#!/usr/bin/perl -w
use strict;
use Parse::Eyapp;
use Parse::Eyapp::Treeregexp;
my $debug = 0;
sub TERMINAL::info { $_[0]{attr} }
my $translationscheme = q{
%metatree
%left '-' '+'
%left '*'
%left NEG
%%
line: %name EXP
exp
;
exp:
%name PLUS
exp.left '+' exp.right
{ $lhs->{n} .= $left->{n} + $right->{n} }
| %name TIMES
exp.left '*' exp.right
{ $lhs->{n} = $left->{n} * $right->{n} }
| %name NUM
$NUM
{ $lhs->{n} = $NUM->{attr} }
| '(' $exp ')' %begin { $exp }
| %name MINUS
exp.left '-' exp.right
{ $lhs->{n} = $left->{n} - $right->{n} }
| %name UMINUS
'-' $exp %prec NEG
{ $lhs->{n} = -$exp->{n} }
;
%%
use Tail2;
}; # end translation scheme
sub show_match {
my $self = shift;
print "Index: $_[1]\n";
}
my $transform = Parse::Eyapp::Treeregexp->new( STRING => q{
delete_code : CODE => { $delete_code->delete() }
{
sub not_semantic {
my $self = shift;
return 1 if ((ref($self) eq 'TERMINAL') and ($self->{token} eq $self->{attr}));
return 0;
}
}
delete_tokens : TERMINAL and { not_semantic($TERMINAL) } => {
$delete_tokens->delete();
}
insert_child : TIMES(NUM(TERMINAL), NUM(TERMINAL)) => {
my $b = Parse::Eyapp::Node->new( 'UMINUS(TERMINAL)',
sub { $_[1]->{attr} = '4.5' });
$insert_child->unshift($b);
}
},
)->generate();
Parse::Eyapp->new_grammar(
input=>$translationscheme,
classname=>'Calc',
firstline =>7,
);
my $parser = Calc->new(); # Create the parser
my $input = "2*3\n";
print $input;
my $t = $parser->Run(\$input);
print $t->str."\n"; # Show the tree
# Get the AST
our ($delete_tokens, $delete_code);
$t->s($delete_tokens, $delete_code);
print $t->str."\n"; # Show the tree
our $insert_child;
$insert_child->s($t);
print $t->str."\n"; # Show the tree