Replace RE2 import with a dependency

third_party/re2/re2/testing/backtrack.cc

Index: third_party/re2/re2/testing/backtrack.cc
diff --git a/third_party/re2/re2/testing/backtrack.cc b/third_party/re2/re2/testing/backtrack.cc
deleted file mode 100644
index a87284017b5f9d720fae25a3bd7454b07140336f..0000000000000000000000000000000000000000
--- a/third_party/re2/re2/testing/backtrack.cc
+++ /dev/null
@@ -1,255 +0,0 @@
-// Copyright 2008 The RE2 Authors.  All Rights Reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Tested by search_test.cc, exhaustive_test.cc, tester.cc
-//
-// Prog::BadSearchBacktrack is a backtracking regular expression search,
-// except that it remembers where it has been, trading a lot of
-// memory for a lot of time. It exists only for testing purposes.
-//
-// Let me repeat that.
-//
-// THIS CODE SHOULD NEVER BE USED IN PRODUCTION:
-//   - It uses a ton of memory.
-//   - It uses a ton of stack.
-//   - It uses CHECK and LOG(FATAL).
-//   - It implements unanchored search by repeated anchored search.
-//
-// On the other hand, it is very simple and a good reference
-// implementation for the more complicated regexp packages.
-//
-// In BUILD, this file is linked into the ":testing" library,
-// not the main library, in order to make it harder to pick up
-// accidentally.
-
-#include "util/util.h"
-#include "re2/prog.h"
-#include "re2/regexp.h"
-
-namespace re2 {
-
-// Backtracker holds the state for a backtracking search.
-//
-// Excluding the search parameters, the main search state
-// is just the "capture registers", which record, for the
-// current execution, the string position at which each
-// parenthesis was passed.  cap_[0] and cap_[1] are the
-// left and right parenthesis in $0, cap_[2] and cap_[3] in $1, etc.
-//
-// To avoid infinite loops during backtracking on expressions
-// like (a*)*, the visited_[] bitmap marks the (state, string-position)
-// pairs that have already been explored and are thus not worth
-// re-exploring if we get there via another path.  Modern backtracking
-// libraries engineer their program representation differently, to make
-// such infinite loops possible to avoid without keeping a giant visited_
-// bitmap, but visited_ works fine for a reference implementation
-// and it has the nice benefit of making the search run in linear time.
-class Backtracker {
- public:
-  explicit Backtracker(Prog* prog);
-  ~Backtracker();
-
-  bool Search(const StringPiece& text, const StringPiece& context,
-              bool anchored, bool longest,
-              StringPiece* submatch, int nsubmatch);
-
- private:
-  // Explores from instruction ip at string position p looking for a match.
-  // Returns true if found (so that caller can stop trying other possibilities).
-  bool Visit(int id, const char* p);
-
-  // Search parameters
-  Prog* prog_;              // program being run
-  StringPiece text_;        // text being searched
-  StringPiece context_;     // greater context of text being searched
-  bool anchored_;           // whether search is anchored at text.begin()
-  bool longest_;            // whether search wants leftmost-longest match
-  bool endmatch_;           // whether search must end at text.end()
-  StringPiece *submatch_;   // submatches to fill in
-  int nsubmatch_;           //   # of submatches to fill in
-
-  // Search state
-  const char* cap_[64];     // capture registers
-  uint32 *visited_;         // bitmap: (Inst*, char*) pairs already backtracked
-  size_t nvisited_;         //   # of words in bitmap
-};
-
-Backtracker::Backtracker(Prog* prog)
-  : prog_(prog),
-    anchored_(false),
-    longest_(false),
-    endmatch_(false),
-    submatch_(NULL),
-    nsubmatch_(0),
-    visited_(NULL),
-    nvisited_(0) {
-}
-
-Backtracker::~Backtracker() {
-  delete[] visited_;
-}
-
-// Runs a backtracking search.
-bool Backtracker::Search(const StringPiece& text, const StringPiece& context,
-                         bool anchored, bool longest,
-                         StringPiece* submatch, int nsubmatch) {
-  text_ = text;
-  context_ = context;
-  if (context_.begin() == NULL)
-    context_ = text;
-  if (prog_->anchor_start() && text.begin() > context_.begin())
-    return false;
-  if (prog_->anchor_end() && text.end() < context_.end())
-    return false;
-  anchored_ = anchored | prog_->anchor_start();
-  longest_ = longest | prog_->anchor_end();
-  endmatch_ = prog_->anchor_end();
-  submatch_ = submatch;
-  nsubmatch_ = nsubmatch;
-  CHECK(2*nsubmatch_ < arraysize(cap_));
-  memset(cap_, 0, sizeof cap_);
-
-  // We use submatch_[0] for our own bookkeeping,
-  // so it had better exist.
