Add m-esr52 at 52.6.0

1 files changed, 836 insertions, 0 deletions

diff --git a/js/src/vm/make_unicode.py b/js/src/vm/make_unicode.py
new file mode 100755
index 000000000..5565d7d14
--- /dev/null
+++ b/js/src/vm/make_unicode.py
@@ -0,0 +1,836 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# Based upon makeunicodedata.py
+# (http://hg.python.org/cpython/file/c8192197d23d/Tools/unicode/makeunicodedata.py)
+# written by Fredrik Lundh (fredrik@pythonware.com)
+#
+#    Copyright (C) 2011 Tom Schuster <evilpies@gmail.com>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation, either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    This program 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 General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from __future__ import print_function
+import csv
+import io
+import re
+import os
+import sys
+from contextlib import closing
+
+# ECMAScript 2016
+# §11.2 White Space
+whitespace = [
+    # python doesn't support using control character names :(
+    0x9, # CHARACTER TABULATION
+    0xb, # LINE TABULATION
+    0xc, # FORM FEED
+    ord(u'\N{SPACE}'),
+    ord(u'\N{NO-BREAK SPACE}'),
+    ord(u'\N{ZERO WIDTH NO-BREAK SPACE}'), # also BOM
+]
+
+# §11.3 Line Terminators
+line_terminator = [
+    0xa, # LINE FEED
+    0xd, # CARRIAGE RETURN
+    ord(u'\N{LINE SEPARATOR}'),
+    ord(u'\N{PARAGRAPH SEPARATOR}'),
+]
+
+# These are also part of IdentifierPart §11.6 Names and Keywords
+compatibility_identifier_part = [
+    ord(u'\N{ZERO WIDTH NON-JOINER}'),
+    ord(u'\N{ZERO WIDTH JOINER}'),
+]
+
+FLAG_SPACE = 1 << 0
+FLAG_UNICODE_ID_START = 1 << 1
+FLAG_UNICODE_ID_CONTINUE_ONLY = 1 << 2
+
+MAX_BMP = 0xffff
+
+public_domain = """
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ */
+"""
+
+mpl_license = """\
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+"""
+
+warning_message = """\
+/* Generated by make_unicode.py DO NOT MODIFY */
+"""
+
+unicode_version_message = """\
+/* Unicode version: {0} */
+"""
+
+def read_unicode_data(unicode_data):
+    """
+        If you want to understand how this wonderful file format works checkout
+          Unicode Standard Annex #44 - Unicode Character Database
+          http://www.unicode.org/reports/tr44/
+    """
+
+    reader = csv.reader(unicode_data, delimiter=';')
+
+    while True:
+        row = reader.next()
+        name = row[1]
+
+        # We need to expand the UAX #44 4.2.3 Code Point Range
+        if name.startswith('<') and name.endswith('First>'):
+            next_row = reader.next()
+
+            for i in range(int(row[0], 16), int(next_row[0], 16) + 1):
+                row[0] = i
+                row[1] = name[1:-8]
+
+                yield row
+        else:
+            row[0] = int(row[0], 16)
+            yield row
+
+def read_case_folding(case_folding):
+    for line in case_folding:
+        if line == '\n' or line.startswith('#'):
+            continue
+        row = line.split('; ')
+        if row[1] in ['F', 'T']:
+            continue
+        row[0] = int(row[0], 16)
+        row[2] = int(row[2], 16)
+        yield row
+
+def read_derived_core_properties(derived_core_properties):
+    for line in derived_core_properties:
+        if line == '\n' or line.startswith('#'):
+            continue
+        row = line.split('#')[0].split(';')
+        char_range = row[0].strip()
+        char_property = row[1].strip()
+        if '..' not in char_range:
+            yield (int(char_range, 16), char_property)
+        else:
+            [start, end] = char_range.split('..')
