Move bundled copy of sqlite one level deeper to better separate it...

third_party/sqlite/src/expr.c

-/*
-** 2001 September 15
-**
-** The author disclaims copyright to this source code.  In place of
-** a legal notice, here is a blessing:
-**
-**    May you do good and not evil.
-**    May you find forgiveness for yourself and forgive others.
-**    May you share freely, never taking more than you give.
-**
-*************************************************************************
-** This file contains routines used for analyzing expressions and
-** for generating VDBE code that evaluates expressions in SQLite.
-*/
-#include "sqliteInt.h"
-
-/*
-** Return the 'affinity' of the expression pExpr if any.
-**
-** If pExpr is a column, a reference to a column via an 'AS' alias,
-** or a sub-select with a column as the return value, then the 
-** affinity of that column is returned. Otherwise, 0x00 is returned,
-** indicating no affinity for the expression.
-**
-** i.e. the WHERE clause expresssions in the following statements all
-** have an affinity:
-**
-** CREATE TABLE t1(a);
-** SELECT * FROM t1 WHERE a;
-** SELECT a AS b FROM t1 WHERE b;
-** SELECT * FROM t1 WHERE (select a from t1);
-*/
-char sqlite3ExprAffinity(Expr *pExpr){
-  int op = pExpr->op;
-  if( op==TK_SELECT ){
-    assert( pExpr->flags&EP_xIsSelect );
-    return sqlite3ExprAffinity(pExpr->x.pSelect->pEList->a[0].pExpr);
-  }
-#ifndef SQLITE_OMIT_CAST
-  if( op==TK_CAST ){
-    assert( !ExprHasProperty(pExpr, EP_IntValue) );
-    return sqlite3AffinityType(pExpr->u.zToken);
-  }
-#endif
-  if( (op==TK_AGG_COLUMN || op==TK_COLUMN || op==TK_REGISTER) 
-   && pExpr->pTab!=0
-  ){
-    /* op==TK_REGISTER && pExpr->pTab!=0 happens when pExpr was originally
-    ** a TK_COLUMN but was previously evaluated and cached in a register */
-    int j = pExpr->iColumn;
-    if( j<0 ) return SQLITE_AFF_INTEGER;
-    assert( pExpr->pTab && j<pExpr->pTab->nCol );
-    return pExpr->pTab->aCol[j].affinity;
-  }
-  return pExpr->affinity;
-}
-
-/*
-** Set the collating sequence for expression pExpr to be the collating
-** sequence named by pToken.   Return a pointer to the revised expression.
-** The collating sequence is marked as "explicit" using the EP_ExpCollate
-** flag.  An explicit collating sequence will override implicit
-** collating sequences.
-*/
-Expr *sqlite3ExprSetColl(Parse *pParse, Expr *pExpr, Token *pCollName){
-  char *zColl = 0;            /* Dequoted name of collation sequence */
-  CollSeq *pColl;
-  sqlite3 *db = pParse->db;
-  zColl = sqlite3NameFromToken(db, pCollName);
-  if( pExpr && zColl ){
-    pColl = sqlite3LocateCollSeq(pParse, zColl);
-    if( pColl ){
-      pExpr->pColl = pColl;
-      pExpr->flags |= EP_ExpCollate;
-    }
-  }
-  sqlite3DbFree(db, zColl);
-  return pExpr;
-}
-
-/*
-** Return the default collation sequence for the expression pExpr. If
-** there is no default collation type, return 0.
-*/
-CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr){
-  CollSeq *pColl = 0;
-  Expr *p = pExpr;
-  while( ALWAYS(p) ){
-    int op;
-    pColl = p->pColl;
-    if( pColl ) break;
-    op = p->op;
-    if( p->pTab!=0 && (
-        op==TK_AGG_COLUMN || op==TK_COLUMN || op==TK_REGISTER || op==TK_TRIGGER
-    )){
-      /* op==TK_REGISTER && p->pTab!=0 happens when pExpr was originally
-      ** a TK_COLUMN but was previously evaluated and cached in a register */
-      const char *zColl;
-      int j = p->iColumn;
-      if( j>=0 ){
-        sqlite3 *db = pParse->db;
-        zColl = p->pTab->aCol[j].zColl;
-        pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
-        pExpr->pColl = pColl;
-      }
-      break;
-    }
-    if( op!=TK_CAST && op!=TK_UPLUS ){
-      break;
-    }
-    p = p->pLeft;
-  }
-  if( sqlite3CheckCollSeq(pParse, pColl) ){ 
-    pColl = 0;
-  }
-  return pColl;
-}
-
-/*
-** pExpr is an operand of a comparison operator.  aff2 is the
-** type affinity of the other operand.  This routine returns the
-** type affinity that should be used for the comparison operator.
-*/
-char sqlite3CompareAffinity(Expr *pExpr, char aff2){
-  char aff1 = sqlite3ExprAffinity(pExpr);
-  if( aff1 && aff2 ){
-    /* Both sides of the comparison are columns. If one has numeric
-    ** affinity, use that. Otherwise use no affinity.
-    */
-    if( sqlite3IsNumericAffinity(aff1) || sqlite3IsNumericAffinity(aff2) ){
-      return SQLITE_AFF_NUMERIC;
-    }else{
-      return SQLITE_AFF_NONE;
-    }
-  }else if( !aff1 && !aff2 ){
-    /* Neither side of the comparison is a column.  Compare the
-    ** results directly.
-    */
-    return SQLITE_AFF_NONE;
-  }else{
-    /* One side is a column, the other is not. Use the columns affinity. */
-    assert( aff1==0 || aff2==0 );
-    return (aff1 + aff2);
-  }
-}
-
-/*
-** pExpr is a comparison operator.  Return the type affinity that should
-** be applied to both operands prior to doing the comparison.
-*/
-static char comparisonAffinity(Expr *pExpr){
-  char aff;
-  assert( pExpr->op==TK_EQ || pExpr->op==TK_IN || pExpr->op==TK_LT ||
-          pExpr->op==TK_GT || pExpr->op==TK_GE || pExpr->op==TK_LE ||
-          pExpr->op==TK_NE );
-  assert( pExpr->pLeft );
-  aff = sqlite3ExprAffinity(pExpr->pLeft);
-  if( pExpr->pRight ){
-    aff = sqlite3CompareAffinity(pExpr->pRight, aff);
-  }else if( ExprHasProperty(pExpr, EP_xIsSelect) ){
-    aff = sqlite3CompareAffinity(pExpr->x.pSelect->pEList->a[0].pExpr, aff);
-  }else if( !aff ){
-    aff = SQLITE_AFF_NONE;
-  }
-  return aff;
-}
-
-/*
-** pExpr is a comparison expression, eg. '=', '<', IN(...) etc.
-** idx_affinity is the affinity of an indexed column. Return true
-** if the index with affinity idx_affinity may be used to implement
-** the comparison in pExpr.
-*/
-int sqlite3IndexAffinityOk(Expr *pExpr, char idx_affinity){
-  char aff = comparisonAffinity(pExpr);
-  switch( aff ){
-    case SQLITE_AFF_NONE:
-      return 1;
-    case SQLITE_AFF_TEXT:
-      return idx_affinity==SQLITE_AFF_TEXT;
-    default:
-      return sqlite3IsNumericAffinity(idx_affinity);
-  }
-}
-
-/*
-** Return the P5 value that should be used for a binary comparison
-** opcode (OP_Eq, OP_Ge etc.) used to compare pExpr1 and pExpr2.
-*/
-static u8 binaryCompareP5(Expr *pExpr1, Expr *pExpr2, int jumpIfNull){
-  u8 aff = (char)sqlite3ExprAffinity(pExpr2);
-  aff = (u8)sqlite3CompareAffinity(pExpr1, aff) | (u8)jumpIfNull;
-  return aff;
-}
-
-/*
-** Return a pointer to the collation sequence that should be used by
-** a binary comparison operator comparing pLeft and pRight.
-**
-** If the left hand expression has a collating sequence type, then it is
-** used. Otherwise the collation sequence for the right hand expression
-** is used, or the default (BINARY) if neither expression has a collating
-** type.
-**
-** Argument pRight (but not pLeft) may be a null pointer. In this case,
-** it is not considered.
-*/
-CollSeq *sqlite3BinaryCompareCollSeq(
-  Parse *pParse, 
-  Expr *pLeft, 
-  Expr *pRight
-){
-  CollSeq *pColl;
-  assert( pLeft );
-  if( pLeft->flags & EP_ExpCollate ){
-    assert( pLeft->pColl );
-    pColl = pLeft->pColl;
-  }else if( pRight && pRight->flags & EP_ExpCollate ){
-    assert( pRight->pColl );
-    pColl = pRight->pColl;
-  }else{
-    pColl = sqlite3ExprCollSeq(pParse, pLeft);
-    if( !pColl ){
-      pColl = sqlite3ExprCollSeq(pParse, pRight);
-    }
-  }
-  return pColl;
-}
-
-/*
-** Generate the operands for a comparison operation.  Before
-** generating the code for each operand, set the EP_AnyAff
-** flag on the expression so that it will be able to used a
-** cached column value that has previously undergone an
-** affinity change.
-*/
-static void codeCompareOperands(
-  Parse *pParse,    /* Parsing and code generating context */
-  Expr *pLeft,      /* The left operand */
-  int *pRegLeft,    /* Register where left operand is stored */
-  int *pFreeLeft,   /* Free this register when done */
-  Expr *pRight,     /* The right operand */
-  int *pRegRight,   /* Register where right operand is stored */
-  int *pFreeRight   /* Write temp register for right operand there */
-){
-  while( pLeft->op==TK_UPLUS ) pLeft = pLeft->pLeft;
-  pLeft->flags |= EP_AnyAff;
-  *pRegLeft = sqlite3ExprCodeTemp(pParse, pLeft, pFreeLeft);
-  while( pRight->op==TK_UPLUS ) pRight = pRight->pLeft;
-  pRight->flags |= EP_AnyAff;
-  *pRegRight = sqlite3ExprCodeTemp(pParse, pRight, pFreeRight);
-}
-
-/*
-** Generate code for a comparison operator.
-*/
-static int codeCompare(
-  Parse *pParse,    /* The parsing (and code generating) context */
-  Expr *pLeft,      /* The left operand */
-  Expr *pRight,     /* The right operand */
-  int opcode,       /* The comparison opcode */
-  int in1, int in2, /* Register holding operands */
-  int dest,         /* Jump here if true.  */
-  int jumpIfNull    /* If true, jump if either operand is NULL */
-){
-  int p5;
-  int addr;
-  CollSeq *p4;
-
-  p4 = sqlite3BinaryCompareCollSeq(pParse, pLeft, pRight);
-  p5 = binaryCompareP5(pLeft, pRight, jumpIfNull);
-  addr = sqlite3VdbeAddOp4(pParse->pVdbe, opcode, in2, dest, in1,
-                           (void*)p4, P4_COLLSEQ);
-  sqlite3VdbeChangeP5(pParse->pVdbe, (u8)p5);
-  if( (p5 & SQLITE_AFF_MASK)!=SQLITE_AFF_NONE ){
-    sqlite3ExprCacheAffinityChange(pParse, in1, 1);
-    sqlite3ExprCacheAffinityChange(pParse, in2, 1);
-  }
-  return addr;
-}
-
-#if SQLITE_MAX_EXPR_DEPTH>0
-/*
-** Check that argument nHeight is less than or equal to the maximum
-** expression depth allowed. If it is not, leave an error message in
-** pParse.
-*/
-int sqlite3ExprCheckHeight(Parse *pParse, int nHeight){
-  int rc = SQLITE_OK;
-  int mxHeight = pParse->db->aLimit[SQLITE_LIMIT_EXPR_DEPTH];
-  if( nHeight>mxHeight ){
-    sqlite3ErrorMsg(pParse, 
-       "Expression tree is too large (maximum depth %d)", mxHeight
-    );
-    rc = SQLITE_ERROR;
-  }
-  return rc;
-}
-
-/* The following three functions, heightOfExpr(), heightOfExprList()
-** and heightOfSelect(), are used to determine the maximum height
-** of any expression tree referenced by the structure passed as the
-** first argument.
-**
-** If this maximum height is greater than the current value pointed
-** to by pnHeight, the second parameter, then set *pnHeight to that
-** value.
-*/
-static void heightOfExpr(Expr *p, int *pnHeight){
-  if( p ){
-    if( p->nHeight>*pnHeight ){
-      *pnHeight = p->nHeight;
-    }
-  }
-}
-static void heightOfExprList(ExprList *p, int *pnHeight){
-  if( p ){
-    int i;
-    for(i=0; i<p->nExpr; i++){
-      heightOfExpr(p->a[i].pExpr, pnHeight);
-    }
-  }
-}
-static void heightOfSelect(Select *p, int *pnHeight){
-  if( p ){
-    heightOfExpr(p->pWhere, pnHeight);
-    heightOfExpr(p->pHaving, pnHeight);
-    heightOfExpr(p->pLimit, pnHeight);
-    heightOfExpr(p->pOffset, pnHeight);
-    heightOfExprList(p->pEList, pnHeight);
-    heightOfExprList(p->pGroupBy, pnHeight);
-    heightOfExprList(p->pOrderBy, pnHeight);
-    heightOfSelect(p->pPrior, pnHeight);
-  }
-}
-
-/*
-** Set the Expr.nHeight variable in the structure passed as an 
-** argument. An expression with no children, Expr.pList or 
-** Expr.pSelect member has a height of 1. Any other expression
-** has a height equal to the maximum height of any other 
-** referenced Expr plus one.
-*/
-static void exprSetHeight(Expr *p){
-  int nHeight = 0;
-  heightOfExpr(p->pLeft, &nHeight);
-  heightOfExpr(p->pRight, &nHeight);
-  if( ExprHasProperty(p, EP_xIsSelect) ){
-    heightOfSelect(p->x.pSelect, &nHeight);
-  }else{
-    heightOfExprList(p->x.pList, &nHeight);
-  }
-  p->nHeight = nHeight + 1;
-}
-
-/*
-** Set the Expr.nHeight variable using the exprSetHeight() function. If
-** the height is greater than the maximum allowed expression depth,
-** leave an error in pParse.
-*/
-void sqlite3ExprSetHeight(Parse *pParse, Expr *p){
-  exprSetHeight(p);
-  sqlite3ExprCheckHeight(pParse, p->nHeight);
-}
-
-/*
-** Return the maximum height of any expression tree referenced
-** by the select statement passed as an argument.
-*/
-int sqlite3SelectExprHeight(Select *p){
-  int nHeight = 0;
-  heightOfSelect(p, &nHeight);
-  return nHeight;
-}
-#else
-  #define exprSetHeight(y)
-#endif /* SQLITE_MAX_EXPR_DEPTH>0 */
-
-/*
-** This routine is the core allocator for Expr nodes.
-**
-** Construct a new expression node and return a pointer to it.  Memory
-** for this node and for the pToken argument is a single allocation
-** obtained from sqlite3DbMalloc().  The calling function
-** is responsible for making sure the node eventually gets freed.
-**
-** If dequote is true, then the token (if it exists) is dequoted.
-** If dequote is false, no dequoting is performance.  The deQuote
-** parameter is ignored if pToken is NULL or if the token does not
-** appear to be quoted.  If the quotes were of the form "..." (double-quotes)
-** then the EP_DblQuoted flag is set on the expression node.
-**
-** Special case:  If op==TK_INTEGER and pToken points to a string that
-** can be translated into a 32-bit integer, then the token is not
-** stored in u.zToken.  Instead, the integer values is written
-** into u.iValue and the EP_IntValue flag is set.  No extra storage
-** is allocated to hold the integer text and the dequote flag is ignored.
-*/
-Expr *sqlite3ExprAlloc(
-  sqlite3 *db,            /* Handle for sqlite3DbMallocZero() (may be null) */
-  int op,                 /* Expression opcode */
-  const Token *pToken,    /* Token argument.  Might be NULL */
-  int dequote             /* True to dequote */
-){
-  Expr *pNew;
-  int nExtra = 0;
-  int iValue = 0;
-
-  if( pToken ){
-    if( op!=TK_INTEGER || pToken->z==0
-          || sqlite3GetInt32(pToken->z, &iValue)==0 ){
-      nExtra = pToken->n+1;
-    }
-  }
-  pNew = sqlite3DbMallocZero(db, sizeof(Expr)+nExtra);
-  if( pNew ){
-    pNew->op = (u8)op;
-    pNew->iAgg = -1;
-    if( pToken ){
-      if( nExtra==0 ){
-        pNew->flags |= EP_IntValue;
-        pNew->u.iValue = iValue;
-      }else{
-        int c;
-        pNew->u.zToken = (char*)&pNew[1];
-        memcpy(pNew->u.zToken, pToken->z, pToken->n);
-        pNew->u.zToken[pToken->n] = 0;
-        if( dequote && nExtra>=3 
-             && ((c = pToken->z[0])=='\'' || c=='"' || c=='[' || c=='`') ){
-          sqlite3Dequote(pNew->u.zToken);
-          if( c=='"' ) pNew->flags |= EP_DblQuoted;
-        }
-      }
-    }
-#if SQLITE_MAX_EXPR_DEPTH>0
-    pNew->nHeight = 1;
-#endif  
-  }
-  return pNew;
-}
-
-/*
-** Allocate a new expression node from a zero-terminated token that has
-** already been dequoted.
-*/
-Expr *sqlite3Expr(
-  sqlite3 *db,            /* Handle for sqlite3DbMallocZero() (may be null) */
-  int op,                 /* Expression opcode */
-  const char *zToken      /* Token argument.  Might be NULL */
-){
-  Token x;
-  x.z = zToken;
-  x.n = zToken ? sqlite3Strlen30(zToken) : 0;
-  return sqlite3ExprAlloc(db, op, &x, 0);
-}
-
-/*
-** Attach subtrees pLeft and pRight to the Expr node pRoot.
-**
-** If pRoot==NULL that means that a memory allocation error has occurred.
-** In that case, delete the subtrees pLeft and pRight.
