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matanlureykevmoo
matanlurey
authored and
kevmoo
committed
Constants reviver (#182)
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6 files changed

+264
-50
lines changed

6 files changed

+264
-50
lines changed

‎lib/source_gen.dart‎

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@@ -9,4 +9,5 @@ export 'src/constants.dart' show ConstantReader;
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export 'src/generator.dart';
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export 'src/generator_for_annotation.dart';
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export 'src/library.dart' show LibraryReader;
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export 'src/revive.dart' show Revivable;
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export 'src/type_checker.dart' show TypeChecker;

‎lib/src/constants.dart‎

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@@ -5,6 +5,7 @@
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import 'package:analyzer/dart/constant/value.dart';
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import 'package:analyzer/dart/element/element.dart';
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import 'revive.dart';
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import 'type_checker.dart';
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/// Throws an exception if [root] or its super(s) does not contain [name].
@@ -50,6 +51,9 @@ abstract class ConstantReader {
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factory ConstantReader(DartObject object) =>
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_isNull(object) ? const _NullConstant() : new _Constant(object);
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/// Constant as any supported literal value.
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dynamic get anyValue;
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/// Returns whether this constant represents a `bool` literal.
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bool get isBool;
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@@ -102,6 +106,13 @@ abstract class ConstantReader {
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/// Reads[ field] from the constant as another constant value.
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ConstantReader read(String field);
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/// Returns as a revived meta class.
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///
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/// This is appropriate for cases where the underlying object is not a literal
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/// and code generators will want to figure out how to "recreate" a constant
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/// at runtime.
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Revivable revive();
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}
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dynamic _throw(String expected, [dynamic object]) {
@@ -112,6 +123,9 @@ dynamic _throw(String expected, [dynamic object]) {
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class _NullConstant implements ConstantReader {
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const _NullConstant();
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@override
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dynamic get anyValue => _throw('dynamic');
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@override
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bool get boolValue => _throw('bool');
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@@ -150,6 +164,9 @@ class _NullConstant implements ConstantReader {
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@override
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ConstantReader read(_) => throw new UnsupportedError('Null');
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@override
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Revivable revive() => throw new UnsupportedError('Null');
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}
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/// Default implementation of [ConstantReader].
@@ -158,6 +175,14 @@ class _Constant implements ConstantReader {
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159176
const _Constant(this._object);
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178+
@override
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dynamic get anyValue =>
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_object.toBoolValue() ??
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_object.toIntValue() ??
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_object.toStringValue() ??
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_object.toListValue() ??
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_object.toMapValue();
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@override
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bool get boolValue =>
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isBool ? _object.toBoolValue() : _throw('bool', _object);
@@ -208,6 +233,9 @@ class _Constant implements ConstantReader {
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return constant;
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}
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@override
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Revivable revive() => reviveInstance(_object);
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@override
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String toString() => 'ConstantReader ${_object}';
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}

