Example of SLIF rewrites for Andreas Kupries

andreas.out

DSL:
:default ::= action => [values] bless => ::lhs
lexeme default = action => [ start, length, value ]
    bless => ::name latm => 1

:start ::= Script
Script ::= Expression+ separator => comma
comma ~ [,]
Expression ::=
    Number bless => primary
    | '(' Expression ')' bless => paren assoc => group
   || Expression '**' Expression bless => exponentiate assoc => right
   || Expression '*' Expression bless => multiply
    | Expression '/' Expression bless => divide
   || Expression '+' Expression bless => add
    | Expression '-' Expression bless => subtract

Number ~ [\d]+
:discard ~ whitespace
whitespace ~ [\s]+
# allow comments
:discard ~ <hash comment>
<hash comment> ~ <terminated hash comment> | <unterminated
   final hash comment>
<terminated hash comment> ~ '#' <hash comment body> <vertical space char>
<unterminated final hash comment> ~ '#' <hash comment body>
<hash comment body> ~ <hash comment char>*
<vertical space char> ~ [\x{A}\x{B}\x{C}\x{D}\x{2028}\x{2029}]
<hash comment char> ~ [^\x{A}\x{B}\x{C}\x{D}\x{2028}\x{2029}]

Internal symbols:
0 Expression[0] <Expression> at priority 0
1 Expression[1] <Expression> at priority 1
2 Expression[2] <Expression> at priority 2
3 Expression[3] <Expression> at priority 3
4 [:start] Internal G1 start symbol
5 [Lex-0] Internal lexical symbol for "'('"
6 [Lex-1] Internal lexical symbol for "')'"
7 [Lex-2] Internal lexical symbol for "'**'"
8 [Lex-3] Internal lexical symbol for "'*'"
9 [Lex-4] Internal lexical symbol for "'/'"
10 [Lex-5] Internal lexical symbol for "'+'"
11 [Lex-6] Internal lexical symbol for "'-'"
12 Script [no description]
13 Expression [no description]
14 comma [no description]
15 Number [no description]

Internal rules:
0: Script -> Script[Seq]
1: Script -> Script[Seq] comma
2: Script[Seq] -> Expression
3: Script[Seq] -> Script[Seq] comma Expression
4: Expression -> Expression[0]
5: Expression[0] -> Expression[1]
6: Expression[1] -> Expression[2]
7: Expression[2] -> Expression[3]
8: Expression[3] -> Number
9: Expression[3] -> [Lex-0] Expression[0] [Lex-1]
10: Expression[2] -> Expression[3] [Lex-2] Expression[2]
11: Expression[1] -> Expression[1] [Lex-3] Expression[2]
12: Expression[1] -> Expression[1] [Lex-4] Expression[2]
13: Expression[0] -> Expression[0] [Lex-5] Expression[1]
14: Expression[0] -> Expression[0] [Lex-6] Expression[1]
15: [:start] -> Script
16: [:start]['] -> [:start]

andreas.t

#!/usr/bin/perl
# Copyright 2015 Jeffrey Kegler
# This file is part of Marpa::R2.  Marpa::R2 is free software: you can
# redistribute it and/or modify it under the terms of the GNU Lesser
# General Public License as published by the Free Software Foundation,
# either version 3 of the License, or (at your option) any later version.
#
# Marpa::R2 is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser
# General Public License along with Marpa::R2.  If not, see
# http://www.gnu.org/licenses/.

# A "full" Synopsis for the intro doc to the SLIF

use 5.010;
use strict;
use warnings;
use English qw( -no_match_vars );
use Scalar::Util;

## no critic (ErrorHandling::RequireCarping);

# Marpa::R2::Display
# name: SLIF full synopsis

use Marpa::R2;

my $source = <<'END_OF_SOURCE';
:default ::= action => [values] bless => ::lhs
lexeme default = action => [ start, length, value ]
    bless => ::name latm => 1

:start ::= Script
Script ::= Expression+ separator => comma
comma ~ [,]
Expression ::=
    Number bless => primary
    | '(' Expression ')' bless => paren assoc => group
   || Expression '**' Expression bless => exponentiate assoc => right
   || Expression '*' Expression bless => multiply
    | Expression '/' Expression bless => divide
   || Expression '+' Expression bless => add
    | Expression '-' Expression bless => subtract

Number ~ [\d]+
:discard ~ whitespace
whitespace ~ [\s]+
# allow comments
:discard ~ <hash comment>
<hash comment> ~ <terminated hash comment> | <unterminated
   final hash comment>
<terminated hash comment> ~ '#' <hash comment body> <vertical space char>
<unterminated final hash comment> ~ '#' <hash comment body>
<hash comment body> ~ <hash comment char>*
<vertical space char> ~ [\x{A}\x{B}\x{C}\x{D}\x{2028}\x{2029}]
<hash comment char> ~ [^\x{A}\x{B}\x{C}\x{D}\x{2028}\x{2029}]
END_OF_SOURCE

my $grammar = Marpa::R2::Scanless::G->new(
    { bless_package => 'My_Nodes', source => \$source } );

my $naif_grammar = $grammar->thick_g1_grammar();
my @naif_symids  = $naif_grammar->symbol_ids();
say "DSL:\n$source";
say "Internal symbols:";
for my $naif_symid (@naif_symids) {
    say join " ", $naif_symid,
        $naif_grammar->symbol_name($naif_symid),
        ($naif_grammar->symbol_description($naif_symid) // '[no description]');
}
say "";
say "Internal rules:";
say $grammar->show_irls();

# vim: expandtab shiftwidth=4:

andreas.out contains an example SLIF script (which is one of the POD synopses), and listings of the internal symbols and internal rules into which it is rewritten. The code which generates this examples is in the andreas.t file.

Thanks. Saved.