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Grammar.pm
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Grammar.pm
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# Copyright 2012 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/.
package Marpa::R2::Grammar;
use 5.010;
use warnings;
# There's a problem with this perlcritic check
# as of 9 Aug 2010
## no critic (TestingAndDebugging::ProhibitNoWarnings)
no warnings qw(recursion qw);
## use critic
use strict;
use vars qw($VERSION $STRING_VERSION);
$VERSION = '2.042000';
$STRING_VERSION = $VERSION;
## no critic(BuiltinFunctions::ProhibitStringyEval)
$VERSION = eval $VERSION;
## use critic
# This structure could be eliminated, and doing so
# would be more efficient, but it is part of the
# external interface. So this is a stub.
BEGIN {
my $structure = <<'END_OF_STRUCTURE';
:package=Marpa::R2::Internal::Symbol
ID { Unique ID }
END_OF_STRUCTURE
Marpa::R2::offset($structure);
} ## end BEGIN
BEGIN {
my $structure = <<'END_OF_STRUCTURE';
:package=Marpa::R2::Internal::Rule
ID
NAME
DISCARD_SEPARATION
MASK { Semantic mask of RHS symbols }
END_OF_STRUCTURE
Marpa::R2::offset($structure);
} ## end BEGIN
BEGIN {
my $structure = <<'END_OF_STRUCTURE';
:package=Marpa::R2::Internal::Grammar
C { A C structure }
TRACER { Also contains a copy of the C structure.
It is used frequently, so that an easy memoization
is probably worthwhile to save a the extra
indirection.
}
RULES { array of rule refs }
SYMBOLS { array of symbol refs }
ACTIONS { Default package in which to find actions }
DEFAULT_ACTION { Action for rules without one }
TRACE_FILE_HANDLE
WARNINGS { print warnings about grammar? }
RULE_NAME_REQUIRED
RULE_BY_NAME
INTERFACE { currently 'standard' or 'stuifzand' }
INTERNAL { internal grammar -- relax various restrictions }
CHARACTER_CLASSES { an hash of
character class regex by symbol name.
Used before precomputation. }
CHARACTER_CLASS_TABLE { An array of symbol ID and
regex. Used after precomputation. }
=LAST_BASIC_DATA_FIELD
{ === Evaluator Fields === }
DEFAULT_EMPTY_ACTION { default value for empty rules }
ACTION_OBJECT
INFINITE_ACTION
=LAST_EVALUATOR_FIELD
PROBLEMS { fatal problems }
=LAST_RECOGNIZER_FIELD
START_NAME { name of original symbol }
INACCESSIBLE_OK
UNPRODUCTIVE_OK
TRACE_RULES
=LAST_FIELD
END_OF_STRUCTURE
Marpa::R2::offset($structure);
} ## end BEGIN
package Marpa::R2::Internal::Grammar;
use English qw( -no_match_vars );
use Marpa::R2::Thin::Trace;
our %DEFAULT_SYMBOLS_RESERVED;
%DEFAULT_SYMBOLS_RESERVED = map { ($_, 1) } split //xms, '}]>)';
sub Marpa::R2::uncaught_error {
my ($error) = @_;
# This would be Carp::confess, but in the testing
# the stack trace includes the hoped for error
# message, which causes spurious success reports.
Carp::croak( "libmarpa reported an error which Marpa::R2 did not catch\n",
$error );
} ## end sub Marpa::R2::uncaught_error
package Marpa::R2::Internal::Grammar;
sub Marpa::R2::Grammar::new {
my ( $class, @arg_hashes ) = @_;
my $grammar = [];
bless $grammar, $class;
# set the defaults and the default defaults
$grammar->[Marpa::R2::Internal::Grammar::TRACE_FILE_HANDLE] = *STDERR;
$grammar->[Marpa::R2::Internal::Grammar::TRACE_RULES] = 0;
$grammar->[Marpa::R2::Internal::Grammar::WARNINGS] = 1;
$grammar->[Marpa::R2::Internal::Grammar::INACCESSIBLE_OK] = {};
$grammar->[Marpa::R2::Internal::Grammar::UNPRODUCTIVE_OK] = {};
$grammar->[Marpa::R2::Internal::Grammar::INFINITE_ACTION] = 'fatal';
$grammar->[Marpa::R2::Internal::Grammar::SYMBOLS] = [];
$grammar->[Marpa::R2::Internal::Grammar::RULES] = [];
$grammar->[Marpa::R2::Internal::Grammar::RULE_BY_NAME] = {};
$grammar->[Marpa::R2::Internal::Grammar::RULE_NAME_REQUIRED] = 0;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C] =
Marpa::R2::Thin::G->new( { if => 1 } );
$grammar->[Marpa::R2::Internal::Grammar::TRACER] =
Marpa::R2::Thin::Trace->new($grammar_c);
$grammar->set(@arg_hashes);
return $grammar;
} ## end sub Marpa::R2::Grammar::new
sub Marpa::R2::Grammar::tracer {
return $_[0]->[Marpa::R2::Internal::Grammar::TRACER];
}
sub Marpa::R2::Grammar::thin {