+            for char in range(int(start, 16), int(end, 16) + 1):
+                yield (char, char_property)
+
+def utf16_encode(code):
+    NonBMPMin = 0x10000
+    LeadSurrogateMin = 0xD800
+    TrailSurrogateMin = 0xDC00
+
+    lead = (code - NonBMPMin) / 1024 + LeadSurrogateMin
+    trail = ((code - NonBMPMin) % 1024) + TrailSurrogateMin
+
+    return lead, trail
+
+def make_non_bmp_convert_macro(out_file, name, convert_map):
+    convert_list = []
+    entry = None
+    for code in sorted(convert_map.keys()):
+        converted = convert_map[code]
+        diff = converted - code
+
+        if entry and code == entry['code'] + entry['length'] and diff == entry['diff']:
+            entry['length'] += 1
+            continue
+
+        entry = { 'code': code, 'diff': diff, 'length': 1 }
+        convert_list.append(entry)
+
+    lines = []
+    for entry in convert_list:
+        from_code = entry['code']
+        to_code = entry['code'] + entry['length'] - 1
+        diff = entry['diff']
+
+        from_lead, from_trail = utf16_encode(from_code)
+        to_lead, to_trail = utf16_encode(to_code)
+
+        assert from_lead == to_lead
+
+        lines.append('    macro(0x{:x}, 0x{:x}, 0x{:x}, 0x{:x}, 0x{:x}, {:d})'.format(
+            from_code, to_code, from_lead, from_trail, to_trail, diff))
+
+    out_file.write('#define FOR_EACH_NON_BMP_{}(macro) \\\n'.format(name))
+    out_file.write(' \\\n'.join(lines))
+    out_file.write('\n')
+
+def process_derived_core_properties(derived_core_properties):
+    id_start = set()
+    id_continue = set()
+
+    for (char, prop) in read_derived_core_properties(derived_core_properties):
+        if prop == 'ID_Start':
+            id_start.add(char)
+        if prop == 'ID_Continue':
+            id_continue.add(char)
+
+    return (id_start, id_continue)
+
+def process_unicode_data(unicode_data, derived_core_properties):
+    dummy = (0, 0, 0)
+    table = [dummy]
+    cache = {dummy: 0}
+    index = [0] * (MAX_BMP + 1)
+    same_upper_map = {}
+    same_upper_dummy = (0, 0, 0)
+    same_upper_table = [same_upper_dummy]
+    same_upper_cache = {same_upper_dummy: 0}
+    same_upper_index = [0] * (MAX_BMP + 1)
+
+    test_table = {}
+    test_space_table = []
+
+    non_bmp_lower_map = {}
+    non_bmp_upper_map = {}
+
+    (id_start, id_continue) = process_derived_core_properties(derived_core_properties)
+
+    for row in read_unicode_data(unicode_data):
+        code = row[0]
+        name = row[1]
+        category = row[2]
+        alias = row[-5]
+        uppercase = row[-3]
+        lowercase = row[-2]
+        flags = 0
+
+        if uppercase:
+            upper = int(uppercase, 16)
+
+            if upper not in same_upper_map:
+                same_upper_map[upper] = [code]
+            else:
+                same_upper_map[upper].append(code)
+        else:
+            upper = code
+
+        if lowercase:
+            lower = int(lowercase, 16)
+        else:
+            lower = code
+
+        if code > MAX_BMP:
+            if code != lower:
+                non_bmp_lower_map[code] = lower
+            if code != upper:
+                non_bmp_upper_map[code] = upper
+            continue
+
+        # we combine whitespace and lineterminators because in pratice we don't need them separated
+        if category == 'Zs' or code in whitespace or code in line_terminator:
+            flags |= FLAG_SPACE
+            test_space_table.append(code)
+
+        # §11.6 (IdentifierStart)
+        if code in id_start:
+            flags |= FLAG_UNICODE_ID_START
+
+        # §11.6 (IdentifierPart)
+        elif code in id_continue or code in compatibility_identifier_part:
+            flags |= FLAG_UNICODE_ID_CONTINUE_ONLY
+
+        test_table[code] = (upper, lower, name, alias)
+
+        up_d = upper - code
+        low_d = lower - code
+
