Initial implementation for 'analysis.setSubscriptions' API.

pkg/analysis_server/lib/src/protocol.dart

Index: pkg/analysis_server/lib/src/protocol.dart
diff --git a/pkg/analysis_server/lib/src/protocol.dart b/pkg/analysis_server/lib/src/protocol.dart
index 07f40085d2e5a8af8b0c4881b486d32edabb84ef..9efbf64f92b4c83ab884d6cb8a25b2f81ab0d878 100644
--- a/pkg/analysis_server/lib/src/protocol.dart
+++ b/pkg/analysis_server/lib/src/protocol.dart
@@ -365,6 +365,41 @@ class RequestDatum {
     }
     return datum;
   }
+
+  /**
+   * Determine if the datum is a map whose values are all string lists.
+   *
+   * Note: we can safely assume that the keys are all strings, since JSON maps
+   * cannot have any other key type.
+   */
+  bool isStringListMap() {
+    if (datum is! Map) {
+      return false;
+    }
+    for (var value in datum.values) {
+      if (value is! List) {
+        return false;
+      }
+      for (var listItem in value) {
+        if (listItem is! String) {
+          return false;
+        }
+      }
+    }
+    return true;
+  }
+
+  /**
+   * Validate that the datum is a map from strings to string listss, and return
+   * it.
+   */
+  Map<String, List<String>> asStringListMap() {
+    if (!isStringListMap()) {
+      throw new RequestFailure(new Response.invalidParameter(request, path,
+          "be a string list map"));
+    }
+    return datum;
+  }
 }
 
 /**
@@ -466,6 +501,14 @@ class Response {
     : this(requestId, new RequestError(-9, message));
 
   /**
+   * Initialize a newly created instance to represent an error condition caused
+   * by a `analysis.setSubscriptions` [request] that includes an unknown
+   * analysis service name.
+   */
+  Response.unknownAnalysisService(Request request, String name)
+    : this(request.id, new RequestError(-10, 'Unknown analysis service: "$name"'));
+
+  /**
    * Initialize a newly created instance based upon the given JSON data
    */
   factory Response.fromJson(Map<String, Object> json) {