.  This is overly pessimistic for look-ahead,
+                //   it assumes that the look-ahead match might be zero-length.
+                //   TODO:  Positive lookahead could recursively do the block, then continue
+                //          with the longer of the block or the value coming in.  Ticket 6060
+                int32_t  depth = (opType == URX_LA_START? 2: 1);;
+                for (;;) {
+                    loc++;
+                    op = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+                    if (URX_TYPE(op) == URX_LA_START) {
+                        // The boilerplate for look-ahead includes two LA_END insturctions,
+                        //    Depth will be decremented by each one when it is seen.
+                        depth += 2;
+                    }
+                    if (URX_TYPE(op) == URX_LB_START) {
+                        depth++;
+                    }
+                    if (URX_TYPE(op) == URX_LA_END) {
+                        depth--;
+                        if (depth == 0) {
+                            break;
+                        }
+                    }
+                    if (URX_TYPE(op)==URX_LBN_END) {
+                        depth--;
+                        if (depth == 0) {
+                            break;
+                        }
+                    }
+                    if (URX_TYPE(op) == URX_STATE_SAVE) {
+                        // Need this because neg lookahead blocks will FAIL to outside
+                        //   of the block.
+                        int32_t  jmpDest = URX_VAL(op);
+                        if (jmpDest > loc) {
+                            if (currentLen < forwardedLength.elementAti(jmpDest)) {
+                                forwardedLength.setElementAt(currentLen, jmpDest);
+                            }
+                        }
+                    }
+                    U_ASSERT(loc <= end);
+                }
+            }
+            break;
+
+        case URX_LA_END:
+        case URX_LB_CONT:
+        case URX_LB_END:
+        case URX_LBN_CONT:
+        case URX_LBN_END:
+            // Only come here if the matching URX_LA_START or URX_LB_START was not in the
+            //   range being sized, which happens when measuring size of look-behind blocks.
+            break;
+
+        default:
+            U_ASSERT(FALSE);
+            }
+
+        }
+
+    // We have finished walking through the ops.  Check whether some forward jump
+    //   propagated a shorter length to location end+1.
+    if (forwardedLength.elementAti(end+1) < currentLen) {
+        currentLen = forwardedLength.elementAti(end+1);
+        U_ASSERT(currentLen>=0 && currentLen < INT32_MAX);
+    }
+
+    return currentLen;
+}
+
+
+
+//------------------------------------------------------------------------------
+//
+//   maxMatchLength    Calculate the length of the longest string that could
+//                     match the specified pattern.
+//                     Length is in 16 bit code units, not code points.
+//
+//                     The calculated length may not be exact.  The returned
+//                     value may be longer than the actual maximum; it must
+//                     never be shorter.
+//
+//------------------------------------------------------------------------------
+int32_t   RegexCompile::maxMatchLength(int32_t start, int32_t end) {
+    if (U_FAILURE(*fStatus)) {
+        return 0;
+    }
+    U_ASSERT(start <= end);
+    U_ASSERT(end < fRXPat->fCompiledPat->size());
+
+
+    int32_t    loc;
+    int32_t    op;
+    int32_t    opType;
+    int32_t    currentLen = 0;
+    UVector32  forwardedLength(end+1, *fStatus);
+    forwardedLength.setSize(end+1);
+
+    for (loc=start; loc<=end; loc++) {
+        forwardedLength.setElementAt(0, loc);
+    }
+
+    for (loc = start; loc<=end; loc++) {
+        op = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+        opType = URX_TYPE(op);
+
+        // The loop is advancing linearly through the pattern.
+        // If the op we are now at was the destination of a branch in the pattern,
+        // and that path has a longer maximum length than the current accumulated value,
+        // replace the current accumulated value.
+        if (forwardedLength.elementAti(loc) > currentLen) {
+            currentLen = forwardedLength.elementAti(loc);
+        }
+
+        switch (opType) {
+            // Ops that don't change the total length matched
+        case URX_RESERVED_OP:
+        case URX_END:
+        case URX_STRING_LEN:
+        case URX_NOP:
+        case URX_START_CAPTURE:
+        case URX_END_CAPTURE:
+        case URX_BACKSLASH_B:
+        case URX_BACKSLASH_BU:
+        case URX_BACKSLASH_G:
+        case URX_BACKSLASH_Z:
+        case URX_CARET:
+        case URX_DOLLAR:
+        case URX_DOLLAR_M:
+        case URX_DOLLAR_D:
+        case URX_DOLLAR_MD:
+        case URX_RELOC_OPRND:
+        case URX_STO_INP_LOC:
+        case URX_CARET_M:
+        case URX_CARET_M_UNIX:
+
+        case URX_STO_SP:          // Setup for atomic or possessive blocks.  Doesn't change what can match.
+        case URX_LD_SP:
+
+        case URX_LB_END:
+        case URX_LB_CONT:
+        case URX_LBN_CONT:
+        case URX_LBN_END:
+            break;
+
+
+            // Ops that increase that cause an unbounded increase in the length
+            //   of a matched string, or that increase it a hard to characterize way.
+            //   Call the max length unbounded, and stop further checking.
+        case URX_BACKREF:         // BackRef.  Must assume that it might be a zero length match
+        case URX_BACKREF_I:
+        case URX_BACKSLASH_X:   // Grahpeme Cluster.  Minimum is 1, max unbounded.
+            currentLen = INT32_MAX;
+            break;
+
+
+            // Ops that match a max of one character (possibly two 16 bit code units.)
+            //
+        case URX_STATIC_SETREF:
+        case URX_STAT_SETREF_N:
+        case URX_SETREF:
+        case URX_BACKSLASH_D:
+        case URX_ONECHAR_I:
+        case URX_DOTANY_ALL:
+        case URX_DOTANY:
+        case URX_DOTANY_UNIX:
+            currentLen+=2;
+            break;
+
+            // Single literal character.  Increase current max length by one or two,
+            //       depending on whether the char is in the supplementary range.