-*/
-void sqlite3ExprAttachSubtrees(
-  sqlite3 *db,
-  Expr *pRoot,
-  Expr *pLeft,
-  Expr *pRight
-){
-  if( pRoot==0 ){
-    assert( db->mallocFailed );
-    sqlite3ExprDelete(db, pLeft);
-    sqlite3ExprDelete(db, pRight);
-  }else{
-    if( pRight ){
-      pRoot->pRight = pRight;
-      if( pRight->flags & EP_ExpCollate ){
-        pRoot->flags |= EP_ExpCollate;
-        pRoot->pColl = pRight->pColl;
-      }
-    }
-    if( pLeft ){
-      pRoot->pLeft = pLeft;
-      if( pLeft->flags & EP_ExpCollate ){
-        pRoot->flags |= EP_ExpCollate;
-        pRoot->pColl = pLeft->pColl;
-      }
-    }
-    exprSetHeight(pRoot);
-  }
-}
-
-/*
-** Allocate a Expr node which joins as many as two subtrees.
-**
-** One or both of the subtrees can be NULL.  Return a pointer to the new
-** Expr node.  Or, if an OOM error occurs, set pParse->db->mallocFailed,
-** free the subtrees and return NULL.
-*/
-Expr *sqlite3PExpr(
-  Parse *pParse,          /* Parsing context */
-  int op,                 /* Expression opcode */
-  Expr *pLeft,            /* Left operand */
-  Expr *pRight,           /* Right operand */
-  const Token *pToken     /* Argument token */
-){
-  Expr *p = sqlite3ExprAlloc(pParse->db, op, pToken, 1);
-  sqlite3ExprAttachSubtrees(pParse->db, p, pLeft, pRight);
-  return p;
-}
-
-/*
-** Join two expressions using an AND operator.  If either expression is
-** NULL, then just return the other expression.
-*/
-Expr *sqlite3ExprAnd(sqlite3 *db, Expr *pLeft, Expr *pRight){
-  if( pLeft==0 ){
-    return pRight;
-  }else if( pRight==0 ){
-    return pLeft;
-  }else{
-    Expr *pNew = sqlite3ExprAlloc(db, TK_AND, 0, 0);
-    sqlite3ExprAttachSubtrees(db, pNew, pLeft, pRight);
-    return pNew;
-  }
-}
-
-/*
-** Construct a new expression node for a function with multiple
-** arguments.
-*/
-Expr *sqlite3ExprFunction(Parse *pParse, ExprList *pList, Token *pToken){
-  Expr *pNew;
-  sqlite3 *db = pParse->db;
-  assert( pToken );
-  pNew = sqlite3ExprAlloc(db, TK_FUNCTION, pToken, 1);
-  if( pNew==0 ){
-    sqlite3ExprListDelete(db, pList); /* Avoid memory leak when malloc fails */
-    return 0;
-  }
-  pNew->x.pList = pList;
-  assert( !ExprHasProperty(pNew, EP_xIsSelect) );
-  sqlite3ExprSetHeight(pParse, pNew);
-  return pNew;
-}
-
-/*
-** Assign a variable number to an expression that encodes a wildcard
-** in the original SQL statement.  
-**
-** Wildcards consisting of a single "?" are assigned the next sequential
-** variable number.
-**
-** Wildcards of the form "?nnn" are assigned the number "nnn".  We make
-** sure "nnn" is not too be to avoid a denial of service attack when
-** the SQL statement comes from an external source.
-**
-** Wildcards of the form ":aaa", "@aaa", or "$aaa" are assigned the same number
-** as the previous instance of the same wildcard.  Or if this is the first
-** instance of the wildcard, the next sequenial variable number is
-** assigned.
-*/
-void sqlite3ExprAssignVarNumber(Parse *pParse, Expr *pExpr){
-  sqlite3 *db = pParse->db;
-  const char *z;
-
-  if( pExpr==0 ) return;
-  assert( !ExprHasAnyProperty(pExpr, EP_IntValue|EP_Reduced|EP_TokenOnly) );
-  z = pExpr->u.zToken;
-  assert( z!=0 );
-  assert( z[0]!=0 );
-  if( z[1]==0 ){
-    /* Wildcard of the form "?".  Assign the next variable number */
-    assert( z[0]=='?' );
-    pExpr->iTable = ++pParse->nVar;
-  }else if( z[0]=='?' ){
-    /* Wildcard of the form "?nnn".  Convert "nnn" to an integer and
-    ** use it as the variable number */
-    int i;
-    pExpr->iTable = i = atoi((char*)&z[1]);
-    testcase( i==0 );
-    testcase( i==1 );
-    testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]-1 );
-    testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] );
-    if( i<1 || i>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){
-      sqlite3ErrorMsg(pParse, "variable number must be between ?1 and ?%d",
-          db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]);
-    }
-    if( i>pParse->nVar ){
-      pParse->nVar = i;
-    }
-  }else{
-    /* Wildcards like ":aaa", "$aaa" or "@aaa".  Reuse the same variable
-    ** number as the prior appearance of the same name, or if the name
-    ** has never appeared before, reuse the same variable number
-    */
-    int i;
-    u32 n;
-    n = sqlite3Strlen30(z);
-    for(i=0; i<pParse->nVarExpr; i++){
-      Expr *pE = pParse->apVarExpr[i];
-      assert( pE!=0 );
-      if( memcmp(pE->u.zToken, z, n)==0 && pE->u.zToken[n]==0 ){
-        pExpr->iTable = pE->iTable;
-        break;
-      }
-    }
-    if( i>=pParse->nVarExpr ){
-      pExpr->iTable = ++pParse->nVar;
-      if( pParse->nVarExpr>=pParse->nVarExprAlloc-1 ){
-        pParse->nVarExprAlloc += pParse->nVarExprAlloc + 10;
-        pParse->apVarExpr =
-            sqlite3DbReallocOrFree(
-              db,
-              pParse->apVarExpr,
-              pParse->nVarExprAlloc*sizeof(pParse->apVarExpr[0])
-            );
-      }
-      if( !db->mallocFailed ){
-        assert( pParse->apVarExpr!=0 );
-        pParse->apVarExpr[pParse->nVarExpr++] = pExpr;
-      }
-    }
-  } 
-  if( !pParse->nErr && pParse->nVar>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){
-    sqlite3ErrorMsg(pParse, "too many SQL variables");
-  }
-}
-
-/*
-** Clear an expression structure without deleting the structure itself.
-** Substructure is deleted.
-*/
-void sqlite3ExprClear(sqlite3 *db, Expr *p){
-  assert( p!=0 );
-  if( !ExprHasAnyProperty(p, EP_TokenOnly) ){
-    sqlite3ExprDelete(db, p->pLeft);
-    sqlite3ExprDelete(db, p->pRight);
-    if( !ExprHasProperty(p, EP_Reduced) && (p->flags2 & EP2_MallocedToken)!=0 ){
-      sqlite3DbFree(db, p->u.zToken);
-    }
-    if( ExprHasProperty(p, EP_xIsSelect) ){
-      sqlite3SelectDelete(db, p->x.pSelect);
-    }else{
-      sqlite3ExprListDelete(db, p->x.pList);
-    }
-  }
-}
-
-/*
-** Recursively delete an expression tree.
-*/
-void sqlite3ExprDelete(sqlite3 *db, Expr *p){
-  if( p==0 ) return;
-  sqlite3ExprClear(db, p);
-  if( !ExprHasProperty(p, EP_Static) ){
-    sqlite3DbFree(db, p);
-  }
-}
-
-/*
-** Return the number of bytes allocated for the expression structure 
-** passed as the first argument. This is always one of EXPR_FULLSIZE,
-** EXPR_REDUCEDSIZE or EXPR_TOKENONLYSIZE.
-*/
-static int exprStructSize(Expr *p){
-  if( ExprHasProperty(p, EP_TokenOnly) ) return EXPR_TOKENONLYSIZE;
-  if( ExprHasProperty(p, EP_Reduced) ) return EXPR_REDUCEDSIZE;
-  return EXPR_FULLSIZE;
-}
-
-/*
-** The dupedExpr*Size() routines each return the number of bytes required
-** to store a copy of an expression or expression tree.  They differ in
-** how much of the tree is measured.
-**
-**     dupedExprStructSize()     Size of only the Expr structure 
-**     dupedExprNodeSize()       Size of Expr + space for token
-**     dupedExprSize()           Expr + token + subtree components
-**
-***************************************************************************
-**
-** The dupedExprStructSize() function returns two values OR-ed together:  
-** (1) the space required for a copy of the Expr structure only and 
-** (2) the EP_xxx flags that indicate what the structure size should be.
-** The return values is always one of:
-**
-**      EXPR_FULLSIZE
-**      EXPR_REDUCEDSIZE   | EP_Reduced
-**      EXPR_TOKENONLYSIZE | EP_TokenOnly
-**
-** The size of the structure can be found by masking the return value
-** of this routine with 0xfff.  The flags can be found by masking the
-** return value with EP_Reduced|EP_TokenOnly.
-**
-** Note that with flags==EXPRDUP_REDUCE, this routines works on full-size
-** (unreduced) Expr objects as they or originally constructed by the parser.
-** During expression analysis, extra information is computed and moved into
-** later parts of teh Expr object and that extra information might get chopped
-** off if the expression is reduced.  Note also that it does not work to
-** make a EXPRDUP_REDUCE copy of a reduced expression.  It is only legal
-** to reduce a pristine expression tree from the parser.  The implementation
-** of dupedExprStructSize() contain multiple assert() statements that attempt
-** to enforce this constraint.
-*/
-static int dupedExprStructSize(Expr *p, int flags){
-  int nSize;
-  assert( flags==EXPRDUP_REDUCE || flags==0 ); /* Only one flag value allowed */
-  if( 0==(flags&EXPRDUP_REDUCE) ){
-    nSize = EXPR_FULLSIZE;
-  }else{
-    assert( !ExprHasAnyProperty(p, EP_TokenOnly|EP_Reduced) );
-    assert( !ExprHasProperty(p, EP_FromJoin) ); 
-    assert( (p->flags2 & EP2_MallocedToken)==0 );
-    assert( (p->flags2 & EP2_Irreducible)==0 );
-    if( p->pLeft || p->pRight || p->pColl || p->x.pList ){
-      nSize = EXPR_REDUCEDSIZE | EP_Reduced;
-    }else{
-      nSize = EXPR_TOKENONLYSIZE | EP_TokenOnly;
-    }
-  }
-  return nSize;
-}
-
-/*
-** This function returns the space in bytes required to store the copy 
-** of the Expr structure and a copy of the Expr.u.zToken string (if that
-** string is defined.)
-*/
-static int dupedExprNodeSize(Expr *p, int flags){
-  int nByte = dupedExprStructSize(p, flags) & 0xfff;
-  if( !ExprHasProperty(p, EP_IntValue) && p->u.zToken ){
-    nByte += sqlite3Strlen30(p->u.zToken)+1;
-  }
-  return ROUND8(nByte);
-}
-
-/*
-** Return the number of bytes required to create a duplicate of the 
-** expression passed as the first argument. The second argument is a
-** mask containing EXPRDUP_XXX flags.
-**
-** The value returned includes space to create a copy of the Expr struct
-** itself and the buffer referred to by Expr.u.zToken, if any.
-**
-** If the EXPRDUP_REDUCE flag is set, then the return value includes 
-** space to duplicate all Expr nodes in the tree formed by Expr.pLeft 
-** and Expr.pRight variables (but not for any structures pointed to or 
-** descended from the Expr.x.pList or Expr.x.pSelect variables).
-*/
-static int dupedExprSize(Expr *p, int flags){
-  int nByte = 0;
-  if( p ){
-    nByte = dupedExprNodeSize(p, flags);
-    if( flags&EXPRDUP_REDUCE ){
-      nByte += dupedExprSize(p->pLeft, flags) + dupedExprSize(p->pRight, flags);
-    }
-  }
-  return nByte;
-}
-
-/*
-** This function is similar to sqlite3ExprDup(), except that if pzBuffer 
-** is not NULL then *pzBuffer is assumed to point to a buffer large enough 
-** to store the copy of expression p, the copies of p->u.zToken
-** (if applicable), and the copies of the p->pLeft and p->pRight expressions,
-** if any. Before returning, *pzBuffer is set to the first byte passed the
-** portion of the buffer copied into by this function.
-*/
-static Expr *exprDup(sqlite3 *db, Expr *p, int flags, u8 **pzBuffer){
-  Expr *pNew = 0;                      /* Value to return */
-  if( p ){
-    const int isReduced = (flags&EXPRDUP_REDUCE);
-    u8 *zAlloc;
-    u32 staticFlag = 0;
-
-    assert( pzBuffer==0 || isReduced );
-
-    /* Figure out where to write the new Expr structure. */
-    if( pzBuffer ){
-      zAlloc = *pzBuffer;
-      staticFlag = EP_Static;
-    }else{
-      zAlloc = sqlite3DbMallocRaw(db, dupedExprSize(p, flags));
-    }
-    pNew = (Expr *)zAlloc;
-
-    if( pNew ){
-      /* Set nNewSize to the size allocated for the structure pointed to
-      ** by pNew. This is either EXPR_FULLSIZE, EXPR_REDUCEDSIZE or
-      ** EXPR_TOKENONLYSIZE. nToken is set to the number of bytes consumed
-      ** by the copy of the p->u.zToken string (if any).
-      */
-      const unsigned nStructSize = dupedExprStructSize(p, flags);
-      const int nNewSize = nStructSize & 0xfff;
-      int nToken;
-      if( !ExprHasProperty(p, EP_IntValue) && p->u.zToken ){
-        nToken = sqlite3Strlen30(p->u.zToken) + 1;
-      }else{
-        nToken = 0;
-      }
-      if( isReduced ){
-        assert( ExprHasProperty(p, EP_Reduced)==0 );
-        memcpy(zAlloc, p, nNewSize);
-      }else{
-        int nSize = exprStructSize(p);
-        memcpy(zAlloc, p, nSize);
-        if( EXPR_FULLSIZE>nSize ){
-          memset(&zAlloc[nSize], 0, EXPR_FULLSIZE-nSize);
-        }
-      }
-
-      /* Set the EP_Reduced, EP_TokenOnly, and EP_Static flags appropriately. */
-      pNew->flags &= ~(EP_Reduced|EP_TokenOnly|EP_Static);
-      pNew->flags |= nStructSize & (EP_Reduced|EP_TokenOnly);
-      pNew->flags |= staticFlag;
-
-      /* Copy the p->u.zToken string, if any. */
-      if( nToken ){
-        char *zToken = pNew->u.zToken = (char*)&zAlloc[nNewSize];
-        memcpy(zToken, p->u.zToken, nToken);
-      }
-
-      if( 0==((p->flags|pNew->flags) & EP_TokenOnly) ){
-        /* Fill in the pNew->x.pSelect or pNew->x.pList member. */
-        if( ExprHasProperty(p, EP_xIsSelect) ){
-          pNew->x.pSelect = sqlite3SelectDup(db, p->x.pSelect, isReduced);
-        }else{
-          pNew->x.pList = sqlite3ExprListDup(db, p->x.pList, isReduced);
-        }
-      }
-
-      /* Fill in pNew->pLeft and pNew->pRight. */
-      if( ExprHasAnyProperty(pNew, EP_Reduced|EP_TokenOnly) ){
-        zAlloc += dupedExprNodeSize(p, flags);
-        if( ExprHasProperty(pNew, EP_Reduced) ){
-          pNew->pLeft = exprDup(db, p->pLeft, EXPRDUP_REDUCE, &zAlloc);
-          pNew->pRight = exprDup(db, p->pRight, EXPRDUP_REDUCE, &zAlloc);
-        }
-        if( pzBuffer ){
-          *pzBuffer = zAlloc;
-        }
-      }else{
-        pNew->flags2 = 0;
-        if( !ExprHasAnyProperty(p, EP_TokenOnly) ){
-          pNew->pLeft = sqlite3ExprDup(db, p->pLeft, 0);
-          pNew->pRight = sqlite3ExprDup(db, p->pRight, 0);
-        }
-      }
-
-    }
-  }
-  return pNew;
-}
-
-/*
-** The following group of routines make deep copies of expressions,
-** expression lists, ID lists, and select statements.  The copies can
-** be deleted (by being passed to their respective ...Delete() routines)
-** without effecting the originals.
-**
-** The expression list, ID, and source lists return by sqlite3ExprListDup(),
-** sqlite3IdListDup(), and sqlite3SrcListDup() can not be further expanded 
-** by subsequent calls to sqlite*ListAppend() routines.
-**
-** Any tables that the SrcList might point to are not duplicated.
-**
-** The flags parameter contains a combination of the EXPRDUP_XXX flags.
-** If the EXPRDUP_REDUCE flag is set, then the structure returned is a
-** truncated version of the usual Expr structure that will be stored as
-** part of the in-memory representation of the database schema.
-*/
-Expr *sqlite3ExprDup(sqlite3 *db, Expr *p, int flags){
-  return exprDup(db, p, flags, 0);
-}
-ExprList *sqlite3ExprListDup(sqlite3 *db, ExprList *p, int flags){
-  ExprList *pNew;
-  struct ExprList_item *pItem, *pOldItem;
-  int i;
-  if( p==0 ) return 0;
-  pNew = sqlite3DbMallocRaw(db, sizeof(*pNew) );
-  if( pNew==0 ) return 0;
-  pNew->iECursor = 0;
-  pNew->nExpr = pNew->nAlloc = p->nExpr;
-  pNew->a = pItem = sqlite3DbMallocRaw(db,  p->nExpr*sizeof(p->a[0]) );
-  if( pItem==0 ){
-    sqlite3DbFree(db, pNew);
-    return 0;
-  } 
-  pOldItem = p->a;
-  for(i=0; i<p->nExpr; i++, pItem++, pOldItem++){
-    Expr *pOldExpr = pOldItem->pExpr;
-    pItem->pExpr = sqlite3ExprDup(db, pOldExpr, flags);
-    pItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
-    pItem->zSpan = sqlite3DbStrDup(db, pOldItem->zSpan);
-    pItem->sortOrder = pOldItem->sortOrder;
-    pItem->done = 0;
-    pItem->iCol = pOldItem->iCol;
-    pItem->iAlias = pOldItem->iAlias;
-  }
-  return pNew;
-}
-
-/*
-** If cursors, triggers, views and subqueries are all omitted from
-** the build, then none of the following routines, except for 
-** sqlite3SelectDup(), can be called. sqlite3SelectDup() is sometimes
-** called with a NULL argument.
