Use copy-swap idiom for GURL::operator=

url/gurl.cc

 // Copyright 2013 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.
 
 #ifdef WIN32
 #include <windows.h>
 #else
 #include <pthread.h>
 #endif
 
@@ skipping 151 matching lines @@
     }
   }
 #endif
 }
 
 GURL::~GURL() {
   delete inner_url_;
 }
 
 GURL& GURL::operator=(const GURL& other) {
-  if (&other == this)
-    return *this;
-
-  spec_ = other.spec_;
-  is_valid_ = other.is_valid_;
-  parsed_ = other.parsed_;
-  delete inner_url_;
-  inner_url_ = NULL;
-  if (other.inner_url_)
-    inner_url_ = new GURL(*other.inner_url_);
-  // Valid filesystem urls should always have an inner_url_.
-  DCHECK(!is_valid_ || !SchemeIsFileSystem() || inner_url_);
+  GURL copy(other);

[cjhopman, 2013/10/22 17:14:01]

This is less subtle than taking the thing by value. I don't really have a
preference either way.

[akalin, 2013/10/22 17:56:41]

http://gotw.ca/gotw/059.htm uses your way so I'm inclined to go with it. :)

[Jeffrey Yasskin, 2013/10/22 18:02:54]

Taking GURL by value saves a copy when the argument is a temporary. The details
are at
http://webcache.googleusercontent.com/search?q=cache:GLdM1_YvqhEJ:cpp-next.co...

[cjhopman, 2013/10/22 19:03:44]

Done.

+  Swap(&copy);
   return *this;
 }
 
 const std::string& GURL::spec() const {
   if (is_valid_ || spec_.empty())
     return spec_;
 
   DCHECK(false) << "Trying to get the spec of an invalid URL!";
   return EmptyStringForGURL();
 }
@@ skipping 321 matching lines @@
 void GURL::Swap(GURL* other) {
   spec_.swap(other->spec_);
   std::swap(is_valid_, other->is_valid_);
   std::swap(parsed_, other->parsed_);
   std::swap(inner_url_, other->inner_url_);
 }
 
 std::ostream& operator<<(std::ostream& out, const GURL& url) {
   return out << url.possibly_invalid_spec();
 }