// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "tools/gn/pattern.h"
#include "tools/gn/value.h"
const char kPattern_Help[] =
"Patterns\n"
" Patterns are VERY limited regular expressions that are used in\n"
" several places.\n"
"\n"
" Patterns must match the entire input string to be counted as a match.\n"
" In regular expression parlance, there is an implicit \"^...$\"\n"
" surrounding your input. If you want to match a substring, you need to\n"
" use wildcards at the beginning and end.\n"
"\n"
" There are only two special tokens understood by the pattern matcher.\n"
" Everything else is a literal.\n"
"\n"
" * Matches zero or more of any character. It does not depend on the\n"
" preceding character (in regular expression parlance it is\n"
" equivalent to \".*\").\n"
"\n"
" \\b Matches a path boundary. This will match the beginning or end of\n"
" a string, or a slash.\n"
"\n"
"Examples\n"
"\n"
" \"*asdf*\"\n"
" Matches a string containing \"asdf\" anywhere.\n"
"\n"
" \"asdf\"\n"
" Matches only the exact string \"asdf\".\n"
"\n"
" \"*.cc\"\n"
" Matches strings ending in the literal \".cc\".\n"
"\n"
" \"\\bwin/*\"\n"
" Matches \"win/foo\" and \"foo/win/bar.cc\" but not \"iwin/foo\".\n";
namespace {
void ParsePattern(const std::string& s, std::vector<Pattern::Subrange>* out) {
// Set when the last subrange is a literal so we can just append when we
// find another literal.
Pattern::Subrange* last_literal = NULL;
for (size_t i = 0; i < s.size(); i++) {
if (s[i] == '*') {
// Don't allow two **.
if (out->size() == 0 ||
(*out)[out->size() - 1].type != Pattern::Subrange::ANYTHING)
out->push_back(Pattern::Subrange(Pattern::Subrange::ANYTHING));
last_literal = NULL;
} else if (s[i] == '\\') {
if (i < s.size() - 1 && s[i + 1] == 'b') {
// "\b" means path boundary.
i++;
out->push_back(Pattern::Subrange(Pattern::Subrange::PATH_BOUNDARY));
last_literal = NULL;
} else {
// Backslash + anything else means that literal char.
if (!last_literal) {
out->push_back(Pattern::Subrange(Pattern::Subrange::LITERAL));
last_literal = &(*out)[out->size() - 1];
}
if (i < s.size() - 1) {
i++;
last_literal->literal.push_back(s[i]);
} else {
// Single backslash at end, use literal backslash.
last_literal->literal.push_back('\\');
}
}
} else {
if (!last_literal) {
out->push_back(Pattern::Subrange(Pattern::Subrange::LITERAL));
last_literal = &(*out)[out->size() - 1];
}
last_literal->literal.push_back(s[i]);
}
}
}
} // namespace
Pattern::Pattern(const std::string& s) {
ParsePattern(s, &subranges_);
is_suffix_ =
(subranges_.size() == 2 &&
subranges_[0].type == Subrange::ANYTHING &&
subranges_[1].type == Subrange::LITERAL);
}
Pattern::~Pattern() {
}
bool Pattern::MatchesString(const std::string& s) const {
// Empty pattern matches only empty string.
if (subranges_.empty())
return s.empty();
if (is_suffix_) {
const std::string& suffix = subranges_[1].literal;
if (suffix.size() > s.size())
return false; // Too short.
return s.compare(s.size() - suffix.size(), suffix.size(), suffix) == 0;
}
return RecursiveMatch(s, 0, 0, true);
}
// We assume the number of ranges is small so recursive is always reasonable.
// Could be optimized to only be recursive for *.
bool Pattern::RecursiveMatch(const std::string& s,
size_t begin_char,
size_t subrange_index,
bool allow_implicit_path_boundary) const {
if (subrange_index >= subranges_.size()) {
// Hit the end of our subranges, the text should also be at the end for a
// match.
return begin_char == s.size();
}
const Subrange& sr = subranges_[subrange_index];
switch (sr.type) {
case Subrange::LITERAL: {
if (s.size() - begin_char < sr.literal.size())
return false; // Not enough room.
if (s.compare(begin_char, sr.literal.size(), sr.literal) != 0)
return false; // Literal doesn't match.
// Recursively check the next one.
return RecursiveMatch(s, begin_char + sr.literal.size(),
subrange_index + 1, true);
}
case Subrange::PATH_BOUNDARY: {
// When we can accept an implicit path boundary, we have to check both
// a match of the literal and the implicit one.
if (allow_implicit_path_boundary &&
(begin_char == 0 || begin_char == s.size())) {
// At implicit path boundary, see if the rest of the pattern matches.
if (RecursiveMatch(s, begin_char, subrange_index + 1, false))
return true;
}
// Check for a literal "/".
if (begin_char < s.size() && s[begin_char] == '/') {
// At explicit boundary, see if the rest of the pattern matches.
if (RecursiveMatch(s, begin_char + 1, subrange_index + 1, true))
return true;
}
return false;
}
case Subrange::ANYTHING: {
if (subrange_index == subranges_.size() - 1)
return true; // * at the end, consider it matching.
size_t min_next_size = sr.MinSize();
// We don't care about exactly what matched as long as there was a match,
// so we can do this front-to-back. If we needed the match, we would
// normally want "*" to be greedy so would work backwards.
for (size_t i = begin_char; i < s.size() - min_next_size; i++) {
// Note: this could probably be faster by detecting the type of the
// next match in advance and checking for a match in this loop rather
// than doing a full recursive call for each character.
if (RecursiveMatch(s, i, subrange_index + 1, true))
return true;
}
return false;
}
default:
NOTREACHED();
}
return false;
}
PatternList::PatternList() {
}
PatternList::~PatternList() {
}
void PatternList::Append(const Pattern& pattern) {
patterns_.push_back(pattern);
}
void PatternList::SetFromValue(const Value& v, Err* err) {
patterns_.clear();
if (v.type() != Value::LIST) {
*err = Err(v.origin(), "This value must be a list.");
return;
}
const std::vector<Value>& list = v.list_value();
for (size_t i = 0; i < list.size(); i++) {
if (!list[i].VerifyTypeIs(Value::STRING, err))
return;
patterns_.push_back(Pattern(list[i].string_value()));
}
}
bool PatternList::MatchesString(const std::string& s) const {
for (size_t i = 0; i < patterns_.size(); i++) {
if (patterns_[i].MatchesString(s))
return true;
}
return false;
}
bool PatternList::MatchesValue(const Value& v) const {
if (v.type() == Value::STRING)
return MatchesString(v.string_value());
return false;
}