-*/
-#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER) \
- || !defined(SQLITE_OMIT_SUBQUERY)
-SrcList *sqlite3SrcListDup(sqlite3 *db, SrcList *p, int flags){
-  SrcList *pNew;
-  int i;
-  int nByte;
-  if( p==0 ) return 0;
-  nByte = sizeof(*p) + (p->nSrc>0 ? sizeof(p->a[0]) * (p->nSrc-1) : 0);
-  pNew = sqlite3DbMallocRaw(db, nByte );
-  if( pNew==0 ) return 0;
-  pNew->nSrc = pNew->nAlloc = p->nSrc;
-  for(i=0; i<p->nSrc; i++){
-    struct SrcList_item *pNewItem = &pNew->a[i];
-    struct SrcList_item *pOldItem = &p->a[i];
-    Table *pTab;
-    pNewItem->zDatabase = sqlite3DbStrDup(db, pOldItem->zDatabase);
-    pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
-    pNewItem->zAlias = sqlite3DbStrDup(db, pOldItem->zAlias);
-    pNewItem->jointype = pOldItem->jointype;
-    pNewItem->iCursor = pOldItem->iCursor;
-    pNewItem->isPopulated = pOldItem->isPopulated;
-    pNewItem->zIndex = sqlite3DbStrDup(db, pOldItem->zIndex);
-    pNewItem->notIndexed = pOldItem->notIndexed;
-    pNewItem->pIndex = pOldItem->pIndex;
-    pTab = pNewItem->pTab = pOldItem->pTab;
-    if( pTab ){
-      pTab->nRef++;
-    }
-    pNewItem->pSelect = sqlite3SelectDup(db, pOldItem->pSelect, flags);
-    pNewItem->pOn = sqlite3ExprDup(db, pOldItem->pOn, flags);
-    pNewItem->pUsing = sqlite3IdListDup(db, pOldItem->pUsing);
-    pNewItem->colUsed = pOldItem->colUsed;
-  }
-  return pNew;
-}
-IdList *sqlite3IdListDup(sqlite3 *db, IdList *p){
-  IdList *pNew;
-  int i;
-  if( p==0 ) return 0;
-  pNew = sqlite3DbMallocRaw(db, sizeof(*pNew) );
-  if( pNew==0 ) return 0;
-  pNew->nId = pNew->nAlloc = p->nId;
-  pNew->a = sqlite3DbMallocRaw(db, p->nId*sizeof(p->a[0]) );
-  if( pNew->a==0 ){
-    sqlite3DbFree(db, pNew);
-    return 0;
-  }
-  for(i=0; i<p->nId; i++){
-    struct IdList_item *pNewItem = &pNew->a[i];
-    struct IdList_item *pOldItem = &p->a[i];
-    pNewItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
-    pNewItem->idx = pOldItem->idx;
-  }
-  return pNew;
-}
-Select *sqlite3SelectDup(sqlite3 *db, Select *p, int flags){
-  Select *pNew;
-  if( p==0 ) return 0;
-  pNew = sqlite3DbMallocRaw(db, sizeof(*p) );
-  if( pNew==0 ) return 0;
-  pNew->pEList = sqlite3ExprListDup(db, p->pEList, flags);
-  pNew->pSrc = sqlite3SrcListDup(db, p->pSrc, flags);
-  pNew->pWhere = sqlite3ExprDup(db, p->pWhere, flags);
-  pNew->pGroupBy = sqlite3ExprListDup(db, p->pGroupBy, flags);
-  pNew->pHaving = sqlite3ExprDup(db, p->pHaving, flags);
-  pNew->pOrderBy = sqlite3ExprListDup(db, p->pOrderBy, flags);
-  pNew->op = p->op;
-  pNew->pPrior = sqlite3SelectDup(db, p->pPrior, flags);
-  pNew->pLimit = sqlite3ExprDup(db, p->pLimit, flags);
-  pNew->pOffset = sqlite3ExprDup(db, p->pOffset, flags);
-  pNew->iLimit = 0;
-  pNew->iOffset = 0;
-  pNew->selFlags = p->selFlags & ~SF_UsesEphemeral;
-  pNew->pRightmost = 0;
-  pNew->addrOpenEphm[0] = -1;
-  pNew->addrOpenEphm[1] = -1;
-  pNew->addrOpenEphm[2] = -1;
-  return pNew;
-}
-#else
-Select *sqlite3SelectDup(sqlite3 *db, Select *p, int flags){
-  assert( p==0 );
-  return 0;
-}
-#endif
-
-
-/*
-** Add a new element to the end of an expression list.  If pList is
-** initially NULL, then create a new expression list.
-**
-** If a memory allocation error occurs, the entire list is freed and
-** NULL is returned.  If non-NULL is returned, then it is guaranteed
-** that the new entry was successfully appended.
-*/
-ExprList *sqlite3ExprListAppend(
-  Parse *pParse,          /* Parsing context */
-  ExprList *pList,        /* List to which to append. Might be NULL */
-  Expr *pExpr             /* Expression to be appended. Might be NULL */
-){
-  sqlite3 *db = pParse->db;
-  if( pList==0 ){
-    pList = sqlite3DbMallocZero(db, sizeof(ExprList) );
-    if( pList==0 ){
-      goto no_mem;
-    }
-    assert( pList->nAlloc==0 );
-  }
-  if( pList->nAlloc<=pList->nExpr ){
-    struct ExprList_item *a;
-    int n = pList->nAlloc*2 + 4;
-    a = sqlite3DbRealloc(db, pList->a, n*sizeof(pList->a[0]));
-    if( a==0 ){
-      goto no_mem;
-    }
-    pList->a = a;
-    pList->nAlloc = sqlite3DbMallocSize(db, a)/sizeof(a[0]);
-  }
-  assert( pList->a!=0 );
-  if( 1 ){
-    struct ExprList_item *pItem = &pList->a[pList->nExpr++];
-    memset(pItem, 0, sizeof(*pItem));
-    pItem->pExpr = pExpr;
-  }
-  return pList;
-
-no_mem:     
-  /* Avoid leaking memory if malloc has failed. */
-  sqlite3ExprDelete(db, pExpr);
-  sqlite3ExprListDelete(db, pList);
-  return 0;
-}
-
-/*
-** Set the ExprList.a[].zName element of the most recently added item
-** on the expression list.
-**
-** pList might be NULL following an OOM error.  But pName should never be
-** NULL.  If a memory allocation fails, the pParse->db->mallocFailed flag
-** is set.
-*/
-void sqlite3ExprListSetName(
-  Parse *pParse,          /* Parsing context */
-  ExprList *pList,        /* List to which to add the span. */
-  Token *pName,           /* Name to be added */
-  int dequote             /* True to cause the name to be dequoted */
-){
-  assert( pList!=0 || pParse->db->mallocFailed!=0 );
-  if( pList ){
-    struct ExprList_item *pItem;
-    assert( pList->nExpr>0 );
-    pItem = &pList->a[pList->nExpr-1];
-    assert( pItem->zName==0 );
-    pItem->zName = sqlite3DbStrNDup(pParse->db, pName->z, pName->n);
-    if( dequote && pItem->zName ) sqlite3Dequote(pItem->zName);
-  }
-}
-
-/*
-** Set the ExprList.a[].zSpan element of the most recently added item
-** on the expression list.
-**
-** pList might be NULL following an OOM error.  But pSpan should never be
-** NULL.  If a memory allocation fails, the pParse->db->mallocFailed flag
-** is set.
-*/
-void sqlite3ExprListSetSpan(
-  Parse *pParse,          /* Parsing context */
-  ExprList *pList,        /* List to which to add the span. */
-  ExprSpan *pSpan         /* The span to be added */
-){
-  sqlite3 *db = pParse->db;
-  assert( pList!=0 || db->mallocFailed!=0 );
-  if( pList ){
-    struct ExprList_item *pItem = &pList->a[pList->nExpr-1];
-    assert( pList->nExpr>0 );
-    assert( db->mallocFailed || pItem->pExpr==pSpan->pExpr );
-    sqlite3DbFree(db, pItem->zSpan);
-    pItem->zSpan = sqlite3DbStrNDup(db, (char*)pSpan->zStart,
-                                    (int)(pSpan->zEnd - pSpan->zStart));
-  }
-}
-
-/*
-** If the expression list pEList contains more than iLimit elements,
-** leave an error message in pParse.
-*/
-void sqlite3ExprListCheckLength(
-  Parse *pParse,
-  ExprList *pEList,
-  const char *zObject
-){
-  int mx = pParse->db->aLimit[SQLITE_LIMIT_COLUMN];
-  testcase( pEList && pEList->nExpr==mx );
-  testcase( pEList && pEList->nExpr==mx+1 );
-  if( pEList && pEList->nExpr>mx ){
-    sqlite3ErrorMsg(pParse, "too many columns in %s", zObject);
-  }
-}
-
-/*
-** Delete an entire expression list.
-*/
-void sqlite3ExprListDelete(sqlite3 *db, ExprList *pList){
-  int i;
-  struct ExprList_item *pItem;
-  if( pList==0 ) return;
-  assert( pList->a!=0 || (pList->nExpr==0 && pList->nAlloc==0) );
-  assert( pList->nExpr<=pList->nAlloc );
-  for(pItem=pList->a, i=0; i<pList->nExpr; i++, pItem++){
-    sqlite3ExprDelete(db, pItem->pExpr);
-    sqlite3DbFree(db, pItem->zName);
-    sqlite3DbFree(db, pItem->zSpan);
-  }
-  sqlite3DbFree(db, pList->a);
-  sqlite3DbFree(db, pList);
-}
-
-/*
-** These routines are Walker callbacks.  Walker.u.pi is a pointer
-** to an integer.  These routines are checking an expression to see
-** if it is a constant.  Set *Walker.u.pi to 0 if the expression is
-** not constant.
-**
-** These callback routines are used to implement the following:
-**
-**     sqlite3ExprIsConstant()
-**     sqlite3ExprIsConstantNotJoin()
-**     sqlite3ExprIsConstantOrFunction()
-**
-*/
-static int exprNodeIsConstant(Walker *pWalker, Expr *pExpr){
-
-  /* If pWalker->u.i is 3 then any term of the expression that comes from
-  ** the ON or USING clauses of a join disqualifies the expression
-  ** from being considered constant. */
-  if( pWalker->u.i==3 && ExprHasAnyProperty(pExpr, EP_FromJoin) ){
-    pWalker->u.i = 0;
-    return WRC_Abort;
-  }
-
-  switch( pExpr->op ){
-    /* Consider functions to be constant if all their arguments are constant
-    ** and pWalker->u.i==2 */
-    case TK_FUNCTION:
-      if( pWalker->u.i==2 ) return 0;
-      /* Fall through */
-    case TK_ID:
-    case TK_COLUMN:
-    case TK_AGG_FUNCTION:
-    case TK_AGG_COLUMN:
-      testcase( pExpr->op==TK_ID );
-      testcase( pExpr->op==TK_COLUMN );
-      testcase( pExpr->op==TK_AGG_FUNCTION );
-      testcase( pExpr->op==TK_AGG_COLUMN );
-      pWalker->u.i = 0;
-      return WRC_Abort;
-    default:
-      testcase( pExpr->op==TK_SELECT ); /* selectNodeIsConstant will disallow */
-      testcase( pExpr->op==TK_EXISTS ); /* selectNodeIsConstant will disallow */
-      return WRC_Continue;
-  }
-}
-static int selectNodeIsConstant(Walker *pWalker, Select *NotUsed){
-  UNUSED_PARAMETER(NotUsed);
-  pWalker->u.i = 0;
-  return WRC_Abort;
-}
-static int exprIsConst(Expr *p, int initFlag){
-  Walker w;
-  w.u.i = initFlag;
-  w.xExprCallback = exprNodeIsConstant;
-  w.xSelectCallback = selectNodeIsConstant;
-  sqlite3WalkExpr(&w, p);
-  return w.u.i;
-}
-
-/*
-** Walk an expression tree.  Return 1 if the expression is constant
-** and 0 if it involves variables or function calls.
-**
-** For the purposes of this function, a double-quoted string (ex: "abc")
-** is considered a variable but a single-quoted string (ex: 'abc') is
-** a constant.
-*/
-int sqlite3ExprIsConstant(Expr *p){
-  return exprIsConst(p, 1);
-}
-
-/*
-** Walk an expression tree.  Return 1 if the expression is constant
-** that does no originate from the ON or USING clauses of a join.
-** Return 0 if it involves variables or function calls or terms from
-** an ON or USING clause.
-*/
-int sqlite3ExprIsConstantNotJoin(Expr *p){
-  return exprIsConst(p, 3);
-}
-
-/*
-** Walk an expression tree.  Return 1 if the expression is constant
-** or a function call with constant arguments.  Return and 0 if there
-** are any variables.
-**
-** For the purposes of this function, a double-quoted string (ex: "abc")
-** is considered a variable but a single-quoted string (ex: 'abc') is
-** a constant.
-*/
-int sqlite3ExprIsConstantOrFunction(Expr *p){
-  return exprIsConst(p, 2);
-}
-
-/*
-** If the expression p codes a constant integer that is small enough
-** to fit in a 32-bit integer, return 1 and put the value of the integer
-** in *pValue.  If the expression is not an integer or if it is too big
-** to fit in a signed 32-bit integer, return 0 and leave *pValue unchanged.
-*/
-int sqlite3ExprIsInteger(Expr *p, int *pValue){
-  int rc = 0;
-  if( p->flags & EP_IntValue ){
-    *pValue = p->u.iValue;
-    return 1;
-  }
-  switch( p->op ){
-    case TK_INTEGER: {
-      rc = sqlite3GetInt32(p->u.zToken, pValue);
-      assert( rc==0 );
-      break;
-    }
-    case TK_UPLUS: {
-      rc = sqlite3ExprIsInteger(p->pLeft, pValue);
-      break;
-    }
-    case TK_UMINUS: {
-      int v;
-      if( sqlite3ExprIsInteger(p->pLeft, &v) ){
-        *pValue = -v;
-        rc = 1;
-      }
-      break;
-    }
-    default: break;
-  }
-  if( rc ){
-    assert( ExprHasAnyProperty(p, EP_Reduced|EP_TokenOnly)
-               || (p->flags2 & EP2_MallocedToken)==0 );
-    p->op = TK_INTEGER;
-    p->flags |= EP_IntValue;
-    p->u.iValue = *pValue;
-  }
-  return rc;
-}
-
-/*
-** Return TRUE if the given string is a row-id column name.
-*/
-int sqlite3IsRowid(const char *z){
-  if( sqlite3StrICmp(z, "_ROWID_")==0 ) return 1;
-  if( sqlite3StrICmp(z, "ROWID")==0 ) return 1;
-  if( sqlite3StrICmp(z, "OID")==0 ) return 1;
-  return 0;
-}
-
-/*
-** Return true if we are able to the IN operator optimization on a
-** query of the form
-**
-**       x IN (SELECT ...)
-**
-** Where the SELECT... clause is as specified by the parameter to this
-** routine.
-**
-** The Select object passed in has already been preprocessed and no
-** errors have been found.
-*/
-#ifndef SQLITE_OMIT_SUBQUERY
-static int isCandidateForInOpt(Select *p){
-  SrcList *pSrc;
-  ExprList *pEList;
-  Table *pTab;
-  if( p==0 ) return 0;                   /* right-hand side of IN is SELECT */
-  if( p->pPrior ) return 0;              /* Not a compound SELECT */
-  if( p->selFlags & (SF_Distinct|SF_Aggregate) ){
-    testcase( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
-    testcase( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );
-    return 0; /* No DISTINCT keyword and no aggregate functions */
-  }
-  assert( p->pGroupBy==0 );              /* Has no GROUP BY clause */
-  if( p->pLimit ) return 0;              /* Has no LIMIT clause */
-  assert( p->pOffset==0 );               /* No LIMIT means no OFFSET */
-  if( p->pWhere ) return 0;              /* Has no WHERE clause */
-  pSrc = p->pSrc;
-  assert( pSrc!=0 );
-  if( pSrc->nSrc!=1 ) return 0;          /* Single term in FROM clause */
-  if( pSrc->a[0].pSelect ) return 0;     /* FROM is not a subquery or view */
-  pTab = pSrc->a[0].pTab;
-  if( NEVER(pTab==0) ) return 0;
-  assert( pTab->pSelect==0 );            /* FROM clause is not a view */
-  if( IsVirtual(pTab) ) return 0;        /* FROM clause not a virtual table */
-  pEList = p->pEList;
-  if( pEList->nExpr!=1 ) return 0;       /* One column in the result set */
-  if( pEList->a[0].pExpr->op!=TK_COLUMN ) return 0; /* Result is a column */
-  return 1;
-}
-#endif /* SQLITE_OMIT_SUBQUERY */
-
-/*
-** This function is used by the implementation of the IN (...) operator.
-** It's job is to find or create a b-tree structure that may be used
-** either to test for membership of the (...) set or to iterate through
-** its members, skipping duplicates.
-**
-** The index of the cursor opened on the b-tree (database table, database index 
-** or ephermal table) is stored in pX->iTable before this function returns.
-** The returned value of this function indicates the b-tree type, as follows:
-**
-**   IN_INDEX_ROWID - The cursor was opened on a database table.
-**   IN_INDEX_INDEX - The cursor was opened on a database index.
-**   IN_INDEX_EPH -   The cursor was opened on a specially created and
-**                    populated epheremal table.