+        case URX_ONECHAR:
+            currentLen++;
+            if (URX_VAL(op) > 0x10000) {
+                currentLen++;
+            }
+            break;
+
+            // Jumps.
+            //
+        case URX_JMP:
+        case URX_JMPX:
+        case URX_JMP_SAV:
+        case URX_JMP_SAV_X:
+            {
+                int32_t  jmpDest = URX_VAL(op);
+                if (jmpDest < loc) {
+                    // Loop of some kind.  Max match length is unbounded.
+                    currentLen = INT32_MAX;
+                } else {
+                    // Forward jump.  Propagate the current min length to the target loc of the jump.
+                    if (forwardedLength.elementAti(jmpDest) < currentLen) {
+                        forwardedLength.setElementAt(currentLen, jmpDest);
+                    }
+                    currentLen = 0;
+                }
+            }
+            break;
+
+        case URX_BACKTRACK:
+            // back-tracks are kind of like a branch, except that the max length was
+            //   propagated already, by the state save.
+            currentLen = forwardedLength.elementAti(loc+1);
+            break;
+
+
+        case URX_STATE_SAVE:
+            {
+                // State Save, for forward jumps, propagate the current minimum.
+                //               of the state save.
+                //             For backwards jumps, they create a loop, maximum
+                //               match length is unbounded.
+                int32_t  jmpDest = URX_VAL(op);
+                if (jmpDest > loc) {
+                    if (currentLen > forwardedLength.elementAti(jmpDest)) {
+                        forwardedLength.setElementAt(currentLen, jmpDest);
+                    }
+                } else {
+                    currentLen = INT32_MAX;
+                }
+            }
+            break;
+
+
+
+
+        case URX_STRING:
+        case URX_STRING_I:
+            {
+                loc++;
+                int32_t stringLenOp = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+                currentLen += URX_VAL(stringLenOp);
+            }
+            break;
+
+
+        case URX_CTR_INIT:
+        case URX_CTR_INIT_NG:
+        case URX_CTR_LOOP:
+        case URX_CTR_LOOP_NG:
+        case URX_LOOP_SR_I:
+        case URX_LOOP_DOT_I:
+        case URX_LOOP_C:
+            // For anything to do with loops, make the match length unbounded.
+            //   Note:  INIT instructions are multi-word.  Can ignore because
+            //          INT32_MAX length will stop the per-instruction loop.
+            currentLen = INT32_MAX;
+            break;
+
+
+
+        case URX_LA_START:
+        case URX_LA_END:
+            // Look-ahead.  Just ignore, treat the look-ahead block as if
+            // it were normal pattern.  Gives a too-long match length,
+            //  but good enough for now.
+            break;
+
+            // End of look-ahead ops should always be consumed by the processing at
+            //  the URX_LA_START op.
+            // U_ASSERT(FALSE);
+            // break;
+
+        case URX_LB_START:
+            {
+                // Look-behind.  Scan forward until the matching look-around end,
+                //   without processing the look-behind block.
+                int32_t  depth = 0;
+                for (;;) {
+                    loc++;
+                    op = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+                    if (URX_TYPE(op) == URX_LA_START || URX_TYPE(op) == URX_LB_START) {
+                        depth++;
+                    }
+                    if (URX_TYPE(op) == URX_LA_END || URX_TYPE(op)==URX_LBN_END) {
+                        if (depth == 0) {
+                            break;
+                        }
+                        depth--;
+                    }
+                    U_ASSERT(loc < end);
+                }
+            }
+            break;
+
+        default:
+            U_ASSERT(FALSE);
+        }
+
+
+        if (currentLen == INT32_MAX) {
+            //  The maximum length is unbounded.
+            //  Stop further processing of the pattern.
+            break;
+        }
+
+    }
+    return currentLen;
+
+}
+
+
+//------------------------------------------------------------------------------
+//
+//   stripNOPs    Remove any NOP operations from the compiled pattern code.
+//                Extra NOPs are inserted for some constructs during the initial
+//                code generation to provide locations that may be patched later.
+//                Many end up unneeded, and are removed by this function.
+//
+//                In order to minimize the number of passes through the pattern,
+//                back-reference fixup is also performed here (adjusting
+//                back-reference operands to point to the correct frame offsets).
+//
+//                In addition, case-insensitive character and string literals are
+//                now case-folded here, rather than when first parsed or at match
+//                time.
+//
+//------------------------------------------------------------------------------
+void RegexCompile::stripNOPs() {
+
+    if (U_FAILURE(*fStatus)) {
+        return;
+    }
+
+    int32_t    end = fRXPat->fCompiledPat->size();
+    UVector32  deltas(end, *fStatus);
+
+    // Make a first pass over the code, computing the amount that things
+    //   will be offset at each location in the original code.
+    int32_t   loc;
+    int32_t   d = 0;
+    for (loc=0; loc<end; loc++) {
+        deltas.addElement(d, *fStatus);
+        int32_t op = (int32_t)fRXPat->fCompiledPat->elementAti(loc);
+        if (URX_TYPE(op) == URX_NOP) {
+            d++;
+        }
+    }
+    
+    UnicodeString caseStringBuffer;
+    int32_t stringDelta = 0;
+
+    // Make a second pass over the code, removing the NOPs by moving following
+    //  code up, and patching operands that refer to code locations that
+    //  are being moved.  The array of offsets from the first step is used
+    //  to compute the new operand values.
+    int32_t src;
+    int32_t dst = 0;
+    for (src=0; src<end; src++) {
+        int32_t op = (int32_t)fRXPat->fCompiledPat->elementAti(src);
+        int32_t opType = URX_TYPE(op);
+        switch (opType) {
+        case URX_NOP:
+            break;
+
+        case URX_STATE_SAVE:
+        case URX_JMP:
+        case URX_CTR_LOOP:
+        case URX_CTR_LOOP_NG:
+        case URX_RELOC_OPRND:
+        case URX_JMPX:
+        case URX_JMP_SAV:
+        case URX_JMP_SAV_X:
+            // These are instructions with operands that refer to code locations.
