Perl ANTLR v3 Target
Author
Ron Blaschke, ron at rblasch.org
Status
Early prototyping phase. A simple lexer is Simple lexer and parser are working.
Progress
Here's a simple example. Note that everything is still subject to change.
...
Note the "no viable alternative" error message for the unrecognized '!'.
2007-06-15
+ Handle lexer actions
Here's another short example, similar to the one above. Note how whitespaces are put into the hidden channel (99) and newlines are skipped.
| Code Block |
|---|
lexer grammar T2;
options { language = Perl5; }
ID : ('a'..'z'\|'A'..'Z')\+ ;
INT : '0'..'9'\+ ;
NEWLINE:'\r'? '\n' { $self->skip(); } ;
WS : (' '\|'\t')\+ { $channel = HIDDEN; } ;
|
| Code Block |
|---|
$ perl t.pl
text: Hello
type: 4
pos: 1:0
channel: 0
token index: -1
text:
type: 7
pos: 1:5
channel: 99
token index: -1
text: World
type: 4
pos: 1:6
channel: 0
token index: -1
line 1:11 no viable alternative at character '!'
text: 42
type: 5
pos: 2:0
channel: 0
token index: -1
|
2007-06-26
+ Simple Parser is working
Quick, what is 2 + 2? If you can't remember here's an easy way to find out. First we need a grammar.
| Code Block |
|---|
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.
| Code Block |
|---|
#!/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(); } |
Finally we're getting to the answer.
| Code Block |
|---|
$ perl t.pl
2 + 2
4
|
2007-08-08
+ Simple expression grammar
The grammar
| Code Block |
|---|
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
| Code Block |
|---|
#!/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();
|
Test run
| Code Block |
|---|
$ perl t.pl
x=1
y=2
3*(x+y)
^Z
9
|
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)