lib/Support/Regex.cpp

   1 //===-- Regex.cpp - Regular Expression matcher implementation -------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements a POSIX regular expression matcher.
  11 //
  12 //===----------------------------------------------------------------------===//
  13 #include "llvm/Support/Regex.h"
  14 #include "llvm/Support/ErrorHandling.h"
  15 #include "llvm/Support/raw_ostream.h"
  16 #include "regex_impl.h"
  17 #include <string>
  18
  19 using namespace llvm;
  20 Regex::Regex(const StringRef &regex, unsigned Flags)
  21 {
  22   unsigned flags = 0;
  23   preg = new struct llvm_regex;
  24   preg->re_endp = regex.end();
  25   if (Flags & IgnoreCase)
  26     flags |= REG_ICASE;
  27   if (Flags & NoSub) {
  28     flags |= REG_NOSUB;
  29     sub = false;
  30   } else {
  31     sub = true;
  32   }
  33   if (Flags & Newline)
  34     flags |= REG_NEWLINE;
  35   error = llvm_regcomp(preg, regex.data(), flags|REG_EXTENDED|REG_PEND);
  36 }
  37
  38 bool Regex::isValid(std::string &Error)
  39 {
  40   if (!error)
  41     return true;
  42
  43   size_t len = llvm_regerror(error, preg, NULL, 0);
  44   char *errbuff = new char[len];
  45   llvm_regerror(error, preg, errbuff, len);
  46   Error.assign(errbuff);
  47   return false;
  48 }
  49
  50 Regex::~Regex()
  51 {
  52   llvm_regfree(preg);
  53   delete preg;
  54 }
  55
  56 bool Regex::match(const StringRef &String, SmallVectorImpl<StringRef> *Matches)
  57 {
  58   unsigned nmatch = Matches ? preg->re_nsub+1 : 0;
  59
  60   if (Matches) {
  61     assert(sub && "Substring matching requested but pattern compiled without");
  62     Matches->clear();
  63   }
  64
  65   // pmatch needs to have at least one element.
  66   SmallVector<llvm_regmatch_t, 2> pm;
  67   pm.resize(nmatch > 0 ? nmatch : 1);
  68   pm[0].rm_so = 0;
  69   pm[0].rm_eo = String.size();
  70
  71   int rc = llvm_regexec(preg, String.data(), nmatch, pm.data(), REG_STARTEND);
  72
  73   if (rc == REG_NOMATCH)
  74     return false;
  75   if (rc != 0) {
  76     // regexec can fail due to invalid pattern or running out of memory.
  77     error = rc;
  78     return false;
  79   }
  80
  81   // There was a match.
  82
  83   if (Matches) { // match position requested
  84     for (unsigned i=0;i<nmatch; i++) {
  85       if (pm[i].rm_so == -1) {
  86         // this group didn't match
  87         Matches->push_back(StringRef());
  88         continue;
  89       }
  90       assert(pm[i].rm_eo > pm[i].rm_so);
  91       Matches->push_back(StringRef(String.data()+pm[i].rm_so,
  92                                    pm[i].rm_eo-pm[i].rm_so));
  93     }
  94   }
  95
  96   return true;
  97 }