+            {
+                int32_t  operandAddress = URX_VAL(op);
+                U_ASSERT(operandAddress>=0 && operandAddress<deltas.size());
+                int32_t fixedOperandAddress = operandAddress - deltas.elementAti(operandAddress);
+                op = URX_BUILD(opType, fixedOperandAddress);
+                fRXPat->fCompiledPat->setElementAt(op, dst);
+                dst++;
+                break;
+            }
+
+        case URX_ONECHAR_I:
+            {
+                UChar32 c = URX_VAL(op);
+                if (u_hasBinaryProperty(c, UCHAR_CASE_SENSITIVE)) {
+                    // We have a cased character to fold
+                    c  = u_foldCase(c, U_FOLD_CASE_DEFAULT);
+                    op = URX_BUILD(URX_ONECHAR_I, c);
+                }
+                
+                fRXPat->fCompiledPat->setElementAt(op, dst);
+                dst++;
+                break;
+            }
+        case URX_STRING_I:
+            {
+                op = URX_BUILD(URX_STRING_I, URX_VAL(op)+stringDelta);
+                
+                src++;
+                int32_t lengthOp = (int32_t)fRXPat->fCompiledPat->elementAti(src);
+                
+                caseStringBuffer.setTo(fRXPat->fLiteralText, URX_VAL(op), URX_VAL(lengthOp));
+                caseStringBuffer.foldCase(U_FOLD_CASE_DEFAULT);
+                
+                int32_t newLen = caseStringBuffer.length();
+                if (newLen <= URX_VAL(lengthOp)) {
+                    // don't shift if we don't have to, take the tiny memory hit of a smaller string
+                    fRXPat->fLiteralText.replace(URX_VAL(op), newLen, caseStringBuffer);
+                } else {
+                    // shift other strings over...at least UnicodeString handles this for us!
+                    fRXPat->fLiteralText.replace(URX_VAL(op), URX_VAL(lengthOp), caseStringBuffer);
+                    stringDelta += newLen - URX_VAL(lengthOp);
+                }
+                lengthOp = URX_BUILD(URX_STRING_LEN, newLen);
+                
+                fRXPat->fCompiledPat->setElementAt(op, dst);
+                fRXPat->fCompiledPat->setElementAt(lengthOp, dst+1);
+                dst += 2;
+                break;
+            }
+        case URX_BACKREF:
+        case URX_BACKREF_I:
+            {
+                int32_t where = URX_VAL(op);
+                if (where > fRXPat->fGroupMap->size()) {
+                    error(U_REGEX_INVALID_BACK_REF);
+                    break;
+                }
+                where = fRXPat->fGroupMap->elementAti(where-1);
+                op    = URX_BUILD(opType, where);
+                fRXPat->fCompiledPat->setElementAt(op, dst);
+                dst++;
+                
+                fRXPat->fNeedsAltInput = TRUE;
+                break;
+            }
+        case URX_STRING:
+            op = URX_BUILD(URX_STRING, URX_VAL(op)+stringDelta);
+            // continue
+        case URX_RESERVED_OP:
+        case URX_RESERVED_OP_N:
+        case URX_BACKTRACK:
+        case URX_END:
+        case URX_ONECHAR:
+        case URX_STRING_LEN:
+        case URX_START_CAPTURE:
+        case URX_END_CAPTURE:
+        case URX_STATIC_SETREF:
+        case URX_STAT_SETREF_N:
+        case URX_SETREF:
+        case URX_DOTANY:
+        case URX_FAIL:
+        case URX_BACKSLASH_B:
+        case URX_BACKSLASH_BU:
+        case URX_BACKSLASH_G:
+        case URX_BACKSLASH_X:
+        case URX_BACKSLASH_Z:
+        case URX_DOTANY_ALL:
+        case URX_BACKSLASH_D:
+        case URX_CARET:
+        case URX_DOLLAR:
+        case URX_CTR_INIT:
+        case URX_CTR_INIT_NG:
+        case URX_DOTANY_UNIX:
+        case URX_STO_SP:
+        case URX_LD_SP:
+        case URX_STO_INP_LOC:
+        case URX_LA_START:
+        case URX_LA_END:
+        case URX_DOLLAR_M:
+        case URX_CARET_M:
+        case URX_CARET_M_UNIX:
+        case URX_LB_START:
+        case URX_LB_CONT:
+        case URX_LB_END:
+        case URX_LBN_CONT:
+        case URX_LBN_END:
+        case URX_LOOP_SR_I:
+        case URX_LOOP_DOT_I:
+        case URX_LOOP_C:
+        case URX_DOLLAR_D:
+        case URX_DOLLAR_MD:
+            // These instructions are unaltered by the relocation.
+            fRXPat->fCompiledPat->setElementAt(op, dst);
+            dst++;
+            break;
+
+        default:
+            // Some op is unaccounted for.
+            U_ASSERT(FALSE);
+            error(U_REGEX_INTERNAL_ERROR);
+        }
+    }
+
+    fRXPat->fCompiledPat->setSize(dst);
+}
+
+
+
+
+//------------------------------------------------------------------------------
+//
+//  Error         Report a rule parse error.
+//                Only report it if no previous error has been recorded.
+//
+//------------------------------------------------------------------------------
+void RegexCompile::error(UErrorCode e) {
+    if (U_SUCCESS(*fStatus)) {
+        *fStatus = e;
+        // Hmm. fParseErr (UParseError) line & offset fields are int32_t in public
+        // API (see common/unicode/parseerr.h), while fLineNum and fCharNum are
+        // int64_t. If the values of the latter are out of range for the former,
+        // set them to the appropriate "field not supported" values.
