CPP: Make libphonenumber depend on its own base/ when it's used in Chromium.

This is done by adding a USE_BOOST compile time flag that is enabled by default
when the library is compiled with CMake (mainly for external users).

In Chromium, the library will be built without the USE_BOOST compile time flag.
Instead the NO_THREAD_SAFETY flag will have to be provided so that the minimal
non-thread-safe subset of base will be used.
This is possible since libphonenumber is only used from the UI thread in
Chromium.

BUG=http://crbug.com/236272
R=jia.shao.peng@gmail.com

Review URL: https://codereview.appspot.com/8859052

git-svn-id: http://libphonenumber.googlecode.com/svn/trunk/cpp/src/phonenumbers@568 ee073f10-1060-11df-b6a4-87a95322a99c

6 files changed, 636 insertions, 21 deletions

diff --git a/base/logging.h b/base/logging.h
index 6cca5c6..47c6cee 100644
--- a/base/logging.h
+++ b/base/logging.h
@@ -21,13 +21,17 @@
 
 #include <cassert>
 
+#if !defined(CHECK_EQ)
 #define CHECK_EQ(X, Y) assert((X) == (Y))
-
-# define DCHECK(X) assert(X)
-# define DCHECK_EQ(X, Y) CHECK_EQ((X), (Y))
-# define DCHECK_GE(X, Y) assert((X) >= (Y))
-# define DCHECK_GT(X, Y) assert((X) > (Y))
-# define DCHECK_LT(X, Y) assert((X) < (Y))
+#endif
+
+#if !defined(DCHECK)
+#define DCHECK(X) assert(X)
+#define DCHECK_EQ(X, Y) CHECK_EQ((X), (Y))
+#define DCHECK_GE(X, Y) assert((X) >= (Y))
+#define DCHECK_GT(X, Y) assert((X) > (Y))
+#define DCHECK_LT(X, Y) assert((X) < (Y))
+#endif
 
