1 files changed, 240 insertions, 0 deletions
diff --git a/js/xpconnect/loader/nsImportModule.h b/js/xpconnect/loader/nsImportModule.h
new file mode 100644
index 0000000000..31f6f8c7c1
--- /dev/null
+++ b/js/xpconnect/loader/nsImportModule.h
@@ -0,0 +1,240 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef nsImportModule_h
+#define nsImportModule_h
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+
+#include "nsCOMPtr.h"
+#include "mozilla/RefPtr.h"
+
+namespace mozilla {
+namespace loader {
+
+nsresult ImportModule(const char* aURI, const char* aExportName,
+                      const nsIID& aIID, void** aResult, bool aInfallible);
+
+nsresult ImportESModule(const char* aURI, const char* aExportName,
+                        const nsIID& aIID, void** aResult, bool aInfallible);
+
+}  // namespace loader
+}  // namespace mozilla
+
+class MOZ_STACK_CLASS nsImportModule final : public nsCOMPtr_helper {
+ public:
+  nsImportModule(const char* aURI, const char* aExportName, nsresult* aErrorPtr,
+                 bool aInfallible)
+      : mURI(aURI),
+        mExportName(aExportName),
+        mErrorPtr(aErrorPtr),
+        mInfallible(aInfallible) {
+    MOZ_ASSERT_IF(mErrorPtr, !mInfallible);
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID,
+                                          void** aResult) const override {
+    nsresult rv = ::mozilla::loader::ImportModule(mURI, mExportName, aIID,
+                                                  aResult, mInfallible);
+    if (mErrorPtr) {
+      *mErrorPtr = rv;
+    }
+    return rv;
+  }
+
+ private:
+  const char* mURI;
+  const char* mExportName;
+  nsresult* mErrorPtr;
+  bool mInfallible;
+};
+
+/**
+ * These helpers make it considerably easier for C++ code to import a JS module
+ * and wrap it in an appropriately-defined XPIDL interface for its exports.
+ * Typical usage is something like:
+ *
+ * Foo.jsm:
+ *
+ *   var EXPORTED_SYMBOLS = ["foo"];
+ *
+ *   function foo(bar) {
+ *     return bar.toString();
+ *   }
+ *
+ * mozIFoo.idl:
+ *
+ *   interface mozIFoo : nsISupports {
+ *     AString foo(double meh);
+ *   }
+ *
+ * Thing.cpp:
+ *
+ *   nsCOMPtr<mozIFoo> foo = do_ImportModule(
+ *     "resource://meh/Foo.jsm");
+ *
+ *   MOZ_TRY(foo->Foo(42));
+ *
+ * For JS modules which export all fields within a single named object, a second
+ * argument can be passed naming that object.
+ *
+ * Foo.jsm:
+ *
+ *   var EXPORTED_SYMBOLS = ["Foo"];
+ *
+ *   var Foo = {
+ *     function foo(bar) {
+ *       return bar.toString();
+ *     }
+ *   };
+ *
+ * Thing.cpp:
+ *
+ *   nsCOMPtr<mozIFoo> foo = do_ImportModule(
+ *       "resource:://meh/Foo.jsm", "Foo");
+ */
+
+template <size_t N>
+inline nsImportModule do_ImportModule(const char (&aURI)[N]) {
+  return {aURI, nullptr, nullptr, /* infallible */ true};
+}
+
+template <size_t N>
+inline nsImportModule do_ImportModule(const char (&aURI)[N],
+                                      const mozilla::fallible_t&) {
+  return {aURI, nullptr, nullptr, /* infallible */ false};
+}
+
+template <size_t N>
+inline nsImportModule do_ImportModule(const char (&aURI)[N], nsresult* aRv) {
+  return {aURI, nullptr, aRv, /* infallible */ false};
+}
+
+template <size_t N, size_t N2>
+inline nsImportModule do_ImportModule(const char (&aURI)[N],
+                                      const char (&aExportName)[N2]) {
+  return {aURI, aExportName, nullptr, /* infallible */ true};
+}
+
+template <size_t N, size_t N2>
+inline nsImportModule do_ImportModule(const char (&aURI)[N],
