Use precompiled Parse::RecDescent parsers for moar speed

Leverage the (hideous but effective) capability of Parse::RecDescent to
precompile concise gramars into multithousand line monsters. Improves
parsing and thus diffing speed considerably, i.e.:

Testing before:
Files=66, Tests=1851, 23 wallclock secs ( 0.38 usr  0.06 sys + 19.96 cusr  1.80 csys = 22.20 CPU)

Testing after:
Files=66, Tests=1858, 17 wallclock secs ( 0.38 usr  0.08 sys + 15.50 cusr  0.74 csys = 16.70 CPU)

A number of cleanups, including grammar fixes when transitioning from
q{} to heredocs. No functional changes at all.

.gitignore

@@ -12,4 +12,5 @@ blib/
 inc/
 pm_to_blib
 t/data/roundtrip_autogen.yaml
+share/PrecompiledParsers/Parse/RecDescent/DDL/SQLT/*.pm
 *.swp

Changes

@@ -1,3 +1,4 @@
+* All parser grammars are now precompiled for speed
 * Proper quoting support in SQLite
 * Support for triggers in PostgreSQL producer and parser
 * Correct Data Type in SQLT::Parser::DBI::PostgreSQL (patch from Andrew Pam)

Makefile.PL

@@ -14,7 +14,7 @@ my $deps = {
     'Carp::Clan'               => 0,
     'IO::Dir'                  => 0,
     'IO::Scalar'               => 2.110,
-    'Parse::RecDescent'        => 1.962002,
+    'Parse::RecDescent'        => 1.964001,
     'Pod::Usage'               => 0,
     'DBI'                      => 0,
     'File::ShareDir'           => 1.0,
@@ -88,8 +88,54 @@ if ($Module::Install::AUTHOR) {
 WriteAll();
 
 sub _recompile_grammars {
-  # placeholder, will be used to recompile P::RD parsers before shipping
-  # will also allow to lose dependency on P::RD
+  require File::Spec;
+
+  my $compiled_parser_dir = File::Spec->catdir(qw/
+    share PrecompiledParsers Parse RecDescent DDL SQLT
+  /);
+
+  # Currently consider only single-name parsers containing a grammar marker
+  # This is somewhat fragile, but better than loading all kinds of parsers
+  # to some of which we may not even have the deps
+  my $parser_libdir = 'lib/SQL/Translator/Parser';
+  for my $parser_fn (glob "$parser_libdir/*.pm") {
+    die "$parser_fn does not look like a readable file\n"
+      unless ( -f $parser_fn and -r $parser_fn );
+
+    my ($type) = $parser_fn =~ /^\Q$parser_libdir\E\/(.+)\.pm$/i
+      or die "$parser_fn not named in expected format\n";
+
+    my $parser_source = do { local (@ARGV, $/) = $parser_fn; <> };
+    next unless $parser_source =~ /\$GRAMMAR.+?END_OF_GRAMMAR/s;
+
+
+    my $precomp_parser_fn = File::Spec->catfile($compiled_parser_dir, "$type.pm");
+
+    next if (
+      -f $precomp_parser_fn
+        and
+      (stat($parser_fn))[9] <= (stat($precomp_parser_fn))[9]
+    );
+
+
+    print "Precompiling parser for $type\n";
+
+    require $parser_fn;
+    require Parse::RecDescent;
+
+    Parse::RecDescent->Precompile(
+      do {
+        no strict 'refs';
+        ${"SQL::Translator::Parser::${type}::GRAMMAR"}
+          || die "No \$GRAMMAR global found in SQL::Translator::Parser::$type ($parser_fn)\n"
+      },
+      "Parse::RecDescent::DDL::SQLT::$type"
+    );
+
+    rename( "$type.pm", $precomp_parser_fn )
+      or die "Unable to move $type.pm to $compiled_parser_dir: $!\n";
+  }
+
 }
 
 sub _recreate_rt_source {

lib/SQL/Translator/Parser/Access.pm

@@ -21,23 +21,19 @@ something similar to the output of mdbtools (http://mdbtools.sourceforge.net/).
 
 use strict;
 use warnings;
-our ( $DEBUG, $GRAMMAR, @EXPORT_OK );
+
 our $VERSION = '1.59';
-$DEBUG   = 0 unless defined $DEBUG;
 
-use Data::Dumper;
-use Parse::RecDescent;
-use Exporter;
-use base qw(Exporter);
+our $DEBUG;
+$DEBUG = 0 unless defined $DEBUG;
 
-@EXPORT_OK = qw(parse);
+use Data::Dumper;
+use SQL::Translator::Utils qw/ddl_parser_instance/;
 
-# Enable warnings within the Parse::RecDescent module.
-$::RD_ERRORS = 1; # Make sure the parser dies when it encounters an error
-$::RD_WARN   = 1; # Enable warnings. This will warn on unused rules &c.
-$::RD_HINT   = 1; # Give out hints to help fix problems.
+use base qw(Exporter);
+our @EXPORT_OK = qw(parse);
 
-$GRAMMAR = q!
+our $GRAMMAR = <<'END_OF_GRAMMAR';
 
 {
     my ( %tables, $table_order, @table_comments );
@@ -263,7 +259,7 @@ not_null     : /not/i /null/i { $return = 0 }
 
 unsigned     : /unsigned/i { $return = 0 }
 
-default_val : /default/i /'(?:.*?\\')*.*?'|(?:')?[\w\d:.-]*(?:')?/
+default_val : /default/i /'(?:.*?\')*.*?'|(?:')?[\w\d:.-]*(?:')?/
     {
         $item[2] =~ s/^\s*'|'\s*$//g;
         $return  =  $item[2];
@@ -379,19 +375,20 @@ VALUE   : /[-+]?\.?\d+(?:[eE]\d+)?/
     | /NULL/
     { 'NULL' }
 
-!;
+END_OF_GRAMMAR
 
 sub parse {
     my ( $translator, $data ) = @_;
-    my $parser = Parse::RecDescent->new($GRAMMAR);
+
+    # Enable warnings within the Parse::RecDescent module.
+    local $::RD_ERRORS = 1 unless defined $::RD_ERRORS; # Make sure the parser dies when it encounters an error
+    local $::RD_WARN   = 1 unless defined $::RD_WARN; # Enable warnings. This will warn on unused rules &c.
+    local $::RD_HINT   = 1 unless defined $::RD_HINT; # Give out hints to help fix problems.
 
     local $::RD_TRACE  = $translator->trace ? 1 : undef;
     local $DEBUG       = $translator->debug;
 
-    unless (defined $parser) {
-        return $translator->error("Error instantiating Parse::RecDescent ".
-            "instance: Bad grammer");
-    }
+    my $parser = ddl_parser_instance('Access');
 
     my $result = $parser->startrule($data);
     return $translator->error( "Parse failed." ) unless defined $result;