1 files changed, 85 insertions, 0 deletions
diff --git a/devtools/shared/specs/string.js b/devtools/shared/specs/string.js
new file mode 100644
index 0000000000..db7d25a9b9
--- /dev/null
+++ b/devtools/shared/specs/string.js
@@ -0,0 +1,85 @@
+/* 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 protocol = require("devtools/shared/protocol");
+const { Arg, RetVal, generateActorSpec } = protocol;
+
+const longStringSpec = generateActorSpec({
+  typeName: "longstractor",
+
+  methods: {
+    substring: {
+      request: {
+        start: Arg(0),
+        end: Arg(1),
+      },
+      response: { substring: RetVal() },
+    },
+    release: { release: true },
+  },
+});
+
+exports.longStringSpec = longStringSpec;
+
+/**
+ * When a caller is expecting a LongString actor but the string is already available on
+ * client, the SimpleStringFront can be used as it shares the same API as a
+ * LongStringFront but will not make unnecessary trips to the server.
+ */
+class SimpleStringFront {
+  constructor(str) {
+    this.str = str;
+  }
+
+  get length() {
+    return this.str.length;
+  }
+
+  get initial() {
+    return this.str;
+  }
+
+  string() {
+    return Promise.resolve(this.str);
+  }
+
+  substring(start, end) {
+    return Promise.resolve(this.str.substring(start, end));
+  }
+
+  release() {
+    this.str = null;
+    return Promise.resolve(undefined);
+  }
+}
+
+exports.SimpleStringFront = SimpleStringFront;
+
+// The long string actor needs some custom marshalling, because it is sometimes
+// returned as a primitive rather than a complete form.
+
+var stringActorType = protocol.types.getType("longstractor");
+protocol.types.addType("longstring", {
+  _actor: true,
+  write: (value, context, detail) => {
+    if (!(context instanceof protocol.Actor)) {
+      throw Error("Passing a longstring as an argument isn't supported.");
+    }
+
+    if (value.short) {
+      return value.str;
+    }
+    return stringActorType.write(value, context, detail);
+  },
+  read: (value, context, detail) => {
+    if (context instanceof protocol.Actor) {
+      throw Error("Passing a longstring as an argument isn't supported.");
+    }
+    if (typeof value === "string") {
+      return new SimpleStringFront(value);
+    }
+    return stringActorType.read(value, context, detail);
+  },
+});