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397 строки
13 KiB
C++
397 строки
13 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: NPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Netscape Public License
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* Version 1.1 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/NPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1998
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Rick Gessner <rickg@netscape.com> (original author)
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* Scott Collins <scc@mozilla.org>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the NPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the NPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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/* nsStr.h --- the underlying buffer for rickg's original string implementations;
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these classes will be replaced by the new shared-buffer string (see bug #53065)
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*/
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#ifndef _nsStr
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#define _nsStr
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#ifndef nsStringDefines_h___
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#include "nsStringDefines.h"
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#endif
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/***********************************************************************
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MODULE NOTES:
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1. There are two philosophies to building string classes:
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A. Hide the underlying buffer & offer API's allow indirect iteration
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B. Reveal underlying buffer, risk corruption, but gain performance
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We chose the option B for performance reasons.
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2 Our internal buffer always holds capacity+1 bytes.
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The nsStr struct is a simple structure (no methods) that contains
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the necessary info to be described as a string. This simple struct
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is manipulated by the static methods provided in this class.
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(Which effectively makes this a library that works on structs).
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There are also object-based versions called nsString and nsAutoString
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which use nsStr but makes it look at feel like an object.
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***********************************************************************/
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/***********************************************************************
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ASSUMPTIONS:
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1. nsStrings and nsAutoString are always null terminated. However,
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since it maintains a length byte, you can store NULL's inside
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the string. Just be careful passing such buffers to 3rd party
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API's that assume that NULL always terminate the buffer.
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2. nsCStrings can be upsampled into nsString without data loss
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3. Char searching is faster than string searching. Use char interfaces
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if your needs will allow it.
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4. It's easy to use the stack for nsAutostring buffer storage (fast too!).
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See the CBufDescriptor class in this file.
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5. If you don't provide the optional count argument to Append() and Insert(),
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the method will assume that the given buffer is terminated by the first
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NULL it encounters.
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6. Downsampling from nsString to nsCString can be lossy -- avoid it if possible!
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7. Calls to ToNewCString() and ToNewUnicode() should be matched with calls to nsMemory::Free().
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***********************************************************************/
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/**********************************************************************************
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AND NOW FOR SOME GENERAL DOCUMENTATION ON STRING USAGE...
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The fundamental datatype in the string library is nsStr. It's a structure that
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provides the buffer storage and meta-info. It also provides a C-style library
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of functions for direct manipulation (for those of you who prefer K&R to Bjarne).
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Here's a diagram of the class hierarchy:
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nsStr
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|___nsString
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| |
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| ------nsAutoString
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|___nsCString
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------nsCAutoString
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Why so many string classes? The 4 variants give you the control you need to
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determine the best class for your purpose. There are 2 dimensions to this
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flexibility: 1) stack vs. heap; and 2) 1-byte chars vs. 2-byte chars.
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Note: While nsAutoString and nsCAutoString begin life using stack-based storage,
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they may not stay that way. Like all nsString classes, autostrings will
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automatically grow to contain the data you provide. When autostrings
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grow beyond their intrinsic buffer, they switch to heap based allocations.
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(We avoid alloca to avoid considerable platform difficulties; see the
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GNU documentation for more details).
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I should also briefly mention that all the string classes use a "memory agent"
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object to perform memory operations. This class proxies the standard nsMemory
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for actual memory calls, but knows the structure of nsStr making heap operations
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more localized.
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CHOOSING A STRING CLASS:
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In order to choose a string class for you purpose, use this handy table:
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heap-based stack-based
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-----------------------------------
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ascii data | nsCString nsCAutoString |
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|----------------------------------
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unicode data | nsString nsAutoString |
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-----------------------------------
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Note: The i18n folks will stenuously object if we get too carried away with the
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use of nsCString's that pass interface boundaries. Try to limit your
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use of these to external interfaces that demand them, or for your own
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private purposes in cases where they'll never be seen by humans.
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--- FAQ ---
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Q. When should I use nsCString instead of nsString?
