1 files changed, 169 insertions, 0 deletions
diff --git a/devtools/shared/protocol/Request.js b/devtools/shared/protocol/Request.js
new file mode 100644
index 0000000000..66e307fb4a
--- /dev/null
+++ b/devtools/shared/protocol/Request.js
@@ -0,0 +1,169 @@
+/* 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";
+
+const { extend } = require("resource://devtools/shared/extend.js");
+var {
+  findPlaceholders,
+  getPath,
+} = require("resource://devtools/shared/protocol/utils.js");
+var { types } = require("resource://devtools/shared/protocol/types.js");
+
+/**
+ * Manages a request template.
+ *
+ * @param object template
+ *    The request template.
+ * @construcor
+ */
+var Request = function(template = {}) {
+  this.type = template.type;
+  this.template = template;
+  this.args = findPlaceholders(template, Arg);
+};
+
+Request.prototype = {
+  /**
+   * Write a request.
+   *
+   * @param array fnArgs
+   *    The function arguments to place in the request.
+   * @param object ctx
+   *    The object making the request.
+   * @returns a request packet.
+   */
+  write(fnArgs, ctx) {
+    const ret = {};
+    for (const key in this.template) {
+      const value = this.template[key];
+      if (value instanceof Arg) {
+        ret[key] = value.write(
+          value.index in fnArgs ? fnArgs[value.index] : undefined,
+          ctx,
+          key
+        );
+      } else if (key == "type") {
+        ret[key] = value;
+      } else {
+        throw new Error(
+          "Request can only an object with `Arg` or `Option` properties"
+        );
+      }
+    }
+    return ret;
+  },
+
+  /**
+   * Read a request.
+   *
+   * @param object packet
+   *    The request packet.
+   * @param object ctx
+   *    The object making the request.
+   * @returns an arguments array
+   */
+  read(packet, ctx) {
+    const fnArgs = [];
+    for (const templateArg of this.args) {
+      const arg = templateArg.placeholder;
+      const path = templateArg.path;
+      const name = path[path.length - 1];
+      arg.read(getPath(packet, path), ctx, fnArgs, name);
+    }
+    return fnArgs;
+  },
+};
+
+exports.Request = Request;
+
+/**
+ * Request/Response templates and generation
+ *
+ * Request packets are specified as json templates with
+ * Arg and Option placeholders where arguments should be
+ * placed.
+ *
+ * Reponse packets are also specified as json templates,
+ * with a RetVal placeholder where the return value should be
+ * placed.
+ */
+
+/**
+ * Placeholder for simple arguments.
+ *
+ * @param number index
+ *    The argument index to place at this position.
+ * @param type type
+ *    The argument should be marshalled as this type.
+ * @constructor
+ */
+var Arg = function(index, type) {
+  this.index = index;
+  // Prevent force loading all Arg types by accessing it only when needed
+  loader.lazyGetter(this, "type", function() {
+    return types.getType(type);
+  });
+};
+
+Arg.prototype = {
+  write(arg, ctx) {
+    return this.type.write(arg, ctx);
+  },
+
+  read(v, ctx, outArgs) {
+    outArgs[this.index] = this.type.read(v, ctx);
+  },
+};
+
+// Outside of protocol.js, Arg is called as factory method, without the new keyword.
+exports.Arg = function(index, type) {
+  return new Arg(index, type);
+};
+
+/**
+ * Placeholder for an options argument value that should be hoisted
+ * into the packet.
+ *
+ * If provided in a method specification:
+ *
+ *   { optionArg: Option(1)}
+ *
+ * Then arguments[1].optionArg will be placed in the packet in this
+ * value's place.
+ *
+ * @param number index
+ *    The argument index of the options value.
+ * @param type type
+ *    The argument should be marshalled as this type.
+ * @constructor
+ */
+var Option = function(index, type) {
+  Arg.call(this, index, type);
+};
+
+Option.prototype = extend(Arg.prototype, {
+  write(arg, ctx, name) {
+    // Ignore if arg is undefined or null; allow other falsy values
+    if (arg == undefined || arg[name] == undefined) {
+      return undefined;
+    }
+    const v = arg[name];
+    return this.type.write(v, ctx);
+  },
+  read(v, ctx, outArgs, name) {
+    if (outArgs[this.index] === undefined) {
+      outArgs[this.index] = {};
+    }
+    if (v === undefined) {
+      return;
+    }
+    outArgs[this.index][name] = this.type.read(v, ctx);
+  },
+});
+
+// Outside of protocol.js, Option is called as factory method, without the new keyword.
+exports.Option = function(index, type) {
+  return new Option(index, type);
+};