michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /*
michael@0:  * A wrapper to contain either an nsAttrValue or an nsAString. This is useful
michael@0:  * because constructing an nsAttrValue from an nsAString can be expensive when
michael@0:  * the buffer of the string is not shared.
michael@0:  *
michael@0:  * Since a raw pointer to the passed-in string is kept, this class should only
michael@0:  * be used on the stack.
michael@0:  */
michael@0: 
michael@0: #ifndef nsAttrValueOrString_h___
michael@0: #define nsAttrValueOrString_h___
michael@0: 
michael@0: #include "nsString.h"
michael@0: #include "nsAttrValue.h"
michael@0: 
michael@0: class MOZ_STACK_CLASS nsAttrValueOrString
michael@0: {
michael@0: public:
michael@0:   nsAttrValueOrString(const nsAString& aValue)
michael@0:     : mAttrValue(nullptr)
michael@0:     , mStringPtr(&aValue)
michael@0:     , mCheapString(nullptr)
michael@0:   { }
michael@0:   nsAttrValueOrString(const nsAttrValue& aValue)
michael@0:     : mAttrValue(&aValue)
michael@0:     , mStringPtr(nullptr)
michael@0:     , mCheapString(nullptr)
michael@0:   { }
michael@0: 
michael@0:   /**
michael@0:    * Returns a reference to the string value of the contents of this object.
michael@0:    *
michael@0:    * When this object points to a string or an nsAttrValue of string or atom
michael@0:    * type this should be fairly cheap. Other nsAttrValue types will be
michael@0:    * serialized the first time this is called and cached from thereon.
michael@0:    */
michael@0:   const nsAString& String() const;
michael@0: 
michael@0:   /**
michael@0:    * Compares the string representation of this object with the string
michael@0:    * representation of an nsAttrValue.
michael@0:    */
michael@0:   bool EqualsAsStrings(const nsAttrValue& aOther) const
michael@0:   {
michael@0:     if (mStringPtr) {
michael@0:       return aOther.Equals(*mStringPtr, eCaseMatters);
michael@0:     }
michael@0:     return aOther.EqualsAsStrings(*mAttrValue);
michael@0:   }
michael@0: 
michael@0: protected:
michael@0:   const nsAttrValue*       mAttrValue;
michael@0:   mutable const nsAString* mStringPtr;
michael@0:   mutable nsCheapString    mCheapString;
michael@0: };
michael@0: 
michael@0: #endif // nsAttrValueOrString_h___