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A. You should really try to stick with nsString, so that we stay as unicode
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compliant as possible. But there are cases where an interface you use requires
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a char*. In such cases, it's fair to use nsCString.
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Q. I know that my string is going to be a certain size. Can I pre-size my nsString?
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A. Yup, here's how:
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{
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nsString mBuffer;
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mBuffer.SetCapacity(aReasonableSize);
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}
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Q. Should nsAutoString or nsCAutoString ever live on the heap?
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A. That would be counterproductive. The point of nsAutoStrings is to preallocate your
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buffers, and to auto-destroy the string when it goes out of scope.
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Q. I already have a char*. Can I use the nsString functionality on that buffer?
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A. Yes you can -- by using an intermediate class called CBufDescriptor.
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The CBufDescriptor class is used to tell nsString about an external buffer (heap or stack) to use
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instead of it's own internal buffers. Here's an example:
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{
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char theBuffer[256];
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CBufDescritor theBufDecriptor( theBuffer, PR_TRUE, sizeof(theBuffer), 0);
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nsCAutoString s3( theBufDescriptor );
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s3="HELLO, my name is inigo montoya, you killed my father, prepare to die!.";
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}
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The assignment statment to s3 will cause the given string to be written to your
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stack-based buffer via the normal nsString/nsCString interfaces. Cool, huh?
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Note however that just like any other nsStringXXX use, if you write more data
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than will fit in the buffer, a visit to the heap manager will be in order.
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Q. What is the simplest way to get from a char* to PRUnichar*?
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A. The simplest way is by construction (or assignment):
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{
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char* theBuf = "hello there";
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nsAutoString foo(theBuf);
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}
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If you don't want the char* to be copied into the nsAutoString, the use a
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CBufDescriptor instead.
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**********************************************************************************/
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#include "nscore.h"
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#include "nsMemory.h"
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#include <string.h>
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#include <stdio.h>
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#include "plhash.h"
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#include "nsStrShared.h"
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//----------------------------------------------------------------------------------------
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#define kDefaultCharSize eTwoByte
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#define kRadix10 (10)
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#define kRadix16 (16)
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#define kAutoDetect (100)
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#define kRadixUnknown (kAutoDetect+1)
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#define IGNORE_CASE (PR_TRUE)
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#define NSSTR_CHARSIZE_BIT (31)
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#define NSSTR_OWNSBUFFER_BIT (30)
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#define NSSTR_CHARSIZE_MASK (1<<NSSTR_CHARSIZE_BIT)
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#define NSSTR_OWNSBUFFER_MASK (1<<NSSTR_OWNSBUFFER_BIT)
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#define NSSTR_CAPACITY_MASK (~(NSSTR_CHARSIZE_MASK | NSSTR_OWNSBUFFER_MASK))
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const PRInt32 kDefaultStringSize = 64;
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const PRInt32 kNotFound = -1;
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//----------------------------------------------------------------------------------------
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class nsAString;
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class NS_COM CBufDescriptor {
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public:
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CBufDescriptor(char* aString, PRBool aStackBased,PRUint32 aCapacity,PRInt32 aLength=-1);
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CBufDescriptor(const char* aString, PRBool aStackBased,PRUint32 aCapacity,PRInt32 aLength=-1);
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CBufDescriptor(PRUnichar* aString, PRBool aStackBased,PRUint32 aCapacity,PRInt32 aLength=-1);
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CBufDescriptor(const PRUnichar* aString,PRBool aStackBased,PRUint32 aCapacity,PRInt32 aLength=-1);
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char* mBuffer;
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eCharSize mCharSize;
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PRUint32 mCapacity;
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PRInt32 mLength;
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PRBool mStackBased;
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PRBool mIsConst;
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};
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//----------------------------------------------------------------------------------------
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struct NS_COM nsStr {
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protected:
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nsStr() {
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MOZ_COUNT_CTOR(nsStr);
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}
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~nsStr() {
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MOZ_COUNT_DTOR(nsStr);
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}
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protected:
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union {
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char* mStr;
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PRUnichar* mUStr;
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};
