// 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.
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import 'dart:async';
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import 'dart:convert';
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import 'package:analyzer/dart/element/element.dart';
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import 'package:build/build.dart';
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import 'package:path/path.dart' as p;
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import 'package:source_gen/source_gen.dart';
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import 'package:json_annotation/json_annotation.dart';
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import 'utils.dart';
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class JsonLiteralGenerator extends GeneratorForAnnotation<JsonLiteral> {
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const JsonLiteralGenerator();
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@override
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Future<String> generateForAnnotatedElement(
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Element element, ConstantReader annotation, BuildStep buildStep) async {
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if (p.isAbsolute(annotation.read('path').stringValue)) {
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throw ArgumentError(
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'`annotation.path` must be relative path to the source file.');
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}
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final sourcePathDir = p.dirname(buildStep.inputId.path);
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final fileId = AssetId(buildStep.inputId.package,
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p.join(sourcePathDir, annotation.read('path').stringValue));
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final content = json.decode(await buildStep.readAsString(fileId));
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final asConst = annotation.read('asConst').boolValue;
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final thing = jsonLiteralAsDart(content).toString();
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final marked = asConst ? 'const' : 'final';
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return '$marked _\$${element.name}JsonLiteral = $thing;';
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}
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}
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/// Returns a [String] representing a valid Dart literal for [value].
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String jsonLiteralAsDart(dynamic value) {
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if (value == null) return 'null';
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if (value is String) return escapeDartString(value);
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if (value is bool || value is num) return value.toString();
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if (value is List) {
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final listItems = value.map(jsonLiteralAsDart).join(', ');
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return '[$listItems]';
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}
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if (value is Map) return jsonMapAsDart(value);
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throw StateError(
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'Should never get here – with ${value.runtimeType} - `$value`.');
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}
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String jsonMapAsDart(Map value) {
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final buffer = StringBuffer();
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buffer.write('{');
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var first = true;
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value.forEach((k, v) {
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if (first) {
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first = false;
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} else {
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buffer.writeln(',');
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}
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buffer.write(escapeDartString(k as String));
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buffer.write(': ');
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buffer.write(jsonLiteralAsDart(v));
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});
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buffer.write('}');
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return buffer.toString();
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}
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