shiftjis.cpp

#include "shiftjis.h"


#define ShiftJIS_func_type function<bool(const unsigned char*)>
#define ShiftJIS_one_byte_func(a,b) \
    [](const unsigned char* s){return *s>=a && *s<=b;}

#define ShiftJIS_two_byte_func(a,b,c,d) \
    [](const unsigned char* s){return *s>=a && *s<=b && s[1]>=c && s[1]<=d;}

vector<pair<int,ShiftJIS_func_type> > ShiftJIS_detect = {
        {2,ShiftJIS_two_byte_func(0x40,0x7E,0x80,0xFC)},  // make this before than 0x00,0x7F
        {2,ShiftJIS_two_byte_func(0x81,0x9F,0xE0,0xEF)},
        {1,ShiftJIS_one_byte_func(0x00,0x7F)},
        {1,ShiftJIS_one_byte_func(0xA1,0xDF)}};


ShiftJISChecker::ShiftJISChecker():
    CheckerBase("shift-jis")
{
}

bool ShiftJISChecker::detect(string str) const
{
    int current_index = -1;
    int length = str.length();
    const unsigned char* buffer = (const unsigned char*)str.c_str();
    while(current_index+1 < length)
    {
        bool flag = false;
        int buffer_left_length = length-current_index-1;
        for(auto detect:ShiftJIS_detect)
        {
            if(detect.first >= buffer_left_length &&
                    detect.second(buffer))
            {
                current_index += detect.first;
                buffer += detect.first;
                flag = true;
                break;
            }
        }
        if(flag==false) break;
    }
    return (current_index+1 == length);
}

ShiftJISChecker _shiftjischecker = ShiftJISChecker();