‎lib/src/revive.dart‎

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@@ -0,0 +1,80 @@
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// Copyright (c) 2017, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
4+
5+
import 'package:analyzer/dart/constant/value.dart';
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import 'package:analyzer/dart/element/element.dart';
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import 'package:analyzer/src/dart/constant/value.dart';
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import 'utils.dart';
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/// Returns a revivable instance of [object].
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///
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/// Optionally specify the [library] type that contains the reference.
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///
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/// Returns [null] if not revivable.
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Revivable reviveInstance(DartObject object, [LibraryElement library]) {
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library ??= object.type.element.library;
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var url = Uri.parse(urlOfElement(object.type.element));
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final clazz = object?.type?.element as ClassElement;
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for (final e in clazz.fields.where(
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(f) => f.isPublic && f.isConst && f.computeConstantValue() == object,
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)) {
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return new Revivable._(source: url, accessor: e.name);
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}
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final i = (object as DartObjectImpl).getInvocation();
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if (i != null &&
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i.constructor.isPublic &&
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i.constructor.enclosingElement.isPublic) {
29+
url = Uri.parse(urlOfElement(i.constructor.enclosingElement));
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return new Revivable._(
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source: url,
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accessor: i.constructor.name,
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namedArguments: i.namedArguments,
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positionalArguments: i.positionalArguments,
35+
);
36+
}
37+
if (library == null) {
38+
return null;
39+
}
40+
for (final e in library.definingCompilationUnit.topLevelVariables.where(
41+
(f) => f.isPublic && f.isConst && f.computeConstantValue() == object,
42+
)) {
43+
return new Revivable._(
44+
source: Uri.parse(urlOfElement(library)).replace(fragment: ''),
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accessor: e.name,
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);
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}
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return null;
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}
50+
51+
/// Decoded "instructions" for re-creating a const [DartObject] at runtime.
52+
class Revivable {
53+
/// A URL pointing to the location and class name.
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///
55+
/// For example, `LinkedHashMap` looks like: `dart:collection#LinkedHashMap`.
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///
57+
/// An accessor to a top-level do does not have a fragment.
58+
final Uri source;
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60+
/// Constructor or getter name used to invoke `const Class(...)`.
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///
62+
/// Optional - if empty string (`''`) then this means the default constructor.
63+
final String accessor;
64+
65+
/// Positional arguments used to invoke the constructor.
66+
final List<DartObject> positionalArguments;
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/// Named arguments used to invoke the constructor.
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final Map<String, DartObject> namedArguments;
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const Revivable._({
72+
this.source,
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this.accessor: '',
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this.positionalArguments: const [],
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this.namedArguments: const {},
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});
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/// Whether this instance is visible outside the same library.
79+
bool get isPrivate => accessor.startsWith('_');
80+
}

‎lib/src/type_checker.dart‎

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@@ -8,6 +8,8 @@ import 'package:analyzer/dart/constant/value.dart';
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import 'package:analyzer/dart/element/element.dart';
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import 'package:analyzer/dart/element/type.dart';
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11+
import 'utils.dart';
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1113
/// An abstraction around doing static type checking at compile/build time.
1214
abstract class TypeChecker {
1315
const TypeChecker._();
@@ -118,51 +120,6 @@ Iterable<InterfaceType> _getAllSupertypes(Element element) sync* {
118120
}
119121
}
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121-
Uri _normalizeUrl(Uri url) {
122-
switch (url.scheme) {
123-
case 'dart':
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return _normalizeDartUrl(url);
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case 'package':
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return _packageToAssetUrl(url);
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default:
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return url;
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}
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}
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132-
/// Make `dart:`-type URLs look like a user-knowable path.
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///
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/// Some internal dart: URLs are something like `dart:core/map.dart`.
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///
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/// This isn't a user-knowable path, so we strip out extra path segments
137-
/// and only expose `dart:core`.
138-
Uri _normalizeDartUrl(Uri url) => url.pathSegments.isNotEmpty
139-
? url.replace(pathSegments: url.pathSegments.take(1))
140-
: url;
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142-
/// Returns a `package:` URL into a `asset:` URL.
143-
///
144-
/// This makes internal comparison logic much easier, but still allows users
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/// to define assets in terms of `package:`, which is something that makes more
146-
/// sense to most.
147-
///
148-
/// For example this transforms `package:source_gen/source_gen.dart` into:
149-
/// `asset:source_gen/lib/source_gen.dart`.
150-
Uri _packageToAssetUrl(Uri url) => url.scheme == 'package'
151-
? url.replace(
152-
scheme: 'asset',
153-
pathSegments: <String>[]
154-
..add(url.pathSegments.first)
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..add('lib')
156-
..addAll(url.pathSegments.skip(1)))
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: url;
158-
159-
/// Returns
160-
String _urlOfElement(Element element) => element.kind == ElementKind.DYNAMIC
161-
? 'dart:core#dynmaic'
162-
: _normalizeUrl(element.source.uri)
163-
.replace(fragment: element.name)
164-
.toString();
165-
166123
// Checks a static type against another static type;
167124
class _LibraryTypeChecker extends TypeChecker {
168125
final DartType _type;
@@ -174,13 +131,13 @@ class _LibraryTypeChecker extends TypeChecker {
174131
element is ClassElement && element == _type.element;
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176133
@override
177-
String toString() => '${_urlOfElement(_type.element)}';
134+
String toString() => '${urlOfElement(_type.element)}';
178135
}
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180137
// Checks a runtime type against a static type.
181138
class _MirrorTypeChecker extends TypeChecker {
182139
static Uri _uriOf(ClassMirror mirror) =>
183-
_normalizeUrl((mirror.owner as LibraryMirror).uri)
140+
normalizeUrl((mirror.owner as LibraryMirror).uri)
184141
.replace(fragment: MirrorSystem.getName(mirror.simpleName));
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186143
// Precomputed type checker for types that already have been used.
@@ -218,14 +175,14 @@ class _UriTypeChecker extends TypeChecker {
218175
int get hashCode => _url.hashCode;
219176

