Include RE2 library

third_party/re2/util/pcre.cc

+// Copyright 2003-2009 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This is a variant of PCRE's pcrecpp.cc, originally written at Google.
+// The main changes are the addition of the HitLimit method and
+// compilation as PCRE in namespace re2.
+
+#include <errno.h>
+#include "util/util.h"
+#include "util/flags.h"
+#include "util/pcre.h"
+
+#ifdef WIN32
+#define strtoll _strtoi64
+#define strtoull _strtoui64
+#endif
+
+#define PCREPORT(level) LOG(level)
+
+// Default PCRE limits.
+// Defaults chosen to allow a plausible amount of CPU and
+// not exceed main thread stacks.  Note that other threads
+// often have smaller stacks, and therefore tightening
+// regexp_stack_limit may frequently be necessary.
+DEFINE_int32(regexp_stack_limit, 256<<10, "default PCRE stack limit (bytes)");
+DEFINE_int32(regexp_match_limit, 1000000,
+             "default PCRE match limit (function calls)");
+
+namespace re2 {
+
+// Maximum number of args we can set
+static const int kMaxArgs = 16;
+static const int kVecSize = (1 + kMaxArgs) * 3;  // results + PCRE workspace
+
+// Approximate size of a recursive invocation of PCRE's
+// internal "match()" frame.  This varies depending on the
+// compiler and architecture, of course, so the constant is
+// just a conservative estimate.  To find the exact number,
+// run regexp_unittest with --regexp_stack_limit=0 under
+// a debugger and look at the frames when it crashes.
+// The exact frame size was 656 in production on 2008/02/03.
+static const int kPCREFrameSize = 700;
+
+// Special name for missing C++ arguments.
+PCRE::Arg PCRE::no_more_args((void*)NULL);
+
+const PCRE::PartialMatchFunctor PCRE::PartialMatch = { };
+const PCRE::FullMatchFunctor PCRE::FullMatch = { } ;
+const PCRE::ConsumeFunctor PCRE::Consume = { };
+const PCRE::FindAndConsumeFunctor PCRE::FindAndConsume = { };
+
+// If a regular expression has no error, its error_ field points here
+static const string empty_string;
+
+void PCRE::Init(const char* pattern, Option options, int match_limit,
+              int stack_limit, bool report_errors) {
+  pattern_ = pattern;
+  options_ = options;
+  match_limit_ = match_limit;
+  stack_limit_ = stack_limit;
+  hit_limit_ = false;
+  error_ = &empty_string;
+  report_errors_ = report_errors;
+  re_full_ = NULL;
+  re_partial_ = NULL;
+
+  if (options & ~(EnabledCompileOptions | EnabledExecOptions)) {
+    error_ = new string("illegal regexp option");
+    PCREPORT(ERROR)
+        << "Error compiling '" << pattern << "': illegal regexp option";
+  } else {
+    re_partial_ = Compile(UNANCHORED);
+    if (re_partial_ != NULL) {
+      re_full_ = Compile(ANCHOR_BOTH);
+    }
+  }
+}
+
+PCRE::PCRE(const char* pattern) {
+  Init(pattern, None, 0, 0, true);
+}
+PCRE::PCRE(const char* pattern, Option option) {
+  Init(pattern, option, 0, 0, true);
+}
+PCRE::PCRE(const string& pattern) {
+  Init(pattern.c_str(), None, 0, 0, true);
+}
+PCRE::PCRE(const string& pattern, Option option) {
+  Init(pattern.c_str(), option, 0, 0, true);
+}
+PCRE::PCRE(const string& pattern, const PCRE_Options& re_option) {
+  Init(pattern.c_str(), re_option.option(), re_option.match_limit(),
+       re_option.stack_limit(), re_option.report_errors());
+}
+
+PCRE::PCRE(const char *pattern, const PCRE_Options& re_option) {
+  Init(pattern, re_option.option(), re_option.match_limit(),
+       re_option.stack_limit(), re_option.report_errors());
+}
+
+PCRE::~PCRE() {
+  if (re_full_ != NULL)         pcre_free(re_full_);
+  if (re_partial_ != NULL)      pcre_free(re_partial_);
+  if (error_ != &empty_string)  delete error_;
+}
+
+pcre* PCRE::Compile(Anchor anchor) {
+  // Special treatment for anchoring.  This is needed because at
+  // runtime pcre only provides an option for anchoring at the
+  // beginning of a string.
+  //
+  // There are three types of anchoring we want:
+  //    UNANCHORED      Compile the original pattern, and use
+  //                    a pcre unanchored match.
+  //    ANCHOR_START    Compile the original pattern, and use
+  //                    a pcre anchored match.