+                                      const char (&aExportName)[N2],
+                                      const mozilla::fallible_t&) {
+  return {aURI, aExportName, nullptr, /* infallible */ false};
+}
+
+template <size_t N, size_t N2>
+inline nsImportModule do_ImportModule(const char (&aURI)[N],
+                                      const char (&aExportName)[N2],
+                                      nsresult* aRv) {
+  return {aURI, aExportName, aRv, /* infallible */ false};
+}
+
+class MOZ_STACK_CLASS nsImportESModule final : public nsCOMPtr_helper {
+ public:
+  nsImportESModule(const char* aURI, const char* aExportName,
+                   nsresult* aErrorPtr, bool aInfallible)
+      : mURI(aURI),
+        mExportName(aExportName),
+        mErrorPtr(aErrorPtr),
+        mInfallible(aInfallible) {
+    MOZ_ASSERT_IF(mErrorPtr, !mInfallible);
+  }
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID,
+                                          void** aResult) const override {
+    nsresult rv = ::mozilla::loader::ImportESModule(mURI, mExportName, aIID,
+                                                    aResult, mInfallible);
+    if (mErrorPtr) {
+      *mErrorPtr = rv;
+    }
+    return rv;
+  }
+
+ private:
+  const char* mURI;
+  const char* mExportName;
+  nsresult* mErrorPtr;
+  bool mInfallible;
+};
+
+/**
+ * Usage with exported name:
+ *
+ * Foo.sys.mjs:
+ *
+ *   export function foo(bar) {
+ *     return bar.toString();
+ *   }
+ *
+ * mozIFoo.idl:
+ *
+ *   interface mozIFoo : nsISupports {
+ *     AString foo(double meh);
+ *   }
+ *
+ * Thing.cpp:
+ *
+ *   nsCOMPtr<mozIFoo> foo = do_ImportESModule(
+ *     "resource://meh/Foo.sys.mjs");
+ *
+ *   MOZ_TRY(foo->Foo(42));
+ *
+ * Usage with a single named object:
+ *
+ * Foo.sys.mjs:
+ *
+ *   export var Foo = {
+ *     function foo(bar) {
+ *       return bar.toString();
+ *     }
+ *   };
+ *
+ * Thing.cpp:
+ *
+ *   nsCOMPtr<mozIFoo> foo = do_ImportESModule(
+ *       "resource:://meh/Foo.sys.mjs", "Foo");
+ */
+
+template <size_t N>
+inline nsImportESModule do_ImportESModule(const char (&aURI)[N]) {
+  return {aURI, nullptr, nullptr, /* infallible */ true};
+}
+
+template <size_t N>
+inline nsImportESModule do_ImportESModule(const char (&aURI)[N],
+                                          const mozilla::fallible_t&) {
+  return {aURI, nullptr, nullptr, /* infallible */ false};
+}
+
+template <size_t N>
+inline nsImportESModule do_ImportESModule(const char (&aURI)[N],
+                                          nsresult* aRv) {
+  return {aURI, nullptr, aRv, /* infallible */ false};
+}
+
+template <size_t N, size_t N2>
+inline nsImportESModule do_ImportESModule(const char (&aURI)[N],
+                                          const char (&aExportName)[N2]) {
+  return {aURI, aExportName, nullptr, /* infallible */ true};
+}
+
+template <size_t N, size_t N2>
+inline nsImportESModule do_ImportESModule(const char (&aURI)[N],
+                                          const char (&aExportName)[N2],
+                                          const mozilla::fallible_t&) {
+  return {aURI, aExportName, nullptr, /* infallible */ false};
+}
+
+template <size_t N, size_t N2>
+inline nsImportESModule do_ImportESModule(const char (&aURI)[N],
+                                          const char (&aExportName)[N2],
+                                          nsresult* aRv) {
+  return {aURI, aExportName, aRv, /* infallible */ false};
+}
+
+#endif  // defined nsImportModule_h