return $_[0]->[Marpa::R2::Internal::Grammar::C];
}
sub Marpa::R2::Grammar::thin_symbol {
my ( $grammar, $symbol_name ) = @_;
return $grammar->[Marpa::R2::Internal::Grammar::TRACER]
->symbol_by_name($symbol_name);
}
use constant GRAMMAR_OPTIONS => [
qw{
_internal_
action_object
actions
infinite_action
default_action
default_empty_action
default_rank
inaccessible_ok
rule_name_required
rules
source
start
symbols
terminals
trace_file_handle
unproductive_ok
warnings
}
];
sub Marpa::R2::Grammar::set {
my ( $grammar, @arg_hashes ) = @_;
# set trace_fh even if no tracing, because we may turn it on in this method
my $trace_fh =
$grammar->[Marpa::R2::Internal::Grammar::TRACE_FILE_HANDLE];
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
for my $args (@arg_hashes) {
my $ref_type = ref $args;
if ( not $ref_type ) {
Carp::croak(
'Marpa::R2::Grammar expects args as ref to HASH; arg was non-reference'
);
}
if ( $ref_type ne 'HASH' ) {
Carp::croak(
"Marpa::R2::Grammar expects args as ref to HASH, got ref to $ref_type instead"
);
}
if (my @bad_options =
grep { not $_ ~~ Marpa::R2::Internal::Grammar::GRAMMAR_OPTIONS }
keys %{$args}
)
{
Carp::croak( 'Unknown option(s) for Marpa::R2::Grammar: ',
join q{ }, @bad_options );
} ## end if ( my @bad_options = grep { not $_ ~~ ...})
# First pass options: These affect processing of other
# options and are expected to take force for the other
# options, even if specified afterwards
if ( defined( my $value = $args->{'_internal_'} ) ) {
$grammar->[Marpa::R2::Internal::Grammar::INTERNAL] = $value;
}
if ( defined( my $value = $args->{'trace_file_handle'} ) ) {
$trace_fh =
$grammar->[Marpa::R2::Internal::Grammar::TRACE_FILE_HANDLE] =
$value;
}
if ( defined( my $value = $args->{'default_rank'} ) ) {
Marpa::R2::exception(
'default_rank option not allowed after grammar is precomputed'
) if $grammar_c->is_precomputed();
$grammar_c->default_rank_set($value);
} ## end if ( defined( my $value = $args->{'default_rank'} ) )
# Second pass options
if ( defined( my $value = $args->{'symbols'} ) ) {
Marpa::R2::exception(
'symbols option not allowed after grammar is precomputed')
if $grammar_c->is_precomputed();
Marpa::R2::exception('symbols value must be REF to HASH')
if ref $value ne 'HASH';
for my $symbol ( sort keys %{$value} ) {
my $properties = $value->{$symbol};
assign_user_symbol( $grammar, $symbol, $properties );
}
} ## end if ( defined( my $value = $args->{'symbols'} ) )
if ( defined( my $value = $args->{'rule_name_required'} ) ) {
$grammar->[Marpa::R2::Internal::Grammar::RULE_NAME_REQUIRED] =
!!$value;
}
if ( defined( my $value = $args->{'terminals'} ) ) {
Marpa::R2::exception(
'terminals option not allowed after grammar is precomputed')
if $grammar_c->is_precomputed();
Marpa::R2::exception('terminals value must be REF to ARRAY')
if ref $value ne 'ARRAY';
for my $symbol ( @{$value} ) {
assign_user_symbol( $grammar, $symbol, { terminal => 1 } );
}
} ## end if ( defined( my $value = $args->{'terminals'} ) )
if ( defined( my $value = $args->{'start'} ) ) {
Marpa::R2::exception(
'start option not allowed after grammar is precomputed')
if $grammar_c->is_precomputed();
$grammar->[Marpa::R2::Internal::Grammar::START_NAME] = $value;
} ## end if ( defined( my $value = $args->{'start'} ) )
my $stuifzand_source;
my $deprecated_source;
if ( defined( my $value = $args->{'source'} ) ) {
Marpa::R2::exception(
'source option not allowed after grammar is precomputed')
if $grammar_c->is_precomputed();
Marpa::R2::exception(
qq{"source" named argument must be string or ref to SCALAR}
) if ref $value ne 'SCALAR';
$stuifzand_source = $value;
}
if ( defined( my $value = $args->{'rules'} ) ) {
Marpa::R2::exception(
'rules option not allowed after grammar is precomputed')
if $grammar_c->is_precomputed();
DO_RULES: {
## These hacks are for previous method of specifying Stuifzand
## grammars. They are now deprecated and undocumented.
## Eventually they may be eliminated.
if ( ref $value eq 'ARRAY'
and scalar @{$value} == 1
and not ref $value->[0] )
{
$value = $value->[0];
} ## end if ( ref $value eq 'ARRAY' and scalar @{$value} == 1...)