+        if (fLineNum > 0x7FFFFFFF) {
+            fParseErr->line   = 0;
+            fParseErr->offset = -1;
+        } else if (fCharNum > 0x7FFFFFFF) {
+            fParseErr->line   = (int32_t)fLineNum;
+            fParseErr->offset = -1;
+        } else {
+            fParseErr->line   = (int32_t)fLineNum;
+            fParseErr->offset = (int32_t)fCharNum;
+        }
+        
+        UErrorCode status = U_ZERO_ERROR; // throwaway status for extracting context
+
+        // Fill in the context.
+        //   Note: extractBetween() pins supplied indicies to the string bounds.
+        uprv_memset(fParseErr->preContext,  0, sizeof(fParseErr->preContext));
+        uprv_memset(fParseErr->postContext, 0, sizeof(fParseErr->postContext));
+        utext_extract(fRXPat->fPattern, fScanIndex-U_PARSE_CONTEXT_LEN+1, fScanIndex, fParseErr->preContext, U_PARSE_CONTEXT_LEN, &status);
+        utext_extract(fRXPat->fPattern, fScanIndex, fScanIndex+U_PARSE_CONTEXT_LEN-1, fParseErr->postContext, U_PARSE_CONTEXT_LEN, &status);
+    }
+}
+
+
+//
+//  Assorted Unicode character constants.
+//     Numeric because there is no portable way to enter them as literals.
+//     (Think EBCDIC).
+//
+static const UChar      chCR        = 0x0d;      // New lines, for terminating comments.
+static const UChar      chLF        = 0x0a;      // Line Feed
+static const UChar      chPound     = 0x23;      // '#', introduces a comment.
+static const UChar      chDigit0    = 0x30;      // '0'
+static const UChar      chDigit7    = 0x37;      // '9'
+static const UChar      chColon     = 0x3A;      // ':'
+static const UChar      chE         = 0x45;      // 'E'
+static const UChar      chQ         = 0x51;      // 'Q'
+static const UChar      chN         = 0x4E;      // 'N'
+static const UChar      chP         = 0x50;      // 'P'
+static const UChar      chBackSlash = 0x5c;      // '\'  introduces a char escape
+static const UChar      chLBracket  = 0x5b;      // '['
+static const UChar      chRBracket  = 0x5d;      // ']'
+static const UChar      chUp        = 0x5e;      // '^'
+static const UChar      chLowerP    = 0x70;
+static const UChar      chLBrace    = 0x7b;      // '{'
+static const UChar      chRBrace    = 0x7d;      // '}'
+static const UChar      chNEL       = 0x85;      //    NEL newline variant
+static const UChar      chLS        = 0x2028;    //    Unicode Line Separator
+
+
+//------------------------------------------------------------------------------
+//
+//  nextCharLL    Low Level Next Char from the regex pattern.
+//                Get a char from the string, keep track of input position
+//                     for error reporting.
+//
+//------------------------------------------------------------------------------
+UChar32  RegexCompile::nextCharLL() {
+    UChar32       ch;
+
+    if (fPeekChar != -1) {
+        ch = fPeekChar;
+        fPeekChar = -1;
+        return ch;
+    }
+    
+    // assume we're already in the right place
+    ch = UTEXT_NEXT32(fRXPat->fPattern);
+    if (ch == U_SENTINEL) {
+        return ch;
+    }
+
+    if (ch == chCR ||
+        ch == chNEL ||
+        ch == chLS   ||
+        (ch == chLF && fLastChar != chCR)) {
+        // Character is starting a new line.  Bump up the line number, and
+        //  reset the column to 0.
+        fLineNum++;
+        fCharNum=0;
+    }
+    else {
+        // Character is not starting a new line.  Except in the case of a
+        //   LF following a CR, increment the column position.
+        if (ch != chLF) {
+            fCharNum++;
+        }
+    }
+    fLastChar = ch;
+    return ch;
+}
+
+//------------------------------------------------------------------------------
+//
+//   peekCharLL    Low Level Character Scanning, sneak a peek at the next
+//                 character without actually getting it.
+//
+//------------------------------------------------------------------------------
+UChar32  RegexCompile::peekCharLL() {
+    if (fPeekChar == -1) {
+        fPeekChar = nextCharLL();
+    }
+    return fPeekChar;
+}
+
+
+//------------------------------------------------------------------------------
+//
+//   nextChar     for pattern scanning.  At this level, we handle stripping
+//                out comments and processing some backslash character escapes.
+//                The rest of the pattern grammar is handled at the next level up.
+//
+//------------------------------------------------------------------------------
+void RegexCompile::nextChar(RegexPatternChar &c) {
+
+    fScanIndex = UTEXT_GETNATIVEINDEX(fRXPat->fPattern);
+    c.fChar    = nextCharLL();
+    c.fQuoted  = FALSE;
+
+    if (fQuoteMode) {
+        c.fQuoted = TRUE;
+        if ((c.fChar==chBackSlash && peekCharLL()==chE) || c.fChar == (UChar32)-1) {
+            fQuoteMode = FALSE;  //  Exit quote mode,
+            nextCharLL();       // discard the E
+            nextChar(c);        // recurse to get the real next char
+        }
+    }
+    else if (fInBackslashQuote) {
+        // The current character immediately follows a '\'
+        // Don't check for any further escapes, just return it as-is.
+        // Don't set c.fQuoted, because that would prevent the state machine from
+        //    dispatching on the character.
+        fInBackslashQuote = FALSE;
+    }
+    else
+    {
+        // We are not in a \Q quoted region \E of the source.
+        //
+        if (fModeFlags & UREGEX_COMMENTS) {
+            //
+            // We are in free-spacing and comments mode.
+            //  Scan through any white space and comments, until we
+            //  reach a significant character or the end of inut.