 template <typename T> T* CHECK_NOTNULL(T* ptr) {
   assert(ptr);
diff --git a/base/memory/scoped_ptr.h b/base/memory/scoped_ptr.h
index d9a08ec..d6147a7 100644
--- a/base/memory/scoped_ptr.h
+++ b/base/memory/scoped_ptr.h
@@ -1,24 +1,454 @@
-// Copyright (C) 2011 The Libphonenumber Authors
+// Copyright (c) 2012 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.
+
+#ifndef I18N_PHONENUMBERS_BASE_MEMORY_SCOPED_PTR_H_
+#define I18N_PHONENUMBERS_BASE_MEMORY_SCOPED_PTR_H_
+
+#if defined(I18N_PHONENUMBERS_USE_BOOST)
+
+#include <boost/scoped_ptr.hpp>
+using boost::scoped_ptr;
+
+#else  // !I18N_PHONENUMBERS_USE_BOOST
+
+// This is an implementation designed to match the anticipated future TR2
+// implementation of the scoped_ptr class and scoped_ptr_malloc (deprecated).
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+#include <algorithm>  // For std::swap().
+
+#include "phonenumbers/base/basictypes.h"
+#include "phonenumbers/base/template_util.h"
+
+namespace base {
+
+// Function object which deletes its parameter, which must be a pointer.
+// If C is an array type, invokes 'delete[]' on the parameter; otherwise,
+// invokes 'delete'. The default deleter for scoped_ptr<T>.
+template <class T>
+struct DefaultDeleter {
+  DefaultDeleter() {}
+  template <typename U> DefaultDeleter(const DefaultDeleter<U>& other) {
+    // IMPLEMENTATION NOTE: C++11 20.7.1.1.2p2 only provides this constructor
+    // if U* is implicitly convertible to T* and U is not an array type.
+    //
+    // Correct implementation should use SFINAE to disable this
+    // constructor. However, since there are no other 1-argument constructors,
+    // using a COMPILE_ASSERT() based on is_convertible<> and requiring
+    // complete types is simpler and will cause compile failures for equivalent
+    // misuses.
+    //
+    // Note, the is_convertible<U*, T*> check also ensures that U is not an
+    // array. T is guaranteed to be a non-array, so any U* where U is an array
+    // cannot convert to T*.
+    enum { T_must_be_complete = sizeof(T) };
+    enum { U_must_be_complete = sizeof(U) };
+    COMPILE_ASSERT((base::is_convertible<U*, T*>::value),
+                   U_ptr_must_implicitly_convert_to_T_ptr);
+  }
+  inline void operator()(T* ptr) const {
+    enum { type_must_be_complete = sizeof(T) };
+    delete ptr;
+  }
+};
+
+// Specialization of DefaultDeleter for array types.
+template <class T>
+struct DefaultDeleter<T[]> {
+  inline void operator()(T* ptr) const {
+    enum { type_must_be_complete = sizeof(T) };
+    delete[] ptr;
+  }
+
+ private:
+  // Disable this operator for any U != T because it is undefined to execute
+  // an array delete when the static type of the array mismatches the dynamic
+  // type.
+  //
+  // References:
+  //   C++98 [expr.delete]p3
+  //   http://cplusplus.github.com/LWG/lwg-defects.html#938
+  template <typename U> void operator()(U* array) const;
+};
+
+template <class T, int n>
+struct DefaultDeleter<T[n]> {
+  // Never allow someone to declare something like scoped_ptr<int[10]>.
+  COMPILE_ASSERT(sizeof(T) == -1, do_not_use_array_with_size_as_type);
+};
+
+// Function object which invokes 'free' on its parameter, which must be
+// a pointer. Can be used to store malloc-allocated pointers in scoped_ptr:
 //
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
+// scoped_ptr<int, base::FreeDeleter> foo_ptr(
+//     static_cast<int*>(malloc(sizeof(int))));
+struct FreeDeleter {
+  inline void operator()(void* ptr) const {
+    free(ptr);
+  }
+};
+
+namespace internal {
+
+// Minimal implementation of the core logic of scoped_ptr, suitable for
+// reuse in both scoped_ptr and its specializations.
+template <class T, class D>
+class scoped_ptr_impl {
+ public:
+  explicit scoped_ptr_impl(T* p) : data_(p) { }
+
+  // Initializer for deleters that have data parameters.
+  scoped_ptr_impl(T* p, const D& d) : data_(p, d) {}
+
+  // Templated constructor that destructively takes the value from another
+  // scoped_ptr_impl.
+  template <typename U, typename V>
+  scoped_ptr_impl(scoped_ptr_impl<U, V>* other)
+      : data_(other->release(), other->get_deleter()) {
+    // We do not support move-only deleters.  We could modify our move
+    // emulation to have base::subtle::move() and base::subtle::forward()