if ( not ref $value ) {
$deprecated_source = \$value;
}
if (defined $deprecated_source and defined $stuifzand_source) {
Marpa::R2::exception(
qq{Attempt to specify BNF via both 'rules' and 'source' named arguments\n},
qq{ You must use one or the other},
)
}
if (defined $deprecated_source) {
$stuifzand_source = $deprecated_source;
last DO_RULES;
}
Marpa::R2::exception(
qq{"rules" named argument must be string or ref to ARRAY}
) if ref $value ne 'ARRAY';
$grammar->[Marpa::R2::Internal::Grammar::INTERFACE] //=
'standard';
Marpa::R2::exception(
qq{Attempt to use the standard interface with a grammar that is already using the BNF interface\n},
qq{ Mixing the BNF and standard interface is not allowed}
)
if $grammar->[Marpa::R2::Internal::Grammar::INTERFACE] ne
'standard';
add_user_rules( $grammar, $value );
} ## end DO_RULES:
} ## end if ( defined( my $value = $args->{'rules'} ) )
if ( defined $stuifzand_source ) {
$grammar->[Marpa::R2::Internal::Grammar::INTERFACE] //=
'stuifzand';
Marpa::R2::exception(
qq{Attempt to use the standard interface with a grammar that is already using the BNF interface\n},
qq{ Mixing the BNF and standard interface is not allowed}
)
if $grammar->[Marpa::R2::Internal::Grammar::INTERFACE] ne
'stuifzand';
Marpa::R2::exception(
qq{Attempt to use the BNF interface with a grammar that is already using the standard interface\n},
qq{ Mixing the BNF and standard interface is not allowed},
)
if $grammar->[Marpa::R2::Internal::Grammar::INTERFACE] ne
'stuifzand';
my $parse_result =
Marpa::R2::Internal::Stuifzand::parse_rules( $grammar,
$stuifzand_source );
my $character_classes = $parse_result->{character_classes};
Marpa::R2::exception(
qq{Attempt to use character class with a grammar that is not scannerless\n},
) if defined $character_classes;
$grammar->[Marpa::R2::Internal::Grammar::CHARACTER_CLASSES] =
$character_classes
if defined $character_classes;
for my $rule ( @{ $parse_result->{rules} } ) {
add_user_rule( $grammar, $rule );
}
} ## end if ( defined $stuifzand_source )
if ( exists $args->{'default_empty_action'} ) {
my $value = $args->{'default_empty_action'};
$grammar->[Marpa::R2::Internal::Grammar::DEFAULT_EMPTY_ACTION] =
$value;
}
if ( defined( my $value = $args->{'actions'} ) ) {
$grammar->[Marpa::R2::Internal::Grammar::ACTIONS] = $value;
}
if ( defined( my $value = $args->{'action_object'} ) ) {
$grammar->[Marpa::R2::Internal::Grammar::ACTION_OBJECT] = $value;
}
if ( defined( my $value = $args->{'default_action'} ) ) {
$grammar->[Marpa::R2::Internal::Grammar::DEFAULT_ACTION] = $value;
}
if ( defined( my $value = $args->{'infinite_action'} ) ) {
if ( $value && $grammar_c->is_precomputed() ) {
say {$trace_fh}
'"infinite_action" option is useless after grammar is precomputed'
or Marpa::R2::exception("Could not print: $ERRNO");
}
Marpa::R2::exception(
q{infinite_action must be 'warn', 'quiet' or 'fatal'})
if not $value ~~ [qw(warn quiet fatal)];
$grammar->[Marpa::R2::Internal::Grammar::INFINITE_ACTION] =
$value;
} ## end if ( defined( my $value = $args->{'infinite_action'}...))
