CMake/Source/cmGeneratorExpressionLexer.cxx
Ben Boeckel 14a13d30ee cmGeneratorExpressionLexer: only tokenize strings with a '$'
In standard libraries, `std::string::find` is usually implemented using
vectorized code. Since the Tokenize method iterates
character-by-character, doing an initial check using `find` improves
performance.
2018-01-31 11:04:36 -05:00

69 lines
1.9 KiB
C++

/* Distributed under the OSI-approved BSD 3-Clause License. See accompanying
file Copyright.txt or https://cmake.org/licensing for details. */
#include "cmGeneratorExpressionLexer.h"
cmGeneratorExpressionLexer::cmGeneratorExpressionLexer()
: SawBeginExpression(false)
, SawGeneratorExpression(false)
{
}
static void InsertText(const char* upto, const char* c,
std::vector<cmGeneratorExpressionToken>& result)
{
if (upto != c) {
result.emplace_back(cmGeneratorExpressionToken::Text, upto, c - upto);
}
}
std::vector<cmGeneratorExpressionToken> cmGeneratorExpressionLexer::Tokenize(
const std::string& input)
{
std::vector<cmGeneratorExpressionToken> result;
if (input.find('$') == std::string::npos) {
result.push_back(cmGeneratorExpressionToken(
cmGeneratorExpressionToken::Text, input.c_str(), input.size()));
return result;
}
const char* c = input.c_str();
const char* upto = c;
for (; *c; ++c) {
switch (*c) {
case '$':
if (c[1] == '<') {
InsertText(upto, c, result);
result.emplace_back(cmGeneratorExpressionToken::BeginExpression, c,
2);
upto = c + 2;
++c;
SawBeginExpression = true;
}
break;
case '>':
InsertText(upto, c, result);
result.emplace_back(cmGeneratorExpressionToken::EndExpression, c, 1);
upto = c + 1;
SawGeneratorExpression = SawBeginExpression;
break;
case ':':
InsertText(upto, c, result);
result.emplace_back(cmGeneratorExpressionToken::ColonSeparator, c, 1);
upto = c + 1;
break;
case ',':
InsertText(upto, c, result);
result.emplace_back(cmGeneratorExpressionToken::CommaSeparator, c, 1);
upto = c + 1;
break;
default:
break;
}
}
InsertText(upto, c, result);
return result;
}