+    // functions that are imperfect emulations of their C++11 equivalents,
+    // but until there's a requirement, just assume deleters are copyable.
+  }
+
+  template <typename U, typename V>
+  void TakeState(scoped_ptr_impl<U, V>* other) {
+    // See comment in templated constructor above regarding lack of support
+    // for move-only deleters.
+    reset(other->release());
+    get_deleter() = other->get_deleter();
+  }
+
+  ~scoped_ptr_impl() {
+    if (data_.ptr != NULL) {
+      // Not using get_deleter() saves one function call in non-optimized
+      // builds.
+      static_cast<D&>(data_)(data_.ptr);
+    }
+  }
+
+  void reset(T* p) {
+    // This is a self-reset, which is no longer allowed: http://crbug.com/162971
+    if (p != NULL && p == data_.ptr)
+      abort();
+
+    // Note that running data_.ptr = p can lead to undefined behavior if
+    // get_deleter()(get()) deletes this. In order to pevent this, reset()
+    // should update the stored pointer before deleting its old value.
+    //
+    // However, changing reset() to use that behavior may cause current code to
+    // break in unexpected ways. If the destruction of the owned object
+    // dereferences the scoped_ptr when it is destroyed by a call to reset(),
+    // then it will incorrectly dispatch calls to |p| rather than the original
+    // value of |data_.ptr|.
+    //
+    // During the transition period, set the stored pointer to NULL while
+    // deleting the object. Eventually, this safety check will be removed to
+    // prevent the scenario initially described from occuring and
+    // http://crbug.com/176091 can be closed.
+    T* old = data_.ptr;
+    data_.ptr = NULL;
+    if (old != NULL)
+      static_cast<D&>(data_)(old);
+    data_.ptr = p;
+  }
+
+  T* get() const { return data_.ptr; }
+
+  D& get_deleter() { return data_; }
+  const D& get_deleter() const { return data_; }
+
+  void swap(scoped_ptr_impl& p2) {
+    // Standard swap idiom: 'using std::swap' ensures that std::swap is
+    // present in the overload set, but we call swap unqualified so that
+    // any more-specific overloads can be used, if available.
+    using std::swap;
+    swap(static_cast<D&>(data_), static_cast<D&>(p2.data_));
+    swap(data_.ptr, p2.data_.ptr);
+  }
+
+  T* release() {
+    T* old_ptr = data_.ptr;
+    data_.ptr = NULL;
+    return old_ptr;
+  }
+
+ private:
+  // Needed to allow type-converting constructor.
+  template <typename U, typename V> friend class scoped_ptr_impl;
+
+  // Use the empty base class optimization to allow us to have a D
+  // member, while avoiding any space overhead for it when D is an
+  // empty class.  See e.g. http://www.cantrip.org/emptyopt.html for a good
+  // discussion of this technique.
+  struct Data : public D {
+    explicit Data(T* ptr_in) : ptr(ptr_in) {}
+    Data(T* ptr_in, const D& other) : D(other), ptr(ptr_in) {}
+    T* ptr;
+  };
+
+  Data data_;
+
+  DISALLOW_COPY_AND_ASSIGN(scoped_ptr_impl);
+};
+
+}  // namespace internal
+
+}  // namespace base
+
+// A scoped_ptr<T> is like a T*, except that the destructor of scoped_ptr<T>
+// automatically deletes the pointer it holds (if any).
+// That is, scoped_ptr<T> owns the T object that it points to.
+// Like a T*, a scoped_ptr<T> may hold either NULL or a pointer to a T object.
+// Also like T*, scoped_ptr<T> is thread-compatible, and once you
+// dereference it, you get the thread safety guarantees of T.
 //
-// http://www.apache.org/licenses/LICENSE-2.0
+// The size of scoped_ptr is small. On most compilers, when using the
+// DefaultDeleter, sizeof(scoped_ptr<T>) == sizeof(T*). Custom deleters will
+// increase the size proportional to whatever state they need to have. See
+// comments inside scoped_ptr_impl<> for details.
 //
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
+// Current implementation targets having a strict subset of  C++11's
+// unique_ptr<> features. Known deficiencies include not supporting move-only
+// deleteres, function pointers as deleters, and deleters with reference
+// types.
+template <class T, class D = base::DefaultDeleter<T> >
+class scoped_ptr {
+ public:
+  // The element and deleter types.
+  typedef T element_type;
+  typedef D deleter_type;
 
