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Parse EBNF: Difference between revisions

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Parse EBNF (view source)

Revision as of 14:58, 28 September 2013

42 bytes added ,  10 years ago
→‎{{header|Perl 6}}: Updated to work with latest version of Rakudo. Minor syntax fixes
(→‎{{header|Perl 6}}: Updated to work with current specs (repetion operator changed). Also displays syntax tree now)
(→‎{{header|Perl 6}}: Updated to work with latest version of Rakudo. Minor syntax fixes)
Line 440:
 
=={{header|Perl 6}}==
{{works with|Rakudo|20122013.0509}}
 
This parses the EBNF rule set using a perl 6 grammar, then if it parses as valid EBNF, constructs a grammar and parses the test strings with that. EBNF rule sets that are naively syntactically correct but missing rules will parse as valid but will give a runtime failure warning about missing methods.
It is implemented and exercised using the flavor of EBNF and test cases specified on the [[Parse EBNF/Tests|test page]].
 
<lang perl6># A perl 6 grammar to parse EBNF
Line 454 ⟶ 455:
rule repeat { '{' <expression> '}' }
rule optional { '[' <expression> ']' }
token identifier { <-[\|\(\)\{\}\[\]\.\;\"\'\s]>+ } #'" Defeat confused syntax highlighting
token literal { ["'" <-[']>+ "'" | '"' <-["]>+ '"'] } #'" Defeat confused syntax highlighting
token title { <literal> }
token comment { <literal> }
Line 463 ⟶ 464:
class EBNF::Actions {
method TOP($/) {
say "Syntax Tree:\n", $/; # Dump the syntax tree to STDOUT
make 'grammar ' ~
($<title> ?? $<title>.subst(/\W/, '', :g) ||!! 'unnamed') ~
" \{\n rule TOP \{^[<" ~ $/<production>[0]<name> ~
">]+\$\}\n " ~ $<production>>>.ast ~ "\}"
}
method production($/) {
make 'token ' ~ $<name> ~ ' {' ~
$<expression>.ast ~ "}\n"
}
method expression($/) { make join '|', $<term>>>.ast }
method term($/) { make join '\h*', $<factor>>>.ast }
method factor($/) {
make $<literal> ?? $<literal> !!
$<group> ?? '[' ~ $<group>.ast ~ ']' !!
$<repeat> ?? '[' ~ $<repeat>.ast ~ '\\s*]*' !!
$<optional> ?? '[' ~ $<optional>.ast ~ ']?' !!
'<' ~ $<identifier> ~ '>'
}
method repeat($/) { make $<expression>.ast }
Line 550 ⟶ 551:
my $i = 1;
for @tests -> $test {
say '*' x 79;▼
unless EBNF.parse($test<ebnf>) {
say "Parsing EBNF grammar:\n";
Line 559 ⟶ 558:
next;
}
my $p = EBNF.parse($test<ebnf>, :actions(EBNF::Actions));
my $grammar = $p.ast;
Line 566 ⟶ 564:
my $fn = 'EBNFtest'~$i++;
my $fh = open($fn, :w) or die "$!\n";
$fh.say( "\{\n", $grammar );
$fh.say( qq|say "Parsing EBNF grammar '$title':\\n";| );
$fh.say( qq|say q<{$test<ebnf>.subst(/^^\h*/,'',:g)}>;| );
$fh.say( q|say "\nValid syntax.\n\nTesting:\n";| );
$fh.say( q|CATCH { diedefault { say " - $_" } };| );
my $len = [max] $test<teststrings>.flat>>.chars;
for $test<teststrings>.flat -> $s {
$fh.say( qq|printf "%{$len}s", '{$s}';\n| ~
qq|printf " - %s\\n", try ({$title}.parse('{$s}'))| ~
qq| ?? 'valid.' !! 'NOT valid.';|
);
}
▲ $fh.say( '*'qq| x"\\n"} 79|);
$fh.close;
say qqx/perl6 $fn/;
say '*' x 79, "\n";
unlink $fn;
}
}</lang>
 
