Add nonstd::unique_ptr as a workaround until std::unique_ptr is allowed.

This is a copy of breakpad's standalone scoped_ptr, which has been
renamed to nonstd::unique_ptr, and from which more complicated classes
have been removed. The reset() method has also been tweaked to more
closely match c++11, and an implicit conversion to bool has been added.

BUG=https://code.google.com/p/pdfium/issues/detail?id=55
R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1091283002

3 files changed, 182 insertions, 0 deletions

diff --git a/third_party/BUILD.gn b/third_party/BUILD.gn
index c6de4535da..18baeb2eb5 100644
--- a/third_party/BUILD.gn
+++ b/third_party/BUILD.gn
@@ -78,6 +78,7 @@ source_set("pdfium_base") {
   sources = [
     "base/logging.h",
     "base/macros.h",
+    "base/nonstd_unique_ptr.h",
     "base/numerics/safe_conversions.h",
     "base/numerics/safe_conversions_impl.h",
     "base/numerics/safe_math.h",
diff --git a/third_party/base/nonstd_unique_ptr.h b/third_party/base/nonstd_unique_ptr.h
new file mode 100644
index 0000000000..9c0b13c1bf
--- /dev/null
+++ b/third_party/base/nonstd_unique_ptr.h
@@ -0,0 +1,180 @@
+// Copyright 2013 Google Inc. All Rights Reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// This is a copy of breakpad's standalone scoped_ptr, which has been
+// renamed to nonstd::unique_ptr, and from which more complicated classes
+// have been removed. The reset() method has also been tweaked to more
+// closely match c++11, and an implicit conversion to bool has been added.
+
+// Scopers help you manage ownership of a pointer, helping you easily manage the
+// a pointer within a scope, and automatically destroying the pointer at the
+// end of a scope.
+//
+// Example usage (unique_ptr):
+//   {
+//     unique_ptr<Foo> foo(new Foo("wee"));
+//   }  // foo goes out of scope, releasing the pointer with it.
+//
+//   {
+//     unique_ptr<Foo> foo;          // No pointer managed.
+//     foo.reset(new Foo("wee"));    // Now a pointer is managed.
+//     foo.reset(new Foo("wee2"));   // Foo("wee") was destroyed.
+//     foo.reset(new Foo("wee3"));   // Foo("wee2") was destroyed.
+//     foo->Method();                // Foo::Method() called.
+//     foo.get()->Method();          // Foo::Method() called.
+//     SomeFunc(foo.release());      // SomeFunc takes ownership, foo no longer
+//                                   // manages a pointer.
+//     foo.reset(new Foo("wee4"));   // foo manages a pointer again.
+//     foo.reset();                  // Foo("wee4") destroyed, foo no longer
+//                                   // manages a pointer.
+//   }  // foo wasn't managing a pointer, so nothing was destroyed.
+
+#ifndef NONSTD_UNIQUE_PTR_H_
+#define NONSTD_UNIQUE_PTR_H_
+
+// This is an implementation designed to match the anticipated future TR2
+// implementation of the unique_ptr class.
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+namespace nonstd {
+
+// A unique_ptr<T> is like a T*, except that the destructor of unique_ptr<T>
+// automatically deletes the pointer it holds (if any).
+// That is, unique_ptr<T> owns the T object that it points to.
+// Like a T*, a unique_ptr<T> may hold either NULL or a pointer to a T object.
+// Also like T*, unique_ptr<T> is thread-compatible, and once you
+// dereference it, you get the threadsafety guarantees of T.
+//
+// The size of a unique_ptr is small:
+// sizeof(unique_ptr<C>) == sizeof(C*)
+template <class C>
+class unique_ptr {
+ public:
+
+  // The element type
+  typedef C element_type;
+
+  // Constructor.  Defaults to initializing with NULL.
+  // There is no way to create an uninitialized unique_ptr.
+  // The input parameter must be allocated with new.
+  explicit unique_ptr(C* p = NULL) : ptr_(p) { }
+
+  // Destructor.  If there is a C object, delete it.
+  // We don't need to test ptr_ == NULL because C++ does that for us.
+  ~unique_ptr() {
+    enum { type_must_be_complete = sizeof(C) };
+    delete ptr_;
+  }
+
+  // Reset.  Deletes the current owned object, if any.
+  // Then takes ownership of a new object, if given.
+  // this->reset(this->get()) works.
+  void reset(C* p = NULL) {
+    if (p != ptr_) {
+      enum { type_must_be_complete = sizeof(C) };
+      C* old_ptr = ptr_;
+      ptr_ = p;
+      delete old_ptr;
+    }
+  }
+
+  // Accessors to get the owned object.
+  // operator* and operator-> will assert() if there is no current object.
+  C& operator*() const {
+    assert(ptr_ != NULL);
+    return *ptr_;
+  }
+  C* operator->() const  {
+    assert(ptr_ != NULL);
+    return ptr_;
+  }
+  C* get() const { return ptr_; }
+
+  // Comparison operators.
+  // These return whether two unique_ptr refer to the same object, not just to
+  // two different but equal objects.
+  bool operator==(C* p) const { return ptr_ == p; }
+  bool operator!=(C* p) const { return ptr_ != p; }
+
+  // Swap two scoped pointers.
+  void swap(unique_ptr& p2) {
+    C* tmp = ptr_;
+    ptr_ = p2.ptr_;
+    p2.ptr_ = tmp;
+  }
+
+  // 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.
+  C* release() {
+    C* retVal = ptr_;
+    ptr_ = NULL;
+    return retVal;
+  }
+
+  // Allow promotion to bool for conditional statements.
+  operator bool() const { return ptr_ != NULL; }
+
+ private:
+  C* ptr_;
+
+  // Forbid comparison of unique_ptr types.  If C2 != C, it totally doesn't
+  // make sense, and if C2 == C, it still doesn't make sense because you should
+  // never have the same object owned by two different unique_ptrs.
+  template <class C2> bool operator==(unique_ptr<C2> const& p2) const;
+  template <class C2> bool operator!=(unique_ptr<C2> const& p2) const;
+
+  // Disallow evil constructors
+  unique_ptr(const unique_ptr&);
+  void operator=(const unique_ptr&);
+};
+
+// Free functions
+template <class C>
+void swap(unique_ptr<C>& p1, unique_ptr<C>& p2) {
+  p1.swap(p2);
+}
+
+template <class C>
+bool operator==(C* p1, const unique_ptr<C>& p2) {
+  return p1 == p2.get();
+}
+
+template <class C>
+bool operator!=(C* p1, const unique_ptr<C>& p2) {
+  return p1 != p2.get();
+}
+
+}  // namespace nonstd
+
+#endif  // NONSTD_UNIQUE_PTR_H_
diff --git a/third_party/third_party.gyp b/third_party/third_party.gyp
index d54905c022..c106f1e314 100644
--- a/third_party/third_party.gyp
+++ b/third_party/third_party.gyp
@@ -66,6 +66,7 @@
       'sources': [
         'base/logging.h',
         'base/macros.h',
+        'base/nonstd_unique_ptr.h'
         'base/template_util.h',
         'base/numerics/safe_conversions.h',
         'base/numerics/safe_conversions_impl.h',