+        assert up_d > -65535 and up_d < 65535
+        assert low_d > -65535 and low_d < 65535
+
+        upper = up_d & 0xffff
+        lower = low_d & 0xffff
+
+        item = (upper, lower, flags)
+
+        i = cache.get(item)
+        if i is None:
+            assert item not in table
+            cache[item] = i = len(table)
+            table.append(item)
+        index[code] = i
+
+    for code in range(0, MAX_BMP + 1):
+        entry = test_table.get(code)
+
+        if not entry:
+            continue
+
+        (upper, lower, name, alias) = entry
+
+        if upper not in same_upper_map:
+            continue
+
+        same_upper_ds = [v - code for v in same_upper_map[upper]]
+
+        assert len(same_upper_ds) <= 3
+        assert all([v > -65535 and v < 65535 for v in same_upper_ds])
+
+        same_upper = [v & 0xffff for v in same_upper_ds]
+        same_upper_0 = same_upper[0] if len(same_upper) >= 1 else 0
+        same_upper_1 = same_upper[1] if len(same_upper) >= 2 else 0
+        same_upper_2 = same_upper[2] if len(same_upper) >= 3 else 0
+
+        item = (same_upper_0, same_upper_1, same_upper_2)
+
+        i = same_upper_cache.get(item)
+        if i is None:
+            assert item not in same_upper_table
+            same_upper_cache[item] = i = len(same_upper_table)
+            same_upper_table.append(item)
+        same_upper_index[code] = i
+
+    return (
+        table, index,
+        same_upper_table, same_upper_index,
+        non_bmp_lower_map, non_bmp_upper_map,
+        test_table, test_space_table,
+    )
+
+def process_case_folding(case_folding):
+    folding_map = {}
+    rev_folding_map = {}
+    folding_dummy = (0, 0, 0, 0)
+    folding_table = [folding_dummy]
+    folding_cache = {folding_dummy: 0}
+    folding_index = [0] * (MAX_BMP + 1)
+
+    folding_tests = []
+    folding_codes = set()
+
+    non_bmp_folding_map = {}
+    non_bmp_rev_folding_map = {}
+
+    for row in read_case_folding(case_folding):
+        code = row[0]
+        mapping = row[2]
+        folding_map[code] = mapping
+
+        if code > MAX_BMP:
+            non_bmp_folding_map[code] = mapping
+            non_bmp_rev_folding_map[mapping] = code
+
+        if mapping not in rev_folding_map:
+            rev_folding_map[mapping] = [code]
+        else:
+            rev_folding_map[mapping].append(code)
+
+        folding_codes.add(code)
+        folding_codes.add(mapping)
+
+    for code in sorted(folding_codes):
+        if code in folding_map:
+            folding = folding_map[code]
+        else:
+            folding = code
+
+        if code in rev_folding_map:
+            rev_folding = rev_folding_map[code]
+        elif folding in rev_folding_map:
+            rev_folding = [c for c in rev_folding_map[folding] if c != code]
+        else:
+            rev_folding = []
+
+        assert len(rev_folding) <= 3
+
+        if folding != code or len(rev_folding):
+            item = [code]
+            if folding != code:
+                item.append(folding)
+            folding_tests.append(item + rev_folding)
+
+        if code > MAX_BMP:
+            continue
+
+        folding_d = folding - code
+        rev_folding_ds = [v - code for v in rev_folding]
+
+        assert folding_d > -65535 and folding_d < 65535
+        assert all([v > -65535 and v < 65535 for v in rev_folding])
+
+        folding = folding_d & 0xffff
+        rev_folding = [v & 0xffff for v in rev_folding_ds]
+        rev_folding_0 = rev_folding[0] if len(rev_folding) >= 1 else 0
+        rev_folding_1 = rev_folding[1] if len(rev_folding) >= 2 else 0
+        rev_folding_2 = rev_folding[2] if len(rev_folding) >= 3 else 0
+
+        item = (folding, rev_folding_0, rev_folding_1, rev_folding_2)
+
+        i = folding_cache.get(item)
+        if i is None:
+            assert item not in folding_table
