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//===-- Regex.cpp - Regular Expression matcher implementation -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a POSIX regular expression matcher.
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/Regex.h"
#include "regex_impl.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include <string>
using namespace llvm;
Regex::Regex(StringRef regex, unsigned Flags) {
unsigned flags = 0;
preg = new llvm_regex();
preg->re_endp = regex.end();
if (Flags & IgnoreCase)
flags |= REG_ICASE;
if (Flags & Newline)
flags |= REG_NEWLINE;
if (!(Flags & BasicRegex))
flags |= REG_EXTENDED;
error = llvm_regcomp(preg, regex.data(), flags|REG_PEND);
}
Regex::~Regex() {
if (preg) {
llvm_regfree(preg);
delete preg;
}
}
bool Regex::isValid(std::string &Error) {
if (!error)
return true;
size_t len = llvm_regerror(error, preg, nullptr, 0);
Error.resize(len - 1);
llvm_regerror(error, preg, &Error[0], len);
return false;
}
/// getNumMatches - In a valid regex, return the number of parenthesized
/// matches it contains.
unsigned Regex::getNumMatches() const {
return preg->re_nsub;
}
bool Regex::match(StringRef String, SmallVectorImpl<StringRef> *Matches){
unsigned nmatch = Matches ? preg->re_nsub+1 : 0;
// pmatch needs to have at least one element.
SmallVector<llvm_regmatch_t, 8> pm;
pm.resize(nmatch > 0 ? nmatch : 1);
pm[0].rm_so = 0;
pm[0].rm_eo = String.size();
int rc = llvm_regexec(preg, String.data(), nmatch, pm.data(), REG_STARTEND);
if (rc == REG_NOMATCH)
return false;
if (rc != 0) {
// regexec can fail due to invalid pattern or running out of memory.
error = rc;
return false;
}
// There was a match.
if (Matches) { // match position requested
Matches->clear();
for (unsigned i = 0; i != nmatch; ++i) {
if (pm[i].rm_so == -1) {
// this group didn't match
Matches->push_back(StringRef());
continue;
}
assert(pm[i].rm_eo >= pm[i].rm_so);
Matches->push_back(StringRef(String.data()+pm[i].rm_so,
pm[i].rm_eo-pm[i].rm_so));
}
}
return true;
}
std::string Regex::sub(StringRef Repl, StringRef String,
std::string *Error) {
SmallVector<StringRef, 8> Matches;
// Reset error, if given.
if (Error && !Error->empty()) *Error = "";
// Return the input if there was no match.
if (!match(String, &Matches))
return String;
// Otherwise splice in the replacement string, starting with the prefix before
// the match.
std::string Res(String.begin(), Matches[0].begin());
// Then the replacement string, honoring possible substitutions.
while (!Repl.empty()) {
// Skip to the next escape.
std::pair<StringRef, StringRef> Split = Repl.split('\\');
// Add the skipped substring.
Res += Split.first;
// Check for terminimation and trailing backslash.
if (Split.second.empty()) {
if (Repl.size() != Split.first.size() &&
Error && Error->empty())
*Error = "replacement string contained trailing backslash";
break;
}
// Otherwise update the replacement string and interpret escapes.
Repl = Split.second;
// FIXME: We should have a StringExtras function for mapping C99 escapes.
switch (Repl[0]) {
// Treat all unrecognized characters as self-quoting.
default:
Res += Repl[0];
Repl = Repl.substr(1);
break;
// Single character escapes.
case 't':
Res += '\t';
Repl = Repl.substr(1);
break;
case 'n':
Res += '\n';
Repl = Repl.substr(1);
break;
// Decimal escapes are backreferences.
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9': {
// Extract the backreference number.
StringRef Ref = Repl.slice(0, Repl.find_first_not_of("0123456789"));
Repl = Repl.substr(Ref.size());
unsigned RefValue;
if (!Ref.getAsInteger(10, RefValue) &&
RefValue < Matches.size())
Res += Matches[RefValue];
else if (Error && Error->empty())
*Error = "invalid backreference string '" + Ref.str() + "'";
break;
}
}
}
// And finally the suffix.
Res += StringRef(Matches[0].end(), String.end() - Matches[0].end());
return Res;
}
// These are the special characters matched in functions like "p_ere_exp".
static const char RegexMetachars[] = "()^$|*+?.[]\\{}";
bool Regex::isLiteralERE(StringRef Str) {
// Check for regex metacharacters. This list was derived from our regex
// implementation in regcomp.c and double checked against the POSIX extended
// regular expression specification.
return Str.find_first_of(RegexMetachars) == StringRef::npos;
}
std::string Regex::escape(StringRef String) {
std::string RegexStr;
for (unsigned i = 0, e = String.size(); i != e; ++i) {
if (strchr(RegexMetachars, String[i]))
RegexStr += '\\';
RegexStr += String[i];
}
return RegexStr;
}
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