-  StringPiece sp0;
-  if (nsubmatch < 1) {
-    submatch_ = &sp0;
-    nsubmatch_ = 1;
-  }
-  submatch_[0] = NULL;
-
-  // Allocate new visited_ bitmap -- size is proportional
-  // to text, so have to reallocate on each call to Search.
-  delete[] visited_;
-  nvisited_ = (prog_->size()*(text.size()+1) + 31)/32;
-  visited_ = new uint32[nvisited_];
-  memset(visited_, 0, nvisited_*sizeof visited_[0]);
-
-  // Anchored search must start at text.begin().
-  if (anchored_) {
-    cap_[0] = text.begin();
-    return Visit(prog_->start(), text.begin());
-  }
-
-  // Unanchored search, starting from each possible text position.
-  // Notice that we have to try the empty string at the end of
-  // the text, so the loop condition is p <= text.end(), not p < text.end().
-  for (const char* p = text.begin(); p <= text.end(); p++) {
-    cap_[0] = p;
-    if (Visit(prog_->start(), p))  // Match must be leftmost; done.
-      return true;
-  }
-  return false;
-}
-
-// Explores from instruction ip at string position p looking for a match.
-// Return true if found (so that caller can stop trying other possibilities).
-bool Backtracker::Visit(int id, const char* p) {
-  // Check bitmap.  If we've already explored from here,
-  // either it didn't match or it did but we're hoping for a better match.
-  // Either way, don't go down that road again.
-  CHECK(p <= text_.end());
-  size_t n = id*(text_.size()+1) + (p - text_.begin());
-  CHECK_LT(n/32, nvisited_);
-  if (visited_[n/32] & (1 << (n&31)))
-    return false;
-  visited_[n/32] |= 1 << (n&31);
-
-  // Pick out byte at current position.  If at end of string,
-  // have to explore in hope of finishing a match.  Use impossible byte -1.
-  int c = -1;
-  if (p < text_.end())
-    c = *p & 0xFF;
-
-  Prog::Inst* ip = prog_->inst(id);
-  switch (ip->opcode()) {
-    default:
-      LOG(FATAL) << "Unexpected opcode: " << (int)ip->opcode();
-      return false;  // not reached
-
-    case kInstAlt:
-    case kInstAltMatch:
-      // Try both possible next states: out is preferred to out1.
-      if (Visit(ip->out(), p)) {
-        if (longest_)
-          Visit(ip->out1(), p);
-        return true;
-      }
-      return Visit(ip->out1(), p);
-
-    case kInstByteRange:
-      if (ip->Matches(c))
-        return Visit(ip->out(), p+1);
-      return false;
-
-    case kInstCapture:
-      if (0 <= ip->cap() && ip->cap() < arraysize(cap_)) {
-        // Capture p to register, but save old value.
-        const char* q = cap_[ip->cap()];
-        cap_[ip->cap()] = p;
-        bool ret = Visit(ip->out(), p);
-        // Restore old value as we backtrack.
-        cap_[ip->cap()] = q;
-        return ret;
-      }
-      return Visit(ip->out(), p);
-
-    case kInstEmptyWidth:
-      if (ip->empty() & ~Prog::EmptyFlags(context_, p))
-        return false;
-      return Visit(ip->out(), p);
-
-    case kInstNop:
-      return Visit(ip->out(), p);
-
-    case kInstMatch:
-      // We found a match.  If it's the best so far, record the
-      // parameters in the caller's submatch_ array.
-      if (endmatch_ && p != context_.end())
-        return false;
-      cap_[1] = p;
-      if (submatch_[0].data() == NULL ||           // First match so far ...
-          (longest_ && p > submatch_[0].end())) {  // ... or better match
-        for (int i = 0; i < nsubmatch_; i++)
-          submatch_[i].set(cap_[2*i],
-                           static_cast<int>(cap_[2*i+1] - cap_[2*i]));
-      }
-      return true;
-
-    case kInstFail:
-      return false;
-  }
-}
-
-// Runs a backtracking search.
-bool Prog::UnsafeSearchBacktrack(const StringPiece& text,
-                                 const StringPiece& context,
-                                 Anchor anchor,
-                                 MatchKind kind,
-                                 StringPiece* match,
-                                 int nmatch) {
-  // If full match, we ask for an anchored longest match
-  // and then check that match[0] == text.
-  // So make sure match[0] exists.
-  StringPiece sp0;
-  if (kind == kFullMatch) {
-    anchor = kAnchored;
-    if (nmatch < 1) {
-      match = &sp0;
-      nmatch = 1;
-    }
-  }
-
-  // Run the search.
-  Backtracker b(this);
-  bool anchored = anchor == kAnchored;
-  bool longest = kind != kFirstMatch;
-  if (!b.Search(text, context, anchored, longest, match, nmatch))
-    return false;
-  if (kind == kFullMatch && match[0].end() != text.end())
-    return false;
-  return true;
-}
-
-}  // namespace re2