1 files changed, 103 insertions, 0 deletions
diff --git a/devtools/client/shared/build/build-debugger.js b/devtools/client/shared/build/build-debugger.js
new file mode 100644
index 0000000000..6cb964bc05
--- /dev/null
+++ b/devtools/client/shared/build/build-debugger.js
@@ -0,0 +1,103 @@
+/* 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 Babel = require("./babel");
+const _path = require("path");
+
+function isRequire(t, node) {
+  return node && t.isCallExpression(node) && node.callee.name == "require";
+}
+
+function shouldLazyLoad(value) {
+  return (
+    !value.includes("codemirror/") &&
+    !value.endsWith(".properties") &&
+    !value.startsWith("devtools/") &&
+    !value.startsWith("resource://devtools/") &&
+    // XXX: the lazyRequire rewriter (in transformMC) fails for this module, it
+    // evaluates `t.thisExpression()` as `void 0` instead of `this`. But the
+    // rewriter still works for other call sites and seems mandatory for the
+    // debugger to start successfully (lazy requires help to break circular
+    // dependencies).
+    value !== "resource://gre/modules/AppConstants.jsm"
+  );
+}
+
+/**
+ * This Babel plugin is used to transpile a single Debugger module into a module that
+ * can be loaded in Firefox via the regular DevTools loader.
+ */
+function transformMC({ types: t }) {
+  return {
+    visitor: {
+      StringLiteral(path, state) {
+        const { filePath } = state.opts;
+        let value = path.node.value;
+
+        if (!isRequire(t, path.parent)) {
+          return;
+        }
+
+        if (shouldLazyLoad(value)) {
+          const requireCall = path.parentPath;
+          const declarator = requireCall.parentPath;
+          const declaration = declarator.parentPath;
+
+          // require()s that are not assigned to a variable cannot be safely lazily required
+          // since we lack anything to initiate the require (= the getter for the variable)
+          if (declarator.type !== "VariableDeclarator") {
+            return;
+          }
+
+          // update relative paths to be "absolute" (starting with devtools/)
+          // e.g. ./utils/source-queue
+          if (value.startsWith(".")) {
+            // Create full path
+            // e.g. z:\build\build\src\devtools\client\debugger\src\utils\source-queue
+            let newValue = _path.join(_path.dirname(filePath), value);
+
+            // Select the devtools portion of the path
+            // e.g. devtools\client\debugger\src\utils\source-queue
+            if (!newValue.startsWith("devtools")) {
+              newValue = newValue.match(/^(.*?)(devtools.*)/)[2];
+            }
+
+            // Replace forward slashes with back slashes
+            // e.g devtools/client/debugger/src/utils/source-queue
+            newValue = newValue.replace(/\\/g, "/");
+
+            value = newValue;
+          }
+
+          // rewrite to: loader.lazyRequireGetter(this, "variableName", "pathToFile")
+          const lazyRequire = t.callExpression(
+            t.memberExpression(
+              t.identifier("loader"),
+              t.identifier("lazyRequireGetter")
+            ),
+            [
+              t.thisExpression(),
+              t.stringLiteral(declarator.node.id.name || ""),
+              t.stringLiteral(value),
+            ]
+          );
+
+          declaration.replaceWith(lazyRequire);
+        }
+      },
+    },
+  };
+}
+
+Babel.registerPlugin("transform-mc", transformMC);
+
+module.exports = function (filePath) {
+  return [
+    "proposal-class-properties",
+    "transform-modules-commonjs",
+    ["transform-mc", { filePath }],
+  ];
+};