// Copyright (c) 2010, Google Inc.

 // All rights reserved.

 //

 // Redistribution and use in source and binary forms, with or without

 // modification, are permitted provided that the following conditions are

 // met:

 //

 //     * Redistributions of source code must retain the above copyright

 // notice, this list of conditions and the following disclaimer.

 //     * Redistributions in binary form must reproduce the above

 // copyright notice, this list of conditions and the following disclaimer

 // in the documentation and/or other materials provided with the

 // distribution.

 //     * Neither the name of Google Inc. nor the names of its

 // contributors may be used to endorse or promote products derived from

 // this software without specific prior written permission.

 //

 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 //

 // Author: Sanjay Ghemawat

 #ifdef HAVE_CONFIG_H

 #include "config.h"

 #endif

 #include <stdlib.h>

 #include <stdio.h>

 #include <ctype.h>

 #include <limits.h>      /* for SHRT_MIN, USHRT_MAX, etc */

 #include <string.h>      /* for memcpy */

 #include <assert.h>

 #include <errno.h>

 #include <string>

 #include <algorithm>

 #include "pcrecpp_internal.h"

 #include "pcre.h"

 #include "pcrecpp.h"

 #include "pcre_stringpiece.h"

 namespace pcrecpp {

 // Maximum number of args we can set

 static const int kMaxArgs = 16;

 static const int kVecSize = (1 + kMaxArgs) * 3;  // results + PCRE workspace

 // Special object that stands-in for no argument

 Arg RE::no_arg((void*)NULL);

 // This is for ABI compatibility with old versions of pcre (pre-7.6),

 // which defined a global no_arg variable instead of putting it in the

 // RE class.  This works on GCC >= 3, at least.  It definitely works

 // for ELF, but may not for other object formats (Mach-O, for

 // instance, does not support aliases.)  We could probably have a more

 // inclusive test if we ever needed it.  (Note that not only the

 // __attribute__ syntax, but also __USER_LABEL_PREFIX__, are

 // gnu-specific.)

 #if defined(__GNUC__) && __GNUC__ >= 3 && defined(__ELF__)

 # define ULP_AS_STRING(x)            ULP_AS_STRING_INTERNAL(x)

 # define ULP_AS_STRING_INTERNAL(x)   #x

 # define USER_LABEL_PREFIX_STR       ULP_AS_STRING(__USER_LABEL_PREFIX__)

 extern Arg no_arg

   __attribute__((alias(USER_LABEL_PREFIX_STR "_ZN7pcrecpp2RE6no_argE")));

 #endif

 // If a regular expression has no error, its error_ field points here

 static const string empty_string;

 // If the user doesn't ask for any options, we just use this one

 static RE_Options default_options;

 void RE::Init(const string& pat, const RE_Options* options) {

   pattern_ = pat;

   if (options == NULL) {

     options_ = default_options;

   } else {

     options_ = *options;

   }

   error_ = &empty_string;

   re_full_ = NULL;

   re_partial_ = NULL;

   re_partial_ = Compile(UNANCHORED);

   if (re_partial_ != NULL) {

     re_full_ = Compile(ANCHOR_BOTH);

   }

 }

 void RE::Cleanup() {

   if (re_full_ != NULL)         (*pcre_free)(re_full_);

   if (re_partial_ != NULL)      (*pcre_free)(re_partial_);

   if (error_ != &empty_string)  delete error_;

 }

 RE::~RE() {

   Cleanup();

 }

 pcre* RE::Compile(Anchor anchor) {

   // First, convert RE_Options into pcre options

   int pcre_options = 0;

   pcre_options = options_.all_options();

   // Special treatment for anchoring.  This is needed because at

   // runtime pcre only provides an option for anchoring at the

   // beginning of a string (unless you use offset).

