diff options
Diffstat (limited to 'extensions/universalchardet/src/base/nsUniversalDetector.cpp')
| -rw-r--r-- | extensions/universalchardet/src/base/nsUniversalDetector.cpp | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/extensions/universalchardet/src/base/nsUniversalDetector.cpp b/extensions/universalchardet/src/base/nsUniversalDetector.cpp new file mode 100644 index 000000000..d272827b8 --- /dev/null +++ b/extensions/universalchardet/src/base/nsUniversalDetector.cpp @@ -0,0 +1,240 @@ +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "nscore.h" + +#include "nsUniversalDetector.h" + +#include "nsMBCSGroupProber.h" +#include "nsEscCharsetProber.h" +#include "nsLatin1Prober.h" + +nsUniversalDetector::nsUniversalDetector() +{ + mDone = false; + mBestGuess = -1; //illegal value as signal + mInTag = false; + mEscCharSetProber = nullptr; + + mStart = true; + mDetectedCharset = nullptr; + mGotData = false; + mInputState = ePureAscii; + mLastChar = '\0'; + + uint32_t i; + for (i = 0; i < NUM_OF_CHARSET_PROBERS; i++) + mCharSetProbers[i] = nullptr; +} + +nsUniversalDetector::~nsUniversalDetector() +{ + for (int32_t i = 0; i < NUM_OF_CHARSET_PROBERS; i++) + delete mCharSetProbers[i]; + + delete mEscCharSetProber; +} + +void +nsUniversalDetector::Reset() +{ + mDone = false; + mBestGuess = -1; //illegal value as signal + mInTag = false; + + mStart = true; + mDetectedCharset = nullptr; + mGotData = false; + mInputState = ePureAscii; + mLastChar = '\0'; + + if (mEscCharSetProber) + mEscCharSetProber->Reset(); + + uint32_t i; + for (i = 0; i < NUM_OF_CHARSET_PROBERS; i++) + if (mCharSetProbers[i]) + mCharSetProbers[i]->Reset(); +} + +//--------------------------------------------------------------------- +#define SHORTCUT_THRESHOLD (float)0.95 +#define MINIMUM_THRESHOLD (float)0.20 + +nsresult nsUniversalDetector::HandleData(const char* aBuf, uint32_t aLen) +{ + if(mDone) + return NS_OK; + + if (aLen > 0) + mGotData = true; + + //If the data starts with BOM, we know it is UTF + if (mStart) + { + mStart = false; + if (aLen >= 2) { + switch (aBuf[0]) { + case '\xEF': + if ((aLen > 2) && ('\xBB' == aBuf[1]) && ('\xBF' == aBuf[2])) { + // EF BB BF UTF-8 encoded BOM + mDetectedCharset = "UTF-8"; + } + break; + case '\xFE': + if ('\xFF' == aBuf[1]) { + // FE FF UTF-16, big endian BOM + mDetectedCharset = "UTF-16BE"; + } + break; + case '\xFF': + if ('\xFE' == aBuf[1]) { + // FF FE UTF-16, little endian BOM + mDetectedCharset = "UTF-16LE"; + } + break; + } // switch + } + + if (mDetectedCharset) + { + mDone = true; + return NS_OK; + } + } + + uint32_t i; + for (i = 0; i < aLen; i++) + { + //other than 0xa0, if every othe character is ascii, the page is ascii + if (aBuf[i] & '\x80' && aBuf[i] != '\xA0') //Since many Ascii only page contains NBSP + { + //we got a non-ascii byte (high-byte) + if (mInputState != eHighbyte) + { + //adjust state + mInputState = eHighbyte; + + //kill mEscCharSetProber if it is active + if (mEscCharSetProber) { + delete mEscCharSetProber; + mEscCharSetProber = nullptr; + } + + //start multibyte and singlebyte charset prober + if (nullptr == mCharSetProbers[0]) + { + mCharSetProbers[0] = new nsMBCSGroupProber(); + if (nullptr == mCharSetProbers[0]) + return NS_ERROR_OUT_OF_MEMORY; + } + if (nullptr == mCharSetProbers[2]) + { + mCharSetProbers[2] = new nsLatin1Prober; + if (nullptr == mCharSetProbers[2]) + return NS_ERROR_OUT_OF_MEMORY; + } + } + } + else + { + //ok, just pure ascii so far + if ((ePureAscii == mInputState) && (aBuf[i] == '\033')) + { + //found escape character + mInputState = eEscAscii; + } + mLastChar = aBuf[i]; + } + } + + nsProbingState st; + switch (mInputState) + { + case eEscAscii: + if (nullptr == mEscCharSetProber) { + mEscCharSetProber = new nsEscCharSetProber(); + if (nullptr == mEscCharSetProber) + return NS_ERROR_OUT_OF_MEMORY; + } + st = mEscCharSetProber->HandleData(aBuf, aLen); + if (st == eFoundIt) + { + mDone = true; + mDetectedCharset = mEscCharSetProber->GetCharSetName(); + } + break; + case eHighbyte: + for (i = 0; i < NUM_OF_CHARSET_PROBERS; i++) + { + if (mCharSetProbers[i]) + { + st = mCharSetProbers[i]->HandleData(aBuf, aLen); + if (st == eFoundIt) + { + mDone = true; + mDetectedCharset = mCharSetProbers[i]->GetCharSetName(); + return NS_OK; + } + } + } + break; + + default: //pure ascii + ;//do nothing here + } + return NS_OK; +} + + +//--------------------------------------------------------------------- +void nsUniversalDetector::DataEnd() +{ + if (!mGotData) + { + // we haven't got any data yet, return immediately + // caller program sometimes call DataEnd before anything has been sent to detector + return; + } + + if (mDetectedCharset) + { + mDone = true; + Report(mDetectedCharset); + return; + } + + switch (mInputState) + { + case eHighbyte: + { + float proberConfidence; + float maxProberConfidence = (float)0.0; + int32_t maxProber = 0; + + for (int32_t i = 0; i < NUM_OF_CHARSET_PROBERS; i++) + { + if (mCharSetProbers[i]) + { + proberConfidence = mCharSetProbers[i]->GetConfidence(); + if (proberConfidence > maxProberConfidence) + { + maxProberConfidence = proberConfidence; + maxProber = i; + } + } + } + //do not report anything because we are not confident of it, that's in fact a negative answer + if (maxProberConfidence > MINIMUM_THRESHOLD) + Report(mCharSetProbers[maxProber]->GetCharSetName()); + } + break; + case eEscAscii: + break; + default: + ; + } + return; +} |