-**
-** An existing b-tree may only be used if the SELECT is of the simple
-** form:
-**
-**     SELECT <column> FROM <table>
-**
-** If the prNotFound parameter is 0, then the b-tree will be used to iterate
-** through the set members, skipping any duplicates. In this case an
-** epheremal table must be used unless the selected <column> is guaranteed
-** to be unique - either because it is an INTEGER PRIMARY KEY or it
-** has a UNIQUE constraint or UNIQUE index.
-**
-** If the prNotFound parameter is not 0, then the b-tree will be used 
-** for fast set membership tests. In this case an epheremal table must 
-** be used unless <column> is an INTEGER PRIMARY KEY or an index can 
-** be found with <column> as its left-most column.
-**
-** When the b-tree is being used for membership tests, the calling function
-** needs to know whether or not the structure contains an SQL NULL 
-** value in order to correctly evaluate expressions like "X IN (Y, Z)".
-** If there is a chance that the b-tree might contain a NULL value at
-** runtime, then a register is allocated and the register number written
-** to *prNotFound. If there is no chance that the b-tree contains a
-** NULL value, then *prNotFound is left unchanged.
-**
-** If a register is allocated and its location stored in *prNotFound, then
-** its initial value is NULL. If the b-tree does not remain constant
-** for the duration of the query (i.e. the SELECT that generates the b-tree
-** is a correlated subquery) then the value of the allocated register is
-** reset to NULL each time the b-tree is repopulated. This allows the
-** caller to use vdbe code equivalent to the following:
-**
-**   if( register==NULL ){
-**     has_null = <test if data structure contains null>
-**     register = 1
-**   }
-**
-** in order to avoid running the <test if data structure contains null>
-** test more often than is necessary.
-*/
-#ifndef SQLITE_OMIT_SUBQUERY
-int sqlite3FindInIndex(Parse *pParse, Expr *pX, int *prNotFound){
-  Select *p;                            /* SELECT to the right of IN operator */
-  int eType = 0;                        /* Type of RHS table. IN_INDEX_* */
-  int iTab = pParse->nTab++;            /* Cursor of the RHS table */
-  int mustBeUnique = (prNotFound==0);   /* True if RHS must be unique */
-
-  /* Check to see if an existing table or index can be used to
-  ** satisfy the query.  This is preferable to generating a new 
-  ** ephemeral table.
-  */
-  p = (ExprHasProperty(pX, EP_xIsSelect) ? pX->x.pSelect : 0);
-  if( ALWAYS(pParse->nErr==0) && isCandidateForInOpt(p) ){
-    sqlite3 *db = pParse->db;              /* Database connection */
-    Expr *pExpr = p->pEList->a[0].pExpr;   /* Expression <column> */
-    int iCol = pExpr->iColumn;             /* Index of column <column> */
-    Vdbe *v = sqlite3GetVdbe(pParse);      /* Virtual machine being coded */
-    Table *pTab = p->pSrc->a[0].pTab;      /* Table <table>. */
-    int iDb;                               /* Database idx for pTab */
-   
-    /* Code an OP_VerifyCookie and OP_TableLock for <table>. */
-    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
-    sqlite3CodeVerifySchema(pParse, iDb);
-    sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
-
-    /* This function is only called from two places. In both cases the vdbe
-    ** has already been allocated. So assume sqlite3GetVdbe() is always
-    ** successful here.
-    */
-    assert(v);
-    if( iCol<0 ){
-      int iMem = ++pParse->nMem;
-      int iAddr;
-
-      iAddr = sqlite3VdbeAddOp1(v, OP_If, iMem);
-      sqlite3VdbeAddOp2(v, OP_Integer, 1, iMem);
-
-      sqlite3OpenTable(pParse, iTab, iDb, pTab, OP_OpenRead);
-      eType = IN_INDEX_ROWID;
-
-      sqlite3VdbeJumpHere(v, iAddr);
-    }else{
-      Index *pIdx;                         /* Iterator variable */
-
-      /* The collation sequence used by the comparison. If an index is to
-      ** be used in place of a temp-table, it must be ordered according
-      ** to this collation sequence.  */
-      CollSeq *pReq = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pExpr);
-
-      /* Check that the affinity that will be used to perform the 
-      ** comparison is the same as the affinity of the column. If
-      ** it is not, it is not possible to use any index.
-      */
-      char aff = comparisonAffinity(pX);
-      int affinity_ok = (pTab->aCol[iCol].affinity==aff||aff==SQLITE_AFF_NONE);
-
-      for(pIdx=pTab->pIndex; pIdx && eType==0 && affinity_ok; pIdx=pIdx->pNext){
-        if( (pIdx->aiColumn[0]==iCol)
-         && sqlite3FindCollSeq(db, ENC(db), pIdx->azColl[0], 0)==pReq
-         && (!mustBeUnique || (pIdx->nColumn==1 && pIdx->onError!=OE_None))
-        ){
-          int iMem = ++pParse->nMem;
-          int iAddr;
-          char *pKey;
-  
-          pKey = (char *)sqlite3IndexKeyinfo(pParse, pIdx);
-          iAddr = sqlite3VdbeAddOp1(v, OP_If, iMem);
-          sqlite3VdbeAddOp2(v, OP_Integer, 1, iMem);
-  
-          sqlite3VdbeAddOp4(v, OP_OpenRead, iTab, pIdx->tnum, iDb,
-                               pKey,P4_KEYINFO_HANDOFF);
-          VdbeComment((v, "%s", pIdx->zName));
-          eType = IN_INDEX_INDEX;
-
-          sqlite3VdbeJumpHere(v, iAddr);
-          if( prNotFound && !pTab->aCol[iCol].notNull ){
-            *prNotFound = ++pParse->nMem;
-          }
-        }
-      }
-    }
-  }
-
-  if( eType==0 ){
-    /* Could not found an existing able or index to use as the RHS b-tree.
-    ** We will have to generate an ephemeral table to do the job.
-    */
-    int rMayHaveNull = 0;
-    eType = IN_INDEX_EPH;
-    if( prNotFound ){
-      *prNotFound = rMayHaveNull = ++pParse->nMem;
-    }else if( pX->pLeft->iColumn<0 && !ExprHasAnyProperty(pX, EP_xIsSelect) ){
-      eType = IN_INDEX_ROWID;
-    }
-    sqlite3CodeSubselect(pParse, pX, rMayHaveNull, eType==IN_INDEX_ROWID);
-  }else{
-    pX->iTable = iTab;
-  }
-  return eType;
-}
-#endif
-
-/*
-** Generate code for scalar subqueries used as an expression
-** and IN operators.  Examples:
-**
-**     (SELECT a FROM b)          -- subquery
-**     EXISTS (SELECT a FROM b)   -- EXISTS subquery
-**     x IN (4,5,11)              -- IN operator with list on right-hand side
-**     x IN (SELECT a FROM b)     -- IN operator with subquery on the right
-**
-** The pExpr parameter describes the expression that contains the IN
-** operator or subquery.
-**
-** If parameter isRowid is non-zero, then expression pExpr is guaranteed
-** to be of the form "<rowid> IN (?, ?, ?)", where <rowid> is a reference
-** to some integer key column of a table B-Tree. In this case, use an
-** intkey B-Tree to store the set of IN(...) values instead of the usual
-** (slower) variable length keys B-Tree.
-**
-** If rMayHaveNull is non-zero, that means that the operation is an IN
-** (not a SELECT or EXISTS) and that the RHS might contains NULLs.
-** Furthermore, the IN is in a WHERE clause and that we really want
-** to iterate over the RHS of the IN operator in order to quickly locate
-** all corresponding LHS elements.  All this routine does is initialize
-** the register given by rMayHaveNull to NULL.  Calling routines will take
-** care of changing this register value to non-NULL if the RHS is NULL-free.
-**
-** If rMayHaveNull is zero, that means that the subquery is being used
-** for membership testing only.  There is no need to initialize any
-** registers to indicate the presense or absence of NULLs on the RHS.
-*/
-#ifndef SQLITE_OMIT_SUBQUERY
-void sqlite3CodeSubselect(
-  Parse *pParse,          /* Parsing context */
-  Expr *pExpr,            /* The IN, SELECT, or EXISTS operator */
-  int rMayHaveNull,       /* Register that records whether NULLs exist in RHS */
-  int isRowid             /* If true, LHS of IN operator is a rowid */
-){
-  int testAddr = 0;                       /* One-time test address */
-  Vdbe *v = sqlite3GetVdbe(pParse);
-  if( NEVER(v==0) ) return;
-  sqlite3ExprCachePush(pParse);
-
-  /* This code must be run in its entirety every time it is encountered
-  ** if any of the following is true:
-  **
-  **    *  The right-hand side is a correlated subquery
-  **    *  The right-hand side is an expression list containing variables
-  **    *  We are inside a trigger
-  **
-  ** If all of the above are false, then we can run this code just once
-  ** save the results, and reuse the same result on subsequent invocations.
-  */
-  if( !ExprHasAnyProperty(pExpr, EP_VarSelect) && !pParse->pTriggerTab ){
-    int mem = ++pParse->nMem;
-    sqlite3VdbeAddOp1(v, OP_If, mem);
-    testAddr = sqlite3VdbeAddOp2(v, OP_Integer, 1, mem);
-    assert( testAddr>0 || pParse->db->mallocFailed );
-  }
-
-  switch( pExpr->op ){
-    case TK_IN: {
-      char affinity;
-      KeyInfo keyInfo;
-      int addr;        /* Address of OP_OpenEphemeral instruction */
-      Expr *pLeft = pExpr->pLeft;
-
-      if( rMayHaveNull ){
-        sqlite3VdbeAddOp2(v, OP_Null, 0, rMayHaveNull);
-      }
-
-      affinity = sqlite3ExprAffinity(pLeft);
-
-      /* Whether this is an 'x IN(SELECT...)' or an 'x IN(<exprlist>)'
-      ** expression it is handled the same way. A virtual table is 
-      ** filled with single-field index keys representing the results
-      ** from the SELECT or the <exprlist>.
-      **
-      ** If the 'x' expression is a column value, or the SELECT...
-      ** statement returns a column value, then the affinity of that
-      ** column is used to build the index keys. If both 'x' and the
-      ** SELECT... statement are columns, then numeric affinity is used
-      ** if either column has NUMERIC or INTEGER affinity. If neither
-      ** 'x' nor the SELECT... statement are columns, then numeric affinity
-      ** is used.
-      */
-      pExpr->iTable = pParse->nTab++;
-      addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pExpr->iTable, !isRowid);
-      memset(&keyInfo, 0, sizeof(keyInfo));
-      keyInfo.nField = 1;
-
-      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
-        /* Case 1:     expr IN (SELECT ...)
-        **
-        ** Generate code to write the results of the select into the temporary
-        ** table allocated and opened above.
-        */
-        SelectDest dest;
-        ExprList *pEList;
-
-        assert( !isRowid );
-        sqlite3SelectDestInit(&dest, SRT_Set, pExpr->iTable);
-        dest.affinity = (u8)affinity;
-        assert( (pExpr->iTable&0x0000FFFF)==pExpr->iTable );
-        if( sqlite3Select(pParse, pExpr->x.pSelect, &dest) ){
-          return;
-        }
-        pEList = pExpr->x.pSelect->pEList;
-        if( ALWAYS(pEList!=0 && pEList->nExpr>0) ){ 
-          keyInfo.aColl[0] = sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft,
-              pEList->a[0].pExpr);
-        }
-      }else if( pExpr->x.pList!=0 ){
-        /* Case 2:     expr IN (exprlist)
-        **
-        ** For each expression, build an index key from the evaluation and
-        ** store it in the temporary table. If <expr> is a column, then use
-        ** that columns affinity when building index keys. If <expr> is not
-        ** a column, use numeric affinity.
-        */
-        int i;
-        ExprList *pList = pExpr->x.pList;
-        struct ExprList_item *pItem;
-        int r1, r2, r3;
-
-        if( !affinity ){
-          affinity = SQLITE_AFF_NONE;
-        }
-        keyInfo.aColl[0] = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
-
-        /* Loop through each expression in <exprlist>. */
-        r1 = sqlite3GetTempReg(pParse);
-        r2 = sqlite3GetTempReg(pParse);
-        sqlite3VdbeAddOp2(v, OP_Null, 0, r2);
-        for(i=pList->nExpr, pItem=pList->a; i>0; i--, pItem++){
-          Expr *pE2 = pItem->pExpr;
-
-          /* If the expression is not constant then we will need to
-          ** disable the test that was generated above that makes sure
-          ** this code only executes once.  Because for a non-constant
-          ** expression we need to rerun this code each time.
-          */
-          if( testAddr && !sqlite3ExprIsConstant(pE2) ){
-            sqlite3VdbeChangeToNoop(v, testAddr-1, 2);
-            testAddr = 0;
-          }
-
-          /* Evaluate the expression and insert it into the temp table */
-          r3 = sqlite3ExprCodeTarget(pParse, pE2, r1);
-          if( isRowid ){
-            sqlite3VdbeAddOp2(v, OP_MustBeInt, r3, sqlite3VdbeCurrentAddr(v)+2);
-            sqlite3VdbeAddOp3(v, OP_Insert, pExpr->iTable, r2, r3);
-          }else{
-            sqlite3VdbeAddOp4(v, OP_MakeRecord, r3, 1, r2, &affinity, 1);
-            sqlite3ExprCacheAffinityChange(pParse, r3, 1);
-            sqlite3VdbeAddOp2(v, OP_IdxInsert, pExpr->iTable, r2);
-          }
-        }
-        sqlite3ReleaseTempReg(pParse, r1);
-        sqlite3ReleaseTempReg(pParse, r2);
-      }
-      if( !isRowid ){
-        sqlite3VdbeChangeP4(v, addr, (void *)&keyInfo, P4_KEYINFO);
-      }
-      break;
-    }
-
-    case TK_EXISTS:
-    case TK_SELECT:
-    default: {
-      /* If this has to be a scalar SELECT.  Generate code to put the
-      ** value of this select in a memory cell and record the number
-      ** of the memory cell in iColumn.  If this is an EXISTS, write
-      ** an integer 0 (not exists) or 1 (exists) into a memory cell
-      ** and record that memory cell in iColumn.
-      */
-      static const Token one = { "1", 1 };  /* Token for literal value 1 */
-      Select *pSel;                         /* SELECT statement to encode */
-      SelectDest dest;                      /* How to deal with SELECt result */
-
-      testcase( pExpr->op==TK_EXISTS );
-      testcase( pExpr->op==TK_SELECT );
-      assert( pExpr->op==TK_EXISTS || pExpr->op==TK_SELECT );
-
-      assert( ExprHasProperty(pExpr, EP_xIsSelect) );
-      pSel = pExpr->x.pSelect;
-      sqlite3SelectDestInit(&dest, 0, ++pParse->nMem);
-      if( pExpr->op==TK_SELECT ){
-        dest.eDest = SRT_Mem;
-        sqlite3VdbeAddOp2(v, OP_Null, 0, dest.iParm);
-        VdbeComment((v, "Init subquery result"));
-      }else{
-        dest.eDest = SRT_Exists;
-        sqlite3VdbeAddOp2(v, OP_Integer, 0, dest.iParm);
-        VdbeComment((v, "Init EXISTS result"));
-      }
-      sqlite3ExprDelete(pParse->db, pSel->pLimit);
-      pSel->pLimit = sqlite3PExpr(pParse, TK_INTEGER, 0, 0, &one);
-      if( sqlite3Select(pParse, pSel, &dest) ){
-        return;
-      }
-      pExpr->iColumn = (i16)dest.iParm;
-      ExprSetIrreducible(pExpr);
-      break;
-    }
-  }
-
-  if( testAddr ){
-    sqlite3VdbeJumpHere(v, testAddr-1);
-  }
-  sqlite3ExprCachePop(pParse, 1);
-
-  return;
-}
-#endif /* SQLITE_OMIT_SUBQUERY */
-
-/*
-** Duplicate an 8-byte value
-*/
-static char *dup8bytes(Vdbe *v, const char *in){
-  char *out = sqlite3DbMallocRaw(sqlite3VdbeDb(v), 8);
-  if( out ){
-    memcpy(out, in, 8);
-  }
-  return out;
-}
-
-/*
-** Generate an instruction that will put the floating point
-** value described by z[0..n-1] into register iMem.
-**
-** The z[] string will probably not be zero-terminated.  But the 
-** z[n] character is guaranteed to be something that does not look
-** like the continuation of the number.
-*/
-static void codeReal(Vdbe *v, const char *z, int negateFlag, int iMem){
-  if( ALWAYS(z!=0) ){
-    double value;
-    char *zV;
-    sqlite3AtoF(z, &value);
-    assert( !sqlite3IsNaN(value) ); /* The new AtoF never returns NaN */
-    if( negateFlag ) value = -value;
-    zV = dup8bytes(v, (char*)&value);
-    sqlite3VdbeAddOp4(v, OP_Real, 0, iMem, 0, zV, P4_REAL);
-  }
-}
-
-
-/*
-** Generate an instruction that will put the integer describe by
-** text z[0..n-1] into register iMem.
-**
-** The z[] string will probably not be zero-terminated.  But the 
-** z[n] character is guaranteed to be something that does not look
-** like the continuation of the number.
-*/
-static void codeInteger(Vdbe *v, Expr *pExpr, int negFlag, int iMem){
-  if( pExpr->flags & EP_IntValue ){
-    int i = pExpr->u.iValue;
-    if( negFlag ) i = -i;
-    sqlite3VdbeAddOp2(v, OP_Integer, i, iMem);
-  }else{
-    const char *z = pExpr->u.zToken;
-    assert( z!=0 );
-    if( sqlite3FitsIn64Bits(z, negFlag) ){
-      i64 value;
-      char *zV;
-      sqlite3Atoi64(z, &value);
-      if( negFlag ) value = -value;
-      zV = dup8bytes(v, (char*)&value);
-      sqlite3VdbeAddOp4(v, OP_Int64, 0, iMem, 0, zV, P4_INT64);
-    }else{
-      codeReal(v, z, negFlag, iMem);
-    }
-  }
-}
-
-/*
-** Clear a cache entry.
