ChineseGroupProber.cpp

/*  -*- C++ -*-
    SPDX-FileCopyrightText: 1998 Netscape Communications Corporation <developer@mozilla.org>
 
    SPDX-License-Identifier: MIT
*/
 
#include "ChineseGroupProber.h"
 
#include "UnicodeGroupProber.h"
#include "nsBig5Prober.h"
#include "nsGB2312Prober.h"
 
#include <stdio.h>
#include <stdlib.h>
 
namespace kencodingprober
{
#ifdef DEBUG_PROBE
static const char *const ProberName[] = {
    "Unicode",
    "GB18030",
    "Big5",
};
 
#endif
 
ChineseGroupProber::ChineseGroupProber()
{
    mProbers[0] = new UnicodeGroupProber();
    mProbers[1] = new nsGB18030Prober();
    mProbers[2] = new nsBig5Prober();
    Reset();
}
 
ChineseGroupProber::~ChineseGroupProber()
{
    for (unsigned int i = 0; i < CN_NUM_OF_PROBERS; i++) {
        delete mProbers[i];
    }
}
 
const char *ChineseGroupProber::GetCharSetName()
{
    if (mBestGuess == -1) {
        GetConfidence();
        if (mBestGuess == -1) {
            mBestGuess = 1; // assume it's GB18030
        }
    }
    return mProbers[mBestGuess]->GetCharSetName();
}
 
void ChineseGroupProber::Reset(void)
{
    mActiveNum = 0;
    for (unsigned int i = 0; i < CN_NUM_OF_PROBERS; i++) {
        if (mProbers[i]) {
            mProbers[i]->Reset();
            mIsActive[i] = true;
            ++mActiveNum;
        } else {
            mIsActive[i] = false;
        }
    }
    mBestGuess = -1;
    mState = eDetecting;
}
 
nsProbingState ChineseGroupProber::HandleData(const char *aBuf, unsigned int aLen)
{
    nsProbingState st;
    unsigned int i;
 
    // do filtering to reduce load to probers
    char *highbyteBuf;
    char *hptr;
    bool keepNext = true; // assume previous is not ascii, it will do no harm except add some noise
    hptr = highbyteBuf = (char *)malloc(aLen);
    if (!hptr) {
        return mState;
    }
    for (i = 0; i < aLen; ++i) {
        if (aBuf[i] & 0x80) {
            *hptr++ = aBuf[i];
            keepNext = true;
        } else {
            // if previous is highbyte, keep this even it is an ASCII
            if (keepNext) {
                *hptr++ = aBuf[i];
                keepNext = false;
            }
        }
    }
 
    for (i = 0; i < CN_NUM_OF_PROBERS; ++i) {
        if (!mIsActive[i]) {
            continue;
        }
        st = mProbers[i]->HandleData(highbyteBuf, hptr - highbyteBuf);
        if (st == eFoundIt) {
            mBestGuess = i;
            mState = eFoundIt;
            break;
        } else if (st == eNotMe) {
            mIsActive[i] = false;
            --mActiveNum;
            if (mActiveNum == 0) {
                mState = eNotMe;
                break;
            }
        }
    }
 
    free(highbyteBuf);
 
    return mState;
}
 
float ChineseGroupProber::GetConfidence(void)
{
    unsigned int i;
    float bestConf = 0.0;
    float cf;
 
    switch (mState) {
    case eFoundIt:
        return (float)0.99;
    case eNotMe:
        return (float)0.01;
    default:
        for (i = 0; i < CN_NUM_OF_PROBERS; ++i) {
            if (!mIsActive[i]) {
                continue;
            }
            cf = mProbers[i]->GetConfidence();
            if (bestConf < cf) {
                bestConf = cf;
                mBestGuess = i;
            }
        }
    }
    return bestConf;
}
 
#ifdef DEBUG_PROBE
void ChineseGroupProber::DumpStatus()
{
    unsigned int i;
    float cf;
 
    GetConfidence();
    for (i = 0; i < CN_NUM_OF_PROBERS; i++) {
        if (!mIsActive[i]) {
            printf("  Chinese group inactive: [%s] (confidence is too low).\r\n", ProberName[i]);
        } else {
            cf = mProbers[i]->GetConfidence();
            printf("  Chinese group %1.3f: [%s]\r\n", cf, ProberName[i]);
        }
    }
}
#endif
}