-// Author: Philippe Liard
+  // Constructor.  Defaults to initializing with NULL.
+  scoped_ptr() : impl_(NULL) { }
 
-#ifndef I18N_PHONENUMBERS_BASE_MEMORY_SCOPED_PTR_H_
-#define I18N_PHONENUMBERS_BASE_MEMORY_SCOPED_PTR_H_
+  // Constructor.  Takes ownership of p.
+  explicit scoped_ptr(element_type* p) : impl_(p) { }
 
-#include <boost/scoped_ptr.hpp>
+  // Constructor.  Allows initialization of a stateful deleter.
+  scoped_ptr(element_type* p, const D& d) : impl_(p, d) { }
 
-using boost::scoped_ptr;
+  // Constructor.  Allows construction from a scoped_ptr rvalue for a
+  // convertible type and deleter.
+  //
+  // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this constructor distinct
+  // from the normal move constructor. By C++11 20.7.1.2.1.21, this constructor
+  // has different post-conditions if D is a reference type. Since this
+  // implementation does not support deleters with reference type,
+  // we do not need a separate move constructor allowing us to avoid one
+  // use of SFINAE. You only need to care about this if you modify the
+  // implementation of scoped_ptr.
+  template <typename U, typename V>
+  scoped_ptr(scoped_ptr<U, V> other) : impl_(&other.impl_) {
+    COMPILE_ASSERT(!base::is_array<U>::value, U_cannot_be_an_array);
+  }
+
+  // operator=.  Allows assignment from a scoped_ptr rvalue for a convertible
+  // type and deleter.
+  //
+  // IMPLEMENTATION NOTE: C++11 unique_ptr<> keeps this operator= distinct from
+  // the normal move assignment operator. By C++11 20.7.1.2.3.4, this templated
+  // form has different requirements on for move-only Deleters. Since this
+  // implementation does not support move-only Deleters, we do not need a
+  // separate move assignment operator allowing us to avoid one use of SFINAE.
+  // You only need to care about this if you modify the implementation of
+  // scoped_ptr.
+  template <typename U, typename V>
+  scoped_ptr& operator=(scoped_ptr<U, V> rhs) {
+    COMPILE_ASSERT(!base::is_array<U>::value, U_cannot_be_an_array);
+    impl_.TakeState(&rhs.impl_);
+    return *this;
+  }
+
+  // Reset.  Deletes the currently owned object, if any.
+  // Then takes ownership of a new object, if given.
+  void reset(element_type* p = NULL) { impl_.reset(p); }
+
+  // Accessors to get the owned object.
+  // operator* and operator-> will assert() if there is no current object.
+  element_type& operator*() const {
+    assert(impl_.get() != NULL);
+    return *impl_.get();
+  }
+  element_type* operator->() const  {
+    assert(impl_.get() != NULL);
+    return impl_.get();
+  }
+  element_type* get() const { return impl_.get(); }
+
+  // Access to the deleter.
+  deleter_type& get_deleter() { return impl_.get_deleter(); }
+  const deleter_type& get_deleter() const { return impl_.get_deleter(); }
+
+  // Allow scoped_ptr<element_type> to be used in boolean expressions, but not
+  // implicitly convertible to a real bool (which is dangerous).
+ private:
+  typedef base::internal::scoped_ptr_impl<element_type, deleter_type>
+      scoped_ptr::*Testable;
+
+ public:
+  operator Testable() const { return impl_.get() ? &scoped_ptr::impl_ : NULL; }
+
+  // Comparison operators.
+  // These return whether two scoped_ptr refer to the same object, not just to
+  // two different but equal objects.
+  bool operator==(const element_type* p) const { return impl_.get() == p; }
+  bool operator!=(const element_type* p) const { return impl_.get() != p; }
+
+  // Swap two scoped pointers.
+  void swap(scoped_ptr& p2) {
+    impl_.swap(p2.impl_);
+  }
+
+  // Release a pointer.
+  // The return value is the current pointer held by this object.
+  // If this object holds a NULL pointer, the return value is NULL.
+  // After this operation, this object will hold a NULL pointer,
+  // and will not own the object any more.
+  element_type* release() {
+    return impl_.release();
+  }
+
+ private:
+  // Needed to reach into |impl_| in the constructor.
+  template <typename U, typename V> friend class scoped_ptr;
+  base::internal::scoped_ptr_impl<element_type, deleter_type> impl_;
+
+  // Forbid comparison of scoped_ptr types.  If U != T, it totally
+  // doesn't make sense, and if U == T, it still doesn't make sense
+  // because you should never have the same object owned by two different
+  // scoped_ptrs.
+  template <class U> bool operator==(scoped_ptr<U> const& p2) const;
+  template <class U> bool operator!=(scoped_ptr<U> const& p2) const;
+};
+
+template <class T, class D>
+class scoped_ptr<T[], D> {
+ public:
+  // The element and deleter types.
+  typedef T element_type;
+  typedef D deleter_type;
+
+  // Constructor.  Defaults to initializing with NULL.