-*/
-static void cacheEntryClear(Parse *pParse, struct yColCache *p){
-  if( p->tempReg ){
-    if( pParse->nTempReg<ArraySize(pParse->aTempReg) ){
-      pParse->aTempReg[pParse->nTempReg++] = p->iReg;
-    }
-    p->tempReg = 0;
-  }
-}
-
-
-/*
-** Record in the column cache that a particular column from a
-** particular table is stored in a particular register.
-*/
-void sqlite3ExprCacheStore(Parse *pParse, int iTab, int iCol, int iReg){
-  int i;
-  int minLru;
-  int idxLru;
-  struct yColCache *p;
-
-  assert( iReg>0 );  /* Register numbers are always positive */
-  assert( iCol>=-1 && iCol<32768 );  /* Finite column numbers */
-
-  /* First replace any existing entry */
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    if( p->iReg && p->iTable==iTab && p->iColumn==iCol ){
-      cacheEntryClear(pParse, p);
-      p->iLevel = pParse->iCacheLevel;
-      p->iReg = iReg;
-      p->affChange = 0;
-      p->lru = pParse->iCacheCnt++;
-      return;
-    }
-  }
-
-  /* Find an empty slot and replace it */
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    if( p->iReg==0 ){
-      p->iLevel = pParse->iCacheLevel;
-      p->iTable = iTab;
-      p->iColumn = iCol;
-      p->iReg = iReg;
-      p->affChange = 0;
-      p->tempReg = 0;
-      p->lru = pParse->iCacheCnt++;
-      return;
-    }
-  }
-
-  /* Replace the last recently used */
-  minLru = 0x7fffffff;
-  idxLru = -1;
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    if( p->lru<minLru ){
-      idxLru = i;
-      minLru = p->lru;
-    }
-  }
-  if( ALWAYS(idxLru>=0) ){
-    p = &pParse->aColCache[idxLru];
-    p->iLevel = pParse->iCacheLevel;
-    p->iTable = iTab;
-    p->iColumn = iCol;
-    p->iReg = iReg;
-    p->affChange = 0;
-    p->tempReg = 0;
-    p->lru = pParse->iCacheCnt++;
-    return;
-  }
-}
-
-/*
-** Indicate that a register is being overwritten.  Purge the register
-** from the column cache.
-*/
-void sqlite3ExprCacheRemove(Parse *pParse, int iReg){
-  int i;
-  struct yColCache *p;
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    if( p->iReg==iReg ){
-      cacheEntryClear(pParse, p);
-      p->iReg = 0;
-    }
-  }
-}
-
-/*
-** Remember the current column cache context.  Any new entries added
-** added to the column cache after this call are removed when the
-** corresponding pop occurs.
-*/
-void sqlite3ExprCachePush(Parse *pParse){
-  pParse->iCacheLevel++;
-}
-
-/*
-** Remove from the column cache any entries that were added since the
-** the previous N Push operations.  In other words, restore the cache
-** to the state it was in N Pushes ago.
-*/
-void sqlite3ExprCachePop(Parse *pParse, int N){
-  int i;
-  struct yColCache *p;
-  assert( N>0 );
-  assert( pParse->iCacheLevel>=N );
-  pParse->iCacheLevel -= N;
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    if( p->iReg && p->iLevel>pParse->iCacheLevel ){
-      cacheEntryClear(pParse, p);
-      p->iReg = 0;
-    }
-  }
-}
-
-/*
-** When a cached column is reused, make sure that its register is
-** no longer available as a temp register.  ticket #3879:  that same
-** register might be in the cache in multiple places, so be sure to
-** get them all.
-*/
-static void sqlite3ExprCachePinRegister(Parse *pParse, int iReg){
-  int i;
-  struct yColCache *p;
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    if( p->iReg==iReg ){
-      p->tempReg = 0;
-    }
-  }
-}
-
-/*
-** Generate code that will extract the iColumn-th column from
-** table pTab and store the column value in a register.  An effort
-** is made to store the column value in register iReg, but this is
-** not guaranteed.  The location of the column value is returned.
-**
-** There must be an open cursor to pTab in iTable when this routine
-** is called.  If iColumn<0 then code is generated that extracts the rowid.
-**
-** This routine might attempt to reuse the value of the column that
-** has already been loaded into a register.  The value will always
-** be used if it has not undergone any affinity changes.  But if
-** an affinity change has occurred, then the cached value will only be
-** used if allowAffChng is true.
-*/
-int sqlite3ExprCodeGetColumn(
-  Parse *pParse,   /* Parsing and code generating context */
-  Table *pTab,     /* Description of the table we are reading from */
-  int iColumn,     /* Index of the table column */
-  int iTable,      /* The cursor pointing to the table */
-  int iReg,        /* Store results here */
-  int allowAffChng /* True if prior affinity changes are OK */
-){
-  Vdbe *v = pParse->pVdbe;
-  int i;
-  struct yColCache *p;
-
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    if( p->iReg>0 && p->iTable==iTable && p->iColumn==iColumn
-           && (!p->affChange || allowAffChng) ){
-      p->lru = pParse->iCacheCnt++;
-      sqlite3ExprCachePinRegister(pParse, p->iReg);
-      return p->iReg;
-    }
-  }  
-  assert( v!=0 );
-  if( iColumn<0 ){
-    sqlite3VdbeAddOp2(v, OP_Rowid, iTable, iReg);
-  }else if( ALWAYS(pTab!=0) ){
-    int op = IsVirtual(pTab) ? OP_VColumn : OP_Column;
-    sqlite3VdbeAddOp3(v, op, iTable, iColumn, iReg);
-    sqlite3ColumnDefault(v, pTab, iColumn, iReg);
-  }
-  sqlite3ExprCacheStore(pParse, iTable, iColumn, iReg);
-  return iReg;
-}
-
-/*
-** Clear all column cache entries.
-*/
-void sqlite3ExprCacheClear(Parse *pParse){
-  int i;
-  struct yColCache *p;
-
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    if( p->iReg ){
-      cacheEntryClear(pParse, p);
-      p->iReg = 0;
-    }
-  }
-}
-
-/*
-** Record the fact that an affinity change has occurred on iCount
-** registers starting with iStart.
-*/
-void sqlite3ExprCacheAffinityChange(Parse *pParse, int iStart, int iCount){
-  int iEnd = iStart + iCount - 1;
-  int i;
-  struct yColCache *p;
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    int r = p->iReg;
-    if( r>=iStart && r<=iEnd ){
-      p->affChange = 1;
-    }
-  }
-}
-
-/*
-** Generate code to move content from registers iFrom...iFrom+nReg-1
-** over to iTo..iTo+nReg-1. Keep the column cache up-to-date.
-*/
-void sqlite3ExprCodeMove(Parse *pParse, int iFrom, int iTo, int nReg){
-  int i;
-  struct yColCache *p;
-  if( NEVER(iFrom==iTo) ) return;
-  sqlite3VdbeAddOp3(pParse->pVdbe, OP_Move, iFrom, iTo, nReg);
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    int x = p->iReg;
-    if( x>=iFrom && x<iFrom+nReg ){
-      p->iReg += iTo-iFrom;
-    }
-  }
-}
-
-/*
-** Generate code to copy content from registers iFrom...iFrom+nReg-1
-** over to iTo..iTo+nReg-1.
-*/
-void sqlite3ExprCodeCopy(Parse *pParse, int iFrom, int iTo, int nReg){
-  int i;
-  if( NEVER(iFrom==iTo) ) return;
-  for(i=0; i<nReg; i++){
-    sqlite3VdbeAddOp2(pParse->pVdbe, OP_Copy, iFrom+i, iTo+i);
-  }
-}
-
-/*
-** Return true if any register in the range iFrom..iTo (inclusive)
-** is used as part of the column cache.
-*/
-static int usedAsColumnCache(Parse *pParse, int iFrom, int iTo){
-  int i;
-  struct yColCache *p;
-  for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-    int r = p->iReg;
-    if( r>=iFrom && r<=iTo ) return 1;
-  }
-  return 0;
-}
-
-/*
-** If the last instruction coded is an ephemeral copy of any of
-** the registers in the nReg registers beginning with iReg, then
-** convert the last instruction from OP_SCopy to OP_Copy.
-*/
-void sqlite3ExprHardCopy(Parse *pParse, int iReg, int nReg){
-  VdbeOp *pOp;
-  Vdbe *v;
-
-  assert( pParse->db->mallocFailed==0 );
-  v = pParse->pVdbe;
-  assert( v!=0 );
-  pOp = sqlite3VdbeGetOp(v, -1);
-  assert( pOp!=0 );
-  if( pOp->opcode==OP_SCopy && pOp->p1>=iReg && pOp->p1<iReg+nReg ){
-    pOp->opcode = OP_Copy;
-  }
-}
-
-/*
-** Generate code to store the value of the iAlias-th alias in register
-** target.  The first time this is called, pExpr is evaluated to compute
-** the value of the alias.  The value is stored in an auxiliary register
-** and the number of that register is returned.  On subsequent calls,
-** the register number is returned without generating any code.
-**
-** Note that in order for this to work, code must be generated in the
-** same order that it is executed.
-**
-** Aliases are numbered starting with 1.  So iAlias is in the range
-** of 1 to pParse->nAlias inclusive.  
-**
-** pParse->aAlias[iAlias-1] records the register number where the value
-** of the iAlias-th alias is stored.  If zero, that means that the
-** alias has not yet been computed.
-*/
-static int codeAlias(Parse *pParse, int iAlias, Expr *pExpr, int target){
-#if 0
-  sqlite3 *db = pParse->db;
-  int iReg;
-  if( pParse->nAliasAlloc<pParse->nAlias ){
-    pParse->aAlias = sqlite3DbReallocOrFree(db, pParse->aAlias,
-                                 sizeof(pParse->aAlias[0])*pParse->nAlias );
-    testcase( db->mallocFailed && pParse->nAliasAlloc>0 );
-    if( db->mallocFailed ) return 0;
-    memset(&pParse->aAlias[pParse->nAliasAlloc], 0,
-           (pParse->nAlias-pParse->nAliasAlloc)*sizeof(pParse->aAlias[0]));
-    pParse->nAliasAlloc = pParse->nAlias;
-  }
-  assert( iAlias>0 && iAlias<=pParse->nAlias );
-  iReg = pParse->aAlias[iAlias-1];
-  if( iReg==0 ){
-    if( pParse->iCacheLevel>0 ){
-      iReg = sqlite3ExprCodeTarget(pParse, pExpr, target);
-    }else{
-      iReg = ++pParse->nMem;
-      sqlite3ExprCode(pParse, pExpr, iReg);
-      pParse->aAlias[iAlias-1] = iReg;
-    }
-  }
-  return iReg;
-#else
-  UNUSED_PARAMETER(iAlias);
-  return sqlite3ExprCodeTarget(pParse, pExpr, target);
-#endif
-}
-
-/*
-** Generate code into the current Vdbe to evaluate the given
-** expression.  Attempt to store the results in register "target".
-** Return the register where results are stored.
-**
-** With this routine, there is no guarantee that results will
-** be stored in target.  The result might be stored in some other
-** register if it is convenient to do so.  The calling function
-** must check the return code and move the results to the desired
-** register.
-*/
-int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
-  Vdbe *v = pParse->pVdbe;  /* The VM under construction */
-  int op;                   /* The opcode being coded */
-  int inReg = target;       /* Results stored in register inReg */
-  int regFree1 = 0;         /* If non-zero free this temporary register */
-  int regFree2 = 0;         /* If non-zero free this temporary register */
-  int r1, r2, r3, r4;       /* Various register numbers */
-  sqlite3 *db = pParse->db; /* The database connection */
-
-  assert( target>0 && target<=pParse->nMem );
-  if( v==0 ){
-    assert( pParse->db->mallocFailed );
-    return 0;
-  }
-
-  if( pExpr==0 ){
-    op = TK_NULL;
-  }else{
-    op = pExpr->op;
-  }
-  switch( op ){
-    case TK_AGG_COLUMN: {
-      AggInfo *pAggInfo = pExpr->pAggInfo;
-      struct AggInfo_col *pCol = &pAggInfo->aCol[pExpr->iAgg];
-      if( !pAggInfo->directMode ){
-        assert( pCol->iMem>0 );
-        inReg = pCol->iMem;
-        break;
-      }else if( pAggInfo->useSortingIdx ){
-        sqlite3VdbeAddOp3(v, OP_Column, pAggInfo->sortingIdx,
-                              pCol->iSorterColumn, target);
-        break;
-      }
-      /* Otherwise, fall thru into the TK_COLUMN case */
-    }
-    case TK_COLUMN: {
-      if( pExpr->iTable<0 ){
-        /* This only happens when coding check constraints */
-        assert( pParse->ckBase>0 );
-        inReg = pExpr->iColumn + pParse->ckBase;
-      }else{
-        testcase( (pExpr->flags & EP_AnyAff)!=0 );
-        inReg = sqlite3ExprCodeGetColumn(pParse, pExpr->pTab,
-                                 pExpr->iColumn, pExpr->iTable, target,
-                                 pExpr->flags & EP_AnyAff);
-      }
-      break;
-    }
-    case TK_INTEGER: {
-      codeInteger(v, pExpr, 0, target);
-      break;
-    }
-    case TK_FLOAT: {
-      assert( !ExprHasProperty(pExpr, EP_IntValue) );
-      codeReal(v, pExpr->u.zToken, 0, target);
-      break;
-    }
-    case TK_STRING: {
-      assert( !ExprHasProperty(pExpr, EP_IntValue) );
-      sqlite3VdbeAddOp4(v, OP_String8, 0, target, 0, pExpr->u.zToken, 0);
-      break;
-    }
-    case TK_NULL: {
-      sqlite3VdbeAddOp2(v, OP_Null, 0, target);
-      break;
-    }
-#ifndef SQLITE_OMIT_BLOB_LITERAL
-    case TK_BLOB: {
-      int n;
-      const char *z;
-      char *zBlob;
-      assert( !ExprHasProperty(pExpr, EP_IntValue) );
-      assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
-      assert( pExpr->u.zToken[1]=='\'' );
-      z = &pExpr->u.zToken[2];
-      n = sqlite3Strlen30(z) - 1;
-      assert( z[n]=='\'' );
-      zBlob = sqlite3HexToBlob(sqlite3VdbeDb(v), z, n);
-      sqlite3VdbeAddOp4(v, OP_Blob, n/2, target, 0, zBlob, P4_DYNAMIC);
-      break;
-    }
-#endif
-    case TK_VARIABLE: {
-      VdbeOp *pOp;
-      assert( !ExprHasProperty(pExpr, EP_IntValue) );
-      assert( pExpr->u.zToken!=0 );
-      assert( pExpr->u.zToken[0]!=0 );
-      if( pExpr->u.zToken[1]==0
-         && (pOp = sqlite3VdbeGetOp(v, -1))->opcode==OP_Variable
-         && pOp->p1+pOp->p3==pExpr->iTable
-         && pOp->p2+pOp->p3==target
-         && pOp->p4.z==0
-      ){
-        /* If the previous instruction was a copy of the previous unnamed
-        ** parameter into the previous register, then simply increment the
-        ** repeat count on the prior instruction rather than making a new
-        ** instruction.