+  //    ANCHOR_BOTH     Tack a "\z" to the end of the original pattern
+  //                    and use a pcre anchored match.
+
+  const char* error;
+  int eoffset;
+  pcre* re;
+  if (anchor != ANCHOR_BOTH) {
+    re = pcre_compile(pattern_.c_str(),
+                      (options_ & EnabledCompileOptions),
+                      &error, &eoffset, NULL);
+  } else {
+    // Tack a '\z' at the end of PCRE.  Parenthesize it first so that
+    // the '\z' applies to all top-level alternatives in the regexp.
+    string wrapped = "(?:";  // A non-counting grouping operator
+    wrapped += pattern_;
+    wrapped += ")\\z";
+    re = pcre_compile(wrapped.c_str(),
+                      (options_ & EnabledCompileOptions),
+                      &error, &eoffset, NULL);
+  }
+  if (re == NULL) {
+    if (error_ == &empty_string) error_ = new string(error);
+    PCREPORT(ERROR) << "Error compiling '" << pattern_ << "': " << error;
+  }
+  return re;
+}
+
+/***** Convenience interfaces *****/
+
+bool PCRE::FullMatchFunctor::operator ()(const StringPiece& text,
+                                       const PCRE& re,
+                                       const Arg& a0,
+                                       const Arg& a1,
+                                       const Arg& a2,
+                                       const Arg& a3,
+                                       const Arg& a4,
+                                       const Arg& a5,
+                                       const Arg& a6,
+                                       const Arg& a7,
+                                       const Arg& a8,
+                                       const Arg& a9,
+                                       const Arg& a10,
+                                       const Arg& a11,
+                                       const Arg& a12,
+                                       const Arg& a13,
+                                       const Arg& a14,
+                                       const Arg& a15) const {
+  const Arg* args[kMaxArgs];
+  int n = 0;
+  if (&a0 == &no_more_args)  goto done; args[n++] = &a0;
+  if (&a1 == &no_more_args)  goto done; args[n++] = &a1;
+  if (&a2 == &no_more_args)  goto done; args[n++] = &a2;
+  if (&a3 == &no_more_args)  goto done; args[n++] = &a3;
+  if (&a4 == &no_more_args)  goto done; args[n++] = &a4;
+  if (&a5 == &no_more_args)  goto done; args[n++] = &a5;
+  if (&a6 == &no_more_args)  goto done; args[n++] = &a6;
+  if (&a7 == &no_more_args)  goto done; args[n++] = &a7;
+  if (&a8 == &no_more_args)  goto done; args[n++] = &a8;
+  if (&a9 == &no_more_args)  goto done; args[n++] = &a9;
+  if (&a10 == &no_more_args) goto done; args[n++] = &a10;
+  if (&a11 == &no_more_args) goto done; args[n++] = &a11;
+  if (&a12 == &no_more_args) goto done; args[n++] = &a12;
+  if (&a13 == &no_more_args) goto done; args[n++] = &a13;
+  if (&a14 == &no_more_args) goto done; args[n++] = &a14;
+  if (&a15 == &no_more_args) goto done; args[n++] = &a15;
+done:
+
+  int consumed;
+  int vec[kVecSize];
+  return re.DoMatchImpl(text, ANCHOR_BOTH, &consumed, args, n, vec, kVecSize);
+}
+
+bool PCRE::PartialMatchFunctor::operator ()(const StringPiece& text,
+                                          const PCRE& re,
+                                          const Arg& a0,
+                                          const Arg& a1,
+                                          const Arg& a2,
+                                          const Arg& a3,
+                                          const Arg& a4,
+                                          const Arg& a5,
+                                          const Arg& a6,
+                                          const Arg& a7,
+                                          const Arg& a8,
+                                          const Arg& a9,
+                                          const Arg& a10,
+                                          const Arg& a11,
+                                          const Arg& a12,
+                                          const Arg& a13,
+                                          const Arg& a14,
+                                          const Arg& a15) const {
+  const Arg* args[kMaxArgs];
+  int n = 0;
+  if (&a0 == &no_more_args)  goto done; args[n++] = &a0;
+  if (&a1 == &no_more_args)  goto done; args[n++] = &a1;
+  if (&a2 == &no_more_args)  goto done; args[n++] = &a2;
+  if (&a3 == &no_more_args)  goto done; args[n++] = &a3;
+  if (&a4 == &no_more_args)  goto done; args[n++] = &a4;