   //

   // 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* compile_error;

   int eoffset;

   pcre* re;

   if (anchor != ANCHOR_BOTH) {

     re = pcre_compile(pattern_.c_str(), pcre_options,

                       &compile_error, &eoffset, NULL);

   } else {

     // Tack a '\z' at the end of RE.  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(), pcre_options,

                       &compile_error, &eoffset, NULL);

   }

   if (re == NULL) {

     if (error_ == &empty_string) error_ = new string(compile_error);

   }

   return re;

 }

 /***** Matching interfaces *****/

 bool RE::FullMatch(const StringPiece& text,

                    const Arg& ptr1,

                    const Arg& ptr2,

                    const Arg& ptr3,

                    const Arg& ptr4,

                    const Arg& ptr5,

                    const Arg& ptr6,

                    const Arg& ptr7,

                    const Arg& ptr8,

                    const Arg& ptr9,

                    const Arg& ptr10,

                    const Arg& ptr11,

                    const Arg& ptr12,

                    const Arg& ptr13,

                    const Arg& ptr14,

                    const Arg& ptr15,

                    const Arg& ptr16) const {

   const Arg* args[kMaxArgs];

   int n = 0;

   if (&ptr1  == &no_arg) goto done; args[n++] = &ptr1;

   if (&ptr2  == &no_arg) goto done; args[n++] = &ptr2;

   if (&ptr3  == &no_arg) goto done; args[n++] = &ptr3;

   if (&ptr4  == &no_arg) goto done; args[n++] = &ptr4;

   if (&ptr5  == &no_arg) goto done; args[n++] = &ptr5;

   if (&ptr6  == &no_arg) goto done; args[n++] = &ptr6;

   if (&ptr7  == &no_arg) goto done; args[n++] = &ptr7;

   if (&ptr8  == &no_arg) goto done; args[n++] = &ptr8;

   if (&ptr9  == &no_arg) goto done; args[n++] = &ptr9;

   if (&ptr10 == &no_arg) goto done; args[n++] = &ptr10;

   if (&ptr11 == &no_arg) goto done; args[n++] = &ptr11;

   if (&ptr12 == &no_arg) goto done; args[n++] = &ptr12;

   if (&ptr13 == &no_arg) goto done; args[n++] = &ptr13;

   if (&ptr14 == &no_arg) goto done; args[n++] = &ptr14;

   if (&ptr15 == &no_arg) goto done; args[n++] = &ptr15;

   if (&ptr16 == &no_arg) goto done; args[n++] = &ptr16;

  done:

   int consumed;

   int vec[kVecSize];

   return DoMatchImpl(text, ANCHOR_BOTH, &consumed, args, n, vec, kVecSize);

 }

 bool RE::PartialMatch(const StringPiece& text,

                       const Arg& ptr1,

                       const Arg& ptr2,

                       const Arg& ptr3,

                       const Arg& ptr4,

                       const Arg& ptr5,

                       const Arg& ptr6,

                       const Arg& ptr7,

                       const Arg& ptr8,

                       const Arg& ptr9,

                       const Arg& ptr10,

                       const Arg& ptr11,

                       const Arg& ptr12,

                       const Arg& ptr13,

                       const Arg& ptr14,

                       const Arg& ptr15,

                       const Arg& ptr16) const {

   const Arg* args[kMaxArgs];

   int n = 0;

   if (&ptr1  == &no_arg) goto done; args[n++] = &ptr1;

   if (&ptr2  == &no_arg) goto done; args[n++] = &ptr2;

   if (&ptr3  == &no_arg) goto done; args[n++] = &ptr3;

   if (&ptr4  == &no_arg) goto done; args[n++] = &ptr4;

   if (&ptr5  == &no_arg) goto done; args[n++] = &ptr5;

   if (&ptr6  == &no_arg) goto done; args[n++] = &ptr6;

   if (&ptr7  == &no_arg) goto done; args[n++] = &ptr7;

   if (&ptr8  == &no_arg) goto done; args[n++] = &ptr8;

   if (&ptr9  == &no_arg) goto done; args[n++] = &ptr9;

   if (&ptr10 == &no_arg) goto done; args[n++] = &ptr10;

   if (&ptr11 == &no_arg) goto done; args[n++] = &ptr11;

   if (&ptr12 == &no_arg) goto done; args[n++] = &ptr12;

   if (&ptr13 == &no_arg) goto done; args[n++] = &ptr13;

   if (&ptr14 == &no_arg) goto done; args[n++] = &ptr14;

   if (&ptr15 == &no_arg) goto done; args[n++] = &ptr15;

   if (&ptr16 == &no_arg) goto done; args[n++] = &ptr16;

  done:

   int consumed;

   int vec[kVecSize];

   return DoMatchImpl(text, UNANCHORED, &consumed, args, n, vec, kVecSize);