-        */
-        pOp->p3++;
-      }else{
-        sqlite3VdbeAddOp3(v, OP_Variable, pExpr->iTable, target, 1);
-        if( pExpr->u.zToken[1]!=0 ){
-          sqlite3VdbeChangeP4(v, -1, pExpr->u.zToken, 0);
-        }
-      }
-      break;
-    }
-    case TK_REGISTER: {
-      inReg = pExpr->iTable;
-      break;
-    }
-    case TK_AS: {
-      inReg = codeAlias(pParse, pExpr->iTable, pExpr->pLeft, target);
-      break;
-    }
-#ifndef SQLITE_OMIT_CAST
-    case TK_CAST: {
-      /* Expressions of the form:   CAST(pLeft AS token) */
-      int aff, to_op;
-      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
-      assert( !ExprHasProperty(pExpr, EP_IntValue) );
-      aff = sqlite3AffinityType(pExpr->u.zToken);
-      to_op = aff - SQLITE_AFF_TEXT + OP_ToText;
-      assert( to_op==OP_ToText    || aff!=SQLITE_AFF_TEXT    );
-      assert( to_op==OP_ToBlob    || aff!=SQLITE_AFF_NONE    );
-      assert( to_op==OP_ToNumeric || aff!=SQLITE_AFF_NUMERIC );
-      assert( to_op==OP_ToInt     || aff!=SQLITE_AFF_INTEGER );
-      assert( to_op==OP_ToReal    || aff!=SQLITE_AFF_REAL    );
-      testcase( to_op==OP_ToText );
-      testcase( to_op==OP_ToBlob );
-      testcase( to_op==OP_ToNumeric );
-      testcase( to_op==OP_ToInt );
-      testcase( to_op==OP_ToReal );
-      if( inReg!=target ){
-        sqlite3VdbeAddOp2(v, OP_SCopy, inReg, target);
-        inReg = target;
-      }
-      sqlite3VdbeAddOp1(v, to_op, inReg);
-      testcase( usedAsColumnCache(pParse, inReg, inReg) );
-      sqlite3ExprCacheAffinityChange(pParse, inReg, 1);
-      break;
-    }
-#endif /* SQLITE_OMIT_CAST */
-    case TK_LT:
-    case TK_LE:
-    case TK_GT:
-    case TK_GE:
-    case TK_NE:
-    case TK_EQ: {
-      assert( TK_LT==OP_Lt );
-      assert( TK_LE==OP_Le );
-      assert( TK_GT==OP_Gt );
-      assert( TK_GE==OP_Ge );
-      assert( TK_EQ==OP_Eq );
-      assert( TK_NE==OP_Ne );
-      testcase( op==TK_LT );
-      testcase( op==TK_LE );
-      testcase( op==TK_GT );
-      testcase( op==TK_GE );
-      testcase( op==TK_EQ );
-      testcase( op==TK_NE );
-      codeCompareOperands(pParse, pExpr->pLeft, &r1, &regFree1,
-                                  pExpr->pRight, &r2, &regFree2);
-      codeCompare(pParse, pExpr->pLeft, pExpr->pRight, op,
-                  r1, r2, inReg, SQLITE_STOREP2);
-      testcase( regFree1==0 );
-      testcase( regFree2==0 );
-      break;
-    }
-    case TK_AND:
-    case TK_OR:
-    case TK_PLUS:
-    case TK_STAR:
-    case TK_MINUS:
-    case TK_REM:
-    case TK_BITAND:
-    case TK_BITOR:
-    case TK_SLASH:
-    case TK_LSHIFT:
-    case TK_RSHIFT: 
-    case TK_CONCAT: {
-      assert( TK_AND==OP_And );
-      assert( TK_OR==OP_Or );
-      assert( TK_PLUS==OP_Add );
-      assert( TK_MINUS==OP_Subtract );
-      assert( TK_REM==OP_Remainder );
-      assert( TK_BITAND==OP_BitAnd );
-      assert( TK_BITOR==OP_BitOr );
-      assert( TK_SLASH==OP_Divide );
-      assert( TK_LSHIFT==OP_ShiftLeft );
-      assert( TK_RSHIFT==OP_ShiftRight );
-      assert( TK_CONCAT==OP_Concat );
-      testcase( op==TK_AND );
-      testcase( op==TK_OR );
-      testcase( op==TK_PLUS );
-      testcase( op==TK_MINUS );
-      testcase( op==TK_REM );
-      testcase( op==TK_BITAND );
-      testcase( op==TK_BITOR );
-      testcase( op==TK_SLASH );
-      testcase( op==TK_LSHIFT );
-      testcase( op==TK_RSHIFT );
-      testcase( op==TK_CONCAT );
-      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
-      r2 = sqlite3ExprCodeTemp(pParse, pExpr->pRight, &regFree2);
-      sqlite3VdbeAddOp3(v, op, r2, r1, target);
-      testcase( regFree1==0 );
-      testcase( regFree2==0 );
-      break;
-    }
-    case TK_UMINUS: {
-      Expr *pLeft = pExpr->pLeft;
-      assert( pLeft );
-      if( pLeft->op==TK_FLOAT ){
-        assert( !ExprHasProperty(pExpr, EP_IntValue) );
-        codeReal(v, pLeft->u.zToken, 1, target);
-      }else if( pLeft->op==TK_INTEGER ){
-        codeInteger(v, pLeft, 1, target);
-      }else{
-        regFree1 = r1 = sqlite3GetTempReg(pParse);
-        sqlite3VdbeAddOp2(v, OP_Integer, 0, r1);
-        r2 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree2);
-        sqlite3VdbeAddOp3(v, OP_Subtract, r2, r1, target);
-        testcase( regFree2==0 );
-      }
-      inReg = target;
-      break;
-    }
-    case TK_BITNOT:
-    case TK_NOT: {
-      assert( TK_BITNOT==OP_BitNot );
-      assert( TK_NOT==OP_Not );
-      testcase( op==TK_BITNOT );
-      testcase( op==TK_NOT );
-      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
-      testcase( regFree1==0 );
-      inReg = target;
-      sqlite3VdbeAddOp2(v, op, r1, inReg);
-      break;
-    }
-    case TK_ISNULL:
-    case TK_NOTNULL: {
-      int addr;
-      assert( TK_ISNULL==OP_IsNull );
-      assert( TK_NOTNULL==OP_NotNull );
-      testcase( op==TK_ISNULL );
-      testcase( op==TK_NOTNULL );
-      sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
-      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
-      testcase( regFree1==0 );
-      addr = sqlite3VdbeAddOp1(v, op, r1);
-      sqlite3VdbeAddOp2(v, OP_AddImm, target, -1);
-      sqlite3VdbeJumpHere(v, addr);
-      break;
-    }
-    case TK_AGG_FUNCTION: {
-      AggInfo *pInfo = pExpr->pAggInfo;
-      if( pInfo==0 ){
-        assert( !ExprHasProperty(pExpr, EP_IntValue) );
-        sqlite3ErrorMsg(pParse, "misuse of aggregate: %s()", pExpr->u.zToken);
-      }else{
-        inReg = pInfo->aFunc[pExpr->iAgg].iMem;
-      }
-      break;
-    }
-    case TK_CONST_FUNC:
-    case TK_FUNCTION: {
-      ExprList *pFarg;       /* List of function arguments */
-      int nFarg;             /* Number of function arguments */
-      FuncDef *pDef;         /* The function definition object */
-      int nId;               /* Length of the function name in bytes */
-      const char *zId;       /* The function name */
-      int constMask = 0;     /* Mask of function arguments that are constant */
-      int i;                 /* Loop counter */
-      u8 enc = ENC(db);      /* The text encoding used by this database */
-      CollSeq *pColl = 0;    /* A collating sequence */
-
-      assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
-      testcase( op==TK_CONST_FUNC );
-      testcase( op==TK_FUNCTION );
-      if( ExprHasAnyProperty(pExpr, EP_TokenOnly) ){
-        pFarg = 0;
-      }else{
-        pFarg = pExpr->x.pList;
-      }
-      nFarg = pFarg ? pFarg->nExpr : 0;
-      assert( !ExprHasProperty(pExpr, EP_IntValue) );
-      zId = pExpr->u.zToken;
-      nId = sqlite3Strlen30(zId);
-      pDef = sqlite3FindFunction(db, zId, nId, nFarg, enc, 0);
-      if( pDef==0 ){
-        sqlite3ErrorMsg(pParse, "unknown function: %.*s()", nId, zId);
-        break;
-      }
-      if( pFarg ){
-        r1 = sqlite3GetTempRange(pParse, nFarg);
-        sqlite3ExprCachePush(pParse);     /* Ticket 2ea2425d34be */
-        sqlite3ExprCodeExprList(pParse, pFarg, r1, 1);
-        sqlite3ExprCachePop(pParse, 1);   /* Ticket 2ea2425d34be */
-      }else{
-        r1 = 0;
-      }
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-      /* Possibly overload the function if the first argument is
-      ** a virtual table column.
-      **
-      ** For infix functions (LIKE, GLOB, REGEXP, and MATCH) use the
-      ** second argument, not the first, as the argument to test to
-      ** see if it is a column in a virtual table.  This is done because
-      ** the left operand of infix functions (the operand we want to
-      ** control overloading) ends up as the second argument to the
-      ** function.  The expression "A glob B" is equivalent to 
-      ** "glob(B,A).  We want to use the A in "A glob B" to test
-      ** for function overloading.  But we use the B term in "glob(B,A)".
-      */
-      if( nFarg>=2 && (pExpr->flags & EP_InfixFunc) ){
-        pDef = sqlite3VtabOverloadFunction(db, pDef, nFarg, pFarg->a[1].pExpr);
-      }else if( nFarg>0 ){
-        pDef = sqlite3VtabOverloadFunction(db, pDef, nFarg, pFarg->a[0].pExpr);
-      }
-#endif
-      for(i=0; i<nFarg; i++){
-        if( i<32 && sqlite3ExprIsConstant(pFarg->a[i].pExpr) ){
-          constMask |= (1<<i);
-        }
-        if( (pDef->flags & SQLITE_FUNC_NEEDCOLL)!=0 && !pColl ){
-          pColl = sqlite3ExprCollSeq(pParse, pFarg->a[i].pExpr);
-        }
-      }
-      if( pDef->flags & SQLITE_FUNC_NEEDCOLL ){
-        if( !pColl ) pColl = db->pDfltColl; 
-        sqlite3VdbeAddOp4(v, OP_CollSeq, 0, 0, 0, (char *)pColl, P4_COLLSEQ);
-      }
-      sqlite3VdbeAddOp4(v, OP_Function, constMask, r1, target,
-                        (char*)pDef, P4_FUNCDEF);
-      sqlite3VdbeChangeP5(v, (u8)nFarg);
-      if( nFarg ){
-        sqlite3ReleaseTempRange(pParse, r1, nFarg);
-      }
-      sqlite3ExprCacheAffinityChange(pParse, r1, nFarg);
-      break;
-    }
-#ifndef SQLITE_OMIT_SUBQUERY
-    case TK_EXISTS:
-    case TK_SELECT: {
-      testcase( op==TK_EXISTS );
-      testcase( op==TK_SELECT );
-      sqlite3CodeSubselect(pParse, pExpr, 0, 0);
-      inReg = pExpr->iColumn;
-      break;
-    }
-    case TK_IN: {
-      int rNotFound = 0;
-      int rMayHaveNull = 0;
-      int j2, j3, j4, j5;
-      char affinity;
-      int eType;
-
-      VdbeNoopComment((v, "begin IN expr r%d", target));
-      eType = sqlite3FindInIndex(pParse, pExpr, &rMayHaveNull);
-      if( rMayHaveNull ){
-        rNotFound = ++pParse->nMem;
-      }
-
-      /* Figure out the affinity to use to create a key from the results
-      ** of the expression. affinityStr stores a static string suitable for
-      ** P4 of OP_MakeRecord.
-      */
-      affinity = comparisonAffinity(pExpr);
-
-
-      /* Code the <expr> from "<expr> IN (...)". The temporary table
-      ** pExpr->iTable contains the values that make up the (...) set.
-      */
-      sqlite3ExprCachePush(pParse);
-      sqlite3ExprCode(pParse, pExpr->pLeft, target);
-      j2 = sqlite3VdbeAddOp1(v, OP_IsNull, target);
-      if( eType==IN_INDEX_ROWID ){
-        j3 = sqlite3VdbeAddOp1(v, OP_MustBeInt, target);
-        j4 = sqlite3VdbeAddOp3(v, OP_NotExists, pExpr->iTable, 0, target);
-        sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
-        j5 = sqlite3VdbeAddOp0(v, OP_Goto);
-        sqlite3VdbeJumpHere(v, j3);
-        sqlite3VdbeJumpHere(v, j4);
-        sqlite3VdbeAddOp2(v, OP_Integer, 0, target);
-      }else{
-        r2 = regFree2 = sqlite3GetTempReg(pParse);
-
-        /* Create a record and test for set membership. If the set contains
-        ** the value, then jump to the end of the test code. The target
-        ** register still contains the true (1) value written to it earlier.
-        */
-        sqlite3VdbeAddOp4(v, OP_MakeRecord, target, 1, r2, &affinity, 1);
-        sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
-        j5 = sqlite3VdbeAddOp3(v, OP_Found, pExpr->iTable, 0, r2);
-
-        /* If the set membership test fails, then the result of the 
-        ** "x IN (...)" expression must be either 0 or NULL. If the set
-        ** contains no NULL values, then the result is 0. If the set 
-        ** contains one or more NULL values, then the result of the
-        ** expression is also NULL.
-        */
-        if( rNotFound==0 ){
-          /* This branch runs if it is known at compile time (now) that 
-          ** the set contains no NULL values. This happens as the result
-          ** of a "NOT NULL" constraint in the database schema. No need
-          ** to test the data structure at runtime in this case.
-          */
-          sqlite3VdbeAddOp2(v, OP_Integer, 0, target);
-        }else{
-          /* This block populates the rNotFound register with either NULL
-          ** or 0 (an integer value). If the data structure contains one
-          ** or more NULLs, then set rNotFound to NULL. Otherwise, set it
-          ** to 0. If register rMayHaveNull is already set to some value
-          ** other than NULL, then the test has already been run and 
-          ** rNotFound is already populated.
-          */
-          static const char nullRecord[] = { 0x02, 0x00 };
-          j3 = sqlite3VdbeAddOp1(v, OP_NotNull, rMayHaveNull);
-          sqlite3VdbeAddOp2(v, OP_Null, 0, rNotFound);
-          sqlite3VdbeAddOp4(v, OP_Blob, 2, rMayHaveNull, 0, 
-                             nullRecord, P4_STATIC);
-          j4 = sqlite3VdbeAddOp3(v, OP_Found, pExpr->iTable, 0, rMayHaveNull);
-          sqlite3VdbeAddOp2(v, OP_Integer, 0, rNotFound);
-          sqlite3VdbeJumpHere(v, j4);
-          sqlite3VdbeJumpHere(v, j3);
-
-          /* Copy the value of register rNotFound (which is either NULL or 0)
-          ** into the target register. This will be the result of the
-          ** expression.
-          */
-          sqlite3VdbeAddOp2(v, OP_Copy, rNotFound, target);
-        }
-      }
-      sqlite3VdbeJumpHere(v, j2);
-      sqlite3VdbeJumpHere(v, j5);
-      sqlite3ExprCachePop(pParse, 1);
-      VdbeComment((v, "end IN expr r%d", target));
-      break;
-    }
-#endif
-    /*
-    **    x BETWEEN y AND z
-    **
-    ** This is equivalent to
-    **
-    **    x>=y AND x<=z
-    **
-    ** X is stored in pExpr->pLeft.
-    ** Y is stored in pExpr->pList->a[0].pExpr.
-    ** Z is stored in pExpr->pList->a[1].pExpr.
-    */
-    case TK_BETWEEN: {
-      Expr *pLeft = pExpr->pLeft;
-      struct ExprList_item *pLItem = pExpr->x.pList->a;
-      Expr *pRight = pLItem->pExpr;
-
-      codeCompareOperands(pParse, pLeft, &r1, &regFree1,
-                                  pRight, &r2, &regFree2);
-      testcase( regFree1==0 );
-      testcase( regFree2==0 );
-      r3 = sqlite3GetTempReg(pParse);
-      r4 = sqlite3GetTempReg(pParse);
-      codeCompare(pParse, pLeft, pRight, OP_Ge,
-                  r1, r2, r3, SQLITE_STOREP2);
-      pLItem++;
-      pRight = pLItem->pExpr;
-      sqlite3ReleaseTempReg(pParse, regFree2);
-      r2 = sqlite3ExprCodeTemp(pParse, pRight, &regFree2);
-      testcase( regFree2==0 );
-      codeCompare(pParse, pLeft, pRight, OP_Le, r1, r2, r4, SQLITE_STOREP2);
-      sqlite3VdbeAddOp3(v, OP_And, r3, r4, target);
-      sqlite3ReleaseTempReg(pParse, r3);
-      sqlite3ReleaseTempReg(pParse, r4);
-      break;
-    }
-    case TK_UPLUS: {
-      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
-      break;
-    }
-
-    case TK_TRIGGER: {
-      /* If the opcode is TK_TRIGGER, then the expression is a reference
-      ** to a column in the new.* or old.* pseudo-tables available to
-      ** trigger programs. In this case Expr.iTable is set to 1 for the
-      ** new.* pseudo-table, or 0 for the old.* pseudo-table. Expr.iColumn
-      ** is set to the column of the pseudo-table to read, or to -1 to
-      ** read the rowid field.
-      **
-      ** The expression is implemented using an OP_Param opcode. The p1
-      ** parameter is set to 0 for an old.rowid reference, or to (i+1)
-      ** to reference another column of the old.* pseudo-table, where 
-      ** i is the index of the column. For a new.rowid reference, p1 is
-      ** set to (n+1), where n is the number of columns in each pseudo-table.
-      ** For a reference to any other column in the new.* pseudo-table, p1
-      ** is set to (n+2+i), where n and i are as defined previously. For
-      ** example, if the table on which triggers are being fired is
-      ** declared as:
-      **
-      **   CREATE TABLE t1(a, b);
-      **
-      ** Then p1 is interpreted as follows:
-      **
-      **   p1==0   ->    old.rowid     p1==3   ->    new.rowid
-      **   p1==1   ->    old.a         p1==4   ->    new.a
-      **   p1==2   ->    old.b         p1==5   ->    new.b       
-      */
-      Table *pTab = pExpr->pTab;
-      int p1 = pExpr->iTable * (pTab->nCol+1) + 1 + pExpr->iColumn;
-
-      assert( pExpr->iTable==0 || pExpr->iTable==1 );
-      assert( pExpr->iColumn>=-1 && pExpr->iColumn<pTab->nCol );
-      assert( pTab->iPKey<0 || pExpr->iColumn!=pTab->iPKey );
-      assert( p1>=0 && p1<(pTab->nCol*2+2) );
-
-      sqlite3VdbeAddOp2(v, OP_Param, p1, target);
-      VdbeComment((v, "%s.%s -> $%d",
-        (pExpr->iTable ? "new" : "old"),
-        (pExpr->iColumn<0 ? "rowid" : pExpr->pTab->aCol[pExpr->iColumn].zName),
-        target
-      ));
-
-      /* If the column has REAL affinity, it may currently be stored as an
-      ** integer. Use OP_RealAffinity to make sure it is really real.  */
-      if( pExpr->iColumn>=0 
-       && pTab->aCol[pExpr->iColumn].affinity==SQLITE_AFF_REAL
-      ){
-        sqlite3VdbeAddOp1(v, OP_RealAffinity, target);
-      }
-      break;
-    }
-
-
-    /*
-    ** Form A:
-    **   CASE x WHEN e1 THEN r1 WHEN e2 THEN r2 ... WHEN eN THEN rN ELSE y END
-    **
-    ** Form B:
-    **   CASE WHEN e1 THEN r1 WHEN e2 THEN r2 ... WHEN eN THEN rN ELSE y END
-    **
-    ** Form A is can be transformed into the equivalent form B as follows:
-    **   CASE WHEN x=e1 THEN r1 WHEN x=e2 THEN r2 ...
-    **        WHEN x=eN THEN rN ELSE y END
-    **
-    ** X (if it exists) is in pExpr->pLeft.
-    ** Y is in pExpr->pRight.  The Y is also optional.  If there is no
-    ** ELSE clause and no other term matches, then the result of the
-    ** exprssion is NULL.
-    ** Ei is in pExpr->pList->a[i*2] and Ri is pExpr->pList->a[i*2+1].
