Refactor language detection logic to allow non-static CLD data sources.

chrome/browser/translate/cld_data_harness_factory.cc

+// Copyright 2014 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 "chrome/browser/translate/cld_data_harness_factory.h"
+
+#include "base/lazy_instance.h"
+#include "chrome/browser/translate/component_cld_data_harness.h"
+#include "chrome/browser/translate/standalone_cld_data_harness.h"
+
+namespace {
+
+// This is the global instance managed by Get/Set
+test::CldDataHarnessFactory* g_instance = NULL;
+

[picksi1, 2014/09/29 15:59:08]

Is this the preferred chromium way of implementing instances/singletons? There
are funky static-variables inside private constructor functions that can be used
to guarantee that singletons stay the only instance of a class.

[Andrew Hayden (chromium.org), 2014/10/30 14:25:14]

Yes. However, I am going to cheat heavily and work around this tiresome
boilerplate by exploiting the singletons to do pointer comparison against
"this". I think you'll find the result far easier to read.

+// Global instance wrappers
+class ComponentCldDataHarnessFactory : public test::CldDataHarnessFactory {
+ public:

[picksi1, 2014/09/29 15:59:08]

This looks like it is derived from a test class, which feels wrong. Is there a
common base class that can be used for both this class and the test class?

[Andrew Hayden (chromium.org), 2014/10/30 14:25:15]

I think you'll like the new version much better.

+  virtual scoped_ptr<test::CldDataHarness> CreateCldDataHarness() OVERRIDE {
+    return test::CldDataHarness::COMPONENT();
+  }
+};
+struct WrappedComponent {
+  WrappedComponent() {
+    value = new ComponentCldDataHarnessFactory();
+  }
+  test::CldDataHarnessFactory* value;

[picksi1, 2014/09/29 15:59:08]

Is the name 'value' correct here? Looks like it should be called
'harnessFactory' or something?

[Andrew Hayden (chromium.org), 2014/10/30 14:25:15]

Idiomatic, but now deleted.

+};
+base::LazyInstance<WrappedComponent>::Leaky g_wrapped_component =
+    LAZY_INSTANCE_INITIALIZER;
+
+class StandaloneCldDataHarnessFactory : public test::CldDataHarnessFactory {
+ public:
+  virtual scoped_ptr<test::CldDataHarness> CreateCldDataHarness() OVERRIDE {
+    return test::CldDataHarness::STANDALONE();
+  }
+};
+struct WrappedStandalone {
+  WrappedStandalone() {
+    value = new StandaloneCldDataHarnessFactory();
+  }
+  test::CldDataHarnessFactory* value;
+};
+base::LazyInstance<WrappedStandalone>::Leaky g_wrapped_standalone =
+    LAZY_INSTANCE_INITIALIZER;
+
+class StaticCldDataHarnessFactory : public test::CldDataHarnessFactory {
+ public:
+  virtual scoped_ptr<test::CldDataHarness> CreateCldDataHarness() OVERRIDE {
+    return test::CldDataHarness::STATIC();
+  }
+};
+struct WrappedStatic {
+  WrappedStatic() {
+    value = new StaticCldDataHarnessFactory();
+  }
+  test::CldDataHarnessFactory* value;
+};
+base::LazyInstance<WrappedStatic>::Leaky g_wrapped_static =
+    LAZY_INSTANCE_INITIALIZER;
+
+class NoneCldDataHarnessFactory : public test::CldDataHarnessFactory {
+ public:
+  virtual scoped_ptr<test::CldDataHarness> CreateCldDataHarness() OVERRIDE {
+    return test::CldDataHarness::NONE();
+  }
+};
+struct WrappedNone {
+  WrappedNone() {
+    value = new NoneCldDataHarnessFactory();
+  }
+  test::CldDataHarnessFactory* value;
+};
+base::LazyInstance<WrappedNone>::Leaky g_wrapped_none =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+namespace test {
+
+CldDataHarnessFactory::CldDataHarnessFactory() {
+  // Nothing
+}
+
+CldDataHarnessFactory::~CldDataHarnessFactory() {
+  // Nothing
+}
+
+scoped_ptr<CldDataHarness> CldDataHarnessFactory::CreateCldDataHarness() {
+  scoped_ptr<CldDataHarness> result(new CldDataHarness());
+  return result.Pass();
+}
+
+CldDataHarnessFactory* CldDataHarnessFactory::Get() {
+  if (g_instance == NULL) {
+    return NONE();
+  }
+  return g_instance;
+}
+
+void CldDataHarnessFactory::Set(CldDataHarnessFactory* instance) {
+  g_instance = instance;
+}
+
+/* static */ CldDataHarnessFactory* CldDataHarnessFactory::NONE() {
+  return g_wrapped_none.Get().value;
+}
+
+/* static */ CldDataHarnessFactory* CldDataHarnessFactory::STATIC() {
+  return g_wrapped_static.Get().value;
+}
+
+/* static */ CldDataHarnessFactory* CldDataHarnessFactory::STANDALONE() {
+  return g_wrapped_standalone.Get().value;
+}
+
+/* static */ CldDataHarnessFactory* CldDataHarnessFactory::COMPONENT() {
+  return g_wrapped_component.Get().value;
+}
+
+}  // namespace test