 }

 bool RE::Consume(StringPiece* input,

                  const Arg& ptr1,

                  const Arg& ptr2,

                  const Arg& ptr3,

                  const Arg& ptr4,

                  const Arg& ptr5,

                  const Arg& ptr6,

                  const Arg& ptr7,

                  const Arg& ptr8,

                  const Arg& ptr9,

                  const Arg& ptr10,

                  const Arg& ptr11,

                  const Arg& ptr12,

                  const Arg& ptr13,

                  const Arg& ptr14,

                  const Arg& ptr15,

                  const Arg& ptr16) const {

   const Arg* args[kMaxArgs];

   int n = 0;

   if (&ptr1  == &no_arg) goto done; args[n++] = &ptr1;

   if (&ptr2  == &no_arg) goto done; args[n++] = &ptr2;

   if (&ptr3  == &no_arg) goto done; args[n++] = &ptr3;

   if (&ptr4  == &no_arg) goto done; args[n++] = &ptr4;

   if (&ptr5  == &no_arg) goto done; args[n++] = &ptr5;

   if (&ptr6  == &no_arg) goto done; args[n++] = &ptr6;

   if (&ptr7  == &no_arg) goto done; args[n++] = &ptr7;

   if (&ptr8  == &no_arg) goto done; args[n++] = &ptr8;

   if (&ptr9  == &no_arg) goto done; args[n++] = &ptr9;

   if (&ptr10 == &no_arg) goto done; args[n++] = &ptr10;

   if (&ptr11 == &no_arg) goto done; args[n++] = &ptr11;

   if (&ptr12 == &no_arg) goto done; args[n++] = &ptr12;

   if (&ptr13 == &no_arg) goto done; args[n++] = &ptr13;

   if (&ptr14 == &no_arg) goto done; args[n++] = &ptr14;

   if (&ptr15 == &no_arg) goto done; args[n++] = &ptr15;

   if (&ptr16 == &no_arg) goto done; args[n++] = &ptr16;

  done:

   int consumed;

   int vec[kVecSize];

   if (DoMatchImpl(*input, ANCHOR_START, &consumed,

                   args, n, vec, kVecSize)) {

     input->remove_prefix(consumed);

     return true;

   } else {

     return false;

   }

 }

 bool RE::FindAndConsume(StringPiece* input,

                         const Arg& ptr1,

                         const Arg& ptr2,

                         const Arg& ptr3,

                         const Arg& ptr4,

                         const Arg& ptr5,

                         const Arg& ptr6,

                         const Arg& ptr7,

                         const Arg& ptr8,

                         const Arg& ptr9,

                         const Arg& ptr10,

                         const Arg& ptr11,

                         const Arg& ptr12,

                         const Arg& ptr13,

                         const Arg& ptr14,

                         const Arg& ptr15,

                         const Arg& ptr16) const {

   const Arg* args[kMaxArgs];

   int n = 0;

   if (&ptr1  == &no_arg) goto done; args[n++] = &ptr1;

   if (&ptr2  == &no_arg) goto done; args[n++] = &ptr2;

   if (&ptr3  == &no_arg) goto done; args[n++] = &ptr3;

   if (&ptr4  == &no_arg) goto done; args[n++] = &ptr4;

   if (&ptr5  == &no_arg) goto done; args[n++] = &ptr5;

   if (&ptr6  == &no_arg) goto done; args[n++] = &ptr6;

   if (&ptr7  == &no_arg) goto done; args[n++] = &ptr7;

   if (&ptr8  == &no_arg) goto done; args[n++] = &ptr8;

   if (&ptr9  == &no_arg) goto done; args[n++] = &ptr9;

   if (&ptr10 == &no_arg) goto done; args[n++] = &ptr10;

   if (&ptr11 == &no_arg) goto done; args[n++] = &ptr11;

