path: root/src/utf8.c

#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>

#include "stmd.h"

static const int8_t utf8proc_utf8class[256] = {
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
    3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
    4, 4, 4, 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0 };

ssize_t utf8proc_charlen(const uint8_t *str, ssize_t str_len)
{
    ssize_t length, i;

    if (!str_len)
        return 0;

    length = utf8proc_utf8class[str[0]];

    if (!length)
        return -1;

    if (str_len >= 0 && length > str_len)
        return -1;

    for (i = 1; i < length; i++) {
        if ((str[i] & 0xC0) != 0x80)
            return -1;
    }

    return length;
}

ssize_t utf8proc_iterate(const uint8_t *str, ssize_t str_len, int32_t *dst)
{
    ssize_t length;
    int32_t uc = -1;

    *dst = -1;
    length = utf8proc_charlen(str, str_len);
    if (length < 0)
        return -1;

    switch (length) {
        case 1:
            uc = str[0];
            break;
        case 2:
            uc = ((str[0] & 0x1F) <<  6) + (str[1] & 0x3F);
            if (uc < 0x80) uc = -1;
            break;
        case 3:
            uc = ((str[0] & 0x0F) << 12) + ((str[1] & 0x3F) <<  6)
                + (str[2] & 0x3F);
            if (uc < 0x800 || (uc >= 0xD800 && uc < 0xE000) ||
                    (uc >= 0xFDD0 && uc < 0xFDF0)) uc = -1;
            break;
        case 4:
            uc = ((str[0] & 0x07) << 18) + ((str[1] & 0x3F) << 12)
                + ((str[2] & 0x3F) <<  6) + (str[3] & 0x3F);
            if (uc < 0x10000 || uc >= 0x110000) uc = -1;
            break;
    }

    if (uc < 0 || ((uc & 0xFFFF) >= 0xFFFE))
        return -1;

    *dst = uc;
    return length;
}

void utf8_encode_char(int32_t uc, gh_buf *buf)
{
    char dst[4];
    int len = 0;

    if (uc < 0x00) {
        assert(false);
    } else if (uc < 0x80) {
        dst[0] = uc;
        len = 1;
    } else if (uc < 0x800) {
        dst[0] = 0xC0 + (uc >> 6);
        dst[1] = 0x80 + (uc & 0x3F);
        len = 2;
    } else if (uc == 0xFFFF) {
        dst[0] = 0xFF;
        return 1;
    } else if (uc == 0xFFFE) {
        dst[0] = 0xFE;
        len = 1;
    } else if (uc < 0x10000) {
        dst[0] = 0xE0 + (uc >> 12);
        dst[1] = 0x80 + ((uc >> 6) & 0x3F);
        dst[2] = 0x80 + (uc & 0x3F);
        len = 3;
    } else if (uc < 0x110000) {
        dst[0] = 0xF0 + (uc >> 18);
        dst[1] = 0x80 + ((uc >> 12) & 0x3F);
        dst[2] = 0x80 + ((uc >> 6) & 0x3F);
        dst[3] = 0x80 + (uc & 0x3F);
        len = 4;
    } else {
        assert(false);
    }

    gh_buf_put(buf, dst, len);
}

void utf8proc_case_fold(gh_buf *dest, const unsigned char *str, int len)
{
    int32_t c;

#define bufpush(x) \
    utf8proc_encode_char(x, dest)

    while (len > 0) {
        ssize_t char_len = utf8proc_iterate(str, len, &c);

        if (char_len < 0) {
            bufpush(0xFFFD);
            continue;
        }

#include "case_fold_switch.inc"

        str += char_len;
        len -= char_len;
    }
}