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update hash code logic on the web
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@yjbanov
yjbanov committed Feb 18, 2020
1 parent cd77e78 commit df5980a
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152 changes: 69 additions & 83 deletions lib/web_ui/lib/src/ui/hash_codes.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -4,102 +4,90 @@

part of ui;

class _HashEnd {
const _HashEnd();
}

class _HashEnd { const _HashEnd(); }
const _HashEnd _hashEnd = _HashEnd();

/// Combine up to twenty values' hashCodes into one value.
/// Jenkins hash function, optimized for small integers.
//
// Borrowed from the dart sdk: sdk/lib/math/jenkins_smi_hash.dart.
class _Jenkins {
static int combine(int hash, Object o) {
assert(o is! Iterable);
hash = 0x1fffffff & (hash + o.hashCode);
hash = 0x1fffffff & (hash + ((0x0007ffff & hash) << 10));
hash = hash ^ (hash >> 6);
return hash;
}

static int finish(int hash) {
hash = 0x1fffffff & (hash + ((0x03ffffff & hash) << 3));
hash = hash ^ (hash >> 11);
hash = 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
return hash;
}
}

/// Combine up to twenty objects' hash codes into one value.
///
/// If you only need to handle one value's hashCode, then just refer to its
/// [hashCode] getter directly.
/// If you only need to handle one object's hash code, then just refer to its
/// [Object.hashCode] getter directly.
///
/// If you need to combine an arbitrary number of values from a List or other
/// Iterable, use [hashList]. The output of hashList can be used as one of the
/// arguments to this function.
/// If you need to combine an arbitrary number of objects from a [List] or other
/// [Iterable], use [hashList]. The output of [hashList] can be used as one of
/// the arguments to this function.
///
/// For example:
///
/// int hashCode => hashValues(foo, bar, hashList(quux), baz);
int hashValues(Object arg01, Object arg02,
[Object arg03 = _hashEnd,
Object arg04 = _hashEnd,
Object arg05 = _hashEnd,
Object arg06 = _hashEnd,
Object arg07 = _hashEnd,
Object arg08 = _hashEnd,
Object arg09 = _hashEnd,
Object arg10 = _hashEnd,
Object arg11 = _hashEnd,
Object arg12 = _hashEnd,
Object arg13 = _hashEnd,
Object arg14 = _hashEnd,
Object arg15 = _hashEnd,
Object arg16 = _hashEnd,
Object arg17 = _hashEnd,
Object arg18 = _hashEnd,
Object arg19 = _hashEnd,
Object arg20 = _hashEnd]) {
int result = 373;
assert(arg01 is! Iterable);
result = 37 * result + arg01.hashCode;
assert(arg02 is! Iterable);
result = 37 * result + arg02.hashCode;
/// ```dart
/// int hashCode => hashValues(foo, bar, hashList(quux), baz);
/// ```
int hashValues(
Object arg01, Object arg02, [ Object arg03 = _hashEnd,
Object arg04 = _hashEnd, Object arg05 = _hashEnd, Object arg06 = _hashEnd,
Object arg07 = _hashEnd, Object arg08 = _hashEnd, Object arg09 = _hashEnd,
Object arg10 = _hashEnd, Object arg11 = _hashEnd, Object arg12 = _hashEnd,
Object arg13 = _hashEnd, Object arg14 = _hashEnd, Object arg15 = _hashEnd,
Object arg16 = _hashEnd, Object arg17 = _hashEnd, Object arg18 = _hashEnd,
Object arg19 = _hashEnd, Object arg20 = _hashEnd ]) {
int result = 0;
result = _Jenkins.combine(result, arg01);
result = _Jenkins.combine(result, arg02);
if (arg03 != _hashEnd) {
assert(arg03 is! Iterable);
result = 37 * result + arg03.hashCode;
result = _Jenkins.combine(result, arg03);
if (arg04 != _hashEnd) {
assert(arg04 is! Iterable);
result = 37 * result + arg04.hashCode;
result = _Jenkins.combine(result, arg04);
if (arg05 != _hashEnd) {
assert(arg05 is! Iterable);
result = 37 * result + arg05.hashCode;
result = _Jenkins.combine(result, arg05);
if (arg06 != _hashEnd) {
assert(arg06 is! Iterable);
result = 37 * result + arg06.hashCode;
result = _Jenkins.combine(result, arg06);
if (arg07 != _hashEnd) {
assert(arg07 is! Iterable);
result = 37 * result + arg07.hashCode;
result = _Jenkins.combine(result, arg07);
if (arg08 != _hashEnd) {
assert(arg08 is! Iterable);
result = 37 * result + arg08.hashCode;
result = _Jenkins.combine(result, arg08);
if (arg09 != _hashEnd) {
assert(arg09 is! Iterable);
result = 37 * result + arg09.hashCode;
result = _Jenkins.combine(result, arg09);
if (arg10 != _hashEnd) {
assert(arg10 is! Iterable);
result = 37 * result + arg10.hashCode;
result = _Jenkins.combine(result, arg10);
if (arg11 != _hashEnd) {
assert(arg11 is! Iterable);
result = 37 * result + arg11.hashCode;
result = _Jenkins.combine(result, arg11);
if (arg12 != _hashEnd) {
assert(arg12 is! Iterable);
result = 37 * result + arg12.hashCode;
result = _Jenkins.combine(result, arg12);
if (arg13 != _hashEnd) {
assert(arg13 is! Iterable);
result = 37 * result + arg13.hashCode;
result = _Jenkins.combine(result, arg13);
if (arg14 != _hashEnd) {
assert(arg14 is! Iterable);
result = 37 * result + arg14.hashCode;
result = _Jenkins.combine(result, arg14);
if (arg15 != _hashEnd) {
assert(arg15 is! Iterable);
result = 37 * result + arg15.hashCode;
result = _Jenkins.combine(result, arg15);
if (arg16 != _hashEnd) {
assert(arg16 is! Iterable);
result = 37 * result + arg16.hashCode;
result = _Jenkins.combine(result, arg16);
if (arg17 != _hashEnd) {
assert(arg17 is! Iterable);
result = 37 * result + arg17.hashCode;
result = _Jenkins.combine(result, arg17);
if (arg18 != _hashEnd) {
assert(arg18 is! Iterable);
result = 37 * result + arg18.hashCode;
result = _Jenkins.combine(result, arg18);
if (arg19 != _hashEnd) {
assert(arg19 is! Iterable);
result = 37 * result + arg19.hashCode;
result = _Jenkins.combine(result, arg19);
if (arg20 != _hashEnd) {
assert(arg20 is! Iterable);
result = 37 * result + arg20.hashCode;
result = _Jenkins.combine(result, arg20);
// I can see my house from here!
}
}
Expand All @@ -119,19 +107,17 @@ int hashValues(Object arg01, Object arg02,
}
}
}
return result;
return _Jenkins.finish(result);
}