   if (&ptr12 == &no_arg) goto done; args[n++] = &ptr12;

   if (&ptr13 == &no_arg) goto done; args[n++] = &ptr13;

   if (&ptr14 == &no_arg) goto done; args[n++] = &ptr14;

   if (&ptr15 == &no_arg) goto done; args[n++] = &ptr15;

   if (&ptr16 == &no_arg) goto done; args[n++] = &ptr16;

  done:

   int consumed;

   int vec[kVecSize];

   if (DoMatchImpl(*input, UNANCHORED, &consumed,

                   args, n, vec, kVecSize)) {

     input->remove_prefix(consumed);

     return true;

   } else {

     return false;

   }

 }

 bool RE::Replace(const StringPiece& rewrite,

                  string *str) const {

   int vec[kVecSize];

   int matches = TryMatch(*str, 0, UNANCHORED, true, vec, kVecSize);

   if (matches == 0)

     return false;

   string s;

   if (!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;

 }

 // Returns PCRE_NEWLINE_CRLF, PCRE_NEWLINE_CR, or PCRE_NEWLINE_LF.

 // Note that PCRE_NEWLINE_CRLF is defined to be P_N_CR | P_N_LF.

 // Modified by PH to add PCRE_NEWLINE_ANY and PCRE_NEWLINE_ANYCRLF.

 static int NewlineMode(int pcre_options) {

   // TODO: if we can make it threadsafe, cache this var

   int newline_mode = 0;

   /* if (newline_mode) return newline_mode; */  // do this once it's cached

   if (pcre_options & (PCRE_NEWLINE_CRLF|PCRE_NEWLINE_CR|PCRE_NEWLINE_LF|

                       PCRE_NEWLINE_ANY|PCRE_NEWLINE_ANYCRLF)) {

     newline_mode = (pcre_options &

                     (PCRE_NEWLINE_CRLF|PCRE_NEWLINE_CR|PCRE_NEWLINE_LF|

                      PCRE_NEWLINE_ANY|PCRE_NEWLINE_ANYCRLF));

   } else {

     int newline;

     pcre_config(PCRE_CONFIG_NEWLINE, &newline);

     if (newline == 10)

       newline_mode = PCRE_NEWLINE_LF;

     else if (newline == 13)

       newline_mode = PCRE_NEWLINE_CR;

     else if (newline == 3338)

       newline_mode = PCRE_NEWLINE_CRLF;

     else if (newline == -1)

       newline_mode = PCRE_NEWLINE_ANY;

     else if (newline == -2)

       newline_mode = PCRE_NEWLINE_ANYCRLF;

     else

       assert(NULL == "Unexpected return value from pcre_config(NEWLINE)");

   }

   return newline_mode;

 }

 int RE::GlobalReplace(const StringPiece& rewrite,

                       string *str) const {

   int count = 0;

   int vec[kVecSize];

   string out;

   int start = 0;

   bool last_match_was_empty_string = false;

   while (start <= static_cast<int>(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 = TryMatch(*str, start, ANCHOR_START, false, vec, kVecSize);

       if (matches <= 0) {

         int matchend = start + 1;     // advance one character.

         // If the current char is CR and we're in CRLF mode, skip LF too.

         // Note it's better to call pcre_fullinfo() than to examine

         // all_options(), since options_ could have changed bewteen

         // compile-time and now, but this is simpler and safe enough.

         // Modified by PH to add ANY and ANYCRLF.

         if (matchend < static_cast<int>(str->length()) &&

             (*str)[start] == '\r' && (*str)[matchend] == '\n' &&

             (NewlineMode(options_.all_options()) == PCRE_NEWLINE_CRLF ||

              NewlineMode(options_.all_options()) == PCRE_NEWLINE_ANY ||

              NewlineMode(options_.all_options()) == PCRE_NEWLINE_ANYCRLF)) {

           matchend++;

         }

         // We also need to advance more than one char if we're in utf8 mode.

