Dart: Adds a program to create snapshots of Mojo apps.

mojo/dart/dart_snapshotter/loader.cc

Index: mojo/dart/dart_snapshotter/loader.cc
diff --git a/mojo/dart/dart_snapshotter/loader.cc b/mojo/dart/dart_snapshotter/loader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fa32659fc74be35455a6115c17622bd1ae0eb695
--- /dev/null
+++ b/mojo/dart/dart_snapshotter/loader.cc
@@ -0,0 +1,134 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "mojo/dart/dart_snapshotter/loader.h"
+
+#include "base/command_line.h"
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/logging.h"
+#include "base/strings/string_util.h"
+#include "mojo/dart/dart_snapshotter/logging.h"
+#include "mojo/dart/dart_snapshotter/scope.h"
+#include "mojo/dart/dart_snapshotter/switches.h"
+
+namespace {
+
+std::string Fetch(const std::string& url) {
+  base::FilePath path(url);
+  std::string source;
+  CHECK(base::ReadFileToString(path, &source)) << url;
+  return source;
+}
+
+base::FilePath SimplifyPath(const base::FilePath& path) {
+  //if (path.IsAbsolute()) return path;

[Cutch, 2015/08/10 20:45:02]

Un-comment or remove before committing 

[zra, 2015/08/10 22:59:21]

Done.

+  std::vector<base::FilePath::StringType> components;
+  path.GetComponents(&components);
+  base::FilePath result;
+  if (path.IsAbsolute()) {
+    base::FilePath root("/");
+    result = root;
+  }
+  for (const auto& component : components) {
+    base::FilePath c(component);
+    if (c.IsAbsolute()) continue;
+    if (component == base::FilePath::kCurrentDirectory)
+      continue;
+    if (component == base::FilePath::kParentDirectory)
+      result = result.DirName();
+    else
+      result = result.Append(component);
+  }
+  return result;
+}
+
+class Loader {
+ public:
+  Loader(const base::FilePath& package_root);
+
+  std::string CanonicalizePackageURL(std::string url);
+  Dart_Handle CanonicalizeURL(Dart_Handle library, Dart_Handle url);
+  Dart_Handle Import(Dart_Handle url);
+  Dart_Handle Source(Dart_Handle library, Dart_Handle url);
+
+ private:
+  base::FilePath package_root_;
+
+  DISALLOW_COPY_AND_ASSIGN(Loader);
+};
+
+Loader::Loader(const base::FilePath& package_root)
+    : package_root_(package_root) {
+}
+
+std::string Loader::CanonicalizePackageURL(std::string url) {
+  DCHECK(StartsWithASCII(url, "package:", true));
+  ReplaceFirstSubstringAfterOffset(&url, 0, "package:", "");
+  return package_root_.Append(url).AsUTF8Unsafe();
+}
+
+Dart_Handle Loader::CanonicalizeURL(Dart_Handle library, Dart_Handle url) {
+  std::string string = StringFromDart(url);
+  if (StartsWithASCII(string, "dart:", true))
+    return url;
+  if (StartsWithASCII(string, "package:", true))
+    return StringToDart(CanonicalizePackageURL(string));
+  base::FilePath base_path(StringFromDart(Dart_LibraryUrl(library)));
+  base::FilePath resolved_path = base_path.DirName().Append(string);
+  base::FilePath normalized_path = SimplifyPath(resolved_path);
+  return StringToDart(normalized_path.AsUTF8Unsafe());
+}
+
+Dart_Handle Loader::Import(Dart_Handle url) {
+  Dart_Handle source = StringToDart(Fetch(StringFromDart(url)));
+  Dart_Handle result = Dart_LoadLibrary(url, source, 0, 0);
+  LogIfError(result);
+  return result;
+}
+
+Dart_Handle Loader::Source(Dart_Handle library, Dart_Handle url) {
+  Dart_Handle source = StringToDart(Fetch(StringFromDart(url)));
+  Dart_Handle result = Dart_LoadSource(library, url, source, 0, 0);
+  LogIfError(result);
+  return result;
+}
+
+Loader* g_loader = nullptr;
+
+Loader& GetLoader() {
+  if (!g_loader) {
+    base::CommandLine& command_line = *base::CommandLine::ForCurrentProcess();
+    CHECK(command_line.HasSwitch(switches::kPackageRoot))
+        << "Need --package-root";
+    g_loader =
+        new Loader(command_line.GetSwitchValuePath(switches::kPackageRoot));
+  }
+  return *g_loader;
+}
+
+}  // namespace
+
+Dart_Handle HandleLibraryTag(Dart_LibraryTag tag,

[Cutch, 2015/08/10 20:45:02]

Why can't you just use:

tonic::DartLibraryLoader::HandleLibraryTag and tonic::DartLibraryProviderFiles ?

[zra, 2015/08/10 22:59:21]

I tried doing this. I'm not sure it's a good trade-off for the added complexity
of setting up the Mojo machinery. I'd like to leave this as-is.

+                             Dart_Handle library,
+                             Dart_Handle url) {
+  CHECK(Dart_IsLibrary(library));
+  CHECK(Dart_IsString(url));
+
+  if (tag == Dart_kCanonicalizeUrl)
+    return GetLoader().CanonicalizeURL(library, url);
+
+  if (tag == Dart_kImportTag)
+    return GetLoader().Import(url);
+
+  if (tag == Dart_kSourceTag)
+    return GetLoader().Source(library, url);
+
+  return Dart_NewApiError("Unknown library tag.");
+}
+
+void LoadScript(const std::string& url) {
+  LogIfError(
+      Dart_LoadScript(StringToDart(url), StringToDart(Fetch(url)), 0, 0));
+}