+            for (;;) {
+                if (c.fChar == (UChar32)-1) {
+                    break;     // End of Input
+                }
+                if  (c.fChar == chPound && fEOLComments == TRUE) {
+                    // Start of a comment.  Consume the rest of it, until EOF or a new line
+                    for (;;) {
+                        c.fChar = nextCharLL();
+                        if (c.fChar == (UChar32)-1 ||  // EOF
+                            c.fChar == chCR        ||
+                            c.fChar == chLF        ||
+                            c.fChar == chNEL       ||
+                            c.fChar == chLS)       {
+                            break;
+                        }
+                    }
+                }
+                // TODO:  check what Java & Perl do with non-ASCII white spaces.  Ticket 6061.
+                if (uprv_isRuleWhiteSpace(c.fChar) == FALSE) {
+                    break;
+                }
+                c.fChar = nextCharLL();
+            }
+        }
+
+        //
+        //  check for backslash escaped characters.
+        //
+        if (c.fChar == chBackSlash) {
+            int64_t pos = UTEXT_GETNATIVEINDEX(fRXPat->fPattern);
+            if (RegexStaticSets::gStaticSets->fUnescapeCharSet.contains(peekCharLL())) {
+                //
+                // A '\' sequence that is handled by ICU's standard unescapeAt function.
+                //   Includes \uxxxx, \n, \r, many others.
+                //   Return the single equivalent character.
+                //
+                nextCharLL();                 // get & discard the peeked char.
+                c.fQuoted = TRUE;
+                
+                if (UTEXT_FULL_TEXT_IN_CHUNK(fRXPat->fPattern, fPatternLength)) {
+                    int32_t endIndex = (int32_t)pos;
+                    c.fChar = u_unescapeAt(uregex_ucstr_unescape_charAt, &endIndex, (int32_t)fPatternLength, (void *)fRXPat->fPattern->chunkContents);
+                    
+                    if (endIndex == pos) {
+                        error(U_REGEX_BAD_ESCAPE_SEQUENCE);
+                    }
+                    fCharNum += endIndex - pos;
+                    UTEXT_SETNATIVEINDEX(fRXPat->fPattern, endIndex);
+                } else {
+                    int32_t offset = 0;
+                    struct URegexUTextUnescapeCharContext context = U_REGEX_UTEXT_UNESCAPE_CONTEXT(fRXPat->fPattern);
+                    
+                    UTEXT_SETNATIVEINDEX(fRXPat->fPattern, pos);
+                    c.fChar = u_unescapeAt(uregex_utext_unescape_charAt, &offset, INT32_MAX, &context);
+
+                    if (offset == 0) {
+                        error(U_REGEX_BAD_ESCAPE_SEQUENCE);
+                    } else if (context.lastOffset == offset) {
+                        UTEXT_PREVIOUS32(fRXPat->fPattern);
+                    } else if (context.lastOffset != offset-1) {
+                        utext_moveIndex32(fRXPat->fPattern, offset - context.lastOffset - 1);
+                    }
+                    fCharNum += offset;
+                }
+            }
+            else if (peekCharLL() == chDigit0) {
+                //  Octal Escape, using Java Regexp Conventions
+                //    which are \0 followed by 1-3 octal digits.
+                //    Different from ICU Unescape handling of Octal, which does not
+                //    require the leading 0.
+                //  Java also has the convention of only consuming 2 octal digits if
+                //    the three digit number would be > 0xff
+                //
+                c.fChar = 0;
+                nextCharLL();    // Consume the initial 0.
+                int index;
+                for (index=0; index<3; index++) {
+                    int32_t ch = peekCharLL();
+                    if (ch<chDigit0 || ch>chDigit7) {
+                        if (index==0) {
+                           // \0 is not followed by any octal digits.
+                           error(U_REGEX_BAD_ESCAPE_SEQUENCE);
+                        }
+                        break;
+                    }
+                    c.fChar <<= 3;
+                    c.fChar += ch&7;
+                    if (c.fChar <= 255) {
+                        nextCharLL();
+                    } else {
+                        // The last digit made the number too big.  Forget we saw it.
+                        c.fChar >>= 3;
+                    }
+                }
+                c.fQuoted = TRUE; 
+            } 
+            else if (peekCharLL() == chQ) {
+                //  "\Q"  enter quote mode, which will continue until "\E"
+                fQuoteMode = TRUE;
+                nextCharLL();       // discard the 'Q'.
+                nextChar(c);        // recurse to get the real next char.
+            }
+            else
+            {
+                // We are in a '\' escape that will be handled by the state table scanner.
+                // Just return the backslash, but remember that the following char is to
+                //  be taken literally.
+                fInBackslashQuote = TRUE;
+            }
+        }
+    }
+
+    // re-enable # to end-of-line comments, in case they were disabled.
+    // They are disabled by the parser upon seeing '(?', but this lasts for
+    //  the fetching of the next character only.
+    fEOLComments = TRUE;
+
+    // putc(c.fChar, stdout);
+}
+
+
+
+//------------------------------------------------------------------------------
+//
+//  scanNamedChar
+ //            Get a UChar32 from a \N{UNICODE CHARACTER NAME} in the pattern.
+//
+//             The scan position will be at the 'N'.  On return
+//             the scan position should be just after the '}'
+//
+//             Return the UChar32
+//
+//------------------------------------------------------------------------------
+UChar32  RegexCompile::scanNamedChar() {
+    if (U_FAILURE(*fStatus)) {
+        return 0;
+    }
+
+    nextChar(fC);
+    if (fC.fChar != chLBrace) {
+        error(U_REGEX_PROPERTY_SYNTAX);
+        return 0;
+    }
+    
+    UnicodeString  charName;
+    for (;;) {
+        nextChar(fC);
+        if (fC.fChar == chRBrace) {
+            break;
+        }
+        if (fC.fChar == -1) {
+            error(U_REGEX_PROPERTY_SYNTAX);
+            return 0;
+        }
+        charName.append(fC.fChar);
+    }
+    
+    char name[100];
+    if (!uprv_isInvariantUString(charName.getBuffer(), charName.length()) ||
+         (uint32_t)charName.length()>=sizeof(name)) {
+        // All Unicode character names have only invariant characters.