 #ifdef SUPPORT_UTF8

         if (options_.utf8()) {

           while (matchend < static_cast<int>(str->length()) &&

                  ((*str)[matchend] & 0xc0) == 0x80)

             matchend++;

         }

 #endif

         if (start < static_cast<int>(str->length()))

           out.append(*str, start, matchend - start);

         start = matchend;

         last_match_was_empty_string = false;

         continue;

       }

     } else {

       matches = 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);

     Rewrite(&out, rewrite, *str, vec, matches);

     start = matchend;

     count++;

     last_match_was_empty_string = (matchstart == matchend);

   }

   if (count == 0)

     return 0;

   if (start < static_cast<int>(str->length()))

     out.append(*str, start, str->length() - start);

   swap(out, *str);

   return count;

 }

 bool RE::Extract(const StringPiece& rewrite,

                  const StringPiece& text,

                  string *out) const {

   int vec[kVecSize];

   int matches = TryMatch(text, 0, UNANCHORED, true, vec, kVecSize);

   if (matches == 0)

     return false;

   out->erase();

   return Rewrite(out, rewrite, text, vec, matches);

 }

 /*static*/ string RE::QuoteMeta(const StringPiece& unquoted) {

   string result;

   // 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; see `perldoc -f quotemeta`.)  The one exception is

   // escaping NUL: rather than doing backslash + NUL, like perl does,

   // we do '\0', because pcre itself doesn't take embedded NUL chars.

   for (int ii = 0; ii < unquoted.size(); ++ii) {

     // Note that using 'isalnum' here raises the benchmark time from

     // 32ns to 58ns:

     if (unquoted[ii] == '\0') {

       result += "\\0";

     } else 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)) {

       result += '\\';

       result += unquoted[ii];

     } else {

       result += unquoted[ii];

     }

   }

   return result;

 }

 /***** Actual matching and rewriting code *****/

 int RE::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) {

     //fprintf(stderr, "Matching against invalid re: %s\n", error_->c_str());

     return 0;

   }

   pcre_extra extra = { 0, 0, 0, 0, 0, 0 };

   if (options_.match_limit() > 0) {

     extra.flags |= PCRE_EXTRA_MATCH_LIMIT;

     extra.match_limit = options_.match_limit();

   }

   if (options_.match_limit_recursion() > 0) {

     extra.flags |= PCRE_EXTRA_MATCH_LIMIT_RECURSION;

     extra.match_limit_recursion = options_.match_limit_recursion();

   }

   // int options = 0;

   // Changed by PH as a result of bugzilla #1288

   int options = (options_.all_options() & PCRE_NO_UTF8_CHECK);

   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 == PCRE_ERROR_NOMATCH) {

     return 0;

   } else if (rc < 0) {

     //fprintf(stderr, "Unexpected return code: %d when matching '%s'\n",

     //        re, pattern_.c_str());

     return 0;

   } else 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;

   }

   return rc;

 }

 bool RE::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) {

     // RE 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 RE::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 space[21];   // use stack allocation for small vecsize (common case)

   int* vec = vecsize <= 21 ? space : new int[vecsize];

   bool retval = DoMatchImpl(text, anchor, consumed, args, n, vec, (int)vecsize);

   if (vec != space) delete [] vec;

   return retval;

 }

 bool RE::Rewrite(string *out, const StringPiece &rewrite,

                  const StringPiece &text, int *vec, int veclen) const {

   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) {

           //fprintf(stderr, requested group %d in regexp %.*s\n",

           //        n, rewrite.size(), 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 += '\\';

       } else {

         //fprintf(stderr, "invalid rewrite pattern: %.*s\n",

         //        rewrite.size(), rewrite.data());

         return false;

       }

     } else {

       *out += c;

     }

   }

   return true;

 }

 // Return the number of capturing subpatterns, or -1 if the

 // regexp wasn't valid on construction.

 int RE::NumberOfCapturingGroups() const {

   if (re_partial_ == NULL) return -1;

   int result;

   int pcre_retval = pcre_fullinfo(re_partial_,  // The regular expression object

                                   NULL,         // We did not study the pattern

                                   PCRE_INFO_CAPTURECOUNT,

                                   &result);

   assert(pcre_retval == 0);

   return result;

 }

 /***** Parsers for various types *****/

 bool 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 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 Arg::parse_stringpiece(const char* str, int n, void* dest) {