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@jeffreykegler
Last active Aug 29, 2015
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Utility for reporting mismatched brackets
#!/usr/bin/env perl
# Copyright 2014 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/.
# This utility searches for mismatched braces --
# curly, square and round.
use 5.010;
use strict;
use warnings;
use Marpa::R2 2.098000;
use Data::Dumper;
use English qw( -no_match_vars );
use Getopt::Long ();
use Test::More;
sub usage {
die "Usage: $PROGRAM_NAME < file\n",
"For testing: $PROGRAM_NAME --test\n";
}
my $testing = 0;
my $verbose = 0;
usage()
if
not Getopt::Long::GetOptions( verbose => \$verbose, test => \$testing );
usage() if @ARGV;
Test::More::plan tests => 5 if $testing;
our $TESTING = $testing;
my $grammar = << '=== GRAMMAR ===';
:default ::= action => [ name, value ]
lexeme default = action => [ name, value ] latm => 1 # to add token names to ast
text ::= pieces
pieces ::= piece*
piece ::= filler | balanced
balanced ::=
lparen pieces rparen
| lcurly pieces rcurly
| lsquare pieces rsquare
# x5b is left square bracket
# x5d is right square bracket
filler ~ [^(){}\x5B\x5D]+
lparen ~ '('
rparen ~ ')'
lcurly ~ '{'
rcurly ~ '}'
lsquare ~ '['
rsquare ~ ']'
=== GRAMMAR ===
my $suffix = '(){}[]';
my %tokens = ();
for my $ix ( 0 .. ( length $suffix ) - 1 ) {
my $char = substr $suffix, $ix, 1;
$tokens{$char} = [ $ix, 1 ];
}
my %matching = ();
my %literal_match = ();
for my $pair (qw% () [] {} %) {
my ( $left, $right ) = split //xms, $pair;
$matching{$left} = $tokens{$right};
$literal_match{$left} = $right;
$matching{$right} = $tokens{$left};
$literal_match{$right} = $left;
} ## end for my $pair (qw% () [] {} %)
my %token_by_name = (
rcurly => $tokens{'}'},
rsquare => $tokens{']'},
rparen => $tokens{')'},
);
my $g = Marpa::R2::Scanless::G->new( { source => \($grammar) } );
my @tests = ();
if ($TESTING) {
@tests = (
[ 'z}ab)({[]})))(([]))zz', '1{ 4( 11( 12(' ],
[ '9\090]{[][][9]89]8[][]90]{[]\{}{}09[]}[', '5[ 16} 16[ 24[ 39]' ],
[ '([]([])([]([]', '13) 13) 13)' ],
[ '([([([([', '8] 8) 8] 8) 8] 8) 8] 8)' ],
[ '({]-[(}-[{)', '2} 2) 2[ 6) 6] 6{ 10} 10] 10(' ],
);
for my $test (@tests) {
my ( $string, $expected_result ) = @{$test};
my $fixes = q{};
test( $g, $string, \$fixes );
diagnostic( "Input: ", substr( $string, 0, 60 ) ) if $verbose;
my $description = qq{Result of "} . ( substr $string, 0, 60 ) . q{"};
Test::More::is( $fixes, $expected_result, $description );
} ## end for my $test (@tests)
} ## end if ($TESTING)
else {
local $RS = undef;
my $input = <>;
my $actual_result = test( $g, $input );
if ( not scalar @{$actual_result} ) {
say '=== All brackets balanced ===';
}
else {
my $divider = "\n" . ( '=' x 20 ) . "\n";
say join $divider, @{$actual_result};
}
} ## end else [ if ($TESTING) ]
sub diagnostic {
if ($TESTING) {
Test::More::diag(@_);
}
else {
say {*STDERR} @_;
}
} ## end sub diagnostic
sub marked_line {
my ( $string, $column1, $column2 ) = @_;
my $max_line_length = 60;
$max_line_length = $column1 if $column1 > $max_line_length;
$max_line_length = $column2
if defined $column2 and $column2 > $max_line_length;
# $pos_column is always the last of the two columns
my $output_line = substr $string, 0, $max_line_length;
my $nl_pos = index $output_line, "\n";
$output_line = substr $output_line, 0, $nl_pos;
my $pointer_line = ( q{ } x $column1 ) . q{^};
if ( defined $column2 ) {
my $further_offset = $column2 - $column1;
$pointer_line .= ( q{ } x ( $further_offset - 1 ) ) . q{^};
}
return join "\n", $output_line, $pointer_line;
} ## end sub marked_line
sub test {
my ( $g, $string, $fixes ) = @_;
my @problems = ();
my @fixes = ();
diagnostic( "Input: ", substr( $string, 0, 60 ) ) if $verbose or $TESTING;
# Record the length of the "real input"
my $input_length = length $string;
my $pos = 0;