Output:
<pre>
*******************************************************************************
Syntax Tree:
q[｢"a" {
a = "a1" ( "a2" | "a3" ) { "a4" } [ "a5" ] "a6" ;
} "z"]｣
title => q[｢"a"]｣
literal => q[｢"a"]｣
production => q[a｢a = "a1" ( "a2" | "a3" ) { "a4" } [ "a5" ] "a6" ;
]｣
name => q[a]｢a｣
identifier => q[a]｢a｣
expression => q[｢"a1" ( "a2" | "a3" ) { "a4" } [ "a5" ] "a6" ]｣
term => q[｢"a1" ( "a2" | "a3" ) { "a4" } [ "a5" ] "a6" ]｣
factor => q[｢"a1" ]｣
literal => q[｢"a1"]｣
factor => q[｢( "a2" | "a3" ) ]｣
group => q[｢( "a2" | "a3" ) ]｣
expression => q[｢"a2" | "a3" ]｣
term => q[｢"a2" ]｣
factor => q[｢"a2" ]｣
literal => q[｢"a2"]｣
term => q[｢ "a3" ]｣
factor => q[｢"a3" ]｣
literal => q[｢"a3"]｣
factor => q[｢{ "a4" } ]｣
repeat => q[｢{ "a4" } ]｣
expression => q[｢"a4" ]｣
term => q[｢"a4" ]｣
factor => q[｢"a4" ]｣
literal => q[｢"a4"]｣
factor => q[｢[ "a5" ] ]｣
optional => q[｢[ "a5" ] ]｣
expression => q[｢"a5" ]｣
term => q[｢"a5" ]｣
factor => q[｢"a5" ]｣
literal => q[｢"a5"]｣
factor => q[｢"a6" ]｣
literal => q[｢"a6"]｣
comment => q[｢"z"]｣
literal => q[｢"z"]｣
 
Parsing EBNF grammar 'a':
Line 648 ⟶ 645:
 
*******************************************************************************
 
*******************************************************************************
Syntax Tree:
q[｢{
expr = term { plus term } .
term = factor { times factor } .
Line 660 ⟶ 657:
number = digit { digit } .
digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" .
}]｣
production => q[expr｢expr = term { plus term } .
]｣
name => q[expr]｢expr｣
identifier => q[expr]｢expr｣
expression => q[term｢term { plus term } ]｣
term => q[term｢term { plus term } ]｣
factor => q[term｢term ]｣
identifier => q[term]｢term｣
factor => q[｢{ plus term } ]｣
repeat => q[｢{ plus term } ]｣
expression => q[plus｢plus term ]｣
term => q[plus｢plus term ]｣
factor => q[plus｢plus ]｣
identifier => q[plus]｢plus｣
factor => q[term｢term ]｣
identifier => q[term]｢term｣
production => q[term｢term = factor { times factor } .
]｣
name => q[term]｢term｣
identifier => q[term]｢term｣
expression => q[factor｢factor { times factor } ]｣
term => q[factor｢factor { times factor } ]｣
factor => q[factor｢factor ]｣
identifier => q[factor]｢factor｣
factor => q[｢{ times factor } ]｣
repeat => q[｢{ times factor } ]｣
expression => q[times｢times factor ]｣
term => q[times｢times factor ]｣
factor => q[times｢times ]｣
identifier => q[times]｢times｣
factor => q[factor｢factor ]｣
identifier => q[factor]｢factor｣
production => q[factor｢factor = number | '(' expr ')' .
 