if ( defined( my $value = $args->{'warnings'} ) ) {
if ( $value && $grammar_c->is_precomputed() ) {
say {$trace_fh}
q{"warnings" option is useless after grammar is precomputed}
or Marpa::R2::exception("Could not print: $ERRNO");
}
$grammar->[Marpa::R2::Internal::Grammar::WARNINGS] = $value;
} ## end if ( defined( my $value = $args->{'warnings'} ) )
if ( defined( my $value = $args->{'inaccessible_ok'} ) ) {
if ( $value && $grammar_c->is_precomputed() ) {
say {$trace_fh}
q{"inaccessible_ok" option is useless after grammar is precomputed}
or Marpa::R2::exception("Could not print: $ERRNO");
} ## end if ( $value && $grammar_c->is_precomputed() )
GIVEN_REF_VALUE: {
my $ref_value = ref $value;
if ( $ref_value eq q{} ) {
$value //= {};
last GIVEN_REF_VALUE;
}
if ( $ref_value eq 'ARRAY' ) {
$value = { map { ( $_, 1 ) } @{$value} };
last GIVEN_REF_VALUE;
}
Marpa::R2::exception(
'value of inaccessible_ok option must be boolean or an array ref'
);
} ## end GIVEN_REF_VALUE:
$grammar->[Marpa::R2::Internal::Grammar::INACCESSIBLE_OK] =
$value;
} ## end if ( defined( my $value = $args->{'inaccessible_ok'}...))
if ( defined( my $value = $args->{'unproductive_ok'} ) ) {
if ( $value && $grammar_c->is_precomputed() ) {
say {$trace_fh}
q{"unproductive_ok" option is useless after grammar is precomputed}
or Marpa::R2::exception("Could not print: $ERRNO");
}
GIVEN_REF_VALUE: {
my $ref_value = ref $value;
if ( $ref_value eq q{} ) {
$value //= {};
last GIVEN_REF_VALUE;
}
if ( $ref_value eq 'ARRAY' ) {
$value = { map { ( $_, 1 ) } @{$value} };
last GIVEN_REF_VALUE;
}
Marpa::R2::exception(
'value of unproductive_ok option must be boolean or an array ref'
);
} ## end GIVEN_REF_VALUE:
$grammar->[Marpa::R2::Internal::Grammar::UNPRODUCTIVE_OK] =
$value;
} ## end if ( defined( my $value = $args->{'unproductive_ok'}...))
} ## end for my $args (@arg_hashes)
return 1;
} ## end sub Marpa::R2::Grammar::set
sub Marpa::R2::Grammar::symbol_reserved_set {
my ( $grammar, $final_character, $boolean ) = @_;
if ( length $final_character != 1 ) {
Marpa::R2::exception( 'symbol_reserved_set(): "',
$final_character, '" is not a symbol' );
}
if ( $final_character eq ']' ) {
return if $boolean;
Marpa::R2::exception(
q{symbol_reserved_set(): Attempt to unreserve ']'; this is not allowed}
);
} ## end if ( $final_character eq ']' ) ([)
if ( not exists $DEFAULT_SYMBOLS_RESERVED{$final_character} ) {
Marpa::R2::exception(
qq{symbol_reserved_set(): "$final_character" is not a reservable symbol}
);
}
# Return a value to make perlcritic happy
return $DEFAULT_SYMBOLS_RESERVED{$final_character} = $boolean ? 1 : 0;
} ## end sub Marpa::R2::Grammar::symbol_reserved_set
sub Marpa::R2::Grammar::precompute {
my $grammar = shift;
my $rules = $grammar->[Marpa::R2::Internal::Grammar::RULES];
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $trace_fh =
$grammar->[Marpa::R2::Internal::Grammar::TRACE_FILE_HANDLE];
my $problems = $grammar->[Marpa::R2::Internal::Grammar::PROBLEMS];
if ($problems) {
Marpa::R2::exception(
Marpa::R2::Grammar::show_problems($grammar),
"Second attempt to precompute grammar with fatal problems\n",
'Marpa::R2 cannot proceed'
);
} ## end if ($problems)
return $grammar if $grammar_c->is_precomputed();
set_start_symbol($grammar);
# Catch errors in precomputation
my $precompute_error_code = $Marpa::R2::Error::NONE;
$grammar_c->throw_set(0);
my $precompute_result = $grammar_c->precompute();
$grammar_c->throw_set(1);
if ( $precompute_result < 0 ) {
($precompute_error_code) = $grammar_c->error();
if ( not defined $precompute_error_code ) {
Marpa::R2::exception(
'libmarpa error, but no error code returned');
}
# If already precomputed, just return success
return $grammar
if $precompute_error_code == $Marpa::R2::Error::PRECOMPUTED;
# Cycles are not necessarily errors,
# and get special handling
$precompute_error_code = $Marpa::R2::Error::NONE
if $precompute_error_code == $Marpa::R2::Error::GRAMMAR_HAS_CYCLE;
} ## end if ( $precompute_result < 0 )
if ( $precompute_error_code != $Marpa::R2::Error::NONE ) {
# Report the errors, then return failure
if ( $precompute_error_code == $Marpa::R2::Error::NO_RULES ) {
Marpa::R2::exception(
'Attempted to precompute grammar with no rules');
}
if ( $precompute_error_code == $Marpa::R2::Error::NULLING_TERMINAL ) {
my @nulling_terminals = ();
my $event_count = $grammar_c->event_count();
EVENT:
for ( my $event_ix = 0; $event_ix < $event_count; $event_ix++ ) {
my ( $event_type, $value ) = $grammar_c->event($event_ix);
if ( $event_type eq 'MARPA_EVENT_NULLING_TERMINAL' ) {
push @nulling_terminals, $grammar->symbol_name($value);
}
} ## end EVENT: for ( my $event_ix = 0; $event_ix < $event_count; ...)