+  if (&a5 == &no_more_args)  goto done; args[n++] = &a5;
+  if (&a6 == &no_more_args)  goto done; args[n++] = &a6;
+  if (&a7 == &no_more_args)  goto done; args[n++] = &a7;
+  if (&a8 == &no_more_args)  goto done; args[n++] = &a8;
+  if (&a9 == &no_more_args)  goto done; args[n++] = &a9;
+  if (&a10 == &no_more_args) goto done; args[n++] = &a10;
+  if (&a11 == &no_more_args) goto done; args[n++] = &a11;
+  if (&a12 == &no_more_args) goto done; args[n++] = &a12;
+  if (&a13 == &no_more_args) goto done; args[n++] = &a13;
+  if (&a14 == &no_more_args) goto done; args[n++] = &a14;
+  if (&a15 == &no_more_args) goto done; args[n++] = &a15;
+done:
+
+  int consumed;
+  int vec[kVecSize];
+  return re.DoMatchImpl(text, UNANCHORED, &consumed, args, n, vec, kVecSize);
+}
+
+bool PCRE::ConsumeFunctor::operator ()(StringPiece* input,
+                                     const PCRE& pattern,
+                                     const Arg& a0,
+                                     const Arg& a1,
+                                     const Arg& a2,
+                                     const Arg& a3,
+                                     const Arg& a4,
+                                     const Arg& a5,
+                                     const Arg& a6,
+                                     const Arg& a7,
+                                     const Arg& a8,
+                                     const Arg& a9,
+                                     const Arg& a10,
+                                     const Arg& a11,
+                                     const Arg& a12,
+                                     const Arg& a13,
+                                     const Arg& a14,
+                                     const Arg& a15) const {
+  const Arg* args[kMaxArgs];
+  int n = 0;
+  if (&a0 == &no_more_args)  goto done; args[n++] = &a0;
+  if (&a1 == &no_more_args)  goto done; args[n++] = &a1;
+  if (&a2 == &no_more_args)  goto done; args[n++] = &a2;
+  if (&a3 == &no_more_args)  goto done; args[n++] = &a3;
+  if (&a4 == &no_more_args)  goto done; args[n++] = &a4;
+  if (&a5 == &no_more_args)  goto done; args[n++] = &a5;
+  if (&a6 == &no_more_args)  goto done; args[n++] = &a6;
+  if (&a7 == &no_more_args)  goto done; args[n++] = &a7;
+  if (&a8 == &no_more_args)  goto done; args[n++] = &a8;
+  if (&a9 == &no_more_args)  goto done; args[n++] = &a9;
+  if (&a10 == &no_more_args) goto done; args[n++] = &a10;
+  if (&a11 == &no_more_args) goto done; args[n++] = &a11;
+  if (&a12 == &no_more_args) goto done; args[n++] = &a12;
+  if (&a13 == &no_more_args) goto done; args[n++] = &a13;
+  if (&a14 == &no_more_args) goto done; args[n++] = &a14;
+  if (&a15 == &no_more_args) goto done; args[n++] = &a15;
+done:
+
+  int consumed;
+  int vec[kVecSize];
+  if (pattern.DoMatchImpl(*input, ANCHOR_START, &consumed,
+                          args, n, vec, kVecSize)) {
+    input->remove_prefix(consumed);
+    return true;
+  } else {
+    return false;
+  }
+}
+
+bool PCRE::FindAndConsumeFunctor::operator ()(StringPiece* input,
+                                            const PCRE& pattern,
+                                            const Arg& a0,
+                                            const Arg& a1,
+                                            const Arg& a2,
+                                            const Arg& a3,
+                                            const Arg& a4,
+                                            const Arg& a5,
+                                            const Arg& a6,
+                                            const Arg& a7,
+                                            const Arg& a8,
+                                            const Arg& a9,
+                                            const Arg& a10,
+                                            const Arg& a11,
+                                            const Arg& a12,
+                                            const Arg& a13,
+                                            const Arg& a14,
+                                            const Arg& a15) const {
+  const Arg* args[kMaxArgs];
+  int n = 0;
+  if (&a0 == &no_more_args)  goto done; args[n++] = &a0;
+  if (&a1 == &no_more_args)  goto done; args[n++] = &a1;
+  if (&a2 == &no_more_args)  goto done; args[n++] = &a2;
+  if (&a3 == &no_more_args)  goto done; args[n++] = &a3;
+  if (&a4 == &no_more_args)  goto done; args[n++] = &a4;
+  if (&a5 == &no_more_args)  goto done; args[n++] = &a5;
+  if (&a6 == &no_more_args)  goto done; args[n++] = &a6;
+  if (&a7 == &no_more_args)  goto done; args[n++] = &a7;
