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Macroprocessor: make the removal of “@#line” directives and extra newlines consistent across LF and CR+LF conventions 

Simplify the algorithm using only regexps, and add comments.
pac-components
Sébastien Villemot 2021-11-19 16:34:29 +01:00
parent 1de3476546
commit 1e4eadb266
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1 changed files with 16 additions and 4 deletions
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20
src/MacroExpandModFile.cc
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@ -50,10 +50,22 @@ macroExpandModFile(const string &filename, const string &basename, const istream
string str(macro_output.str());
if (!line_macro)
{
str = regex_replace(str, regex(R"((^|\n)\s*@#line.*)"), "");
auto compareNewline = [](char i, char j) { return i == '\n' && j == '\n'; };
str.erase(0, str.find_first_not_of('\n'));
str.erase(unique(str.begin(), str.end(), compareNewline), str.end());
/* Remove the @#line directives.
Unfortunately GCC 11 does not yet support std::regex::multiline
(despite it being in the C++17 standard), so we are forced to use
a trick to emulate the “usual” behaviour of the caret ^;
here, the latter only matches the beginning of file.
This also means that we are forced to remove the EOL before the
@#line, and not the one after it (matching the EOL before and the
EOL after in the same regexp does not work). */
str = regex_replace(str, regex(R"((^|\r?\n)@#line.*)"), "");
/* Remove the EOLs at the beginning of the output, the first one
being a remnant of the first @#line directive. */
str = regex_replace(str, regex(R"(^(\r?\n)+)"), "");
/* Replace sequences of several newlines by a single newline (in
both LF and CR+LF conventions). */
str = regex_replace(str, regex(R"(\n{2,})"), "\n");
str = regex_replace(str, regex(R"((\r\n){2,})"), "\r\n");
}
macro_output_file << str;
macro_output_file.close();