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packages/analyzer/lib/src/plugin/plugin_configuration.dart

Index: packages/analyzer/lib/src/plugin/plugin_configuration.dart
diff --git a/packages/analyzer/lib/src/plugin/plugin_configuration.dart b/packages/analyzer/lib/src/plugin/plugin_configuration.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9365a3c3eefe8a75fa4c31c718874ec12896077f
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+++ b/packages/analyzer/lib/src/plugin/plugin_configuration.dart
@@ -0,0 +1,198 @@
+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library analyzer.src.plugin.plugin_configuration;
+
+import 'package:analyzer/plugin/options.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:yaml/yaml.dart';
+
+const _analyzerOptionScope = 'analyzer';
+
+const _pluginOptionScope = 'plugins';
+
+/// Parse the given string into a plugin manifest.
+PluginManifest parsePluginManifestString(String manifestSource) {
+  var yaml = loadYaml(manifestSource);
+  if (yaml == null) {
+    return null;
+  }
+  _verifyMap(yaml, 'plugin manifest');
+  Iterable<String> pluginHost = _parseHosts(yaml['contributes_to']);
+  PluginInfo plugin = _parsePlugin(yaml);
+  return new PluginManifest(contributesTo: pluginHost, plugin: plugin);
+}
+
+String _asString(dynamic yaml) {
+  if (yaml != null && yaml is! String) {
+    throw new PluginConfigFormatException(
+        'Unable to parse pugin manifest, '
+        'expected `String`, got `${yaml.runtimeType}`',
+        yaml);
+  }
+  return yaml;
+}
+
+Iterable<String> _parseHosts(dynamic yaml) {
+  List<String> hosts = <String>[];
+  if (yaml is String) {
+    hosts.add(yaml);
+  } else if (yaml is YamlList) {
+    yaml.forEach((h) => hosts.add(_asString(h)));
+  }
+  return hosts;
+}
+
+PluginInfo _parsePlugin(dynamic yaml) {
+  if (yaml != null) {
+    _verifyMap(yaml, 'plugin manifest');
+    return new PluginInfo._fromYaml(details: yaml);
+  }
+  return null;
+}
+
+PluginInfo _processPluginMapping(dynamic name, dynamic details) {
+  if (name is String) {
+    if (details is String) {
+      return new PluginInfo(name: name, version: details);
+    }
+    if (details is YamlMap) {
+      return new PluginInfo._fromYaml(name: name, details: details);
+    }
+  }
+
+  return null;
+}
+
+_verifyMap(dynamic yaml, String context) {
+  if (yaml is! YamlMap) {
+    throw new PluginConfigFormatException(
+        'Unable to parse $context, '
+        'expected `YamlMap`, got `${yaml.runtimeType}`',
+        yaml);
+  }
+}
+
+/// A callback for error handling.
+typedef ErrorHandler(Exception e);
+
+/// Describes plugin configuration information as extracted from an
+/// analysis options map or plugin manifest.
+class PluginConfig {
+  final Iterable<PluginInfo> plugins;
+  PluginConfig(this.plugins);
+
+  /// Create a plugin configuration from an options map.
+  factory PluginConfig.fromOptions(Map<String, YamlNode> options) {
+    List<PluginInfo> plugins = [];
+    var analyzerOptions = options[_analyzerOptionScope];
+    if (analyzerOptions != null) {
+      if (analyzerOptions is YamlMap) {
+        var pluginConfig = analyzerOptions[_pluginOptionScope];
+        if (pluginConfig is YamlMap) {
+          pluginConfig.forEach((name, details) {
+            var plugin = _processPluginMapping(name, details);
+            if (plugin != null) {
+              plugins.add(plugin);
+            }
+          });
+        } else {
+          // Anything but an empty list of plugins is treated as a format error.
+          if (pluginConfig != null) {
+            throw new PluginConfigFormatException(
+                'Unrecognized plugin config format, expected `YamlMap`, '
+                'got `${pluginConfig.runtimeType}`',
+                pluginConfig);
+          }
+        }
+      }
+    }
+
+    return new PluginConfig(plugins);
+  }
+}
+
+/// Thrown on bad plugin config format.
+class PluginConfigFormatException implements Exception {
+  /// Descriptive message.
+  final message;
+
+  /// The `plugin:` yaml node for generating detailed error feedback.
+  final yamlNode;
+  PluginConfigFormatException(this.message, this.yamlNode);
+}
+
+/// Extracts plugin config details from analysis options.
+class PluginConfigOptionsProcessor extends OptionsProcessor {
+  final ErrorHandler _errorHandler;
+
+  PluginConfig _config;
+
+  PluginConfigOptionsProcessor([this._errorHandler]);
+
+  /// The processed plugin config.
+  PluginConfig get config => _config;
+
+  @override
+  void onError(Exception exception) {
+    if (_errorHandler != null) {
+      _errorHandler(exception);
+    }
+  }
+
+  @override
+  void optionsProcessed(
+      AnalysisContext context, Map<String, YamlNode> options) {
+    _config = new PluginConfig.fromOptions(options);
+  }
+}
+
+/// Describes plugin information.
+class PluginInfo {
+  final String name;
+  final String className;
+  final String version;
+  final String libraryUri;
+  final String packageName;
+  final String path;
+  PluginInfo(
+      {this.name,
+      this.version,
+      this.className,
+      this.libraryUri,
+      this.packageName,
+      this.path});
+
+  factory PluginInfo._fromYaml({String name, YamlMap details}) =>
+      new PluginInfo(
+          name: name,
+          version: _asString(details['version']),
+          className: _asString(details['class_name']),
+          libraryUri: _asString(details['library_uri']),
+          packageName: _asString(details['package_name']),
+          path: _asString(details['path']));
+}
+
+/// Plugin manifests accompany plugin packages, providing
+/// configuration information for published plugins.
+///
+/// Provisionally, plugin manifests live in a file `plugin.yaml`
+/// at the root of the plugin package.
+///
+///     my_plugin/
+///       bin/
+///       lib/
+///       plugin.yaml
+///       pubspec.yaml
+///
+/// Provisional manifest file format:
+///
+///     class_name: MyAnalyzerPlugin
+///     library_uri: 'my_plugin/my_analyzer_plugin.dart'
+///     contributes_to: analyzer
+class PluginManifest {
+  PluginInfo plugin;
+  Iterable<String> contributesTo;
+  PluginManifest({this.plugin, this.contributesTo});
+}