my @nulling_terminal_messages =
map {qq{Nulling symbol "$_" is also a terminal\n}}
@nulling_terminals;
Marpa::R2::exception( @nulling_terminal_messages,
'A terminal symbol cannot also be a nulling symbol' );
} ## end if ( $precompute_error_code == ...)
if ( $precompute_error_code == $Marpa::R2::Error::COUNTED_NULLABLE ) {
my @counted_nullables = ();
my $event_count = $grammar_c->event_count();
EVENT:
for ( my $event_ix = 0; $event_ix < $event_count; $event_ix++ ) {
my ( $event_type, $value ) = $grammar_c->event($event_ix);
if ( $event_type eq 'MARPA_EVENT_COUNTED_NULLABLE' ) {
push @counted_nullables, $grammar->symbol_name($value);
}
} ## end EVENT: for ( my $event_ix = 0; $event_ix < $event_count; ...)
my @counted_nullable_messages = map {
q{Nullable symbol "}
. $_
. qq{" is on rhs of counted rule\n}
} @counted_nullables;
Marpa::R2::exception( @counted_nullable_messages,
'Counted nullables confuse Marpa -- please rewrite the grammar'
);
} ## end if ( $precompute_error_code == ...)
if ( $precompute_error_code == $Marpa::R2::Error::NO_START_SYMBOL ) {
Marpa::R2::exception('No start symbol');
}
if ( $precompute_error_code == $Marpa::R2::Error::START_NOT_LHS ) {
my $name = $grammar->[Marpa::R2::Internal::Grammar::START_NAME];
Marpa::R2::exception(
qq{Start symbol "$name" not on LHS of any rule});
}
if ( $precompute_error_code == $Marpa::R2::Error::UNPRODUCTIVE_START )
{
my $name = $grammar->[Marpa::R2::Internal::Grammar::START_NAME];
Marpa::R2::exception(qq{Unproductive start symbol: "$name"});
}
Marpa::R2::uncaught_error( scalar $grammar_c->error() );
} ## end if ( $precompute_error_code != $Marpa::R2::Error::NONE)
# Shadow all the new rules
{
my $highest_rule_id = $grammar_c->highest_rule_id();
RULE:
for ( my $rule_id = 0; $rule_id <= $highest_rule_id; $rule_id++ ) {
next RULE if defined $rules->[$rule_id];
# The Marpa::R2 logic assumes no "gaps" in the rule numbering,
# which is currently the case for Libmarpa,
# but not guaranteed.
shadow_rule( $grammar, $rule_id );
} ## end RULE: for ( my $rule_id = 0; $rule_id <= $highest_rule_id; ...)
}
my $infinite_action =
$grammar->[Marpa::R2::Internal::Grammar::INFINITE_ACTION];
# Above I went through the error events
# Here I go through the events for situations where there was no
# hard error returned from libmarpa
my $loop_rule_count = 0;
{
my $event_count = $grammar_c->event_count();
EVENT:
for ( my $event_ix = 0; $event_ix < $event_count; $event_ix++ ) {
my ( $event_type, $value ) = $grammar_c->event($event_ix);
if ( $event_type ne 'MARPA_EVENT_LOOP_RULES' ) {
Marpa::R2::exception(
qq{Unknown grammar precomputation event; type="$event_type"}
);
}
$loop_rule_count = $value;
} ## end EVENT: for ( my $event_ix = 0; $event_ix < $event_count; ...)
}
if ( $loop_rule_count and $infinite_action ne 'quiet' ) {
my @loop_rules =
grep { $grammar_c->rule_is_loop($_) } ( 0 .. $#{$rules} );
for my $rule_id (@loop_rules) {
print {$trace_fh}
'Cycle found involving rule: ',
$grammar->brief_rule($rule_id), "\n"
or Marpa::R2::exception("Could not print: $ERRNO");
} ## end for my $rule_id (@loop_rules)
Marpa::R2::exception('Cycles in grammar, fatal error')
if $infinite_action eq 'fatal';
} ## end if ( $loop_rule_count and $infinite_action ne 'quiet')