]｣
name => q[factor]｢factor｣
identifier => q[factor]｢factor｣
expression => q[number｢number | '(' expr ')' ]｣
term => q[number｢number ]｣
factor => q[number｢number ]｣
identifier => q[number]｢number｣
term => q[｢ '(' expr ')' ]｣
factor => q[｢'(' ]｣
literal => q[｢'(']｣
factor => q[expr｢expr ]｣
identifier => q[expr]｢expr｣
factor => q[｢')' ]｣
literal => q[｢')']｣
production => q[plus｢plus = "+" | "-" .
]｣
name => q[plus]｢plus｣
identifier => q[plus]｢plus｣
expression => q[｢"+" | "-" ]｣
term => q[｢"+" ]｣
factor => q[｢"+" ]｣
literal => q[｢"+"]｣
term => q[｢ "-" ]｣
factor => q[｢"-" ]｣
literal => q[｢"-"]｣
production => q[times｢times = "*" | "/" .
 
]｣
name => q[times]｢times｣
identifier => q[times]｢times｣
expression => q[｢"*" | "/" ]｣
term => q[｢"*" ]｣
factor => q[｢"*" ]｣
literal => q[｢"*"]｣
term => q[｢ "/" ]｣
factor => q[｢"/" ]｣
literal => q[｢"/"]｣
production => q[number｢number = digit { digit } .
]｣
name => q[number]｢number｣
identifier => q[number]｢number｣
expression => q[digit｢digit { digit } ]｣
term => q[digit｢digit { digit } ]｣
factor => q[digit｢digit ]｣
identifier => q[digit]｢digit｣
factor => q[｢{ digit } ]｣
repeat => q[｢{ digit } ]｣
expression => q[digit｢digit ]｣
term => q[digit｢digit ]｣
factor => q[digit｢digit ]｣
identifier => q[digit]｢digit｣
production => q[digit｢digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" .
]｣
name => q[digit]｢digit｣
identifier => q[digit]｢digit｣
expression => q[｢"0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ]｣
term => q[｢"0" ]｣
factor => q[｢"0" ]｣
literal => q[｢"0"]｣
term => q[｢ "1" ]｣
factor => q[｢"1" ]｣
literal => q[｢"1"]｣
term => q[｢ "2" ]｣
factor => q[｢"2" ]｣
literal => q[｢"2"]｣
term => q[｢ "3" ]｣
factor => q[｢"3" ]｣
literal => q[｢"3"]｣
term => q[｢ "4" ]｣
factor => q[｢"4" ]｣
literal => q[｢"4"]｣
term => q[｢ "5" ]｣
factor => q[｢"5" ]｣
literal => q[｢"5"]｣
term => q[｢ "6" ]｣
factor => q[｢"6" ]｣
literal => q[｢"6"]｣
term => q[｢ "7" ]｣
factor => q[｢"7" ]｣
literal => q[｢"7"]｣
term => q[｢ "8" ]｣
factor => q[｢"8" ]｣
literal => q[｢"8"]｣
term => q[｢ "9" ]｣
factor => q[｢"9" ]｣
literal => q[｢"9"]｣
 
Parsing EBNF grammar 'unnamed':
Line 808 ⟶ 805:
 
*******************************************************************************
 
*******************************************************************************
Parsing EBNF grammar:
 
Line 815 ⟶ 812:
Invalid syntax. Can not be parsed.
 
*******************************************************************************
*******************************************************************************
Parsing EBNF grammar:
Line 823 ⟶ 819:
Invalid syntax. Can not be parsed.
 
*******************************************************************************
*******************************************************************************
Parsing EBNF grammar:
Line 831 ⟶ 826:
Invalid syntax. Can not be parsed.
 
*******************************************************************************
*******************************************************************************
Syntax Tree:
q[｢{ foo = bar . }]｣
production => q[foo｢foo = bar . ]｣
name => q[foo]｢foo｣
identifier => q[foo]｢foo｣
expression => q[bar｢bar ]｣
term => q[bar｢bar ]｣
factor => q[bar｢bar ]｣
identifier => q[bar]｢bar｣
 
Parsing EBNF grammar 'unnamed':
Line 853 ⟶ 847:
foobar - No such method 'bar' for invocant of type 'unnamed'
 
*******************************************************************************</pre>
</pre>
 
=={{header|PicoLisp}}==
Thundergnat
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