+        // The API to get a character, given a name, accepts only char *, forcing us to convert,
+        //   which requires this error check
+        error(U_REGEX_PROPERTY_SYNTAX);
+        return 0;
+    }
+    charName.extract(0, charName.length(), name, sizeof(name), US_INV);
+
+    UChar32  theChar = u_charFromName(U_UNICODE_CHAR_NAME, name, fStatus);
+    if (U_FAILURE(*fStatus)) {
+        error(U_REGEX_PROPERTY_SYNTAX);
+    }
+
+    nextChar(fC);      // Continue overall regex pattern processing with char after the '}'
+    return theChar;
+}
+
+//------------------------------------------------------------------------------
+//
+//  scanProp   Construct a UnicodeSet from the text at the current scan
+//             position, which will be of the form \p{whaterver}
+//
+//             The scan position will be at the 'p' or 'P'.  On return
+//             the scan position should be just after the '}'
+//
+//             Return a UnicodeSet, constructed from the \P pattern,
+//             or NULL if the pattern is invalid.
+//
+//------------------------------------------------------------------------------
+UnicodeSet *RegexCompile::scanProp() {
+    UnicodeSet    *uset = NULL;
+
+    if (U_FAILURE(*fStatus)) {
+        return NULL;
+    }
+    U_ASSERT(fC.fChar == chLowerP || fC.fChar == chP);
+    UBool negated = (fC.fChar == chP);
+
+    UnicodeString propertyName;
+    nextChar(fC);
+    if (fC.fChar != chLBrace) {
+        error(U_REGEX_PROPERTY_SYNTAX);
+        return NULL;
+    }
+    for (;;) {
+        nextChar(fC);
+        if (fC.fChar == chRBrace) {
+            break;
+        }
+        if (fC.fChar == -1) {
+            // Hit the end of the input string without finding the closing '}'
+            error(U_REGEX_PROPERTY_SYNTAX);
+            return NULL;
+        }
+        propertyName.append(fC.fChar);
+    }
+    uset = createSetForProperty(propertyName, negated);
+    nextChar(fC);    // Move input scan to position following the closing '}'
+    return uset;
+}
+
+//------------------------------------------------------------------------------
+//
+//  scanPosixProp   Construct a UnicodeSet from the text at the current scan
+//             position, which is expected be of the form [:property expression:]
+//
+//             The scan position will be at the opening ':'.  On return
+//             the scan position must be on the closing ']'
+//
+//             Return a UnicodeSet constructed from the pattern,
+//             or NULL if this is not a valid POSIX-style set expression.
+//             If not a property expression, restore the initial scan position
+//                (to the opening ':')
+//
+//               Note:  the opening '[:' is not sufficient to guarantee that
+//                      this is a [:property:] expression.
+//                      [:'+=,] is a perfectly good ordinary set expression that
+//                              happens to include ':' as one of its characters.
+//
+//------------------------------------------------------------------------------
+UnicodeSet *RegexCompile::scanPosixProp() {
+    UnicodeSet    *uset = NULL;
+
+    if (U_FAILURE(*fStatus)) {
+        return NULL;
+    }
+
+    U_ASSERT(fC.fChar == chColon);
+
+    // Save the scanner state.
+    // TODO:  move this into the scanner, with the state encapsulated in some way.  Ticket 6062
+    int64_t     savedScanIndex        = fScanIndex;
+    int64_t     savedNextIndex        = UTEXT_GETNATIVEINDEX(fRXPat->fPattern);
+    UBool       savedQuoteMode        = fQuoteMode;
+    UBool       savedInBackslashQuote = fInBackslashQuote;
+    UBool       savedEOLComments      = fEOLComments;
+    int64_t     savedLineNum          = fLineNum;
+    int64_t     savedCharNum          = fCharNum;
+    UChar32     savedLastChar         = fLastChar;
+    UChar32     savedPeekChar         = fPeekChar;
+    RegexPatternChar savedfC          = fC;
+
+    // Scan for a closing ].   A little tricky because there are some perverse
+    //   edge cases possible.  "[:abc\Qdef:] \E]"  is a valid non-property expression,
+    //   ending on the second closing ]. 
+
+    UnicodeString propName;
+    UBool         negated  = FALSE;
+
+    // Check for and consume the '^' in a negated POSIX property, e.g.  [:^Letter:]
+    nextChar(fC);
+    if (fC.fChar == chUp) {
+       negated = TRUE;
+       nextChar(fC);
+    }
+    
+    // Scan for the closing ":]", collecting the property name along the way.
+    UBool  sawPropSetTerminator = FALSE;
+    for (;;) {
+        propName.append(fC.fChar);
+        nextChar(fC);
+        if (fC.fQuoted || fC.fChar == -1) {
+            // Escaped characters or end of input - either says this isn't a [:Property:]
+            break;
+        }
+        if (fC.fChar == chColon) {
+            nextChar(fC);
+            if (fC.fChar == chRBracket) {
+                sawPropSetTerminator = TRUE;
+            }
+            break;
+        }
+    }
+    
+    if (sawPropSetTerminator) {
+        uset = createSetForProperty(propName, negated);
+    }
+    else
+    {
+        // No closing ":]".
+        //  Restore the original scan position.
+        //  The main scanner will retry the input as a normal set expression,
+        //    not a [:Property:] expression.