220177
/// Url as a [Uri] object, lazily constructed.
221-
Uri get uri => _cache[this] ??= _normalizeUrl(Uri.parse(_url));
178+
Uri get uri => _cache[this] ??= normalizeUrl(Uri.parse(_url));
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223180
/// Returns whether this type represents the same as [url].
224181
bool hasSameUrl(dynamic url) =>
225-
uri.toString() == (url is String ? url : _normalizeUrl(url).toString());
182+
uri.toString() == (url is String ? url : normalizeUrl(url).toString());
226183

227184
@override
228-
bool isExactly(Element element) => hasSameUrl(_urlOfElement(element));
185+
bool isExactly(Element element) => hasSameUrl(urlOfElement(element));
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230187
@override
231188
String toString() => '${uri}';

‎lib/src/utils.dart‎

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@@ -76,6 +76,51 @@ String suggestLibraryName(AssetId source) {
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return '${source.package}.${parts.join('.')}';
7777
}
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79+
/// Returns a URL representing [element].
80+
String urlOfElement(Element element) => element.kind == ElementKind.DYNAMIC
81+
? 'dart:core#dynmaic'
82+
: normalizeUrl(element.source.uri)
83+
.replace(fragment: element.name)
84+
.toString();
85+
86+
Uri normalizeUrl(Uri url) {
87+
switch (url.scheme) {
88+
case 'dart':
89+
return normalizeDartUrl(url);
90+
case 'package':
91+
return packageToAssetUrl(url);
92+
default:
93+
return url;
94+
}
95+
}
96+
97+
/// Make `dart:`-type URLs look like a user-knowable path.
98+
///
99+
/// Some internal dart: URLs are something like `dart:core/map.dart`.
100+
///
101+
/// This isn't a user-knowable path, so we strip out extra path segments
102+
/// and only expose `dart:core`.
103+
Uri normalizeDartUrl(Uri url) => url.pathSegments.isNotEmpty
104+
? url.replace(pathSegments: url.pathSegments.take(1))
105+
: url;
106+
107+
/// Returns a `package:` URL into a `asset:` URL.
108+
///
109+
/// This makes internal comparison logic much easier, but still allows users
110+
/// to define assets in terms of `package:`, which is something that makes more
111+
/// sense to most.
112+
///
113+
/// For example this transforms `package:source_gen/source_gen.dart` into:
114+
/// `asset:source_gen/lib/source_gen.dart`.
115+
Uri packageToAssetUrl(Uri url) => url.scheme == 'package'
116+
? url.replace(
117+
scheme: 'asset',
118+
pathSegments: <String>[]
119+
..add(url.pathSegments.first)
120+
..add('lib')
121+
..addAll(url.pathSegments.skip(1)))
122+
: url;
123+
79124
/// Returns all of the declarations in [unit], including [unit] as the first
80125
/// item.
81126
Iterable<Element> getElementsFromLibraryElement(LibraryElement unit) sync* {

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