Perl ANTLR v3 Target
Author
Ron Blaschke, ron at rblasch.org
Status
Early prototyping phase. Simple lexer and parser are working.
...
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grammar MExpr;
options {
language = Perl5;
}
prog: stat+ ;
stat: expr NEWLINE { print "$expr.value\n"; }
| NEWLINE
;
expr returns [value]
: e=atom { $value = $e.value; }
( '+' e=atom { $value += $e.value; }
| '-' e=atom { $value -= $e.value; }
)*
;
atom returns [value]
: INT { $value = $INT.text; }
| '(' expr ')' { $value = $expr.value; }
;
ID : ('a'..'z'|'A'..'Z')+ ;
INT : '0'..'9'+ ;
NEWLINE:'\r'? '\n' ;
WS : (' '|'\t')+ { \$self->skip(); } ;
|
And here's the test program.
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#!/usr/bin/perl
use strict;
use warnings;
use ANTLR::Runtime::ANTLRStringStream;
use ANTLR::Runtime::CommonTokenStream;
use MExprLexer;
use MExprParser;
while (<>) {
my $input = ANTLR::Runtime::ANTLRStringStream->new($_);
my $lexer = MExprLexer->new($input);
my $tokens = ANTLR::Runtime::CommonTokenStream->new({ token_source => $lexer });
my $parser = MExprParser->new($tokens);
$parser->prog();
}
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Finally we're getting to the answer.
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$ perl t.pl
2 + 2
4
|
2007-08-08
+ Simple expression grammar
The grammar
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grammar Expr; options { language = Perl5; } @header { } @members { my %memory; } prog: stat+ ; stat: expr NEWLINE { print "$expr.value\n"; } | ID '=' expr NEWLINE { $memory{$ID.text} = $expr.value; } | NEWLINE ; expr returns [value] : e=multExpr { $value = $e.value; } ( '+' e=multExpr { $value += $e.value; } | '-' e=multExpr { $value -= $e.value; } )* ; multExpr returns [value] : e=atom { $value = $e.value; } ('*' e=atom { $value *= $e.value; })* ; atom returns [value] : INT { $value = $INT.text; } | ID { my $v = $memory{$ID.text}; if (defined $v) { $value = $v; } else { print STDERR "undefined variable $ID.text\n"; } } | '(' expr ')' { $value = $expr.value; } ; ID : ('a'..'z'|'A'..'Z')+ ; INT : '0'..'9'+ ; NEWLINE:'\r'? '\n' ; WS : (' '|'\t')+ { $self->skip(); } ; |
Test program
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#!/usr/bin/perl
use strict;
use warnings;
use blib '../..';
use ANTLR::Runtime::ANTLRStringStream;
use ANTLR::Runtime::CommonTokenStream;
use ExprLexer;
use ExprParser;
my $in;
{
undef $/;
$in = <>;
}
my $input = ANTLR::Runtime::ANTLRStringStream->new($in);
my $lexer = ExprLexer->new($input);
my $tokens = ANTLR::Runtime::CommonTokenStream->new({ token_source => $lexer });
my $parser = ExprParser->new($tokens);
$parser->prog();
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Test run
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$ perl t.pl
x=1
y=2
3*(x+y)
^Z
9
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2008-02-23
Started real porting effort. The goal is to port one ANTLR runtime class at a time from Java to Perl, including full API coverage and documentation. First stop of the porting train: ANTLR::Runtime::BitSet.
2008-11-18
Got the first parser working: SimpleCalc, taken from the Five minute introduction to ANTLR 3.
Author
Ronald Blaschke (ron at rblasch org)