# For Ruby Slippers, put a set of matching brackets into a suffix
# of the input.
# We wil carefully set our lengths when reading,
# so that we don't treat to accidentally read this, while reading
# the "real input".
$string .= $suffix;
# state $recce_debug_args = { trace_terminals => 1, trace_values => 1 };
state $recce_debug_args = {};
my $recce = Marpa::R2::Scanless::R->new(
{ grammar => $g,
## Ask Marpa to generate an event on rejection
rejection => 'event',
},
$recce_debug_args
);
# Note that we make sure only to read the "real input"
$pos = $recce->read( \$string, $pos, $input_length );
# For the entire input string ...
READ: while ( $pos < $input_length ) {
# Check if we stopped due to a rejection event.
# Any other event is an error.
my $rejection = 0;
EVENT:
for my $event ( @{ $recce->events() } ) {
my ($name) = @{$event};
if ( $name eq q{'rejected} ) {
$rejection = 1;
next EVENT;
}
die join q{ }, "Spurious event at position $pos: '$name'";
} ## end EVENT: for my $event ( @{ $recce->events() } )
# No rejection event?
# Then just start up again
if ( not $rejection ) {
# Note that we make sure we don't try to read the suffix
$pos = $recce->resume( $pos, $input_length - $pos );
next READ;
} ## end if ( not $rejection )
# If here, we rejected the next input token
# What terminals do we expect?
my @expected = @{ $recce->terminals_expected() };
# Find, among the expected terminals, a closing bracket.
# If there is more than one, pick one at random.
my ($token) =
grep {defined}
map { $token_by_name{$_} } @{ $recce->terminals_expected() };
# If no closing bracket is expected, then we need
# a new opening bracket in order to continue.
# Find out which one.
my $opening = not defined $token;
if ($opening) {
my $nextchar = substr $string, $pos, 1;
$token = $matching{$nextchar};
}
# If $token is not defined, all of the following have happened:
#
# 1.) We rejected the last set of tokens;
# 2.) We do not expect a closing bracket, so supplying a
# closing bracket will not fix the problem; and
# 3.) We do not expect an opening bracket, so supplying one
# of them will not fix the problem either.
#
# In other words, we have a problem with no possible
# solution. Actually, this should never happen.
# If it does, we abend.
die "Rejection at pos $pos: ", substr( $string, $pos, 10 )
if not defined $token;
# If we are here, we know what we need to continue
# parsing. We concoct a "Ruby Slippers token"
# and read it from the suffix.
my ( $token_start, $token_length ) = @{$token};
$token_start += $input_length;
my $token_literal = substr $string, $token_start, $token_length;
my $result = $recce->resume( $token_start, $token_length );
die "Read of Ruby slippers token failed"
if $result != $token_start + $token_length;
# Used for testing
push @fixes, "$pos$token_literal" if $fixes;
# We've done the Ruby Slippers thing, and are ready to
# continue reading.
# But first we want to report the error.
my ( $pos_line, $pos_column ) = $recce->line_column($pos);
my $problem;
# Report the error if it was a case of a missing open bracket.
if ($opening) {
$problem = join "\n",
"* Line $pos_line, column $pos_column: Missing open $token_literal",
marked_line(
( substr $string,
$pos - ( $pos_column - 1 ),
-( length $suffix ) + 1
),
$pos_column - 1
);
push @problems, [ $pos_line, $pos_column, $problem ];
diagnostic(
"* Line $pos_line, column $pos_column: Missing open $token_literal"
) if $verbose;
next READ;
} ## end if ($opening)
