gecko/netwerk/base/public/nsReadLine.h
2011-10-17 10:59:28 -04:00

201 lines
6.6 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* 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
* Boris Zbarsky <bzbarsky@mit.edu>.
* Portions created by the Initial Developer are Copyright (C) 2001
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Christian Biesinger <cbiesinger@web.de>
* Mats Palmgren <mats.palmgren@bredband.net>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef nsReadLine_h__
#define nsReadLine_h__
#include "prmem.h"
#include "nsIInputStream.h"
/**
* @file
* Functions to read complete lines from an input stream.
*
* To properly use the helper function in here (NS_ReadLine) the caller
* needs to declare a pointer to an nsLineBuffer, call
* NS_InitLineBuffer on it, and pass it to NS_ReadLine every time it
* wants a line out.
*
* When done, the pointer should be freed using PR_Free.
*/
/**
* @internal
* Buffer size. This many bytes will be buffered. If a line is longer than this,
* the partial line will be appended to the out parameter of NS_ReadLine and the
* buffer will be emptied.
* Note: if you change this constant, please update the regression test in
* netwerk/test/unit/test_readline.js accordingly (bug 397850).
*/
#define kLineBufferSize 4096
/**
* @internal
* Line buffer structure, buffers data from an input stream.
* The buffer is empty when |start| == |end|.
* Invariant: |start| <= |end|
*/
template<typename CharT>
class nsLineBuffer {
public:
CharT buf[kLineBufferSize+1];
CharT* start;
CharT* end;
};
/**
* Initialize a line buffer for use with NS_ReadLine.
*
* @param aBufferPtr
* Pointer to pointer to a line buffer. Upon successful return,
* *aBufferPtr will contain a valid pointer to a line buffer, for use
* with NS_ReadLine. Use PR_Free when the buffer is no longer needed.
*
* @retval NS_OK Success.
* @retval NS_ERROR_OUT_OF_MEMORY Not enough memory to allocate the line buffer.
*
* @par Example:
* @code
* nsLineBuffer* lb;
* rv = NS_InitLineBuffer(&lb);
* if (NS_SUCCEEDED(rv)) {
* // do stuff...
* PR_Free(lb);
* }
* @endcode
*/
template<typename CharT>
nsresult
NS_InitLineBuffer (nsLineBuffer<CharT> ** aBufferPtr) {
*aBufferPtr = PR_NEW(nsLineBuffer<CharT>);
if (!(*aBufferPtr))
return NS_ERROR_OUT_OF_MEMORY;
(*aBufferPtr)->start = (*aBufferPtr)->end = (*aBufferPtr)->buf;
return NS_OK;
}
/**
* Read a line from an input stream. Lines are separated by '\r' (0x0D) or '\n'
* (0x0A), or "\r\n" or "\n\r".
*
* @param aStream
* The stream to read from
* @param aBuffer
* The line buffer to use. Must have been inited with
* NS_InitLineBuffer before. A single line buffer must not be used with
* different input streams.
* @param aLine [out]
* The string where the line will be stored.
* @param more [out]
* Whether more data is available in the buffer. If true, NS_ReadLine may
* be called again to read further lines. Otherwise, further calls to
* NS_ReadLine will return an error.
*
* @retval NS_OK
* Read successful
* @retval error
* Input stream returned an error upon read. See
* nsIInputStream::read.
*/
template<typename CharT, class StreamType, class StringType>
nsresult
NS_ReadLine (StreamType* aStream, nsLineBuffer<CharT> * aBuffer,
StringType & aLine, bool *more)
{
CharT eolchar = 0; // the first eol char or 1 after \r\n or \n\r is found
aLine.Truncate();
while (1) { // will be returning out of this loop on eol or eof
if (aBuffer->start == aBuffer->end) { // buffer is empty. Read into it.
PRUint32 bytesRead;
nsresult rv = aStream->Read(aBuffer->buf, kLineBufferSize, &bytesRead);
if (NS_FAILED(rv) || NS_UNLIKELY(bytesRead == 0)) {
*more = false;
return rv;
}
aBuffer->start = aBuffer->buf;
aBuffer->end = aBuffer->buf + bytesRead;
*(aBuffer->end) = '\0';
}
/*
* Walk the buffer looking for an end-of-line.
* There are 3 cases to consider:
* 1. the eol char is the last char in the buffer
* 2. the eol char + one more char at the end of the buffer
* 3. the eol char + two or more chars at the end of the buffer
* we need at least one char after the first eol char to determine if
* it's a \r\n or \n\r sequence (and skip over it), and we need one
* more char after the end-of-line to set |more| correctly.
*/
CharT* current = aBuffer->start;
if (NS_LIKELY(eolchar == 0)) {
for ( ; current < aBuffer->end; ++current) {
if (*current == '\n' || *current == '\r') {
eolchar = *current;
*current++ = '\0';
aLine.Append(aBuffer->start);
break;
}
}
}
if (NS_LIKELY(eolchar != 0)) {
for ( ; current < aBuffer->end; ++current) {
if ((eolchar == '\r' && *current == '\n') ||
(eolchar == '\n' && *current == '\r')) {
eolchar = 1;
continue;
}
aBuffer->start = current;
*more = true;
return NS_OK;
}
}
if (eolchar == 0)
aLine.Append(aBuffer->start);
aBuffer->start = aBuffer->end; // mark the buffer empty
}
}
#endif // nsReadLine_h__