make_perl_groups.pl

Documentation: regexp/syntax

     1#!/usr/bin/perl
     2# Copyright 2008 The Go Authors. All rights reserved.
     3# Use of this source code is governed by a BSD-style
     4# license that can be found in the LICENSE file.
     5
     6# Modified version of RE2's make_perl_groups.pl.
     7
     8# Generate table entries giving character ranges
     9# for POSIX/Perl character classes.  Rather than
    10# figure out what the definition is, it is easier to ask
    11# Perl about each letter from 0-128 and write down
    12# its answer.
    13
    14@posixclasses = (
    15	"[:alnum:]",
    16	"[:alpha:]",
    17	"[:ascii:]",
    18	"[:blank:]",
    19	"[:cntrl:]",
    20	"[:digit:]",
    21	"[:graph:]",
    22	"[:lower:]",
    23	"[:print:]",
    24	"[:punct:]",
    25	"[:space:]",
    26	"[:upper:]",
    27	"[:word:]",
    28	"[:xdigit:]",
    29);
    30
    31@perlclasses = (
    32	"\\d",
    33	"\\s",
    34	"\\w",
    35);
    36
    37%overrides = (
    38	# Prior to Perl 5.18, \s did not match vertical tab.
    39	# RE2 preserves that original behaviour.
    40	"\\s:11" => 0,
    41);
    42
    43sub ComputeClass($) {
    44  my @ranges;
    45  my ($class) = @_;
    46  my $regexp = "[$class]";
    47  my $start = -1;
    48  for (my $i=0; $i<=129; $i++) {
    49    if ($i == 129) { $i = 256; }
    50    if ($i <= 128 && ($overrides{"$class:$i"} // chr($i) =~ $regexp)) {
    51      if ($start < 0) {
    52        $start = $i;
    53      }
    54    } else {
    55      if ($start >= 0) {
    56        push @ranges, [$start, $i-1];
    57      }
    58      $start = -1;
    59    }
    60  }
    61  return @ranges;
    62}
    63
    64sub PrintClass($$@) {
    65  my ($cname, $name, @ranges) = @_;
    66  print "var code$cname = []rune{  /* $name */\n";
    67  for (my $i=0; $i<@ranges; $i++) {
    68    my @a = @{$ranges[$i]};
    69    printf "\t0x%x, 0x%x,\n", $a[0], $a[1];
    70  }
    71  print "}\n\n";
    72  my $n = @ranges;
    73  $negname = $name;
    74  if ($negname =~ /:/) {
    75    $negname =~ s/:/:^/;
    76  } else {
    77    $negname =~ y/a-z/A-Z/;
    78  }
    79  return "\t`$name`: {+1, code$cname},\n" .
    80  	"\t`$negname`: {-1, code$cname},\n";
    81}
    82
    83my $gen = 0;
    84
    85sub PrintClasses($@) {
    86  my ($cname, @classes) = @_;
    87  my @entries;
    88  foreach my $cl (@classes) {
    89    my @ranges = ComputeClass($cl);
    90    push @entries, PrintClass(++$gen, $cl, @ranges);
    91  }
    92  print "var ${cname}Group = map[string]charGroup{\n";
    93  foreach my $e (@entries) {
    94    print $e;
    95  }
    96  print "}\n";
    97  my $count = @entries;
    98}
    99
   100print <<EOF;
   101// Copyright 2013 The Go Authors. All rights reserved.
   102// Use of this source code is governed by a BSD-style
   103// license that can be found in the LICENSE file.
   104
   105// GENERATED BY make_perl_groups.pl; DO NOT EDIT.
   106// make_perl_groups.pl >perl_groups.go
   107
   108package syntax
   109
   110EOF
   111
   112PrintClasses("perl", @perlclasses);
   113PrintClasses("posix", @posixclasses);
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