# A bit hackish here: INACCESSIBLE_OK is not a HASH ref iff
# it is a Boolean TRUE indicating that all inaccessibles are OK.
# A Boolean FALSE will have been replaced with an empty hash.
if ($grammar->[Marpa::R2::Internal::Grammar::WARNINGS]
and ref(
my $ok = $grammar->[Marpa::R2::Internal::Grammar::INACCESSIBLE_OK]
) eq 'HASH'
)
{
SYMBOL:
for my $symbol (
@{ Marpa::R2::Grammar::inaccessible_symbols($grammar) } )
{
# Inaccessible internal symbols may be created
# from inaccessible use symbols -- ignore these.
# This assumes that Marpa's logic
# is correct and that
# it is not creating inaccessible symbols from
# accessible ones.
next SYMBOL if $symbol =~ /\]/xms;
next SYMBOL if $ok->{$symbol};
say {$trace_fh} "Inaccessible symbol: $symbol"
or Marpa::R2::exception("Could not print: $ERRNO");
} ## end SYMBOL: for my $symbol ( @{ ...})
} ## end if ( $grammar->[Marpa::R2::Internal::Grammar::WARNINGS...])
# A bit hackish here: UNPRODUCTIVE_OK is not a HASH ref iff
# it is a Boolean TRUE indicating that all inaccessibles are OK.
# A Boolean FALSE will have been replaced with an empty hash.
if ($grammar->[Marpa::R2::Internal::Grammar::WARNINGS]
and ref(
my $ok = $grammar->[Marpa::R2::Internal::Grammar::UNPRODUCTIVE_OK]
) eq 'HASH'
)
{
SYMBOL:
for my $symbol (
@{ Marpa::R2::Grammar::unproductive_symbols($grammar) } )
{
# Unproductive internal symbols may be created
# from unproductive use symbols -- ignore these.
# This assumes that Marpa's logic
# is correct and that
# it is not creating unproductive symbols from
# productive ones.
next SYMBOL if $symbol =~ /\]/xms;
next SYMBOL if $ok->{$symbol};
say {$trace_fh} "Unproductive symbol: $symbol"
or Marpa::R2::exception("Could not print: $ERRNO");
} ## end SYMBOL: for my $symbol ( @{ ...})
} ## end if ( $grammar->[Marpa::R2::Internal::Grammar::WARNINGS...])
# If we are using scannerless parsing, set that up
my $cc_hash = $grammar->[Marpa::R2::Internal::Grammar::CHARACTER_CLASSES];
if (defined $cc_hash) {
my $class_table = $grammar->[Marpa::R2::Internal::Grammar::CHARACTER_CLASS_TABLE] = [];
for my $cc_symbol ( sort keys %{$cc_hash} ) {
my $regex = $cc_hash->{$cc_symbol};
push @{$class_table},
[ $grammar->thin_symbol($cc_symbol), $regex ];
}
}
# Save some memory
$grammar->[Marpa::R2::Internal::Grammar::CHARACTER_CLASSES] = undef;
return $grammar;
} ## end sub Marpa::R2::Grammar::precompute
sub Marpa::R2::Grammar::rule_by_name {
my ( $grammar, $name ) = @_;
return $grammar->[Marpa::R2::Internal::Grammar::RULE_BY_NAME]->{$name};
}
sub Marpa::R2::Grammar::show_problems {
my ($grammar) = @_;
my $problems = $grammar->[Marpa::R2::Internal::Grammar::PROBLEMS];
if ($problems) {
my $problem_count = scalar @{$problems};
return
"Grammar has $problem_count problems:\n"
. ( join "\n", @{$problems} ) . "\n";
} ## end if ($problems)
return "Grammar has no problems\n";
} ## end sub Marpa::R2::Grammar::show_problems
sub Marpa::R2::Grammar::show_symbol {
my ( $grammar, $symbol ) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $text = q{};
my $symbol_id = $symbol->[Marpa::R2::Internal::Symbol::ID];
my $name = $grammar->symbol_name($symbol_id);
$text .= "$symbol_id: $name";
my @tag_list = ();
$grammar_c->symbol_is_productive($symbol_id)
or push @tag_list, 'unproductive';
$grammar_c->symbol_is_accessible($symbol_id)
or push @tag_list, 'inaccessible';
$grammar_c->symbol_is_nulling($symbol_id) and push @tag_list, 'nulling';
$grammar_c->symbol_is_terminal($symbol_id) and push @tag_list, 'terminal';
$text .= join q{ }, q{,}, @tag_list if scalar @tag_list;
$text .= "\n";
return $text;
} ## end sub Marpa::R2::Grammar::show_symbol
sub Marpa::R2::Grammar::show_symbols {
my ($grammar) = @_;
my $symbols = $grammar->[Marpa::R2::Internal::Grammar::SYMBOLS];
my $text = q{};
for my $symbol_ref ( @{$symbols} ) {
$text .= $grammar->show_symbol($symbol_ref);
}
return $text;
} ## end sub Marpa::R2::Grammar::show_symbols
sub Marpa::R2::Grammar::show_nulling_symbols {
