Re: Autotrees !!

Jeffrey asked:

        > Is there an example of an OO processor that handles the parse
        > tree that autotree produces?

I have a few, two of which I've appended below. I'll add them into the next
distribution too.

Damian

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#! /usr/local/bin/perl -sw

# PARSE AND EVALUATE LOGICAL EXPRESSIONS WITH A AUTOGENERATED OO PARSE TREE

use Parse::RecDescent;
use Data::Dumper;

my $parse = Parse::RecDescent->new(<<'EOG');

<autotree>
        expr    :       set | clear | disj
        set     :       'set' atom
        clear   :       'clear' atom
        disj    :       <leftop: conj 'or' conj>
                                { bless $item[-1], $item[0] }
        conj    :       <leftop: unary 'and' unary>
                                { bless $item[-1], $item[0] }
        unary   :       neg | bracket | atom
        bracket :       '(' expr ')'
        neg     :       'not' unary
        atom    :       /[a-z]+/i
EOG

while (<>)
{
        my $tree = $parse->expr($_);
        print Data::Dumper->Dump([$tree]);
        print $tree->eval(), "\n" if $tree;
}

BEGIN {@var{qw(a c e)} = (1,1,1);}

sub returning
{
         # local $^W;
         # print +(caller(1))[3], " returning ($_[0])\n";
        $_[0];
}

sub expr::eval     { my $type = $_[0]->{set}||$_[0]->{clear}||$_[0]->{disj};
                     returning $type->eval() }
sub disj::eval     { returning join '', map {$_->eval()} @{$_[0]} }
sub conj::eval     { returning ! join '', map {! $_->eval()} @{$_[0]} }
sub unary::eval    { my $type = $_[0]->{neg}||$_[0]->{bracket}||$_[0]->{atom};
                     returning $type->eval() }
sub bracket::eval  { returning $_[0]->{expr}->eval() }
sub neg::eval      { returning ! $_[0]->{unary}->eval() }
sub set::eval      { returning $::var{$_[0]->{atom}->name()} = 1 }
sub clear::eval    { returning $::var{$_[0]->{atom}->name()} = 0 }
sub atom::eval     { returning $::var{$_[0]->{__VALUE__}} }
sub atom::name     { returning $_[0]->{__VALUE__} }

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#! /usr/local/bin/perl -w

use Parse::RecDescent;

# $RD_TRACE = 1;

my $parser = Parse::RecDescent->new(<<'EOGRAMMAR');

<autotree>

        file:           element(s)

        element:        command | literal

        command:        '\\' literal options(?) args(?)

        options:        '[' option(s? /,/) ']'
        
        args:           '{' element(s?) '}'

        option:         /[^][\\$&%#_{}~^ \t\n,]+/

        literal:        /[^][\\$&%#_{}~^ \t\n]+/


EOGRAMMAR


local $/;
my $tree = $parser->file(<DATA>);

use AutoDump;
#show $tree;

$tree->explain(0);

sub file::explain
{
        my ($self, $level) = @_;
        for (@{$self->{element}})
        {
                $_->explain($level);
                print "\n";
        }
}

sub element::explain
{
        my ($self, $level) = @_;
        ($self->{command}||$self->{literal})->explain($level)
}

sub command::explain
{
        my ($self, $level) = @_;
        print "\t"x$level, "Command: $self->{literal}{__VALUE__}\n";
        print "\t"x$level, "\tOptions:\n";
        $self->{options}[0]->explain($level+2) if @{$self->{options}};
        print "\t"x$level, "\tArgs:\n";
        $self->{args}[0]->explain($level+2) if @{$self->{args}};
}

sub options::explain
{
        my ($self, $level) = @_;
        $_->explain($level) foreach @{$self->{__DIRECTIVE1__}};
}

sub args::explain
{
        my ($self, $level) = @_;
        $_->explain($level) foreach @{$self->{element}};
}


sub option::explain
{
        my ($self, $level) = @_;
        print "\t"x$level, "Option: $self->{__VALUE__}\n";
}

sub literal::explain
{
        my ($self, $level) = @_;
        print "\t"x$level, "Literal: $self->{__VALUE__}\n";
}


__DATA__

\documentclass[a4paper,11pt]{article}
\usepackage{latexsym}
\author{D. Conway}
\title{Parsing \LaTeX{}}
\begin{document}
\maketitle
\tableofcontents
\section{Description}
...is easy \footnote{But not \emph{necessarily} simple}.
\end{document}

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