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PRUint32 mLength;
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PRUint32 mCapacityAndFlags;
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inline PRUint32 GetCapacity() const {
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// actual capacity is one less than is stored
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return (mCapacityAndFlags & NSSTR_CAPACITY_MASK);
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}
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inline PRBool GetOwnsBuffer() const {
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return ((mCapacityAndFlags & NSSTR_OWNSBUFFER_MASK) != 0);
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}
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inline eCharSize GetCharSize() const {
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return eCharSize(mCapacityAndFlags >> NSSTR_CHARSIZE_BIT);
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}
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private:
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inline void SetInternalCapacity(PRUint32 aCapacity) {
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mCapacityAndFlags =
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((mCapacityAndFlags & ~NSSTR_CAPACITY_MASK) |
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(aCapacity & NSSTR_CAPACITY_MASK));
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}
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inline void SetCharSize(eCharSize aCharSize) {
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mCapacityAndFlags =
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((mCapacityAndFlags & ~NSSTR_CHARSIZE_MASK) |
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(PRUint32(aCharSize) << NSSTR_CHARSIZE_BIT));
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}
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inline void SetOwnsBuffer(PRBool aOwnsBuffer) {
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mCapacityAndFlags =
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(mCapacityAndFlags & ~NSSTR_OWNSBUFFER_MASK |
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(aOwnsBuffer ? 1 : 0) << NSSTR_OWNSBUFFER_BIT);
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}
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public:
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friend NS_COM
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char*
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ToNewUTF8String( const nsAString& aSource );
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friend inline void AddNullTerminator(nsStr& aDest);
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friend inline PRUnichar GetCharAt(const nsStr& aDest,PRUint32 anIndex);
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friend class nsStrPrivate;
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friend class nsString;
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friend class nsCString;
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};
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/**************************************************************
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A couple of tiny helper methods used in the string classes.
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**************************************************************/
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inline PRInt32 MinInt(PRInt32 anInt1,PRInt32 anInt2){
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return (anInt1<anInt2) ? anInt1 : anInt2;
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}
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inline PRInt32 MaxInt(PRInt32 anInt1,PRInt32 anInt2){
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return (anInt1<anInt2) ? anInt2 : anInt1;
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}
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inline void AddNullTerminator(nsStr& aDest) {
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if(eTwoByte==aDest.GetCharSize())
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aDest.mUStr[aDest.mLength]=0;
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else aDest.mStr[aDest.mLength]=0;
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}
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/**
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* Deprecated: don't use |Recycle|, just call |nsMemory::Free| directly
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*
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* Return the given buffer to the heap manager. Calls allocator::Free()
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* @return string length
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*/
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inline void Recycle( char* aBuffer) { nsMemory::Free(aBuffer); }
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inline void Recycle( PRUnichar* aBuffer) { nsMemory::Free(aBuffer); }
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/**
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* This method is used to access a given char in the given string
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*
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* @update gess 01/04/99
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* @param aDest is the nsStr to be appended to
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* @param anIndex tells us where in dest to get the char from
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* @return the given char, or 0 if anIndex is out of range
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*/
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inline PRUnichar GetCharAt(const nsStr& aDest,PRUint32 anIndex) {
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if(anIndex<aDest.mLength) {
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return (eTwoByte==aDest.GetCharSize()) ? aDest.mUStr[anIndex] : (PRUnichar)aDest.mStr[anIndex];
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}//if
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return 0;
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}
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#ifdef NS_STR_STATS
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class nsStringInfo {
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public:
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nsStringInfo(nsStr& str);
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~nsStringInfo() {}
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static nsStringInfo* GetInfo(nsStr& str);
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static void Seen(nsStr& str);
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static void Report(FILE* out = stdout);
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static PRIntn ReportEntry(PLHashEntry *he, PRIntn i, void *arg);
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protected:
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nsStr mStr;
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PRUint32 mCount;
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};
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#define NSSTR_SEEN(str) nsStringInfo::Seen(str)
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#else // !NS_STR_STATS
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#define NSSTR_SEEN(str) /* nothing */
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#endif // !NS_STR_STATS
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#endif // _nsStr
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