path: root/src/utf8.c

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

#include "utf8.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 };

static void encode_unknown(strbuf *buf)
{
    static const uint8_t repl[] = {239, 191, 189};
    strbuf_put(buf, repl, 3);
}

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

    if (!str_len)
        return 0;

    length = utf8proc_utf8class[str[0]];

    if (!length)
        return -1;

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

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

    return length;
}

void utf8proc_detab(strbuf *ob, const uint8_t *line, size_t size)
{
    static const uint8_t whitespace[] = "    ";

    size_t i = 0, tab = 0;

    while (i < size) {
        size_t org = i;

        while (i < size && line[i] != '\t' && line[i] <= 0x80) {
            i++; tab++;
        }

        if (i > org)
            strbuf_put(ob, line + org, i - org);

        if (i >= size)
            break;

        if (line[i] == '\t') {
            int numspaces = 4 - (tab % 4);
            strbuf_put(ob, whitespace, numspaces);
            i += 1;
            tab += numspaces;
        } else {
            int charlen = utf8proc_charlen(line + i, size - i);

            if (charlen >= 0) {
                strbuf_put(ob, line + i, charlen);
            } else {
                encode_unknown(ob);
                charlen = -charlen;
            }

            i += charlen;
            tab += 1;
        }
    }
}

int utf8proc_iterate(const uint8_t *str, int str_len, int32_t *dst)
{
    int 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 utf8proc_encode_char(int32_t uc, strbuf *buf)
{
    uint8_t dst[4];
    int len = 0;

    assert(uc >= 0);

    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;
        len = 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 {
        encode_unknown(buf);
        return;
    }

    strbuf_put(buf, dst, len);
}

void utf8proc_case_fold(strbuf *dest, const uint8_t *str, int len)
{
    int32_t c;

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

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

        if (char_len >= 0) {
#include "case_fold_switch.inc"
        } else {
            encode_unknown(dest);
            char_len = -char_len;
        }

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