# Report the error if it was a case of a missing close bracket.
# We've created a properly bracketed span of the input, using
# the Ruby Slippers token. Use Marpa's tables to find its
# beginning.
my ($opening_bracket) = $recce->last_completed_span('balanced');
my ( $line, $column ) = $recce->line_column($opening_bracket);
my $opening_column0 = $opening_bracket - ( $column - 1 );
if ( $line == $pos_line ) {
# Report a missing close bracket for cases contained in
# a single text line
$problem = join "\n",
"* Line $line, column $column: Missing close $token_literal, "
. "problem detected at line $pos_line, column $pos_column",
marked_line(
substr(
$string,
$pos - ( $pos_column - 1 ),
-( length $suffix ) + 1
),
$column - 1,
$pos_column - 1
);
} ## end if ( $line == $pos_line )
else {
# Report a missing close bracket for cases that span
# two or more text lines
$problem = join "\n",
"* Line $line, column $column: No matching bracket for "
. q{'}
. $literal_match{$token_literal} . q{', },
marked_line(
substr( $string, $opening_column0, -( length $suffix ) + 1 ),
$column - 1
),
, "* Problem detected at line $pos_line, column $pos_column:",
marked_line(
substr(
$string,
$pos - ( $pos_column - 1 ),
-( length $suffix ) + 1
),
$pos_column - 1
);
} ## end else [ if ( $line == $pos_line ) ]
# Add our report to the list of problems.
push @problems, [ $line, $column, $problem ];
diagnostic(
"* Line $line, column $column: Missing close $token_literal, ",
"problem detected at line $pos_line, column $pos_column"
) if $verbose;
} ## end READ: while ( $pos < $input_length )
# At this point we have finished the input.
# Now we must deal with opening brackets which
# were never closed.
# The logic here is a simplified version of that of the main
# reading loop.
TRAILER: while (1) {
# Programming note: this is so similar to the code of the
# main reading loop, it is tempting to combine them and use
# a flag.
# But there are quite a few small differences,
# so that would be much less readable.
# And for efficiency purposes, this is a kind of "hand-unrolling"
# of a loop, with optimization of the code.
my $rejection = 0;
EVENT:
for my $event ( @{ $recce->events() } ) {
my ($name) = @{$event};
if ( $name eq q{'rejected} ) {
$rejection = 1;
next EVENT;
}
die join q{ }, "Spurious event at position $pos: '$name'";
} ## end EVENT: for my $event ( @{ $recce->events() } )
die "Rejection at end of string" if $rejection;
my @expected = @{ $recce->terminals_expected() };
# say STDERR join " ", "terminals expected:", @expected;
my ($token) =
grep {defined}
map { $token_by_name{$_} } @{ $recce->terminals_expected() };
last TRAILER if not defined $token;
my ( $token_start, $token_length ) = @{$token};
$token_start += $input_length;
my $token_literal = substr $string, $token_start, $token_length;
my $result = $recce->resume( $token_start, $token_length );
die "Read of Ruby slippers token failed"
if $result != $token_start + $token_length;
# Used for testing
push @fixes, "$pos$token_literal" if $fixes;
my ($opening_bracket) = $recce->last_completed_span('balanced');
my ( $line, $column ) = $recce->line_column($opening_bracket);
my $opening_column0 = $opening_bracket - ( $column - 1 );
my $problem = join "\n",
"* Line $line, column $column: Opening " . q{'}
. $literal_match{$token_literal}
. q{' never closed, problem detected at end of string},
marked_line(
substr( $string, $opening_column0, -( length $suffix ) + 1 ),
$column - 1 );
push @problems, [ $line, $column, $problem ];
} ## end TRAILER: while (1)
# For testing
if ( ref $fixes ) {
${$fixes} = join " ", @fixes;
}
# The problems do not necessarily occur in lexical order.
# Sort them so that they can be reported that way.
my @sorted_problems =
sort { $a->[0] <=> $b->[0] or $a->[1] <=> $b->[1] } @problems;
my @result = map { $_->[-1] } @sorted_problems;
return \@result;
} ## end sub test
# vim: expandtab shiftwidth=4:
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