create_hash_table

#! /usr/bin/env perl
#
# Static Hashtable Generator
#
# (c) 2000-2002 by Harri Porten <porten@kde.org> and
#                  David Faure <faure@kde.org>
# Modified (c) 2004 by Nikolas Zimmermann <wildfox@kde.org>
# Copyright (C) 2007-2018 Apple Inc. All rights reserved.
#
# This library 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 2 of the License, or (at your option) any later version.
#
# This library 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 this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
#
 
use strict;
use warnings;
use Getopt::Long qw(:config pass_through);

my $file = shift @ARGV or die("Must provide source file as final argument.");

open(IN, $file) or die "No such file $file";

my @keys = ();
my @attrs = ();
my @values = ();
my @hashes = ();
my @table = ();
my @links = ();

my $hasSetter = "false";

my $includeBuiltin = 0;
my $inside = 0;
my $name;
my $pefectHashSize;
my $compactSize;
my $compactHashSizeMask;
my $banner = 0;
sub calcPerfectHashSize();
sub calcCompactHashSize();
sub output();
sub jsc_ucfirst($);
sub hashValue($);

while (<IN>) {
    chomp;
    s/^\s+//;
    next if /^\#|^$/; # Comment or blank line. Do nothing.
    if (/^\@begin/ && !$inside) {
        if (/^\@begin\s*([:_\w]+)\s*\d*\s*$/) {
            $inside = 1;
            $name = $1;
        } else {
            print STDERR "WARNING: \@begin without table name, skipping $_\n";
        }
    } elsif (/^\@end\s*$/ && $inside) {
        calcPerfectHashSize();
        calcCompactHashSize();
        output();

        @keys = ();
        @attrs = ();
        @values = ();
        @hashes = ();
        @table = ();
        @links = ();
        $includeBuiltin = 0;

        $inside = 0;
    } elsif (/^(\S+)\s*(\S+)\s*([\w\|]*)\s*(\w*)\s*(\w*)\s*$/ && $inside) {
        my $key = $1;
        my $val = $2;
        my $att = $3;
        my $param = $4;
        my $intrinsic = $5;

        push(@keys, $key);
        push(@attrs, length($att) > 0 ? $att : "None");

        if ($val eq "JSBuiltin") {
            $includeBuiltin = 1;
        }

        if ($att =~ m/Function/) {
            push(@values, { "type" => "PropertyAttribute::Function", "function" => $val, "params" => (length($param) ? $param : ""), "intrinsic" => (length($intrinsic) ? $intrinsic : "NoIntrinsic") });
            #printf STDERR "WARNING: Number of arguments missing for $key/$val\n" if (length($param) == 0);
        } elsif ($att =~ m/Accessor/) {
            my $get = $val;
            my $put = "nullptr";
            $hasSetter = "true";
            push(@values, { "type" => "PropertyAttribute::Accessor", "get" => $get, "put" => $put });
        } elsif ($att =~ m/CellProperty/) {
            my $property = $val;
            push(@values, { "type" => "PropertyAttribute::CellProperty", "property" => $property });
        } elsif ($att =~ m/ClassStructure/) {
            my $property = $val;
            push(@values, { "type" => "PropertyAttribute::ClassStructure", "property" => $property });
        } elsif ($att =~ m/PropertyCallback/) {
            my $cback = $val;
            push(@values, { "type" => "PropertyAttribute::PropertyCallback", "cback" => $cback });
        } elsif (length($att)) {
            my $get = $val;
            my $put = "0";
            if (!($att =~ m/ReadOnly/)) {
                $put = "set" . jsc_ucfirst($val);
            }
            $hasSetter = "true";
            push(@values, { "type" => "PropertyAttribute::Property", "get" => $get, "put" => $put });
        } else {
            push(@values, { "type" => "Lexer", "value" => $val });
        }
        push(@hashes, hashValue($key));
    } elsif ($inside) {
        die "invalid data {" . $_ . "}";
    }
}

die "missing closing \@end" if ($inside);

sub jsc_ucfirst($)
{
    my ($value) = @_;

    if ($value =~ /js/) {
        $value =~ s/js/JS/;
        return $value;
    }

    return ucfirst($value);
}


sub ceilingToPowerOf2
{
    my ($pefectHashSize) = @_;