+  if (&a8 == &no_more_args)  goto done; args[n++] = &a8;
+  if (&a9 == &no_more_args)  goto done; args[n++] = &a9;
+  if (&a10 == &no_more_args) goto done; args[n++] = &a10;
+  if (&a11 == &no_more_args) goto done; args[n++] = &a11;
+  if (&a12 == &no_more_args) goto done; args[n++] = &a12;
+  if (&a13 == &no_more_args) goto done; args[n++] = &a13;
+  if (&a14 == &no_more_args) goto done; args[n++] = &a14;
+  if (&a15 == &no_more_args) goto done; args[n++] = &a15;
+done:
+
+  int consumed;
+  int vec[kVecSize];
+  if (pattern.DoMatchImpl(*input, UNANCHORED, &consumed,
+                          args, n, vec, kVecSize)) {
+    input->remove_prefix(consumed);
+    return true;
+  } else {
+    return false;
+  }
+}
+
+bool PCRE::Replace(string *str,
+                 const PCRE& pattern,
+                 const StringPiece& rewrite) {
+  int vec[kVecSize];
+  int matches = pattern.TryMatch(*str, 0, UNANCHORED, true, vec, kVecSize);
+  if (matches == 0)
+    return false;
+
+  string s;
+  if (!pattern.Rewrite(&s, rewrite, *str, vec, matches))
+    return false;
+
+  assert(vec[0] >= 0);
+  assert(vec[1] >= 0);
+  str->replace(vec[0], vec[1] - vec[0], s);
+  return true;
+}
+
+int PCRE::GlobalReplace(string *str,
+                      const PCRE& pattern,
+                      const StringPiece& rewrite) {
+  int count = 0;
+  int vec[kVecSize];
+  string out;
+  int start = 0;
+  bool last_match_was_empty_string = false;
+
+  for (; start <= str->length();) {
+    // If the previous match was for the empty string, we shouldn't
+    // just match again: we'll match in the same way and get an
+    // infinite loop.  Instead, we do the match in a special way:
+    // anchored -- to force another try at the same position --
+    // and with a flag saying that this time, ignore empty matches.
+    // If this special match returns, that means there's a non-empty
+    // match at this position as well, and we can continue.  If not,
+    // we do what perl does, and just advance by one.
+    // Notice that perl prints '@@@' for this;
+    //    perl -le '$_ = "aa"; s/b*|aa/@/g; print'
+    int matches;
+    if (last_match_was_empty_string) {
+      matches = pattern.TryMatch(*str, start, ANCHOR_START, false,
+                                 vec, kVecSize);
+      if (matches <= 0) {
+        if (start < str->length())
+          out.push_back((*str)[start]);
+        start++;
+        last_match_was_empty_string = false;
+        continue;
+      }
+    } else {
+      matches = pattern.TryMatch(*str, start, UNANCHORED, true, vec, kVecSize);
+      if (matches <= 0)
+        break;
+    }
+    int matchstart = vec[0], matchend = vec[1];
+    assert(matchstart >= start);
+    assert(matchend >= matchstart);
+
+    out.append(*str, start, matchstart - start);
+    pattern.Rewrite(&out, rewrite, *str, vec, matches);
+    start = matchend;
+    count++;
+    last_match_was_empty_string = (matchstart == matchend);
+  }
+
+  if (count == 0)
+    return 0;
+
+  if (start < str->length())
+    out.append(*str, start, str->length() - start);
+  swap(out, *str);
+  return count;
+}
+
+bool PCRE::Extract(const StringPiece &text,
+                 const PCRE& pattern,
+                 const StringPiece &rewrite,
+                 string *out) {
+  int vec[kVecSize];
+  int matches = pattern.TryMatch(text, 0, UNANCHORED, true, vec, kVecSize);
+  if (matches == 0)
+    return false;
+  out->clear();
+  return pattern.Rewrite(out, rewrite, text, vec, matches);
+}
+
+string PCRE::QuoteMeta(const StringPiece& unquoted) {
+  string result;
+  result.reserve(unquoted.size() << 1);
+
+  // Escape any ascii character not in [A-Za-z_0-9].
+  //
+  // Note that it's legal to escape a character even if it has no
+  // special meaning in a regular expression -- so this function does
+  // that.  (This also makes it identical to the perl function of the
+  // same name except for the null-character special case;
+  // see `perldoc -f quotemeta`.)
+  for (int ii = 0; ii < unquoted.length(); ++ii) {
+    // Note that using 'isalnum' here raises the benchmark time from
+    // 32ns to 58ns:
+    if ((unquoted[ii] < 'a' || unquoted[ii] > 'z') &&
+        (unquoted[ii] < 'A' || unquoted[ii] > 'Z') &&
+        (unquoted[ii] < '0' || unquoted[ii] > '9') &&
+        unquoted[ii] != '_' &&
+        // If this is the part of a UTF8 or Latin1 character, we need
+        // to copy this byte without escaping.  Experimentally this is
+        // what works correctly with the regexp library.