+  scoped_ptr() : impl_(NULL) { }
+
+  // Constructor. Stores the given array. Note that the argument's type
+  // must exactly match T*. In particular:
+  // - it cannot be a pointer to a type derived from T, because it is
+  //   inherently unsafe in the general case to access an array through a
+  //   pointer whose dynamic type does not match its static type (eg., if
+  //   T and the derived types had different sizes access would be
+  //   incorrectly calculated). Deletion is also always undefined
+  //   (C++98 [expr.delete]p3). If you're doing this, fix your code.
+  // - it cannot be NULL, because NULL is an integral expression, not a
+  //   pointer to T. Use the no-argument version instead of explicitly
+  //   passing NULL.
+  // - it cannot be const-qualified differently from T per unique_ptr spec
+  //   (http://cplusplus.github.com/LWG/lwg-active.html#2118). Users wanting
+  //   to work around this may use implicit_cast<const T*>().
+  //   However, because of the first bullet in this comment, users MUST
+  //   NOT use implicit_cast<Base*>() to upcast the static type of the array.
+  explicit scoped_ptr(element_type* array) : impl_(array) { }
+
+  // Reset.  Deletes the currently owned array, if any.
+  // Then takes ownership of a new object, if given.
+  void reset(element_type* array = NULL) { impl_.reset(array); }
+
+  // Accessors to get the owned array.
+  element_type& operator[](size_t i) const {
+    assert(impl_.get() != NULL);
+    return impl_.get()[i];
+  }
+  element_type* get() const { return impl_.get(); }
+
+  // Access to the deleter.
+  deleter_type& get_deleter() { return impl_.get_deleter(); }
+  const deleter_type& get_deleter() const { return impl_.get_deleter(); }
+
+  // Allow scoped_ptr<element_type> to be used in boolean expressions, but not
+  // implicitly convertible to a real bool (which is dangerous).
+ private:
+  typedef base::internal::scoped_ptr_impl<element_type, deleter_type>
+      scoped_ptr::*Testable;
+
+ public:
+  operator Testable() const { return impl_.get() ? &scoped_ptr::impl_ : NULL; }
+
+  // Comparison operators.
+  // These return whether two scoped_ptr refer to the same object, not just to
+  // two different but equal objects.
+  bool operator==(element_type* array) const { return impl_.get() == array; }
+  bool operator!=(element_type* array) const { return impl_.get() != array; }
+
+  // Swap two scoped pointers.
+  void swap(scoped_ptr& p2) {
+    impl_.swap(p2.impl_);
+  }
+
+  // Release a pointer.
+  // The return value is the current pointer held by this object.
+  // If this object holds a NULL pointer, the return value is NULL.
+  // After this operation, this object will hold a NULL pointer,
+  // and will not own the object any more.
+  element_type* release() {
+    return impl_.release();
+  }
+
+ private:
+  // Force element_type to be a complete type.
+  enum { type_must_be_complete = sizeof(element_type) };
+
+  // Actually hold the data.
+  base::internal::scoped_ptr_impl<element_type, deleter_type> impl_;
+
+  // Disable initialization from any type other than element_type*, by
+  // providing a constructor that matches such an initialization, but is
+  // private and has no definition. This is disabled because it is not safe to
+  // call delete[] on an array whose static type does not match its dynamic
+  // type.
+  template <typename U> explicit scoped_ptr(U* array);
+  explicit scoped_ptr(int disallow_construction_from_null);
+
+  // Disable reset() from any type other than element_type*, for the same
+  // reasons as the constructor above.
+  template <typename U> void reset(U* array);
+  void reset(int disallow_reset_from_null);
+
+  // Forbid comparison of scoped_ptr types.  If U != T, it totally
+  // doesn't make sense, and if U == T, it still doesn't make sense
+  // because you should never have the same object owned by two different
+  // scoped_ptrs.
+  template <class U> bool operator==(scoped_ptr<U> const& p2) const;
+  template <class U> bool operator!=(scoped_ptr<U> const& p2) const;
+};
+
+// Free functions
+template <class T, class D>
+void swap(scoped_ptr<T, D>& p1, scoped_ptr<T, D>& p2) {
+  p1.swap(p2);
+}
+
+template <class T, class D>
+bool operator==(T* p1, const scoped_ptr<T, D>& p2) {
+  return p1 == p2.get();
+}
+
+template <class T, class D>
+bool operator!=(T* p1, const scoped_ptr<T, D>& p2) {
+  return p1 != p2.get();
+}
+
+// A function to convert T* into scoped_ptr<T>
+// Doing e.g. make_scoped_ptr(new FooBarBaz<type>(arg)) is a shorter notation
+// for scoped_ptr<FooBarBaz<type> >(new FooBarBaz<type>(arg))
+template <typename T>
+scoped_ptr<T> make_scoped_ptr(T* ptr) {
+  return scoped_ptr<T>(ptr);
+}
 
