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comparison: netwerk/base/public/nsReadLine.h
netwerk/base/public/nsReadLine.h
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| 1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- | |
| 2 * | |
| 3 * This Source Code Form is subject to the terms of the Mozilla Public | |
| 4 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 6 | |
| 7 #ifndef nsReadLine_h__ | |
| 8 #define nsReadLine_h__ | |
| 9 | |
| 10 #include "nsIInputStream.h" | |
| 11 #include "mozilla/Likely.h" | |
| 12 | |
| 13 /** | |
| 14 * @file | |
| 15 * Functions to read complete lines from an input stream. | |
| 16 * | |
| 17 * To properly use the helper function in here (NS_ReadLine) the caller should | |
| 18 * create a nsLineBuffer<T> with new, and pass it to NS_ReadLine every time it | |
| 19 * wants a line out. | |
| 20 * | |
| 21 * When done, the object should be deleted. | |
| 22 */ | |
| 23 | |
| 24 /** | |
| 25 * @internal | |
| 26 * Buffer size. This many bytes will be buffered. If a line is longer than this, | |
| 27 * the partial line will be appended to the out parameter of NS_ReadLine and the | |
| 28 * buffer will be emptied. | |
| 29 * Note: if you change this constant, please update the regression test in | |
| 30 * netwerk/test/unit/test_readline.js accordingly (bug 397850). | |
| 31 */ | |
| 32 #define kLineBufferSize 4096 | |
| 33 | |
| 34 /** | |
| 35 * @internal | |
| 36 * Line buffer structure, buffers data from an input stream. | |
| 37 * The buffer is empty when |start| == |end|. | |
| 38 * Invariant: |start| <= |end| | |
| 39 */ | |
| 40 template<typename CharT> | |
| 41 class nsLineBuffer { | |
| 42 public: | |
| 43 nsLineBuffer() : start(buf), end(buf) { } | |
| 44 | |
| 45 CharT buf[kLineBufferSize+1]; | |
| 46 CharT* start; | |
| 47 CharT* end; | |
| 48 }; | |
| 49 | |
| 50 /** | |
| 51 * Read a line from an input stream. Lines are separated by '\r' (0x0D) or '\n' | |
| 52 * (0x0A), or "\r\n" or "\n\r". | |
| 53 * | |
| 54 * @param aStream | |
| 55 * The stream to read from | |
| 56 * @param aBuffer | |
| 57 * The line buffer to use. A single line buffer must not be used with | |
| 58 * different input streams. | |
| 59 * @param aLine [out] | |
| 60 * The string where the line will be stored. | |
| 61 * @param more [out] | |
| 62 * Whether more data is available in the buffer. If true, NS_ReadLine may | |
| 63 * be called again to read further lines. Otherwise, further calls to | |
| 64 * NS_ReadLine will return an error. | |
| 65 * | |
| 66 * @retval NS_OK | |
| 67 * Read successful | |
| 68 * @retval error | |
| 69 * Input stream returned an error upon read. See | |
| 70 * nsIInputStream::read. | |
| 71 */ | |
| 72 template<typename CharT, class StreamType, class StringType> | |
| 73 nsresult | |
| 74 NS_ReadLine (StreamType* aStream, nsLineBuffer<CharT> * aBuffer, | |
| 75 StringType & aLine, bool *more) | |
| 76 { | |
| 77 CharT eolchar = 0; // the first eol char or 1 after \r\n or \n\r is found | |
| 78 | |
| 79 aLine.Truncate(); | |
| 80 | |
| 81 while (1) { // will be returning out of this loop on eol or eof | |
| 82 if (aBuffer->start == aBuffer->end) { // buffer is empty. Read into it. | |
| 83 uint32_t bytesRead; | |
| 84 nsresult rv = aStream->Read(aBuffer->buf, kLineBufferSize, &bytesRead); | |
| 85 if (NS_FAILED(rv) || MOZ_UNLIKELY(bytesRead == 0)) { | |
| 86 *more = false; | |
| 87 return rv; | |
| 88 } | |
| 89 aBuffer->start = aBuffer->buf; | |
| 90 aBuffer->end = aBuffer->buf + bytesRead; | |
| 91 *(aBuffer->end) = '\0'; | |
| 92 } | |
| 93 | |
| 94 /* | |
| 95 * Walk the buffer looking for an end-of-line. | |
| 96 * There are 3 cases to consider: | |
| 97 * 1. the eol char is the last char in the buffer | |
| 98 * 2. the eol char + one more char at the end of the buffer | |
| 99 * 3. the eol char + two or more chars at the end of the buffer | |
| 100 * we need at least one char after the first eol char to determine if | |
| 101 * it's a \r\n or \n\r sequence (and skip over it), and we need one | |
| 102 * more char after the end-of-line to set |more| correctly. | |
| 103 */ | |
| 104 CharT* current = aBuffer->start; | |
| 105 if (MOZ_LIKELY(eolchar == 0)) { | |
| 106 for ( ; current < aBuffer->end; ++current) { | |
| 107 if (*current == '\n' || *current == '\r') { | |
| 108 eolchar = *current; | |
| 109 *current++ = '\0'; | |
| 110 aLine.Append(aBuffer->start); | |
| 111 break; | |
| 112 } | |
| 113 } | |
| 114 } | |
| 115 if (MOZ_LIKELY(eolchar != 0)) { | |
| 116 for ( ; current < aBuffer->end; ++current) { | |
| 117 if ((eolchar == '\r' && *current == '\n') || | |
| 118 (eolchar == '\n' && *current == '\r')) { | |
| 119 eolchar = 1; | |
| 120 continue; | |
| 121 } | |
| 122 aBuffer->start = current; | |
| 123 *more = true; | |
| 124 return NS_OK; | |
| 125 } | |
| 126 } | |
| 127 | |
| 128 if (eolchar == 0) | |
| 129 aLine.Append(aBuffer->start); | |
| 130 aBuffer->start = aBuffer->end; // mark the buffer empty | |
| 131 } | |
| 132 } | |
| 133 | |
| 134 #endif // nsReadLine_h__ |