+        !(unquoted[ii] & 128)) {
+      if (unquoted[ii] == '\0') {  // Special handling for null chars.
+        // Can't use "\\0" since the next character might be a digit.
+        result += "\\x00";
+        continue;
+      }
+      result += '\\';
+    }
+    result += unquoted[ii];
+  }
+
+  return result;
+}
+
+/***** Actual matching and rewriting code *****/
+
+bool PCRE::HitLimit() {
+  return hit_limit_;
+}
+
+void PCRE::ClearHitLimit() {
+  hit_limit_ = 0;
+}
+
+int PCRE::TryMatch(const StringPiece& text,
+                 int startpos,
+                 Anchor anchor,
+                 bool empty_ok,
+                 int *vec,
+                 int vecsize) const {
+  pcre* re = (anchor == ANCHOR_BOTH) ? re_full_ : re_partial_;
+  if (re == NULL) {
+    PCREPORT(ERROR) << "Matching against invalid re: " << *error_;
+    return 0;
+  }
+
+  int match_limit = match_limit_;
+  if (match_limit <= 0) {
+    match_limit = FLAGS_regexp_match_limit;
+  }
+
+  int stack_limit = stack_limit_;
+  if (stack_limit <= 0) {
+    stack_limit = FLAGS_regexp_stack_limit;
+  }
+
+  pcre_extra extra = { 0 };
+  if (match_limit > 0) {
+    extra.flags |= PCRE_EXTRA_MATCH_LIMIT;
+    extra.match_limit = match_limit;
+  }
+  if (stack_limit > 0) {
+    extra.flags |= PCRE_EXTRA_MATCH_LIMIT_RECURSION;
+    extra.match_limit_recursion = stack_limit / kPCREFrameSize;
+  }
+
+  int options = 0;
+  if (anchor != UNANCHORED)
+    options |= PCRE_ANCHORED;
+  if (!empty_ok)
+    options |= PCRE_NOTEMPTY;
+
+  int rc = pcre_exec(re,              // The regular expression object
+                     &extra,
+                     (text.data() == NULL) ? "" : text.data(),
+                     text.size(),
+                     startpos,
+                     options,
+                     vec,
+                     vecsize);
+
+  // Handle errors
+  if (rc == 0) {
+    // pcre_exec() returns 0 as a special case when the number of
+    // capturing subpatterns exceeds the size of the vector.
+    // When this happens, there is a match and the output vector
+    // is filled, but we miss out on the positions of the extra subpatterns.
+    rc = vecsize / 2;
+  } else if (rc < 0) {
+    switch (rc) {
+      case PCRE_ERROR_NOMATCH:
+        return 0;
+      case PCRE_ERROR_MATCHLIMIT:
+        // Writing to hit_limit is not safe if multiple threads
+        // are using the PCRE, but the flag is only intended
+        // for use by unit tests anyway, so we let it go.
+        hit_limit_ = true;
+        PCREPORT(WARNING) << "Exceeded match limit of " << match_limit
+                        << " when matching '" << pattern_ << "'"
+                        << " against text that is " << text.size() << " bytes.";
+        return 0;
+      case PCRE_ERROR_RECURSIONLIMIT:
+        // See comment about hit_limit above.
+        hit_limit_ = true;
+        PCREPORT(WARNING) << "Exceeded stack limit of " << stack_limit
+                        << " when matching '" << pattern_ << "'"
+                        << " against text that is " << text.size() << " bytes.";
+        return 0;
+      default:
+        // There are other return codes from pcre.h :
+        // PCRE_ERROR_NULL           (-2)
+        // PCRE_ERROR_BADOPTION      (-3)
+        // PCRE_ERROR_BADMAGIC       (-4)
+        // PCRE_ERROR_UNKNOWN_NODE   (-5)
+        // PCRE_ERROR_NOMEMORY       (-6)
+        // PCRE_ERROR_NOSUBSTRING    (-7)
+        // ...
+        PCREPORT(ERROR) << "Unexpected return code: " << rc
+                      << " when matching '" << pattern_ << "'"
+                      << ", re=" << re
+                      << ", text=" << text
+                      << ", vec=" << vec
+                      << ", vecsize=" << vecsize;
+        return 0;
+    }
+  }
+
+  return rc;
+}
+
+bool PCRE::DoMatchImpl(const StringPiece& text,
+                     Anchor anchor,
+                     int* consumed,
+                     const Arg* const* args,
+                     int n,
+                     int* vec,
+                     int vecsize) const {
+  assert((1 + n) * 3 <= vecsize);  // results + PCRE workspace
+  int matches = TryMatch(text, 0, anchor, true, vec, vecsize);
+  assert(matches >= 0);  // TryMatch never returns negatives
+  if (matches == 0)
+    return false;
+
+  *consumed = vec[1];
+
+  if (n == 0 || args == NULL) {
+    // We are not interested in results
+    return true;
+  }
+  if (NumberOfCapturingGroups() < n) {
+    // PCRE has fewer capturing groups than number of arg pointers passed in
+    return false;
+  }
+
+  // If we got here, we must have matched the whole pattern.