+            folding_cache[item] = i = len(folding_table)
+            folding_table.append(item)
+        folding_index[code] = i
+    return (
+        folding_table, folding_index,
+        non_bmp_folding_map, non_bmp_rev_folding_map,
+        folding_tests
+    )
+
+def make_non_bmp_file(version,
+                      non_bmp_lower_map, non_bmp_upper_map,
+                      non_bmp_folding_map, non_bmp_rev_folding_map):
+    file_name = 'UnicodeNonBMP.h';
+    with io.open(file_name, mode='wb') as non_bmp_file:
+        non_bmp_file.write(mpl_license)
+        non_bmp_file.write('\n')
+        non_bmp_file.write(warning_message)
+        non_bmp_file.write(unicode_version_message.format(version))
+        non_bmp_file.write("""
+#ifndef vm_UnicodeNonBMP_h
+#define vm_UnicodeNonBMP_h
+
+""")
+
+        make_non_bmp_convert_macro(non_bmp_file, 'LOWERCASE', non_bmp_lower_map)
+        non_bmp_file.write('\n')
+        make_non_bmp_convert_macro(non_bmp_file, 'UPPERCASE', non_bmp_upper_map)
+        non_bmp_file.write('\n')
+        make_non_bmp_convert_macro(non_bmp_file, 'CASE_FOLDING', non_bmp_folding_map)
+        non_bmp_file.write('\n')
+        make_non_bmp_convert_macro(non_bmp_file, 'REV_CASE_FOLDING', non_bmp_rev_folding_map)
+
+        non_bmp_file.write("""
+#endif /* vm_UnicodeNonBMP_h */
+""")
+
+def make_bmp_mapping_test(version, test_table):
+    file_name = '../tests/ecma_5/String/string-upper-lower-mapping.js'
+    with io.open(file_name, mode='wb') as test_mapping:
+        test_mapping.write(warning_message)
+        test_mapping.write(unicode_version_message.format(version))
+        test_mapping.write(public_domain)
+        test_mapping.write('var mapping = [\n')
+        for code in range(0, MAX_BMP + 1):
+            entry = test_table.get(code)
+
+            if entry:
+                (upper, lower, name, alias) = entry
+                test_mapping.write('  [' + hex(upper) + ', ' + hex(lower) + '], /* ' +
+                        name + (' (' + alias + ')' if alias else '') + ' */\n')
+            else:
+                test_mapping.write('  [' + hex(code) + ', ' + hex(code) + '],\n')
+        test_mapping.write('];')
+        test_mapping.write("""
+assertEq(mapping.length, 0x10000);
+for (var i = 0; i <= 0xffff; i++) {
+    var char = String.fromCharCode(i);
+    var info = mapping[i];
+
+    assertEq(char.toUpperCase().charCodeAt(0), info[0]);
+    assertEq(char.toLowerCase().charCodeAt(0), info[1]);
+}
+
+if (typeof reportCompare === "function")
+    reportCompare(true, true);
+""")
+
+def make_non_bmp_mapping_test(version, non_bmp_upper_map, non_bmp_lower_map):
+    file_name = '../tests/ecma_6/String/string-code-point-upper-lower-mapping.js'
+    with io.open(file_name, mode='wb') as test_non_bmp_mapping:
+        test_non_bmp_mapping.write(warning_message)
+        test_non_bmp_mapping.write(unicode_version_message.format(version))
+        test_non_bmp_mapping.write(public_domain)
+        for code in sorted(non_bmp_upper_map.keys()):
+            test_non_bmp_mapping.write("""\
+assertEq(String.fromCodePoint(0x{:x}).toUpperCase().codePointAt(0), 0x{:x});
+""".format(code, non_bmp_upper_map[code]))
+        for code in sorted(non_bmp_lower_map.keys()):
+            test_non_bmp_mapping.write("""\
+assertEq(String.fromCodePoint(0x{:x}).toLowerCase().codePointAt(0), 0x{:x});
+""".format(code, non_bmp_lower_map[code]))
+
+        test_non_bmp_mapping.write("""
+if (typeof reportCompare === "function")
+    reportCompare(true, true);
+""")
+
+def make_space_test(version, test_space_table):
+    file_name = '../tests/ecma_5/String/string-space-trim.js'
+    with io.open(file_name, mode='wb') as test_space:
+        test_space.write(warning_message)
+        test_space.write(unicode_version_message.format(version))
+        test_space.write(public_domain)
+        test_space.write('var onlySpace = String.fromCharCode(' +