+#endif  // !I18N_PHONENUMBERS_USE_BOOST
 #endif  // I18N_PHONENUMBERS_BASE_MEMORY_SCOPED_PTR_H_
diff --git a/base/memory/singleton.h b/base/memory/singleton.h
index 86d3cbc..43c5a1a 100644
--- a/base/memory/singleton.h
+++ b/base/memory/singleton.h
@@ -17,6 +17,8 @@
 #ifndef I18N_PHONENUMBERS_BASE_SINGLETON_H_
 #define I18N_PHONENUMBERS_BASE_SINGLETON_H_
 
+#if defined(I18N_PHONENUMBERS_USE_BOOST)
+
 #include <boost/scoped_ptr.hpp>
 #include <boost/thread/once.hpp>
 #include <boost/utility.hpp>
@@ -46,6 +48,31 @@ class Singleton : private boost::noncopyable {
 template <class T> boost::scoped_ptr<T> Singleton<T>::instance;
 template <class T> boost::once_flag Singleton<T>::flag = BOOST_ONCE_INIT;
 
+#else  // !I18N_PHONENUMBERS_USE_BOOST
+
+#include "phonenumbers/base/thread_safety_check.h"
+
+namespace i18n {
+namespace phonenumbers {
+
+// Note that this implementation is not thread-safe. For a thread-safe
+// implementation, please compile with -DI18N_PHONENUMBERS_USE_BOOST.
+template <class T>
+class Singleton {
+ public:
+  virtual ~Singleton() {}
+
+  static T* GetInstance() {
+    static T* instance = NULL;
+    if (!instance) {
+      instance = new T();
+    }
+    return instance;
+  }
+};
+
+#endif  // !I18N_PHONENUMBERS_USE_BOOST
+
 }  // namespace phonenumbers
 }  // namespace i18n
 
diff --git a/base/synchronization/lock.h b/base/synchronization/lock.h
index 29e9bf2..502c75f 100644
--- a/base/synchronization/lock.h
+++ b/base/synchronization/lock.h
@@ -17,6 +17,7 @@
 #ifndef I18N_PHONENUMBERS_BASE_SYNCHRONIZATION_LOCK_H_
 #define I18N_PHONENUMBERS_BASE_SYNCHRONIZATION_LOCK_H_
 
+#if defined(I18N_PHONENUMBERS_USE_BOOST)
 #include <boost/thread/mutex.hpp>
 
 namespace base {
@@ -24,4 +25,20 @@ namespace base {
   typedef boost::mutex::scoped_lock AutoLock;
 }
 