+  // We do not need (can not do) any more checks on the value of 'matches' here
+  // -- see the comment for TryMatch.
+  for (int i = 0; i < n; i++) {
+    const int start = vec[2*(i+1)];
+    const int limit = vec[2*(i+1)+1];
+    if (!args[i]->Parse(text.data() + start, limit-start)) {
+      // TODO: Should we indicate what the error was?
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool PCRE::DoMatch(const StringPiece& text,
+                 Anchor anchor,
+                 int* consumed,
+                 const Arg* const args[],
+                 int n) const {
+  assert(n >= 0);
+  size_t const vecsize = (1 + n) * 3;  // results + PCRE workspace
+                                       // (as for kVecSize)
+  int *vec = new int[vecsize];
+  bool b = DoMatchImpl(text, anchor, consumed, args, n, vec, vecsize);
+  delete[] vec;
+  return b;
+}
+
+bool PCRE::Rewrite(string *out, const StringPiece &rewrite,
+                 const StringPiece &text, int *vec, int veclen) const {
+  int number_of_capturing_groups = NumberOfCapturingGroups();
+  for (const char *s = rewrite.data(), *end = s + rewrite.size();
+       s < end; s++) {
+    int c = *s;
+    if (c == '\\') {
+      c = *++s;
+      if (isdigit(c)) {
+        int n = (c - '0');
+        if (n >= veclen) {
+          if (n <= number_of_capturing_groups) {
+            // unmatched optional capturing group. treat
+            // its value as empty string; i.e., nothing to append.
+          } else {
+            PCREPORT(ERROR) << "requested group " << n
+                          << " in regexp " << rewrite.data();
+            return false;
+          }
+        }
+        int start = vec[2 * n];
+        if (start >= 0)
+          out->append(text.data() + start, vec[2 * n + 1] - start);
+      } else if (c == '\\') {
+        out->push_back('\\');
+      } else {
+        PCREPORT(ERROR) << "invalid rewrite pattern: " << rewrite.data();
+        return false;
+      }
+    } else {
+      out->push_back(c);
+    }
+  }
+  return true;
+}
+
+bool PCRE::CheckRewriteString(const StringPiece& rewrite, string* error) const {
+  int max_token = -1;
+  for (const char *s = rewrite.data(), *end = s + rewrite.size();
+       s < end; s++) {
+    int c = *s;
+    if (c != '\\') {
+      continue;
+    }
+    if (++s == end) {
+      *error = "Rewrite schema error: '\\' not allowed at end.";
+      return false;
+    }
+    c = *s;
+    if (c == '\\') {
+      continue;
+    }
+    if (!isdigit(c)) {
+      *error = "Rewrite schema error: "
+               "'\\' must be followed by a digit or '\\'.";
+      return false;
+    }
+    int n = (c - '0');
+    if (max_token < n) {
+      max_token = n;
+    }
+  }
+
+  if (max_token > NumberOfCapturingGroups()) {
+    SStringPrintf(error, "Rewrite schema requests %d matches, "
+                  "but the regexp only has %d parenthesized subexpressions.",
+                  max_token, NumberOfCapturingGroups());
+    return false;
+  }
+  return true;
+}
+
+
+// Return the number of capturing subpatterns, or -1 if the
+// regexp wasn't valid on construction.