+                        ', '.join(map(lambda c: hex(c), test_space_table)) + ');\n')
+        test_space.write("""
+assertEq(onlySpace.trim(), "");
+assertEq((onlySpace + 'aaaa').trim(), 'aaaa');
+assertEq(('aaaa' + onlySpace).trim(), 'aaaa');
+assertEq((onlySpace + 'aaaa' + onlySpace).trim(), 'aaaa');
+
+if (typeof reportCompare === "function")
+    reportCompare(true, true);
+""")
+
+def make_icase_test(version, folding_tests):
+    file_name = '../tests/ecma_6/RegExp/unicode-ignoreCase.js'
+    with io.open(file_name, mode='wb') as test_icase:
+        test_icase.write(warning_message)
+        test_icase.write(unicode_version_message.format(version))
+        test_icase.write(public_domain)
+        test_icase.write("""
+var BUGNUMBER = 1135377;
+var summary = "Implement RegExp unicode flag -- ignoreCase flag.";
+
+print(BUGNUMBER + ": " + summary);
+
+function test(code, ...equivs) {
+  var codeRe = new RegExp(String.fromCodePoint(code) + "+", "iu");
+  var ans = String.fromCodePoint(code) + equivs.map(c => String.fromCodePoint(c)).join("");
+  assertEqArray(codeRe.exec("<" + ans + ">"), [ans]);
+  codeRe = new RegExp("[" + String.fromCodePoint(code) + "]+", "iu");
+  assertEqArray(codeRe.exec("<" + ans + ">"), [ans]);
+}
+""")
+        for args in folding_tests:
+            test_icase.write('test(' + ','.join([hex(c) for c in args]) + ');\n')
+        test_icase.write("""
+if (typeof reportCompare === "function")
+    reportCompare(true, true);
+""")
+
+def make_unicode_file(version,
+                      table, index,
+                      same_upper_table, same_upper_index,
+                      folding_table, folding_index):
+    index1, index2, shift = splitbins(index)
+
+    # Don't forget to update CharInfo in Unicode.h if you need to change this
+    assert shift == 6
+
+    same_upper_index1, same_upper_index2, same_upper_shift = splitbins(same_upper_index)
+
+    # Don't forget to update CodepointsWithSameUpperCaseInfo in Unicode.h if you need to change this
+    assert same_upper_shift == 6
+
+    folding_index1, folding_index2, folding_shift = splitbins(folding_index)
+
+    # Don't forget to update CaseFoldInfo in Unicode.h if you need to change this
+    assert folding_shift == 6
+
+    # verify correctness
+    for char in index:
+        test = table[index[char]]
+
+        idx = index1[char >> shift]
+        idx = index2[(idx << shift) + (char & ((1 << shift) - 1))]
+
+        assert test == table[idx]
+
+    # verify correctness
+    for char in same_upper_index:
+        test = same_upper_table[same_upper_index[char]]
+
+        idx = same_upper_index1[char >> same_upper_shift]
+        idx = same_upper_index2[(idx << same_upper_shift) + (char & ((1 << same_upper_shift) - 1))]
+
+        assert test == same_upper_table[idx]
+
+    # verify correctness
+    for char in folding_index:
+        test = folding_table[folding_index[char]]
+
+        idx = folding_index1[char >> folding_shift]
+        idx = folding_index2[(idx << folding_shift) + (char & ((1 << folding_shift) - 1))]
+
+        assert test == folding_table[idx]
+
+    comment = """
+/*
+ * So how does indexing work?
+ * First let's have a look at a char16_t, 16-bits:
+ *              [................]
+ * Step 1:
+ *  Extracting the upper 11 bits from the char16_t.
+ *   upper = char >>  5 ([***********.....])
+ * Step 2:
+ *  Using these bits to get an reduced index from index1.
+ *   index = index1[upper]
+ * Step 3:
+ *  Combining the index and the bottom 5 bits of the original char16_t.
+ *   real_index = index2[(index << 5) + (char & ((1 << 5) - 1))] ([...********+++++])
+ *
+ * The advantage here is that the biggest number in index1 doesn't need 10 bits,
+ * but 7 and we save some memory.
+ *
+ * Step 4:
+ *  Get the character informations by looking up real_index in js_charinfo.