    my $powerOf2 = 1;
    while ($pefectHashSize > $powerOf2) {
        $powerOf2 <<= 1;
    }

    return $powerOf2;
}

sub calcPerfectHashSize()
{
tableSizeLoop:
    for ($pefectHashSize = ceilingToPowerOf2(scalar @keys); ; $pefectHashSize += $pefectHashSize) {
        my @table = ();
        foreach my $key (@keys) {
            my $h = hashValue($key) % $pefectHashSize;
            next tableSizeLoop if $table[$h];
            $table[$h] = 1;
        }
        last;
    }
}

sub leftShift($$) {
    my ($value, $distance) = @_;
    return (($value << $distance) & 0xFFFFFFFF);
}

sub calcCompactHashSize()
{
    my $compactHashSize = ceilingToPowerOf2(2 * @keys);
    $compactHashSizeMask = $compactHashSize - 1;
    $compactSize = $compactHashSize;
    my $collisions = 0;
    my $maxdepth = 0;
    my $i = 0;
    foreach my $key (@keys) {
        my $depth = 0;
        my $h = hashValue($key) % $compactHashSize;
        while (defined($table[$h])) {
            if (defined($links[$h])) {
                $h = $links[$h];
                $depth++;
            } else {
                $collisions++;
                $links[$h] = $compactSize;
                $h = $compactSize;
                $compactSize++;
            }
        }
        $table[$h] = $i;
        $i++;
        $maxdepth = $depth if ( $depth > $maxdepth);
    }
}

# Paul Hsieh's SuperFastHash
# http://www.azillionmonkeys.com/qed/hash.html
sub hashValue($) {
  my @chars = split(/ */, $_[0]);

  # This hash is designed to work on 16-bit chunks at a time. But since the normal case
  # (above) is to hash UTF-16 characters, we just treat the 8-bit chars as if they
  # were 16-bit chunks, which should give matching results

  my $EXP2_32 = 4294967296;

  my $hash = 0x9e3779b9;
  my $l    = scalar @chars; #I wish this was in Ruby --- Maks
  my $rem  = $l & 1;
  $l = $l >> 1;

  my $s = 0;

  # Main loop
  for (; $l > 0; $l--) {
    $hash   += ord($chars[$s]);
    my $tmp = leftShift(ord($chars[$s+1]), 11) ^ $hash;
    $hash   = (leftShift($hash, 16)% $EXP2_32) ^ $tmp;
    $s += 2;
    $hash += $hash >> 11;
    $hash %= $EXP2_32;
  }

  # Handle end case
  if ($rem != 0) {
    $hash += ord($chars[$s]);
    $hash ^= (leftShift($hash, 11)% $EXP2_32);
    $hash += $hash >> 17;
  }

  # Force "avalanching" of final 127 bits
  $hash ^= leftShift($hash, 3);
  $hash += ($hash >> 5);
  $hash = ($hash% $EXP2_32);
  $hash ^= (leftShift($hash, 2)% $EXP2_32);
  $hash += ($hash >> 15);
  $hash = $hash% $EXP2_32;
  $hash ^= (leftShift($hash, 10)% $EXP2_32);

  # Save 8 bits for StringImpl to use as flags.
  $hash &= 0xffffff;

  # This avoids ever returning a hash code of 0, since that is used to
  # signal "hash not computed yet". Setting the high bit maintains
  # reasonable fidelity to a hash code of 0 because it is likely to yield
  # exactly 0 when hash lookup masks out the high bits.
  $hash = (0x80000000 >> 8) if ($hash == 0);

  return $hash;
}

sub output() {
    if (!$banner) {
        $banner = 1;
        print "// Automatically generated from $file using $0. DO NOT EDIT!\n";
    }

    my $nameEntries = "${name}Values";
    $nameEntries =~ s/:/_/g;
    my $nameIndex = "${name}Index";
    $nameIndex =~ s/:/_/g;

