100 lines
1.6 KiB
Perl
Executable File
100 lines
1.6 KiB
Perl
Executable File
use v5.10;
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use warnings;
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use Parse::RecDescent;
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$RD_TRACE = 1;
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my $parser = Parse::RecDescent->new(<<'EOGRAMMAR');
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<autotree>
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file: element(s)
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element: command | literal
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command: '\\' literal options(?) args(?)
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options: '[' option(s? /,/) ']'
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args: '{' element(s?) '}'
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option: /[^][\\$&%#_{}~^ \t\n,]+/
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literal: /[^][\\$&%#_{}~^ \t\n]+/
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EOGRAMMAR
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local $/;
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my $tree = $parser->file(<DATA>);
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$tree->explain(0);
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sub file::explain
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{
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my ($self, $level) = @_;
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for (@{$self->{'element(s)'}})
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{
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$_->explain($level);
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print "\n";
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}
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}
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sub element::explain
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{
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my ($self, $level) = @_;
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($self->{command}||$self->{literal})->explain($level)
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}
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sub command::explain
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{
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my ($self, $level) = @_;
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print "\t"x$level, "Command: $self->{literal}{__VALUE__}\n";
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print "\t"x$level, "\tOptions:\n";
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$self->{'options(?)'}[0]->explain($level+2) if @{$self->{'options(?)'}};
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print "\t"x$level, "\tArgs:\n";
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$self->{'args(?)'}[0]->explain($level+2) if @{$self->{'args(?)'}};
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}
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sub options::explain
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{
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my ($self, $level) = @_;
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$_->explain($level) foreach @{$self->{'option(s?)'}};
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}
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sub args::explain
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{
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my ($self, $level) = @_;
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$_->explain($level) foreach @{$self->{'element(s?)'}};
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}
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sub option::explain
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{
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my ($self, $level) = @_;
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print "\t"x$level, "Option: $self->{__VALUE__}\n";
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}
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sub literal::explain
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{
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my ($self, $level) = @_;
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print "\t"x$level, "Literal: $self->{__VALUE__}\n";
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}
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__DATA__
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\documentclass[a4paper,11pt]{article}
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\usepackage{latexsym}
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\author{D. Conway}
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\title{Parsing \LaTeX{}}
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\begin{document}
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\maketitle
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\tableofcontents
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\section{Description}
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...is easy \footnote{But not \emph{necessarily} simple}.
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\end{document}
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