+        fScanIndex        = savedScanIndex;
+        fQuoteMode        = savedQuoteMode;
+        fInBackslashQuote = savedInBackslashQuote;
+        fEOLComments      = savedEOLComments;
+        fLineNum          = savedLineNum;
+        fCharNum          = savedCharNum;
+        fLastChar         = savedLastChar;
+        fPeekChar         = savedPeekChar;
+        fC                = savedfC;
+        UTEXT_SETNATIVEINDEX(fRXPat->fPattern, savedNextIndex);
+    }
+    return uset;
+}
+
+static inline void addIdentifierIgnorable(UnicodeSet *set, UErrorCode& ec) {
+    set->add(0, 8).add(0x0e, 0x1b).add(0x7f, 0x9f);
+    addCategory(set, U_GC_CF_MASK, ec);
+}
+
+//
+//  Create a Unicode Set from a Unicode Property expression.
+//     This is common code underlying both \p{...} ane [:...:] expressions.
+//     Includes trying the Java "properties" that aren't supported as
+//     normal ICU UnicodeSet properties 
+//
+static const UChar posSetPrefix[] = {0x5b, 0x5c, 0x70, 0x7b, 0}; // "[\p{"
+static const UChar negSetPrefix[] = {0x5b, 0x5c, 0x50, 0x7b, 0}; // "[\P{"
+UnicodeSet *RegexCompile::createSetForProperty(const UnicodeString &propName, UBool negated) {
+    UnicodeString   setExpr;
+    UnicodeSet      *set;
+    uint32_t        usetFlags = 0;
+    
+    if (U_FAILURE(*fStatus)) {
+        return NULL;
+    }
+
+    //
+    //  First try the property as we received it
+    //
+    if (negated) {
+        setExpr.append(negSetPrefix, -1);
+    } else {
+        setExpr.append(posSetPrefix, -1);
+    }
+    setExpr.append(propName);
+    setExpr.append(chRBrace);
+    setExpr.append(chRBracket);
+    if (fModeFlags & UREGEX_CASE_INSENSITIVE) {
+        usetFlags |= USET_CASE_INSENSITIVE;
+    }
+    set = new UnicodeSet(setExpr, usetFlags, NULL, *fStatus);
+    if (U_SUCCESS(*fStatus)) {
+       return set;
+    }
+    delete set;
+    set = NULL;
+    
+    //
+    //  The property as it was didn't work.
+
+    //  Do [:word:]. It is not recognized as a property by UnicodeSet.  "word" not standard POSIX 
+    //     or standard Java, but many other regular expression packages do recognize it.
+    
+    if (propName.caseCompare(UNICODE_STRING_SIMPLE("word"), 0) == 0) {
+        *fStatus = U_ZERO_ERROR;
+        set = new UnicodeSet(*(fRXPat->fStaticSets[URX_ISWORD_SET]));
+        if (set == NULL) {
+            *fStatus = U_MEMORY_ALLOCATION_ERROR;
+            return set;
+        }
+        if (negated) {
+            set->complement();
+        }
+        return set;
+    }
+
+
+    //    Do Java fixes -
+    //       InGreek -> InGreek or Coptic, that being the official Unicode name for that block.
+    //       InCombiningMarksforSymbols -> InCombiningDiacriticalMarksforSymbols.
+    //
+    //       Note on Spaces:  either "InCombiningMarksForSymbols" or "InCombining Marks for Symbols"
+    //                        is accepted by Java.  The property part of the name is compared 
+    //                        case-insenstively.  The spaces must be exactly as shown, either
+    //                        all there, or all omitted, with exactly one at each position
+    //                        if they are present.  From checking against JDK 1.6
+    //
+    //       This code should be removed when ICU properties support the Java  compatibility names
+    //          (ICU 4.0?)
+    //
+    UnicodeString mPropName = propName;
+    if (mPropName.caseCompare(UNICODE_STRING_SIMPLE("InGreek"), 0) == 0) {
+        mPropName = UNICODE_STRING_SIMPLE("InGreek and Coptic");
+    }
+    if (mPropName.caseCompare(UNICODE_STRING_SIMPLE("InCombining Marks for Symbols"), 0) == 0 ||
+        mPropName.caseCompare(UNICODE_STRING_SIMPLE("InCombiningMarksforSymbols"), 0) == 0) {
+        mPropName = UNICODE_STRING_SIMPLE("InCombining Diacritical Marks for Symbols");
+    }
+    else if (mPropName.compare(UNICODE_STRING_SIMPLE("all")) == 0) {
+        mPropName = UNICODE_STRING_SIMPLE("javaValidCodePoint");
+    }
+    
+    //    See if the property looks like a Java "InBlockName", which
+    //    we will recast as "Block=BlockName"
+    //
+    static const UChar IN[] = {0x49, 0x6E, 0};  // "In"
+    static const UChar BLOCK[] = {0x42, 0x6C, 0x6f, 0x63, 0x6b, 0x3d, 00};  // "Block="
+    if (mPropName.startsWith(IN, 2) && propName.length()>=3) {
+        setExpr.truncate(4);   // Leaves "[\p{", or "[\P{"
+        setExpr.append(BLOCK, -1);
+        setExpr.append(UnicodeString(mPropName, 2));  // Property with the leading "In" removed.
+        setExpr.append(chRBrace);
+        setExpr.append(chRBracket);
+        *fStatus = U_ZERO_ERROR;
+        set = new UnicodeSet(setExpr, usetFlags, NULL, *fStatus);
+        if (U_SUCCESS(*fStatus)) {
+            return set;
+        }
+        delete set;
+        set = NULL;
+    }
+
+    if (propName.startsWith(UNICODE_STRING_SIMPLE("java")) ||
+        propName.compare(UNICODE_STRING_SIMPLE("all")) == 0)
+    {
+        UErrorCode localStatus = U_ZERO_ERROR;
+        //setExpr.remove();
+        set = new UnicodeSet();
+        //
+        //  Try the various Java specific properties.