    print "\n";
    print "#include \"JSCBuiltins.h\"\n" if ($includeBuiltin);
    print "#include \"Lookup.h\"\n";
    print "\n";
    print "namespace JSC {\n";
    print "\n";
    if ($compactSize != 0) {
        print "static const struct CompactHashIndex ${nameIndex}\[$compactSize\] = {\n";
        for (my $i = 0; $i < $compactSize; $i++) {
            my $T = -1;
            if (defined($table[$i])) { $T = $table[$i]; }
            my $L = -1;
            if (defined($links[$i])) { $L = $links[$i]; }
            print "    { $T, $L },\n";
        }
    } else {
        # MSVC dislikes empty arrays.
        print "static const struct CompactHashIndex ${nameIndex}\[1\] = {\n";
        print "    { 0, 0 }\n";
    }
    print "};\n";
    print "\n";

    my $packedSize = scalar @keys;
    if ($packedSize != 0) {
        print "static const struct HashTableValue ${nameEntries}\[$packedSize\] = {\n";
    } else {
        # MSVC dislikes empty arrays.
        print "static const struct HashTableValue ${nameEntries}\[1\] = {\n";
        print "    { nullptr, 0, NoIntrinsic, { 0, 0 } }\n";
    }
    my $i = 0;
    foreach my $key (@keys) {
        my $firstValue = "";
        my $secondValue = "";
        my $firstCastStr = "";
        my $secondCastStr = "";
        my $intrinsic = "NoIntrinsic";

        if ($values[$i]{"type"} eq "PropertyAttribute::Function") {
            $firstCastStr = "static_cast<RawNativeFunction>";
            $firstValue = $values[$i]{"function"};
            $secondValue = $values[$i]{"params"};
            $intrinsic = $values[$i]{"intrinsic"};
        } elsif ($values[$i]{"type"} eq "PropertyAttribute::Accessor") {
            $firstCastStr = "static_cast<RawNativeFunction>";
            $secondCastStr = "static_cast<RawNativeFunction>";
            $firstValue = $values[$i]{"get"};
            $secondValue = $values[$i]{"put"};
        } elsif ($values[$i]{"type"} eq "PropertyAttribute::Property") {
            $firstCastStr = "static_cast<PropertySlot::GetValueFunc>";
            $secondCastStr = "static_cast<PutPropertySlot::PutValueFunc>";
            $firstValue = $values[$i]{"get"};
            $secondValue = $values[$i]{"put"};
        } elsif ($values[$i]{"type"} eq "Lexer") {
            $firstValue = $values[$i]{"value"};
            $secondValue = "0";
        } elsif ($values[$i]{"type"} eq "PropertyAttribute::CellProperty" || $values[$i]{"type"} eq "PropertyAttribute::ClassStructure") {
            $values[$i]{"property"} =~ /\A([a-zA-Z0-9_]+)::(.*)\Z/ or die;
            $firstValue = "OBJECT_OFFSETOF($1, $2)";
            $secondValue = "0";
        } elsif ($values[$i]{"type"} eq "PropertyAttribute::PropertyCallback") {
            $firstCastStr = "static_cast<LazyPropertyCallback>";
            $firstValue = $values[$i]{"cback"};
            $secondValue = "0";
        }

        my $attributes = "PropertyAttribute::" . $attrs[$i];
        $attributes =~ s/\|/\|PropertyAttribute::/g;
        $attributes = "static_cast<unsigned>(" . $attributes . ")";
        if ($values[$i]{"type"} eq "PropertyAttribute::Function" && $firstValue eq "JSBuiltin")  {
            my $tableHead = $name;
            $tableHead =~ s/Table$//;
            print "   { \"$key\", (($attributes) & ~PropertyAttribute::Function) | PropertyAttribute::Builtin, $intrinsic, { (intptr_t)static_cast<BuiltinGenerator>(" . $tableHead . ucfirst($key) . "CodeGenerator), (intptr_t)$secondValue } },\n";
        }
        else {
            print "   { \"$key\", $attributes, $intrinsic, { (intptr_t)" . $firstCastStr . "($firstValue), (intptr_t)" . $secondCastStr . "($secondValue) } },\n";
        }
        $i++;
    }
    print "};\n";
    print "\n";
    print "static const struct HashTable $name =\n";
    print "    \{ $packedSize, $compactHashSizeMask, $hasSetter, nullptr, $nameEntries, $nameIndex \};\n";
    print "\n";
    print "} // namespace JSC\n";
}