Plugin manifest parsing.

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

Index: pkg/analyzer/lib/src/plugin/plugin_configuration.dart
diff --git a/pkg/analyzer/lib/src/plugin/plugin_configuration.dart b/pkg/analyzer/lib/src/plugin/plugin_configuration.dart
index 9809bdcfea4178342983ae43647eb0e7075945c7..9bd0da3973901528cfd16527d788b9e1a3027240 100644
--- a/pkg/analyzer/lib/src/plugin/plugin_configuration.dart
+++ b/pkg/analyzer/lib/src/plugin/plugin_configuration.dart
@@ -11,30 +11,75 @@ 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(
-          name: name,
-          version: details['version'],
-          className: details['class_name'],
-          libraryUri: details['library_uri'],
-          packageName: details['package_name'],
-          path: details['path']);
+      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.
+/// analysis options map or plugin manifest.
 class PluginConfig {
   final Iterable<PluginInfo> plugins;
   PluginConfig(this.plugins);
@@ -57,7 +102,7 @@ class PluginConfig {
           // 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 `${pluginConfig.runtimeType}`)',
+                'Unrecognized plugin config format, expected `YamlMap`, got `${pluginConfig.runtimeType}`',
                 pluginConfig);
           }
         }
@@ -117,4 +162,36 @@ class PluginInfo {
       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});
 }