-    **
-    ** The result of the expression is the Ri for the first matching Ei,
-    ** or if there is no matching Ei, the ELSE term Y, or if there is
-    ** no ELSE term, NULL.
-    */
-    default: assert( op==TK_CASE ); {
-      int endLabel;                     /* GOTO label for end of CASE stmt */
-      int nextCase;                     /* GOTO label for next WHEN clause */
-      int nExpr;                        /* 2x number of WHEN terms */
-      int i;                            /* Loop counter */
-      ExprList *pEList;                 /* List of WHEN terms */
-      struct ExprList_item *aListelem;  /* Array of WHEN terms */
-      Expr opCompare;                   /* The X==Ei expression */
-      Expr cacheX;                      /* Cached expression X */
-      Expr *pX;                         /* The X expression */
-      Expr *pTest = 0;                  /* X==Ei (form A) or just Ei (form B) */
-      VVA_ONLY( int iCacheLevel = pParse->iCacheLevel; )
-
-      assert( !ExprHasProperty(pExpr, EP_xIsSelect) && pExpr->x.pList );
-      assert((pExpr->x.pList->nExpr % 2) == 0);
-      assert(pExpr->x.pList->nExpr > 0);
-      pEList = pExpr->x.pList;
-      aListelem = pEList->a;
-      nExpr = pEList->nExpr;
-      endLabel = sqlite3VdbeMakeLabel(v);
-      if( (pX = pExpr->pLeft)!=0 ){
-        cacheX = *pX;
-        testcase( pX->op==TK_COLUMN );
-        testcase( pX->op==TK_REGISTER );
-        cacheX.iTable = sqlite3ExprCodeTemp(pParse, pX, &regFree1);
-        testcase( regFree1==0 );
-        cacheX.op = TK_REGISTER;
-        opCompare.op = TK_EQ;
-        opCompare.pLeft = &cacheX;
-        pTest = &opCompare;
-      }
-      for(i=0; i<nExpr; i=i+2){
-        sqlite3ExprCachePush(pParse);
-        if( pX ){
-          assert( pTest!=0 );
-          opCompare.pRight = aListelem[i].pExpr;
-        }else{
-          pTest = aListelem[i].pExpr;
-        }
-        nextCase = sqlite3VdbeMakeLabel(v);
-        testcase( pTest->op==TK_COLUMN );
-        sqlite3ExprIfFalse(pParse, pTest, nextCase, SQLITE_JUMPIFNULL);
-        testcase( aListelem[i+1].pExpr->op==TK_COLUMN );
-        testcase( aListelem[i+1].pExpr->op==TK_REGISTER );
-        sqlite3ExprCode(pParse, aListelem[i+1].pExpr, target);
-        sqlite3VdbeAddOp2(v, OP_Goto, 0, endLabel);
-        sqlite3ExprCachePop(pParse, 1);
-        sqlite3VdbeResolveLabel(v, nextCase);
-      }
-      if( pExpr->pRight ){
-        sqlite3ExprCachePush(pParse);
-        sqlite3ExprCode(pParse, pExpr->pRight, target);
-        sqlite3ExprCachePop(pParse, 1);
-      }else{
-        sqlite3VdbeAddOp2(v, OP_Null, 0, target);
-      }
-      assert( db->mallocFailed || pParse->nErr>0 
-           || pParse->iCacheLevel==iCacheLevel );
-      sqlite3VdbeResolveLabel(v, endLabel);
-      break;
-    }
-#ifndef SQLITE_OMIT_TRIGGER
-    case TK_RAISE: {
-      assert( pExpr->affinity==OE_Rollback 
-           || pExpr->affinity==OE_Abort
-           || pExpr->affinity==OE_Fail
-           || pExpr->affinity==OE_Ignore
-      );
-      if( !pParse->pTriggerTab ){
-        sqlite3ErrorMsg(pParse,
-                       "RAISE() may only be used within a trigger-program");
-        return 0;
-      }
-      if( pExpr->affinity==OE_Abort ){
-        sqlite3MayAbort(pParse);
-      }
-      assert( !ExprHasProperty(pExpr, EP_IntValue) );
-      if( pExpr->affinity==OE_Ignore ){
-        sqlite3VdbeAddOp4(
-            v, OP_Halt, SQLITE_OK, OE_Ignore, 0, pExpr->u.zToken,0);
-      }else{
-        sqlite3HaltConstraint(pParse, pExpr->affinity, pExpr->u.zToken, 0);
-      }
-
-      break;
-    }
-#endif
-  }
-  sqlite3ReleaseTempReg(pParse, regFree1);
-  sqlite3ReleaseTempReg(pParse, regFree2);
-  return inReg;
-}
-
-/*
-** Generate code to evaluate an expression and store the results
-** into a register.  Return the register number where the results
-** are stored.
-**
-** If the register is a temporary register that can be deallocated,
-** then write its number into *pReg.  If the result register is not
-** a temporary, then set *pReg to zero.
-*/
-int sqlite3ExprCodeTemp(Parse *pParse, Expr *pExpr, int *pReg){
-  int r1 = sqlite3GetTempReg(pParse);
-  int r2 = sqlite3ExprCodeTarget(pParse, pExpr, r1);
-  if( r2==r1 ){
-    *pReg = r1;
-  }else{
-    sqlite3ReleaseTempReg(pParse, r1);
-    *pReg = 0;
-  }
-  return r2;
-}
-
-/*
-** Generate code that will evaluate expression pExpr and store the
-** results in register target.  The results are guaranteed to appear
-** in register target.
-*/
-int sqlite3ExprCode(Parse *pParse, Expr *pExpr, int target){
-  int inReg;
-
-  assert( target>0 && target<=pParse->nMem );
-  inReg = sqlite3ExprCodeTarget(pParse, pExpr, target);
-  assert( pParse->pVdbe || pParse->db->mallocFailed );
-  if( inReg!=target && pParse->pVdbe ){
-    sqlite3VdbeAddOp2(pParse->pVdbe, OP_SCopy, inReg, target);
-  }
-  return target;
-}
-
-/*
-** Generate code that evalutes the given expression and puts the result
-** in register target.
-**
-** Also make a copy of the expression results into another "cache" register
-** and modify the expression so that the next time it is evaluated,
-** the result is a copy of the cache register.
-**
-** This routine is used for expressions that are used multiple 
-** times.  They are evaluated once and the results of the expression
-** are reused.
-*/
-int sqlite3ExprCodeAndCache(Parse *pParse, Expr *pExpr, int target){
-  Vdbe *v = pParse->pVdbe;
-  int inReg;
-  inReg = sqlite3ExprCode(pParse, pExpr, target);
-  assert( target>0 );
-  /* This routine is called for terms to INSERT or UPDATE.  And the only
-  ** other place where expressions can be converted into TK_REGISTER is
-  ** in WHERE clause processing.  So as currently implemented, there is
-  ** no way for a TK_REGISTER to exist here.  But it seems prudent to
-  ** keep the ALWAYS() in case the conditions above change with future
-  ** modifications or enhancements. */
-  if( ALWAYS(pExpr->op!=TK_REGISTER) ){  
-    int iMem;
-    iMem = ++pParse->nMem;
-    sqlite3VdbeAddOp2(v, OP_Copy, inReg, iMem);
-    pExpr->iTable = iMem;
-    pExpr->op = TK_REGISTER;
-  }
-  return inReg;
-}
-
-/*
-** Return TRUE if pExpr is an constant expression that is appropriate
-** for factoring out of a loop.  Appropriate expressions are:
-**
-**    *  Any expression that evaluates to two or more opcodes.
-**
-**    *  Any OP_Integer, OP_Real, OP_String, OP_Blob, OP_Null, 
-**       or OP_Variable that does not need to be placed in a 
-**       specific register.
-**
-** There is no point in factoring out single-instruction constant
-** expressions that need to be placed in a particular register.  
-** We could factor them out, but then we would end up adding an
-** OP_SCopy instruction to move the value into the correct register
-** later.  We might as well just use the original instruction and
-** avoid the OP_SCopy.
-*/
-static int isAppropriateForFactoring(Expr *p){
-  if( !sqlite3ExprIsConstantNotJoin(p) ){
-    return 0;  /* Only constant expressions are appropriate for factoring */
-  }
-  if( (p->flags & EP_FixedDest)==0 ){
-    return 1;  /* Any constant without a fixed destination is appropriate */
-  }
-  while( p->op==TK_UPLUS ) p = p->pLeft;
-  switch( p->op ){
-#ifndef SQLITE_OMIT_BLOB_LITERAL
-    case TK_BLOB:
-#endif
-    case TK_VARIABLE:
-    case TK_INTEGER:
-    case TK_FLOAT:
-    case TK_NULL:
-    case TK_STRING: {
-      testcase( p->op==TK_BLOB );
-      testcase( p->op==TK_VARIABLE );
-      testcase( p->op==TK_INTEGER );
-      testcase( p->op==TK_FLOAT );
-      testcase( p->op==TK_NULL );
-      testcase( p->op==TK_STRING );
-      /* Single-instruction constants with a fixed destination are
-      ** better done in-line.  If we factor them, they will just end
-      ** up generating an OP_SCopy to move the value to the destination
-      ** register. */
-      return 0;
-    }
-    case TK_UMINUS: {
-      if( p->pLeft->op==TK_FLOAT || p->pLeft->op==TK_INTEGER ){
-        return 0;
-      }
-      break;
-    }
-    default: {
-      break;
-    }
-  }
-  return 1;
-}
-
-/*
-** If pExpr is a constant expression that is appropriate for
-** factoring out of a loop, then evaluate the expression
-** into a register and convert the expression into a TK_REGISTER
-** expression.
-*/
-static int evalConstExpr(Walker *pWalker, Expr *pExpr){
-  Parse *pParse = pWalker->pParse;
-  switch( pExpr->op ){
-    case TK_REGISTER: {
-      return WRC_Prune;
-    }
-    case TK_FUNCTION:
-    case TK_AGG_FUNCTION:
-    case TK_CONST_FUNC: {
-      /* The arguments to a function have a fixed destination.
-      ** Mark them this way to avoid generated unneeded OP_SCopy
-      ** instructions. 
-      */
-      ExprList *pList = pExpr->x.pList;
-      assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
-      if( pList ){
-        int i = pList->nExpr;
-        struct ExprList_item *pItem = pList->a;
-        for(; i>0; i--, pItem++){
-          if( ALWAYS(pItem->pExpr) ) pItem->pExpr->flags |= EP_FixedDest;
-        }
-      }
-      break;
-    }
-  }
-  if( isAppropriateForFactoring(pExpr) ){
-    int r1 = ++pParse->nMem;
-    int r2;
-    r2 = sqlite3ExprCodeTarget(pParse, pExpr, r1);
-    if( NEVER(r1!=r2) ) sqlite3ReleaseTempReg(pParse, r1);
-    pExpr->op2 = pExpr->op;
-    pExpr->op = TK_REGISTER;
-    pExpr->iTable = r2;
-    return WRC_Prune;
-  }
-  return WRC_Continue;
-}
-
-/*
-** Preevaluate constant subexpressions within pExpr and store the
-** results in registers.  Modify pExpr so that the constant subexpresions
-** are TK_REGISTER opcodes that refer to the precomputed values.
-*/
-void sqlite3ExprCodeConstants(Parse *pParse, Expr *pExpr){
-  Walker w;
-  w.xExprCallback = evalConstExpr;
-  w.xSelectCallback = 0;
-  w.pParse = pParse;
-  sqlite3WalkExpr(&w, pExpr);
-}
-
-
-/*
-** Generate code that pushes the value of every element of the given
-** expression list into a sequence of registers beginning at target.
-**
-** Return the number of elements evaluated.
-*/
-int sqlite3ExprCodeExprList(
-  Parse *pParse,     /* Parsing context */
-  ExprList *pList,   /* The expression list to be coded */
-  int target,        /* Where to write results */
-  int doHardCopy     /* Make a hard copy of every element */
-){
-  struct ExprList_item *pItem;
-  int i, n;
-  assert( pList!=0 );
-  assert( target>0 );
-  n = pList->nExpr;
-  for(pItem=pList->a, i=0; i<n; i++, pItem++){
-    if( pItem->iAlias ){
-      int iReg = codeAlias(pParse, pItem->iAlias, pItem->pExpr, target+i);
-      Vdbe *v = sqlite3GetVdbe(pParse);
-      if( iReg!=target+i ){
-        sqlite3VdbeAddOp2(v, OP_SCopy, iReg, target+i);
-      }
-    }else{
-      sqlite3ExprCode(pParse, pItem->pExpr, target+i);
-    }
-    if( doHardCopy && !pParse->db->mallocFailed ){
-      sqlite3ExprHardCopy(pParse, target, n);
-    }
-  }
-  return n;
-}
-
-/*
-** Generate code for a boolean expression such that a jump is made
-** to the label "dest" if the expression is true but execution
-** continues straight thru if the expression is false.
-**
-** If the expression evaluates to NULL (neither true nor false), then
-** take the jump if the jumpIfNull flag is SQLITE_JUMPIFNULL.
-**
-** This code depends on the fact that certain token values (ex: TK_EQ)
-** are the same as opcode values (ex: OP_Eq) that implement the corresponding
-** operation.  Special comments in vdbe.c and the mkopcodeh.awk script in
-** the make process cause these values to align.  Assert()s in the code
-** below verify that the numbers are aligned correctly.
-*/
-void sqlite3ExprIfTrue(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
-  Vdbe *v = pParse->pVdbe;
-  int op = 0;
-  int regFree1 = 0;
-  int regFree2 = 0;
-  int r1, r2;
-
-  assert( jumpIfNull==SQLITE_JUMPIFNULL || jumpIfNull==0 );
-  if( NEVER(v==0) )     return;  /* Existance of VDBE checked by caller */
-  if( NEVER(pExpr==0) ) return;  /* No way this can happen */
-  op = pExpr->op;
-  switch( op ){
-    case TK_AND: {
-      int d2 = sqlite3VdbeMakeLabel(v);
-      testcase( jumpIfNull==0 );
-      sqlite3ExprCachePush(pParse);
-      sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2,jumpIfNull^SQLITE_JUMPIFNULL);
-      sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
-      sqlite3VdbeResolveLabel(v, d2);
-      sqlite3ExprCachePop(pParse, 1);
-      break;
-    }
-    case TK_OR: {
-      testcase( jumpIfNull==0 );
-      sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
-      sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
-      break;
-    }
-    case TK_NOT: {
-      testcase( jumpIfNull==0 );
-      sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
-      break;
-    }
-    case TK_LT:
-    case TK_LE:
-    case TK_GT:
-    case TK_GE:
-    case TK_NE:
-    case TK_EQ: {
-      assert( TK_LT==OP_Lt );
-      assert( TK_LE==OP_Le );
-      assert( TK_GT==OP_Gt );
-      assert( TK_GE==OP_Ge );
-      assert( TK_EQ==OP_Eq );
-      assert( TK_NE==OP_Ne );
-      testcase( op==TK_LT );
-      testcase( op==TK_LE );
-      testcase( op==TK_GT );
-      testcase( op==TK_GE );
-      testcase( op==TK_EQ );
-      testcase( op==TK_NE );
-      testcase( jumpIfNull==0 );
-      codeCompareOperands(pParse, pExpr->pLeft, &r1, &regFree1,
-                                  pExpr->pRight, &r2, &regFree2);
-      codeCompare(pParse, pExpr->pLeft, pExpr->pRight, op,
-                  r1, r2, dest, jumpIfNull);
-      testcase( regFree1==0 );
-      testcase( regFree2==0 );
-      break;
-    }
-    case TK_ISNULL:
-    case TK_NOTNULL: {
-      assert( TK_ISNULL==OP_IsNull );
-      assert( TK_NOTNULL==OP_NotNull );
-      testcase( op==TK_ISNULL );
-      testcase( op==TK_NOTNULL );
-      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
-      sqlite3VdbeAddOp2(v, op, r1, dest);
-      testcase( regFree1==0 );
-      break;
-    }
-    case TK_BETWEEN: {
-      /*    x BETWEEN y AND z
-      **
-      ** Is equivalent to 
-      **
-      **    x>=y AND x<=z
-      **
-      ** Code it as such, taking care to do the common subexpression
-      ** elementation of x.
-      */
-      Expr exprAnd;
-      Expr compLeft;
-      Expr compRight;
-      Expr exprX;
-
-      assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
-      exprX = *pExpr->pLeft;
-      exprAnd.op = TK_AND;
-      exprAnd.pLeft = &compLeft;
-      exprAnd.pRight = &compRight;
-      compLeft.op = TK_GE;
-      compLeft.pLeft = &exprX;
-      compLeft.pRight = pExpr->x.pList->a[0].pExpr;
-      compRight.op = TK_LE;
-      compRight.pLeft = &exprX;
-      compRight.pRight = pExpr->x.pList->a[1].pExpr;
-      exprX.iTable = sqlite3ExprCodeTemp(pParse, &exprX, &regFree1);
-      testcase( regFree1==0 );
-      exprX.op = TK_REGISTER;
-      testcase( jumpIfNull==0 );
-      sqlite3ExprIfTrue(pParse, &exprAnd, dest, jumpIfNull);
-      break;
-    }
-    default: {
-      r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
-      sqlite3VdbeAddOp3(v, OP_If, r1, dest, jumpIfNull!=0);
-      testcase( regFree1==0 );
-      testcase( jumpIfNull==0 );
-      break;
-    }
-  }
-  sqlite3ReleaseTempReg(pParse, regFree1);
-  sqlite3ReleaseTempReg(pParse, regFree2);  
-}
-
-/*
-** Generate code for a boolean expression such that a jump is made
-** to the label "dest" if the expression is false but execution
-** continues straight thru if the expression is true.
-**
-** If the expression evaluates to NULL (neither true nor false) then
-** jump if jumpIfNull is SQLITE_JUMPIFNULL or fall through if jumpIfNull
-** is 0.
