1 files changed, 104 insertions, 0 deletions
diff --git a/devtools/shared/protocol/Front/FrontClassWithSpec.js b/devtools/shared/protocol/Front/FrontClassWithSpec.js
new file mode 100644
index 0000000000..c098a4ffeb
--- /dev/null
+++ b/devtools/shared/protocol/Front/FrontClassWithSpec.js
@@ -0,0 +1,104 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+var { Front } = require("devtools/shared/protocol/Front");
+
+/**
+ * Generates request methods as described by the given actor specification on
+ * the given front prototype. Returns the front prototype.
+ */
+var generateRequestMethods = function(actorSpec, frontProto) {
+  if (frontProto._actorSpec) {
+    throw new Error("frontProto called twice on the same front prototype!");
+  }
+
+  frontProto.typeName = actorSpec.typeName;
+
+  // Generate request methods.
+  const methods = actorSpec.methods;
+  methods.forEach(spec => {
+    const name = spec.name;
+
+    frontProto[name] = function(...args) {
+      // If the front is destroyed, the request will not be able to complete.
+      if (this.isDestroyed()) {
+        throw new Error(
+          `Can not send request '${name}' because front '${this.typeName}' is already destroyed.`
+        );
+      }
+
+      let packet;
+      try {
+        packet = spec.request.write(args, this);
+      } catch (ex) {
+        console.error("Error writing request: " + name);
+        throw ex;
+      }
+      if (spec.oneway) {
+        // Fire-and-forget oneway packets.
+        this.send(packet);
+        return undefined;
+      }
+
+      return this.request(packet).then(response => {
+        let ret;
+        try {
+          ret = spec.response.read(response, this);
+        } catch (ex) {
+          console.error("Error reading response to: " + name + "\n" + ex);
+          throw ex;
+        }
+        return ret;
+      });
+    };
+
+    // Release methods should call the destroy function on return.
+    if (spec.release) {
+      const fn = frontProto[name];
+      frontProto[name] = function(...args) {
+        return fn.apply(this, args).then(result => {
+          this.destroy();
+          return result;
+        });
+      };
+    }
+  });
+
+  // Process event specifications
+  frontProto._clientSpec = {};
+
+  const actorEvents = actorSpec.events;
+  if (actorEvents) {
+    frontProto._clientSpec.events = new Map();
+
+    for (const [name, request] of actorEvents) {
+      frontProto._clientSpec.events.set(request.type, {
+        name,
+        request,
+      });
+    }
+  }
+
+  frontProto._actorSpec = actorSpec;
+
+  return frontProto;
+};
+
+/**
+ * Create a front class for the given actor specification and front prototype.
+ *
+ * @param object actorSpec
+ *    The actor specification you're creating a front for.
+ * @param object proto
+ *    The object prototype.  Must have a 'typeName' property,
+ *    should have method definitions, can have event definitions.
+ */
+var FrontClassWithSpec = function(actorSpec) {
+  class OneFront extends Front {}
+  generateRequestMethods(actorSpec, OneFront.prototype);
+  return OneFront;
+};
+exports.FrontClassWithSpec = FrontClassWithSpec;