+        //   These all begin with "java"
+        //
+        if (mPropName.compare(UNICODE_STRING_SIMPLE("javaDefined")) == 0) {
+            addCategory(set, U_GC_CN_MASK, localStatus);
+            set->complement();
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaDigit")) == 0) {
+            addCategory(set, U_GC_ND_MASK, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaIdentifierIgnorable")) == 0) {
+            addIdentifierIgnorable(set, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaISOControl")) == 0) {
+            set->add(0, 0x1F).add(0x7F, 0x9F);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaJavaIdentifierPart")) == 0) {
+            addCategory(set, U_GC_L_MASK, localStatus);
+            addCategory(set, U_GC_SC_MASK, localStatus);
+            addCategory(set, U_GC_PC_MASK, localStatus);
+            addCategory(set, U_GC_ND_MASK, localStatus);
+            addCategory(set, U_GC_NL_MASK, localStatus);
+            addCategory(set, U_GC_MC_MASK, localStatus);
+            addCategory(set, U_GC_MN_MASK, localStatus);
+            addIdentifierIgnorable(set, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaJavaIdentifierStart")) == 0) {
+            addCategory(set, U_GC_L_MASK, localStatus);
+            addCategory(set, U_GC_NL_MASK, localStatus);
+            addCategory(set, U_GC_SC_MASK, localStatus);
+            addCategory(set, U_GC_PC_MASK, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaLetter")) == 0) {
+            addCategory(set, U_GC_L_MASK, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaLetterOrDigit")) == 0) {
+            addCategory(set, U_GC_L_MASK, localStatus);
+            addCategory(set, U_GC_ND_MASK, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaLowerCase")) == 0) {
+            addCategory(set, U_GC_LL_MASK, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaMirrored")) == 0) {
+            set->applyIntPropertyValue(UCHAR_BIDI_MIRRORED, 1, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaSpaceChar")) == 0) {
+            addCategory(set, U_GC_Z_MASK, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaSupplementaryCodePoint")) == 0) {
+            set->add(0x10000, UnicodeSet::MAX_VALUE);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaTitleCase")) == 0) {
+            addCategory(set, U_GC_LT_MASK, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaUnicodeIdentifierStart")) == 0) {
+            addCategory(set, U_GC_L_MASK, localStatus);
+            addCategory(set, U_GC_NL_MASK, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaUnicodeIdentifierPart")) == 0) {
+            addCategory(set, U_GC_L_MASK, localStatus);
+            addCategory(set, U_GC_PC_MASK, localStatus);
+            addCategory(set, U_GC_ND_MASK, localStatus);
+            addCategory(set, U_GC_NL_MASK, localStatus);
+            addCategory(set, U_GC_MC_MASK, localStatus);
+            addCategory(set, U_GC_MN_MASK, localStatus);
+            addIdentifierIgnorable(set, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaUpperCase")) == 0) {
+            addCategory(set, U_GC_LU_MASK, localStatus);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaValidCodePoint")) == 0) {
+            set->add(0, UnicodeSet::MAX_VALUE);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaWhitespace")) == 0) {
+            addCategory(set, U_GC_Z_MASK, localStatus);
+            set->removeAll(UnicodeSet().add(0xa0).add(0x2007).add(0x202f));
+            set->add(9, 0x0d).add(0x1c, 0x1f);
+        }
+        else if (mPropName.compare(UNICODE_STRING_SIMPLE("all")) == 0) {
+            set->add(0, UnicodeSet::MAX_VALUE);
+        }
+
+        if (U_SUCCESS(localStatus) && !set->isEmpty()) {
+            *fStatus = U_ZERO_ERROR;
+            if (usetFlags & USET_CASE_INSENSITIVE) {
+                set->closeOver(USET_CASE_INSENSITIVE);
+            }
+            if (negated) {
+                set->complement();
+            }
+            return set;
+        }
+        delete set;
+        set = NULL;
+    }
+    error(*fStatus);
+    return NULL; 
+}
+
+
+
+//
+//  SetEval   Part of the evaluation of [set expressions].
+//            Perform any pending (stacked) operations with precedence
+//            equal or greater to that of the next operator encountered
+//            in the expression.
+//
+void RegexCompile::setEval(int32_t nextOp) {
+    UnicodeSet *rightOperand = NULL;
+    UnicodeSet *leftOperand  = NULL;
+    for (;;) {
+        U_ASSERT(fSetOpStack.empty()==FALSE);
+        int32_t pendingSetOperation = fSetOpStack.peeki();
+        if ((pendingSetOperation&0xffff0000) < (nextOp&0xffff0000)) {
+            break;
+        }
+        fSetOpStack.popi();
+        U_ASSERT(fSetStack.empty() == FALSE);
+        rightOperand = (UnicodeSet *)fSetStack.peek();
+        switch (pendingSetOperation) {
+            case setNegation:
+                rightOperand->complement();
+                break;
+            case setCaseClose:
+                // TODO: need a simple close function.  Ticket 6065
+                rightOperand->closeOver(USET_CASE_INSENSITIVE);
+                rightOperand->removeAllStrings();
+                break;
+            case setDifference1:
+            case setDifference2:
+                fSetStack.pop();
+                leftOperand = (UnicodeSet *)fSetStack.peek();
+                leftOperand->removeAll(*rightOperand);
+                delete rightOperand;
+                break;
+            case setIntersection1:
+            case setIntersection2:
+                fSetStack.pop();
+                leftOperand = (UnicodeSet *)fSetStack.peek();
+                leftOperand->retainAll(*rightOperand);
+                delete rightOperand;
+                break;
+            case setUnion:
+                fSetStack.pop();
+                leftOperand = (UnicodeSet *)fSetStack.peek();
+                leftOperand->addAll(*rightOperand);
+                delete rightOperand;
+                break;
+            default:
+                U_ASSERT(FALSE);
+                break;
+            }
+        }
+    }
+
+void RegexCompile::setPushOp(int32_t op) {
+    setEval(op);
+    fSetOpStack.push(op, *fStatus);
+    fSetStack.push(new UnicodeSet(), *fStatus);
+}
+
+U_NAMESPACE_END
+#endif  // !UCONFIG_NO_REGULAR_EXPRESSIONS
+