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43 lines
899 B
Perl
43 lines
899 B
Perl
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#!/usr/bin/perl
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use warnings;
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use strict;
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if (@ARGV != 2) {
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die <<END;
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usage: ifdef-how <file> <line>
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Print the sequence of preprocessor conditionals which lead to the
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given line being retained after preprocessing. There is no output
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if the line is always retained. Conditionals that must be true are
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printed verbatim; conditionals that musy be false have their
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preprocessor keyword prefixed with NOT.
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Warning: this program does not parse comments or strings, so it will
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not handle tricky code correctly.
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END
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}
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my $file = shift;
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my $line = shift;
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open my $fh, '<', $file
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or die "ifdef-how: open $file: $!\n";
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my @stack;
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while (<$fh>) {
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last if $. == $line;
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if (m{^\s*#\s*(if|ifdef|ifndef)\b}) {
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push @stack, $_;
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}
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if (m{^\s*#\s*(elif|else)\b}) {
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$stack[-1] =~ s{^(\s*#\s*)(?!NOT)\b}{${1}NOT}gm;
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$stack[-1] .= $_;
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}
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if (m{^\s*#\s*endif\b}) {
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pop @stack;
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}
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}
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print @stack;
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