+int PCRE::NumberOfCapturingGroups() const {
+  if (re_partial_ == NULL) return -1;
+
+  int result;
+  CHECK(pcre_fullinfo(re_partial_,       // The regular expression object
+                      NULL,              // We did not study the pattern
+                      PCRE_INFO_CAPTURECOUNT,
+                      &result) == 0);
+  return result;
+}
+
+
+/***** Parsers for various types *****/
+
+bool PCRE::Arg::parse_null(const char* str, int n, void* dest) {
+  // We fail if somebody asked us to store into a non-NULL void* pointer
+  return (dest == NULL);
+}
+
+bool PCRE::Arg::parse_string(const char* str, int n, void* dest) {
+  if (dest == NULL) return true;
+  reinterpret_cast<string*>(dest)->assign(str, n);
+  return true;
+}
+
+bool PCRE::Arg::parse_stringpiece(const char* str, int n, void* dest) {
+  if (dest == NULL) return true;
+  reinterpret_cast<StringPiece*>(dest)->set(str, n);
+  return true;
+}
+
+bool PCRE::Arg::parse_char(const char* str, int n, void* dest) {
+  if (n != 1) return false;
+  if (dest == NULL) return true;
+  *(reinterpret_cast<char*>(dest)) = str[0];
+  return true;
+}
+
+bool PCRE::Arg::parse_uchar(const char* str, int n, void* dest) {
+  if (n != 1) return false;
+  if (dest == NULL) return true;
+  *(reinterpret_cast<unsigned char*>(dest)) = str[0];
+  return true;
+}
+
+// Largest number spec that we are willing to parse
+static const int kMaxNumberLength = 32;
+
+// PCREQUIPCRES "buf" must have length at least kMaxNumberLength+1
+// PCREQUIPCRES "n > 0"
+// Copies "str" into "buf" and null-terminates if necessary.
+// Returns one of:
+//      a. "str" if no termination is needed
+//      b. "buf" if the string was copied and null-terminated
+//      c. "" if the input was invalid and has no hope of being parsed
+static const char* TerminateNumber(char* buf, const char* str, int n) {
+  if ((n > 0) && isspace(*str)) {
+    // We are less forgiving than the strtoxxx() routines and do not
+    // allow leading spaces.
+    return "";
+  }
+
+  // See if the character right after the input text may potentially
+  // look like a digit.
+  if (isdigit(str[n]) ||
+      ((str[n] >= 'a') && (str[n] <= 'f')) ||
+      ((str[n] >= 'A') && (str[n] <= 'F'))) {
+    if (n > kMaxNumberLength) return ""; // Input too big to be a valid number
+    memcpy(buf, str, n);
+    buf[n] = '\0';
+    return buf;
+  } else {
+    // We can parse right out of the supplied string, so return it.
+    return str;
+  }
+}
+
+bool PCRE::Arg::parse_long_radix(const char* str,
+                               int n,
+                               void* dest,
+                               int radix) {
+  if (n == 0) return false;
+  char buf[kMaxNumberLength+1];
+  str = TerminateNumber(buf, str, n);
+  char* end;
+  errno = 0;
+  long r = strtol(str, &end, radix);
+  if (end != str + n) return false;   // Leftover junk
+  if (errno) return false;
+  if (dest == NULL) return true;
+  *(reinterpret_cast<long*>(dest)) = r;
+  return true;
+}
+
+bool PCRE::Arg::parse_ulong_radix(const char* str,
+                                int n,
+                                void* dest,
+                                int radix) {
+  if (n == 0) return false;
+  char buf[kMaxNumberLength+1];
+  str = TerminateNumber(buf, str, n);
+  if (str[0] == '-') {
+   // strtoul() will silently accept negative numbers and parse
+   // them.  This module is more strict and treats them as errors.
+   return false;
+  }
+
+  char* end;
+  errno = 0;
+  unsigned long r = strtoul(str, &end, radix);
+  if (end != str + n) return false;   // Leftover junk
+  if (errno) return false;
+  if (dest == NULL) return true;
+  *(reinterpret_cast<unsigned long*>(dest)) = r;
+  return true;
+}
+
+bool PCRE::Arg::parse_short_radix(const char* str,
+                                int n,
+                                void* dest,
+                                int radix) {
+  long r;
+  if (!parse_long_radix(str, n, &r, radix)) return false; // Could not parse
+  if ((short)r != r) return false;       // Out of range
+  if (dest == NULL) return true;
+  *(reinterpret_cast<short*>(dest)) = r;
+  return true;
+}
+
+bool PCRE::Arg::parse_ushort_radix(const char* str,
+                                 int n,
+                                 void* dest,
+                                 int radix) {
+  unsigned long r;
+  if (!parse_ulong_radix(str, n, &r, radix)) return false; // Could not parse
+  if ((ushort)r != r) return false;                      // Out of range
+  if (dest == NULL) return true;
+  *(reinterpret_cast<unsigned short*>(dest)) = r;
+  return true;
+}
+
+bool PCRE::Arg::parse_int_radix(const char* str,
+                              int n,
+                              void* dest,
+                              int radix) {
+  long r;
+  if (!parse_long_radix(str, n, &r, radix)) return false; // Could not parse
+  if ((int)r != r) return false;         // Out of range
+  if (dest == NULL) return true;
+  *(reinterpret_cast<int*>(dest)) = r;
+  return true;
+}
+
+bool PCRE::Arg::parse_uint_radix(const char* str,
+                               int n,
+                               void* dest,
+                               int radix) {
+  unsigned long r;
+  if (!parse_ulong_radix(str, n, &r, radix)) return false; // Could not parse
+  if ((uint)r != r) return false;                       // Out of range
+  if (dest == NULL) return true;
+  *(reinterpret_cast<unsigned int*>(dest)) = r;
+  return true;
+}
+
+bool PCRE::Arg::parse_longlong_radix(const char* str,
+                                   int n,
+                                   void* dest,
+                                   int radix) {
+  if (n == 0) return false;
+  char buf[kMaxNumberLength+1];
+  str = TerminateNumber(buf, str, n);
+  char* end;
+  errno = 0;
+  int64 r = strtoll(str, &end, radix);
+  if (end != str + n) return false;   // Leftover junk
+  if (errno) return false;
+  if (dest == NULL) return true;
+  *(reinterpret_cast<int64*>(dest)) = r;
+  return true;
+}
+
+bool PCRE::Arg::parse_ulonglong_radix(const char* str,
+                                    int n,
+                                    void* dest,
+                                    int radix) {
+  if (n == 0) return false;
+  char buf[kMaxNumberLength+1];
+  str = TerminateNumber(buf, str, n);
+  if (str[0] == '-') {
+    // strtoull() will silently accept negative numbers and parse
+    // them.  This module is more strict and treats them as errors.