+ *
+ * Pseudocode of generation:
+ *
+ * let table be the mapping of char16_t => js_charinfo_index
+ * let index1 be an empty array
+ * let index2 be an empty array
+ * let cache be a hash map
+ *
+ * while shift is less then maximal amount you can shift 0xffff before it's 0
+ *  let chunks be table split in chunks of size 2**shift
+ *
+ *  for every chunk in chunks
+ *   if chunk is in cache
+ *    let index be cache[chunk]
+ *   else
+ *    let index be the max key of index2 + 1
+ *    for element in chunk
+ *     push element to index2
+ *    put index as chunk in cache
+ *
+ *   push index >> shift to index1
+ *
+ *  increase shift
+ *  stop if you found the best shift
+ */
+"""
+    def dump(data, name, file):
+        file.write('const uint8_t unicode::' + name + '[] = {\n')
+
+        line = pad = ' ' * 4
+        lines = []
+        for entry in data:
+            assert entry < 256
+            s = str(entry)
+            s = s.rjust(3)
+
+            if len(line + s) + 5 > 99:
+                lines.append(line.rstrip())
+                line = pad + s + ', '
+            else:
+                line = line + s + ', '
+        lines.append(line.rstrip())
+
+        file.write('\n'.join(lines))
+        file.write('\n};\n')
+
+    file_name = 'Unicode.cpp'
+    with io.open(file_name, 'wb') as data_file:
+        data_file.write(warning_message)
+        data_file.write(unicode_version_message.format(version))
+        data_file.write(public_domain)
+        data_file.write('#include "vm/Unicode.h"\n\n')
+        data_file.write('using namespace js;\n')
+        data_file.write('using namespace js::unicode;\n')
+        data_file.write(comment)
+        data_file.write('const CharacterInfo unicode::js_charinfo[] = {\n')
+        for d in table:
+            data_file.write('    {')
+            data_file.write(', '.join((str(e) for e in d)))
+            data_file.write('},\n')
+        data_file.write('};\n')
+        data_file.write('\n')
+
+        dump(index1, 'index1', data_file)
+        data_file.write('\n')
+        dump(index2, 'index2', data_file)
+        data_file.write('\n')
+
+        data_file.write('const CodepointsWithSameUpperCaseInfo unicode::js_codepoints_with_same_upper_info[] = {\n')
+        for d in same_upper_table:
+            data_file.write('    {')
+            data_file.write(', '.join((str(e) for e in d)))
+            data_file.write('},\n')
+        data_file.write('};\n')
+        data_file.write('\n')
+
+        dump(same_upper_index1, 'codepoints_with_same_upper_index1', data_file)
+        data_file.write('\n')
+        dump(same_upper_index2, 'codepoints_with_same_upper_index2', data_file)
+        data_file.write('\n')
+
+        data_file.write('const FoldingInfo unicode::js_foldinfo[] = {\n')
+        for d in folding_table:
+            data_file.write('    {')
+            data_file.write(', '.join((str(e) for e in d)))
+            data_file.write('},\n')
+        data_file.write('};\n')
+        data_file.write('\n')
+
+        dump(folding_index1, 'folding_index1', data_file)
+        data_file.write('\n')
+        dump(folding_index2, 'folding_index2', data_file)
+        data_file.write('\n')
+
+def getsize(data):
+    """ return smallest possible integer size for the given array """
+    maxdata = max(data)
+    assert maxdata < 2**32
+
+    if maxdata < 256:
+        return 1
+    elif maxdata < 65536:
+        return 2
+    else:
+        return 4
+
+def splitbins(t):
+    """t -> (t1, t2, shift).  Split a table to save space.
+
+    t is a sequence of ints.  This function can be useful to save space if
+    many of the ints are the same.  t1 and t2 are lists of ints, and shift
+    is an int, chosen to minimize the combined size of t1 and t2 (in C
+    code), and where for each i in range(len(t)),
+        t[i] == t2[(t1[i >> shift] << shift) + (i & mask)]
+    where mask is a bitmask isolating the last "shift" bits.
+    """
+
+    def dump(t1, t2, shift, bytes):
+        print("%d+%d bins at shift %d; %d bytes" % (
+            len(t1), len(t2), shift, bytes), file=sys.stderr)
+        print("Size of original table:", len(t)*getsize(t), \
+            "bytes", file=sys.stderr)
+    n = len(t)-1    # last valid index
+    maxshift = 0    # the most we can shift n and still have something left
+    if n > 0:
+        while n >> 1:
+            n >>= 1
+            maxshift += 1
+    del n
+    bytes = sys.maxsize  # smallest total size so far
+    t = tuple(t)    # so slices can be dict keys
+    for shift in range(maxshift + 1):
+        t1 = []
+        t2 = []
+        size = 2**shift
+        bincache = {}
+
+        for i in range(0, len(t), size):
+            bin = t[i:i + size]
+
+            index = bincache.get(bin)
+            if index is None:
+                index = len(t2)
+                bincache[bin] = index
+                t2.extend(bin)
+            t1.append(index >> shift)
+
+        # determine memory size
+        b = len(t1) * getsize(t1) + len(t2) * getsize(t2)
+        if b < bytes:
+            best = t1, t2, shift
+            bytes = b
+    t1, t2, shift = best
+
+    print("Best:", end=' ', file=sys.stderr)
+    dump(t1, t2, shift, bytes)
+
+    # exhaustively verify that the decomposition is correct
+    mask = 2**shift - 1
+    for i in range(len(t)):
+        assert t[i] == t2[(t1[i >> shift] << shift) + (i & mask)]
+    return best
+
+def update_unicode(args):
+    import urllib2
+
+    version = args.version
+    if version is not None:
+        baseurl = 'http://unicode.org/Public'
+        if version == 'UNIDATA':
+            url = '%s/%s' % (baseurl, version)
+        else:
+            url = '%s/%s/ucd' % (baseurl, version)
+
+    print('Arguments:')
+    if version is not None:
+        print('\tVersion: %s' % version)
+        print('\tDownload url: %s' % url)
+    else:
+        print('\tUsing local files.')