my ($grammar) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $symbols = $grammar->[Marpa::R2::Internal::Grammar::SYMBOLS];
return join q{ }, sort map { $grammar->symbol_name($_) }
grep { $grammar_c->symbol_is_nulling($_) } ( 0 .. $#{$symbols} );
} ## end sub Marpa::R2::Grammar::show_nulling_symbols
sub Marpa::R2::Grammar::show_productive_symbols {
my ($grammar) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $symbols = $grammar->[Marpa::R2::Internal::Grammar::SYMBOLS];
return join q{ }, sort map { $grammar->symbol_name($_) }
grep { $grammar_c->symbol_is_productive($_) } ( 0 .. $#{$symbols} );
} ## end sub Marpa::R2::Grammar::show_productive_symbols
sub Marpa::R2::Grammar::show_accessible_symbols {
my ($grammar) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $symbols = $grammar->[Marpa::R2::Internal::Grammar::SYMBOLS];
return join q{ }, sort map { $grammar->symbol_name($_) }
grep { $grammar_c->symbol_is_accessible($_) } ( 0 .. $#{$symbols} );
} ## end sub Marpa::R2::Grammar::show_accessible_symbols
sub Marpa::R2::Grammar::inaccessible_symbols {
my ($grammar) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $symbols = $grammar->[Marpa::R2::Internal::Grammar::SYMBOLS];
return [
sort map { $grammar->symbol_name($_) }
grep { !$grammar_c->symbol_is_accessible($_) }
( 0 .. $#{$symbols} )
];
} ## end sub Marpa::R2::Grammar::inaccessible_symbols
sub Marpa::R2::Grammar::unproductive_symbols {
my ($grammar) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $symbols = $grammar->[Marpa::R2::Internal::Grammar::SYMBOLS];
return [
sort map { $grammar->symbol_name($_) }
grep { !$grammar_c->symbol_is_productive($_) }
( 0 .. $#{$symbols} )
];
} ## end sub Marpa::R2::Grammar::unproductive_symbols
sub Marpa::R2::Grammar::brief_rule {
my ( $grammar, $rule_id ) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my ( $lhs, @rhs ) = $grammar->rule($rule_id);
my $minimum = $grammar_c->sequence_min($rule_id);
my $quantifier = defined $minimum ? $minimum <= 0 ? q{*} : q{+} : q{};
return ( join q{ }, "$rule_id:", $lhs, '->', @rhs ) . $quantifier;
} ## end sub Marpa::R2::Grammar::brief_rule
sub Marpa::R2::Grammar::show_rule {
my ( $grammar, $rule ) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $rule_id = $rule->[Marpa::R2::Internal::Rule::ID];
my @comment = ();
$grammar_c->rule_length($rule_id) == 0 and push @comment, 'empty';
$grammar->rule_is_used($rule_id) or push @comment, '!used';
$grammar_c->rule_is_productive($rule_id) or push @comment, 'unproductive';
$grammar_c->rule_is_accessible($rule_id) or push @comment, 'inaccessible';
$rule->[Marpa::R2::Internal::Rule::DISCARD_SEPARATION]
and push @comment, 'discard_sep';
my $text = $grammar->brief_rule($rule_id);
if (@comment) {
$text .= q{ } . ( join q{ }, q{/*}, @comment, q{*/} );
}
return $text .= "\n";
} # sub show_rule
sub Marpa::R2::Grammar::show_rules {
my ($grammar) = @_;
my $rules = $grammar->[Marpa::R2::Internal::Grammar::RULES];
my $text;
for my $rule ( @{$rules} ) {
$text .= $grammar->show_rule($rule);
}
return $text;
} ## end sub Marpa::R2::Grammar::show_rules
# This logic tests for gaps in the rule numbering.
# Currently there are none, but Libmarpa does not
# guarantee this.
sub Marpa::R2::Grammar::rule_ids {
my ($grammar) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
return
grep { $grammar_c->rule_length($_); }
0 .. $grammar_c->highest_rule_id();
} ## end sub Marpa::R2::Grammar::rule_ids
sub Marpa::R2::Grammar::rule {
my ( $grammar, $rule_id ) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $rule_length = $grammar_c->rule_length($rule_id);
return if not defined $rule_length;
my @symbol_ids = ( $grammar_c->rule_lhs($rule_id) );
push @symbol_ids,
map { $grammar_c->rule_rhs( $rule_id, $_ ) }
( 0 .. $rule_length - 1 );
my @symbol_names = ();
for my $symbol_id (@symbol_ids) {
## The name of the symbols, before the BNF rewrites
push @symbol_names,
Marpa::R2::Grammar::original_symbol_name(
$grammar->symbol_name($symbol_id) );
} ## end for my $symbol_id (@symbol_ids)
return @symbol_names;