+    return false;
+  }
+  char* end;
+  errno = 0;
+  uint64 r = strtoull(str, &end, radix);
+  if (end != str + n) return false;   // Leftover junk
+  if (errno) return false;
+  if (dest == NULL) return true;
+  *(reinterpret_cast<uint64*>(dest)) = r;
+  return true;
+}
+
+bool PCRE::Arg::parse_double(const char* str, int n, void* dest) {
+  if (n == 0) return false;
+  static const int kMaxLength = 200;
+  char buf[kMaxLength];
+  if (n >= kMaxLength) return false;
+  memcpy(buf, str, n);
+  buf[n] = '\0';
+  errno = 0;
+  char* end;
+  double r = strtod(buf, &end);
+  if (end != buf + n) {
+#ifdef COMPILER_MSVC
+    // Microsoft's strtod() doesn't handle inf and nan, so we have to
+    // handle it explicitly.  Speed is not important here because this
+    // code is only called in unit tests.
+    bool pos = true;
+    const char* i = buf;
+    if ('-' == *i) {
+      pos = false;
+      ++i;
+    } else if ('+' == *i) {
+      ++i;
+    }
+    if (0 == stricmp(i, "inf") || 0 == stricmp(i, "infinity")) {
+      r = numeric_limits<double>::infinity();
+      if (!pos)
+        r = -r;
+    } else if (0 == stricmp(i, "nan")) {
+      r = numeric_limits<double>::quiet_NaN();
+    } else {
+      return false;
+    }
+#else
+    return false;   // Leftover junk
+#endif
+  }
+  if (errno) return false;
+  if (dest == NULL) return true;
+  *(reinterpret_cast<double*>(dest)) = r;
+  return true;
+}
+
+bool PCRE::Arg::parse_float(const char* str, int n, void* dest) {
+  double r;
+  if (!parse_double(str, n, &r)) return false;
+  if (dest == NULL) return true;
+  *(reinterpret_cast<float*>(dest)) = static_cast<float>(r);
+  return true;
+}
+
+
+#define DEFINE_INTEGER_PARSERS(name)                                        \
+  bool PCRE::Arg::parse_##name(const char* str, int n, void* dest) {          \
+    return parse_##name##_radix(str, n, dest, 10);                          \
+  }                                                                         \
+  bool PCRE::Arg::parse_##name##_hex(const char* str, int n, void* dest) {    \
+    return parse_##name##_radix(str, n, dest, 16);                          \
+  }                                                                         \
+  bool PCRE::Arg::parse_##name##_octal(const char* str, int n, void* dest) {  \
+    return parse_##name##_radix(str, n, dest, 8);                           \
+  }                                                                         \
+  bool PCRE::Arg::parse_##name##_cradix(const char* str, int n, void* dest) { \
+    return parse_##name##_radix(str, n, dest, 0);                           \
+  }
+
+DEFINE_INTEGER_PARSERS(short);
+DEFINE_INTEGER_PARSERS(ushort);
+DEFINE_INTEGER_PARSERS(int);
+DEFINE_INTEGER_PARSERS(uint);
+DEFINE_INTEGER_PARSERS(long);
+DEFINE_INTEGER_PARSERS(ulong);
+DEFINE_INTEGER_PARSERS(longlong);
+DEFINE_INTEGER_PARSERS(ulonglong);
+
+#undef DEFINE_INTEGER_PARSERS
+
+}  // namespace re2