/// Combine the hashCodes of an arbitrary number of values from an Iterable into
/// one value. This function will return the same value if given "null" as if
/// given an empty list.
int hashList(Iterable<Object> args) {
int result = 373;
if (args != null) {
for (Object arg in args) {
assert(arg is! Iterable);
result = 37 * result + arg.hashCode;
}
/// Combine the [Object.hashCode] values of an arbitrary number of objects from
/// an [Iterable] into one value. This function will return the same value if
/// given null as if given an empty list.
int hashList(Iterable<Object> arguments) {
int result = 0;
if (arguments != null) {
for (Object argument in arguments)
result = _Jenkins.combine(result, argument);
}
return result;
return _Jenkins.finish(result);
}
122 changes: 122 additions & 0 deletions lib/web_ui/test/hash_codes_test.dart
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,122 @@
// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:test/test.dart';
import 'package:ui/ui.dart';

// The biggest integer value that can be represented in JavaScript is 1 << 53.
// However, the 1 << 53 expression cannot be used in JavaScript because that
// would apply the bitwise shift to a "number" (i.e. float64), which is
// meaningless. Instead, a decimal literal is used here.
const int _kBiggestExactJavaScriptInt = 9007199254740992;

void main() {
test('hashValues can hash lots of huge values effectively', () {
expect(
hashValues(
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
),
496984395,
);
// Hash a slightly smaller number to verify that the hash code is different.
expect(
hashValues(
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt - 1,
),
455584273,
);
});

test('hashList can hash lots of huge values effectively', () {
expect(
hashList(<int>[
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
]),
496984395,
);
// Hash a slightly smaller number to verify that the hash code is different.
expect(
hashList(<int>[
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt,
_kBiggestExactJavaScriptInt - 1,
]),
455584273,
);
});
}

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