+#else  // I18N_PHONENUMBERS_USE_BOOST
+#include "phonenumbers/base/thread_safety_check.h"
+
+namespace base {
+
+// Dummy lock implementation. If you care about thread-safety, please compile
+// with -DI18N_PHONENUMBERS_USE_BOOST.
+struct Lock {};
+
+struct AutoLock {
+  AutoLock(Lock) {}
+};
+
+}  // namespace base
+
+#endif  // I18N_PHONENUMBERS_USE_BOOST
 #endif  // I18N_PHONENUMBERS_BASE_SYNCHRONIZATION_LOCK_H_
diff --git a/base/template_util.h b/base/template_util.h
new file mode 100644
index 0000000..8076e1e
--- /dev/null
+++ b/base/template_util.h
@@ -0,0 +1,106 @@
+// Copyright (c) 2011 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.
+
+#ifndef I18N_PHONENUMBERS_BASE_TEMPLATE_UTIL_H_
+#define I18N_PHONENUMBERS_BASE_TEMPLATE_UTIL_H_
+
+#include <cstddef>  // For size_t.
+
+namespace base {
+
+// template definitions from tr1
+
+template<class T, T v>
+struct integral_constant {
+  static const T value = v;
+  typedef T value_type;
+  typedef integral_constant<T, v> type;
+};
+
+template <class T, T v> const T integral_constant<T, v>::value;
+
+typedef integral_constant<bool, true> true_type;
+typedef integral_constant<bool, false> false_type;
+
+template <class T> struct is_pointer : false_type {};
+template <class T> struct is_pointer<T*> : true_type {};
+
+template <class T, class U> struct is_same : public false_type {};
+template <class T> struct is_same<T,T> : true_type {};
+
+template<class> struct is_array : public false_type {};
+template<class T, size_t n> struct is_array<T[n]> : public true_type {};
+template<class T> struct is_array<T[]> : public true_type {};
+
+template <class T> struct is_non_const_reference : false_type {};
+template <class T> struct is_non_const_reference<T&> : true_type {};
+template <class T> struct is_non_const_reference<const T&> : false_type {};
+
+template <class T> struct is_void : false_type {};
+template <> struct is_void<void> : true_type {};
+
+namespace internal {
+
+// Types YesType and NoType are guaranteed such that sizeof(YesType) <
+// sizeof(NoType).
+typedef char YesType;
+
+struct NoType {
+  YesType dummy[2];
+};
+
+// This class is an implementation detail for is_convertible, and you
+// don't need to know how it works to use is_convertible. For those
+// who care: we declare two different functions, one whose argument is
+// of type To and one with a variadic argument list. We give them
+// return types of different size, so we can use sizeof to trick the
+// compiler into telling us which function it would have chosen if we
+// had called it with an argument of type From.  See Alexandrescu's
+// _Modern C++ Design_ for more details on this sort of trick.
+
+struct ConvertHelper {
+  template <typename To>
+  static YesType Test(To);
+
+  template <typename To>
+  static NoType Test(...);
+
+  template <typename From>
+  static From& Create();
+};
+
+// Used to determine if a type is a struct/union/class. Inspired by Boost's
+// is_class type_trait implementation.
+struct IsClassHelper {
+  template <typename C>
+  static YesType Test(void(C::*)(void));
+
+  template <typename C>
+  static NoType Test(...);
+};
+
+}  // namespace internal
+
+// Inherits from true_type if From is convertible to To, false_type otherwise.
+//
+// Note that if the type is convertible, this will be a true_type REGARDLESS
+// of whether or not the conversion would emit a warning.
+template <typename From, typename To>
+struct is_convertible
+    : integral_constant<bool,
+                        sizeof(internal::ConvertHelper::Test<To>(
+                                   internal::ConvertHelper::Create<From>())) ==
+                        sizeof(internal::YesType)> {
+};
+
+template <typename T>
+struct is_class
+    : integral_constant<bool,
+                        sizeof(internal::IsClassHelper::Test<T>(0)) ==
+                            sizeof(internal::YesType)> {
+};
+
+}  // namespace base
+
+#endif  // I18N_PHONENUMBERS_BASE_TEMPLATE_UTIL_H_
diff --git a/base/thread_safety_check.h b/base/thread_safety_check.h
new file mode 100644
index 0000000..b11bdf5
--- /dev/null
+++ b/base/thread_safety_check.h
@@ -0,0 +1,31 @@
+// Copyright (C) 2013 The Libphonenumber Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Author: Philippe Liard
+
+#ifndef I18N_PHONENUMBERS_BASE_THREAD_SAFETY_CHECK_H_
+#define I18N_PHONENUMBERS_BASE_THREAD_SAFETY_CHECK_H_
+
+#if !defined(I18N_PHONENUMBERS_USE_BOOST)
+
+// Note that I18N_PHONENUMBERS_NO_THREAD_SAFETY must be defined only to let the
+// user of the library know that it can't be used in a thread-safe manner when
+// it is not depending on Boost.
+#if !defined(I18N_PHONENUMBERS_NO_THREAD_SAFETY)
+#error "Building without Boost, please provide -DNO_THREAD_SAFETY"
+#endif
+
+#endif
+
+#endif  // I18N_PHONENUMBERS_BASE_THREAD_SAFETY_CHECK_H_