+        print('\tAlways make sure you have the newest Unicode files!')
+    print('')
+
+    def download_or_open(fname):
+        tfile_path = os.path.join(os.getcwd(), fname)
+        if version is not None:
+            print('Downloading %s...' % fname)
+            unicode_data_url = '%s/%s' % (url, fname)
+            with closing(urllib2.urlopen(unicode_data_url)) as reader:
+                data = reader.read()
+            tfile = io.open(tfile_path, 'w+b')
+            tfile.write(data)
+            tfile.flush()
+            tfile.seek(0)
+        else:
+            if not os.path.isfile(tfile_path):
+                raise RuntimeError('File not found: %s' % tfile_path)
+            tfile = io.open(tfile_path, 'rb');
+        return tfile
+
+    def version_from_file(f, fname):
+        pat_version = re.compile(r"# %s-(?P<version>\d+\.\d+\.\d+).txt" % fname)
+        return pat_version.match(f.readline()).group("version")
+
+    with download_or_open('UnicodeData.txt') as unicode_data, \
+         download_or_open('CaseFolding.txt') as case_folding, \
+         download_or_open('DerivedCoreProperties.txt') as derived_core_properties:
+        unicode_version = version_from_file(derived_core_properties, 'DerivedCoreProperties')
+
+        print('Processing...')
+        (
+            table, index,
+            same_upper_table, same_upper_index,
+            non_bmp_lower_map, non_bmp_upper_map,
+            test_table, test_space_table
+        ) = process_unicode_data(unicode_data, derived_core_properties)
+        (
+            folding_table, folding_index,
+            non_bmp_folding_map, non_bmp_rev_folding_map,
+            folding_tests
+        ) = process_case_folding(case_folding)
+
+    print('Generating...')
+    make_unicode_file(unicode_version,
+                      table, index,
+                      same_upper_table, same_upper_index,
+                      folding_table, folding_index)
+    make_non_bmp_file(unicode_version,
+                      non_bmp_lower_map, non_bmp_upper_map,
+                      non_bmp_folding_map, non_bmp_rev_folding_map)
+
+    make_bmp_mapping_test(unicode_version, test_table)
+    make_non_bmp_mapping_test(unicode_version, non_bmp_upper_map, non_bmp_lower_map)
+    make_space_test(unicode_version, test_space_table)
+    make_icase_test(unicode_version, folding_tests)
+
+if __name__ == '__main__':
+    import argparse
+
+    # This script must be run from js/src/vm to work correctly.
+    if '/'.join(os.path.normpath(os.getcwd()).split(os.sep)[-3:]) != 'js/src/vm':
+        raise RuntimeError('%s must be run from js/src/vm' % sys.argv[0])
+
+    parser = argparse.ArgumentParser(description='Update Unicode data.')
+
+    parser.add_argument('--version',
+                        help='Optional Unicode version number. If specified, downloads the\
+                              selected version from <http://unicode.org/Public>. If not specified\
+                              uses the existing local files to generate the Unicode data. The\
+                              number must match a published Unicode version, e.g. use\
+                              "--version=8.0.0" to download Unicode 8 files. Alternatively use\
+                              "--version=UNIDATA" to download the latest published version.')
+
+    parser.set_defaults(func=update_unicode)
+
+    args = parser.parse_args()
+    args.func(args)