-*/
-void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
-  Vdbe *v = pParse->pVdbe;
-  int op = 0;
-  int regFree1 = 0;
-  int regFree2 = 0;
-  int r1, r2;
-
-  assert( jumpIfNull==SQLITE_JUMPIFNULL || jumpIfNull==0 );
-  if( NEVER(v==0) ) return; /* Existance of VDBE checked by caller */
-  if( pExpr==0 )    return;
-
-  /* The value of pExpr->op and op are related as follows:
-  **
-  **       pExpr->op            op
-  **       ---------          ----------
-  **       TK_ISNULL          OP_NotNull
-  **       TK_NOTNULL         OP_IsNull
-  **       TK_NE              OP_Eq
-  **       TK_EQ              OP_Ne
-  **       TK_GT              OP_Le
-  **       TK_LE              OP_Gt
-  **       TK_GE              OP_Lt
-  **       TK_LT              OP_Ge
-  **
-  ** For other values of pExpr->op, op is undefined and unused.
-  ** The value of TK_ and OP_ constants are arranged such that we
-  ** can compute the mapping above using the following expression.
-  ** Assert()s verify that the computation is correct.
-  */
-  op = ((pExpr->op+(TK_ISNULL&1))^1)-(TK_ISNULL&1);
-
-  /* Verify correct alignment of TK_ and OP_ constants
-  */
-  assert( pExpr->op!=TK_ISNULL || op==OP_NotNull );
-  assert( pExpr->op!=TK_NOTNULL || op==OP_IsNull );
-  assert( pExpr->op!=TK_NE || op==OP_Eq );
-  assert( pExpr->op!=TK_EQ || op==OP_Ne );
-  assert( pExpr->op!=TK_LT || op==OP_Ge );
-  assert( pExpr->op!=TK_LE || op==OP_Gt );
-  assert( pExpr->op!=TK_GT || op==OP_Le );
-  assert( pExpr->op!=TK_GE || op==OP_Lt );
-
-  switch( pExpr->op ){
-    case TK_AND: {
-      testcase( jumpIfNull==0 );
-      sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
-      sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
-      break;
-    }
-    case TK_OR: {
-      int d2 = sqlite3VdbeMakeLabel(v);
-      testcase( jumpIfNull==0 );
-      sqlite3ExprCachePush(pParse);
-      sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2, jumpIfNull^SQLITE_JUMPIFNULL);
-      sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
-      sqlite3VdbeResolveLabel(v, d2);
-      sqlite3ExprCachePop(pParse, 1);
-      break;
-    }
-    case TK_NOT: {
-      sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
-      break;
-    }
-    case TK_LT:
-    case TK_LE:
-    case TK_GT:
-    case TK_GE:
-    case TK_NE:
-    case TK_EQ: {
-      testcase( op==TK_LT );
-      testcase( op==TK_LE );
-      testcase( op==TK_GT );
-      testcase( op==TK_GE );
-      testcase( op==TK_EQ );
-      testcase( op==TK_NE );
-      testcase( jumpIfNull==0 );
-      codeCompareOperands(pParse, pExpr->pLeft, &r1, &regFree1,
-                                  pExpr->pRight, &r2, &regFree2);
-      codeCompare(pParse, pExpr->pLeft, pExpr->pRight, op,
-                  r1, r2, dest, jumpIfNull);
-      testcase( regFree1==0 );
-      testcase( regFree2==0 );
-      break;
-    }
-    case TK_ISNULL:
-    case TK_NOTNULL: {
-      testcase( op==TK_ISNULL );
-      testcase( op==TK_NOTNULL );
-      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
-      sqlite3VdbeAddOp2(v, op, r1, dest);
-      testcase( regFree1==0 );
-      break;
-    }
-    case TK_BETWEEN: {
-      /*    x BETWEEN y AND z
-      **
-      ** Is equivalent to 
-      **
-      **    x>=y AND x<=z
-      **
-      ** Code it as such, taking care to do the common subexpression
-      ** elementation of x.
-      */
-      Expr exprAnd;
-      Expr compLeft;
-      Expr compRight;
-      Expr exprX;
-
-      assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
-      exprX = *pExpr->pLeft;
-      exprAnd.op = TK_AND;
-      exprAnd.pLeft = &compLeft;
-      exprAnd.pRight = &compRight;
-      compLeft.op = TK_GE;
-      compLeft.pLeft = &exprX;
-      compLeft.pRight = pExpr->x.pList->a[0].pExpr;
-      compRight.op = TK_LE;
-      compRight.pLeft = &exprX;
-      compRight.pRight = pExpr->x.pList->a[1].pExpr;
-      exprX.iTable = sqlite3ExprCodeTemp(pParse, &exprX, &regFree1);
-      testcase( regFree1==0 );
-      exprX.op = TK_REGISTER;
-      testcase( jumpIfNull==0 );
-      sqlite3ExprIfFalse(pParse, &exprAnd, dest, jumpIfNull);
-      break;
-    }
-    default: {
-      r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
-      sqlite3VdbeAddOp3(v, OP_IfNot, r1, dest, jumpIfNull!=0);
-      testcase( regFree1==0 );
-      testcase( jumpIfNull==0 );
-      break;
-    }
-  }
-  sqlite3ReleaseTempReg(pParse, regFree1);
-  sqlite3ReleaseTempReg(pParse, regFree2);
-}
-
-/*
-** Do a deep comparison of two expression trees.  Return TRUE (non-zero)
-** if they are identical and return FALSE if they differ in any way.
-**
-** Sometimes this routine will return FALSE even if the two expressions
-** really are equivalent.  If we cannot prove that the expressions are
-** identical, we return FALSE just to be safe.  So if this routine
-** returns false, then you do not really know for certain if the two
-** expressions are the same.  But if you get a TRUE return, then you
-** can be sure the expressions are the same.  In the places where
-** this routine is used, it does not hurt to get an extra FALSE - that
-** just might result in some slightly slower code.  But returning
-** an incorrect TRUE could lead to a malfunction.
-*/
-int sqlite3ExprCompare(Expr *pA, Expr *pB){
-  int i;
-  if( pA==0||pB==0 ){
-    return pB==pA;
-  }
-  assert( !ExprHasAnyProperty(pA, EP_TokenOnly|EP_Reduced) );
-  assert( !ExprHasAnyProperty(pB, EP_TokenOnly|EP_Reduced) );
-  if( ExprHasProperty(pA, EP_xIsSelect) || ExprHasProperty(pB, EP_xIsSelect) ){
-    return 0;
-  }
-  if( (pA->flags & EP_Distinct)!=(pB->flags & EP_Distinct) ) return 0;
-  if( pA->op!=pB->op ) return 0;
-  if( !sqlite3ExprCompare(pA->pLeft, pB->pLeft) ) return 0;
-  if( !sqlite3ExprCompare(pA->pRight, pB->pRight) ) return 0;
-
-  if( pA->x.pList && pB->x.pList ){
-    if( pA->x.pList->nExpr!=pB->x.pList->nExpr ) return 0;
-    for(i=0; i<pA->x.pList->nExpr; i++){
-      Expr *pExprA = pA->x.pList->a[i].pExpr;
-      Expr *pExprB = pB->x.pList->a[i].pExpr;
-      if( !sqlite3ExprCompare(pExprA, pExprB) ) return 0;
-    }
-  }else if( pA->x.pList || pB->x.pList ){
-    return 0;
-  }
-
-  if( pA->iTable!=pB->iTable || pA->iColumn!=pB->iColumn ) return 0;
-  if( ExprHasProperty(pA, EP_IntValue) ){
-    if( !ExprHasProperty(pB, EP_IntValue) || pA->u.iValue!=pB->u.iValue ){
-      return 0;
-    }
-  }else if( pA->op!=TK_COLUMN && pA->u.zToken ){
-    if( ExprHasProperty(pB, EP_IntValue) || NEVER(pB->u.zToken==0) ) return 0;
-    if( sqlite3StrICmp(pA->u.zToken,pB->u.zToken)!=0 ){
-      return 0;
-    }
-  }
-  return 1;
-}
-
-
-/*
-** Add a new element to the pAggInfo->aCol[] array.  Return the index of
-** the new element.  Return a negative number if malloc fails.
-*/
-static int addAggInfoColumn(sqlite3 *db, AggInfo *pInfo){
-  int i;
-  pInfo->aCol = sqlite3ArrayAllocate(
-       db,
-       pInfo->aCol,
-       sizeof(pInfo->aCol[0]),
-       3,
-       &pInfo->nColumn,
-       &pInfo->nColumnAlloc,
-       &i
-  );
-  return i;
-}    
-
-/*
-** Add a new element to the pAggInfo->aFunc[] array.  Return the index of
-** the new element.  Return a negative number if malloc fails.
-*/
-static int addAggInfoFunc(sqlite3 *db, AggInfo *pInfo){
-  int i;
-  pInfo->aFunc = sqlite3ArrayAllocate(
-       db, 
-       pInfo->aFunc,
-       sizeof(pInfo->aFunc[0]),
-       3,
-       &pInfo->nFunc,
-       &pInfo->nFuncAlloc,
-       &i
-  );
-  return i;
-}    
-
-/*
-** This is the xExprCallback for a tree walker.  It is used to
-** implement sqlite3ExprAnalyzeAggregates().  See sqlite3ExprAnalyzeAggregates
-** for additional information.
-*/
-static int analyzeAggregate(Walker *pWalker, Expr *pExpr){
-  int i;
-  NameContext *pNC = pWalker->u.pNC;
-  Parse *pParse = pNC->pParse;
-  SrcList *pSrcList = pNC->pSrcList;
-  AggInfo *pAggInfo = pNC->pAggInfo;
-
-  switch( pExpr->op ){
-    case TK_AGG_COLUMN:
-    case TK_COLUMN: {
-      testcase( pExpr->op==TK_AGG_COLUMN );
-      testcase( pExpr->op==TK_COLUMN );
-      /* Check to see if the column is in one of the tables in the FROM
-      ** clause of the aggregate query */
-      if( ALWAYS(pSrcList!=0) ){
-        struct SrcList_item *pItem = pSrcList->a;
-        for(i=0; i<pSrcList->nSrc; i++, pItem++){
-          struct AggInfo_col *pCol;
-          assert( !ExprHasAnyProperty(pExpr, EP_TokenOnly|EP_Reduced) );
-          if( pExpr->iTable==pItem->iCursor ){
-            /* If we reach this point, it means that pExpr refers to a table
-            ** that is in the FROM clause of the aggregate query.  
-            **
-            ** Make an entry for the column in pAggInfo->aCol[] if there
-            ** is not an entry there already.
-            */
-            int k;
-            pCol = pAggInfo->aCol;
-            for(k=0; k<pAggInfo->nColumn; k++, pCol++){
-              if( pCol->iTable==pExpr->iTable &&
-                  pCol->iColumn==pExpr->iColumn ){
-                break;
-              }
-            }
-            if( (k>=pAggInfo->nColumn)
-             && (k = addAggInfoColumn(pParse->db, pAggInfo))>=0 
-            ){
-              pCol = &pAggInfo->aCol[k];
-              pCol->pTab = pExpr->pTab;
-              pCol->iTable = pExpr->iTable;
-              pCol->iColumn = pExpr->iColumn;
-              pCol->iMem = ++pParse->nMem;
-              pCol->iSorterColumn = -1;
-              pCol->pExpr = pExpr;
-              if( pAggInfo->pGroupBy ){
-                int j, n;
-                ExprList *pGB = pAggInfo->pGroupBy;
-                struct ExprList_item *pTerm = pGB->a;
-                n = pGB->nExpr;
-                for(j=0; j<n; j++, pTerm++){
-                  Expr *pE = pTerm->pExpr;
-                  if( pE->op==TK_COLUMN && pE->iTable==pExpr->iTable &&
-                      pE->iColumn==pExpr->iColumn ){
-                    pCol->iSorterColumn = j;
-                    break;
-                  }
-                }
-              }
-              if( pCol->iSorterColumn<0 ){
-                pCol->iSorterColumn = pAggInfo->nSortingColumn++;
-              }
-            }
-            /* There is now an entry for pExpr in pAggInfo->aCol[] (either
-            ** because it was there before or because we just created it).
-            ** Convert the pExpr to be a TK_AGG_COLUMN referring to that
-            ** pAggInfo->aCol[] entry.
-            */
-            ExprSetIrreducible(pExpr);
-            pExpr->pAggInfo = pAggInfo;
-            pExpr->op = TK_AGG_COLUMN;
-            pExpr->iAgg = (i16)k;
-            break;
-          } /* endif pExpr->iTable==pItem->iCursor */
-        } /* end loop over pSrcList */
-      }
-      return WRC_Prune;
-    }
-    case TK_AGG_FUNCTION: {
-      /* The pNC->nDepth==0 test causes aggregate functions in subqueries
-      ** to be ignored */
-      if( pNC->nDepth==0 ){
-        /* Check to see if pExpr is a duplicate of another aggregate 
-        ** function that is already in the pAggInfo structure
-        */
-        struct AggInfo_func *pItem = pAggInfo->aFunc;
-        for(i=0; i<pAggInfo->nFunc; i++, pItem++){
-          if( sqlite3ExprCompare(pItem->pExpr, pExpr) ){
-            break;
-          }
-        }
-        if( i>=pAggInfo->nFunc ){
-          /* pExpr is original.  Make a new entry in pAggInfo->aFunc[]
-          */
-          u8 enc = ENC(pParse->db);
-          i = addAggInfoFunc(pParse->db, pAggInfo);
-          if( i>=0 ){
-            assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
-            pItem = &pAggInfo->aFunc[i];
-            pItem->pExpr = pExpr;
-            pItem->iMem = ++pParse->nMem;
-            assert( !ExprHasProperty(pExpr, EP_IntValue) );
-            pItem->pFunc = sqlite3FindFunction(pParse->db,
-                   pExpr->u.zToken, sqlite3Strlen30(pExpr->u.zToken),
-                   pExpr->x.pList ? pExpr->x.pList->nExpr : 0, enc, 0);
-            if( pExpr->flags & EP_Distinct ){
-              pItem->iDistinct = pParse->nTab++;
-            }else{
-              pItem->iDistinct = -1;
-            }
-          }
-        }
-        /* Make pExpr point to the appropriate pAggInfo->aFunc[] entry
-        */
-        assert( !ExprHasAnyProperty(pExpr, EP_TokenOnly|EP_Reduced) );
-        ExprSetIrreducible(pExpr);
-        pExpr->iAgg = (i16)i;
-        pExpr->pAggInfo = pAggInfo;
-        return WRC_Prune;
-      }
-    }
-  }
-  return WRC_Continue;
-}
-static int analyzeAggregatesInSelect(Walker *pWalker, Select *pSelect){
-  NameContext *pNC = pWalker->u.pNC;
-  if( pNC->nDepth==0 ){
-    pNC->nDepth++;
-    sqlite3WalkSelect(pWalker, pSelect);
-    pNC->nDepth--;
-    return WRC_Prune;
-  }else{
-    return WRC_Continue;
-  }
-}
-
-/*
-** Analyze the given expression looking for aggregate functions and
-** for variables that need to be added to the pParse->aAgg[] array.
-** Make additional entries to the pParse->aAgg[] array as necessary.
-**
-** This routine should only be called after the expression has been
-** analyzed by sqlite3ResolveExprNames().
-*/
-void sqlite3ExprAnalyzeAggregates(NameContext *pNC, Expr *pExpr){
-  Walker w;
-  w.xExprCallback = analyzeAggregate;
-  w.xSelectCallback = analyzeAggregatesInSelect;
-  w.u.pNC = pNC;
-  assert( pNC->pSrcList!=0 );
-  sqlite3WalkExpr(&w, pExpr);
-}
-
-/*
-** Call sqlite3ExprAnalyzeAggregates() for every expression in an
-** expression list.  Return the number of errors.
-**
-** If an error is found, the analysis is cut short.
-*/
-void sqlite3ExprAnalyzeAggList(NameContext *pNC, ExprList *pList){
-  struct ExprList_item *pItem;
-  int i;
-  if( pList ){
-    for(pItem=pList->a, i=0; i<pList->nExpr; i++, pItem++){
-      sqlite3ExprAnalyzeAggregates(pNC, pItem->pExpr);
-    }
-  }
-}
-
-/*
-** Allocate a single new register for use to hold some intermediate result.
-*/
-int sqlite3GetTempReg(Parse *pParse){
-  if( pParse->nTempReg==0 ){
-    return ++pParse->nMem;
-  }
-  return pParse->aTempReg[--pParse->nTempReg];
-}
-
-/*
-** Deallocate a register, making available for reuse for some other
-** purpose.
-**
-** If a register is currently being used by the column cache, then
-** the dallocation is deferred until the column cache line that uses
-** the register becomes stale.
-*/
-void sqlite3ReleaseTempReg(Parse *pParse, int iReg){
-  if( iReg && pParse->nTempReg<ArraySize(pParse->aTempReg) ){
-    int i;
-    struct yColCache *p;
-    for(i=0, p=pParse->aColCache; i<SQLITE_N_COLCACHE; i++, p++){
-      if( p->iReg==iReg ){
-        p->tempReg = 1;
-        return;
-      }
-    }
-    pParse->aTempReg[pParse->nTempReg++] = iReg;
-  }
-}
-
-/*
-** Allocate or deallocate a block of nReg consecutive registers
-*/
-int sqlite3GetTempRange(Parse *pParse, int nReg){
-  int i, n;
-  i = pParse->iRangeReg;
-  n = pParse->nRangeReg;
-  if( nReg<=n && !usedAsColumnCache(pParse, i, i+n-1) ){
-    pParse->iRangeReg += nReg;
-    pParse->nRangeReg -= nReg;
-  }else{
-    i = pParse->nMem+1;
-    pParse->nMem += nReg;
-  }
-  return i;
-}
-void sqlite3ReleaseTempRange(Parse *pParse, int iReg, int nReg){
-  if( nReg>pParse->nRangeReg ){
-    pParse->nRangeReg = nReg;
-    pParse->iRangeReg = iReg;
-  }
-}