gecko-dev/xpcom/string/public/nsPrintfCString.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1994-2000 Netscape Communications Corporation. All
* Rights Reserved.
*
* Original Author:
* Scott Collins <scc@mozilla.org>
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the
* terms of the GNU General Public License Version 2 or later (the
* "GPL"), in which case the provisions of the GPL are applicable
* instead of those above. If you wish to allow use of your
* version of this file only under the terms of the GPL and not to
* allow others to use your version of this file under the MPL,
* indicate your decision by deleting the provisions above and
* replace them with the notice and other provisions required by
* the GPL. If you do not delete the provisions above, a recipient
* may use your version of this file under either the MPL or the
* GPL.
*/
#ifndef nsPrintfCString_h___
#define nsPrintfCString_h___
#ifndef nsAString_h___
#include "nsAString.h"
#endif
/**
* |nsPrintfCString| lets you use a formated |printf| string as an |nsAReadableCString|.
*
* myCStr += nsPrintfCString("%f", 13.917);
* // ...a general purpose substitute for |AppendFloat|
*
* For longer patterns, you'll want to use the constructor that takes a length
*
* nsPrintfCString(128, "%f, %f, %f, %f, %f, %f, %f, %i, %f", x, y, z, 3.2, j, k, l, 3, 3.1);
*
* Exceding the default size (which you must specify in the constructor, it is not determined)
* causes an allocation, so avoid that. If your formatted string exceeds the allocated space, it is
* cut off at the size of the buffer, no error is reported (and no out-of-bounds writing occurs).
* This class is intended to be useful for numbers and short
* strings, not arbitrary formatting of other strings (e.g., with %s). There is currently no
* wide version of this class, since wide |printf| is not generally available. That means
* to get a wide version of your formatted data, you must, e.g.,
*
* CopyASCIItoUCS2(nsPrintfCString("%f", 13.917"), myStr);
*
* That's another good reason to avoid this class for anything but numbers ... as strings can be
* much more efficiently handled with |NS_LITERAL_[C]STRING| and |nsLiteral[C]String|.
*/
class nsPrintfCString
: public nsACString
{
enum { kLocalBufferSize=15 };
// ought to be large enough for most things ... a |long long| needs at most 20 (so you'd better ask)
// pinkerton suggests 7. We should measure and decide what's appropriate
public:
explicit nsPrintfCString( const char* format, ... );
nsPrintfCString( size_t n, const char* format, ...);
~nsPrintfCString();
virtual PRUint32 Length() const;
protected:
virtual const char* GetReadableFragment( nsReadableFragment<char>&, nsFragmentRequest, PRUint32 ) const;
virtual char* GetWritableFragment( nsWritableFragment<char>&, nsFragmentRequest, PRUint32 ) { return 0; }
// virtual PRBool GetReadableFragment( nsReadableFragment<char>& aFragment, nsFragmentRequest aRequest ) const;
private:
char* mStart;
PRUint32 mLength;
char mLocalBuffer[ kLocalBufferSize + 1 ];
};
#endif // !defined(nsPrintfCString_h___)