} ## end sub Marpa::R2::Grammar::rule
# Internal, for use with in coordinating thin and thick
# interfaces. NOT DOCUMENTED.
sub Marpa::R2::Grammar::_rule_mask {
my ( $grammar, $rule_id ) = @_;
my $rules = $grammar->[Marpa::R2::Internal::Grammar::RULES];
my $rule = $rules->[$rule_id];
return $rule->[Marpa::R2::Internal::Rule::MASK];
} ## end sub Marpa::R2::Grammar::rule
# Deprecated and for removal
# Used in blog post, and part of
# CPAN version 2.023_008 but
# never documented in any CPAN version
sub Marpa::R2::Grammar::bnf_rule {
goto &Marpa::R2::Grammar::rule;
} ## end sub Marpa::R2::Grammar::bnf_rule
sub Marpa::R2::Grammar::show_dotted_rule {
my ( $grammar, $rule_id, $dot_position ) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my ( $lhs, @rhs ) = $grammar->rule($rule_id);
my $minimum = $grammar_c->sequence_min($rule_id);
if (defined $minimum) {
my $quantifier = $minimum <= 0 ? q{*} : q{+} ;
$rhs[0] .= $quantifier;
}
$dot_position = 0 if $dot_position < 0;
splice @rhs, $dot_position, 0, q{.};
return join q{ }, $lhs, q{->}, @rhs;
} ## end sub Marpa::R2::Grammar::show_dotted_rule
# Used by lexers to check that symbol is a terminal
sub Marpa::R2::Grammar::check_terminal {
my ( $grammar, $name ) = @_;
return 0 if not defined $name;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $symbol_id =
$grammar->[Marpa::R2::Internal::Grammar::TRACER]
->symbol_by_name($name);
return 0 if not defined $symbol_id;
my $symbols = $grammar->[Marpa::R2::Internal::Grammar::SYMBOLS];
my $symbol = $symbols->[$symbol_id];
return $grammar_c->symbol_is_terminal($symbol_id) ? 1 : 0;
} ## end sub Marpa::R2::Grammar::check_terminal
sub Marpa::R2::Grammar::symbol_name {
my ( $grammar, $id ) = @_;
my $symbol_name =
$grammar->[Marpa::R2::Internal::Grammar::TRACER]->symbol_name($id);
return defined $symbol_name ? $symbol_name : '[SYMBOL#' . $id . ']';
} ## end sub Marpa::R2::Grammar::symbol_name
sub shadow_symbol {
my ( $grammar, $symbol_id ) = @_;
my $symbols = $grammar->[Marpa::R2::Internal::Grammar::SYMBOLS];
my $symbol = $symbols->[$symbol_id] = [];
$symbol->[Marpa::R2::Internal::Symbol::ID] = $symbol_id;
return $symbol;
} ## end sub shadow_symbol
# Create the structure which "shadows" the libmarpa rule
sub shadow_rule {
my ( $grammar, $rule_id ) = @_;
my $rules = $grammar->[Marpa::R2::Internal::Grammar::RULES];
my $new_rule = $rules->[$rule_id] = [];
$new_rule->[Marpa::R2::Internal::Rule::ID] = $rule_id;
return $new_rule;
} ## end sub shadow_rule
sub assign_symbol {
my ( $grammar, $name ) = @_;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
my $tracer = $grammar->[Marpa::R2::Internal::Grammar::TRACER];
my $symbol_id = $tracer->symbol_by_name($name);
if ( defined $symbol_id ) {
my $symbols = $grammar->[Marpa::R2::Internal::Grammar::SYMBOLS];
return $symbols->[$symbol_id];
}
$symbol_id = $tracer->symbol_new($name);
return shadow_symbol( $grammar, $symbol_id );
} ## end sub assign_symbol
sub assign_user_symbol {
my $grammar = shift;
my $name = shift;
my $options = shift;
my $grammar_c = $grammar->[Marpa::R2::Internal::Grammar::C];
if ( my $type = ref $name ) {
Marpa::R2::exception(
"Symbol name was ref to $type; it must be a scalar string");
}
my $final_symbol = substr $name, -1;
if ( $DEFAULT_SYMBOLS_RESERVED{$final_symbol} ) {
Marpa::R2::exception(
qq{Symbol name $name ends in "$final_symbol": that's not allowed}
);
}
my $symbol = assign_symbol( $grammar, $name );
my $symbol_id = $symbol->[Marpa::R2::Internal::Symbol::ID];
PROPERTY: for my $property ( sort keys %{$options} ) {
if ( not $property ~~ [qw(terminal rank )] ) {
Marpa::R2::exception(qq{Unknown symbol property "$property"});
}
if ( $property eq 'terminal' ) {
my $value = $options->{$property};
$grammar_c->symbol_is_terminal_set( $symbol_id, $value );
}