gp_utf_pos.h

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// SPDX-License-Identifier: LGPL-2.1-or-later
/*
 * Copyright (C) 2022 Cyril Hrubis <metan@ucw.cz>
 */
 
#ifndef UTILS_GP_UTF_POS_H
#define UTILS_GP_UTF_POS_H
 
#include <utils/gp_utf.h>
#include <stdint.h>
#include <stddef.h>
#include <unistd.h>
 
typedef struct gp_utf8_pos {
        size_t bytes;
        size_t chars;
} gp_utf8_pos;
 
static inline gp_utf8_pos gp_utf8_pos_first(void)
{
        return (gp_utf8_pos){0, 0};
}
 
static inline gp_utf8_pos gp_utf8_pos_last(const char *str)
{
        gp_utf8_pos ret = {0, 0};
 
        for (;;) {
                int8_t chsz = gp_utf8_next_chsz(str, ret.bytes);
 
                if (chsz <= 0)
                        return ret;
 
                ret.bytes += chsz;
                ret.chars++;
        }
}
 
static inline int gp_utf8_pos_at_end(const char *str, gp_utf8_pos pos)
{
        return !str[pos.bytes];
}
 
static inline int gp_utf8_pos_at_home(gp_utf8_pos pos)
{
        return !pos.bytes;
}
 
static inline int gp_utf8_pos_eq(gp_utf8_pos a, gp_utf8_pos b)
{
        return a.bytes == b.bytes;
}
 
static inline int gp_utf8_pos_gt(gp_utf8_pos a, gp_utf8_pos b)
{
        return a.bytes > b.bytes;
}
 
static inline int gp_utf8_pos_ge(gp_utf8_pos a, gp_utf8_pos b)
{
        return a.bytes >= b.bytes;
}
 
static inline gp_utf8_pos gp_utf8_pos_sub(gp_utf8_pos a, gp_utf8_pos b)
{
        gp_utf8_pos res = {
                .bytes = a.bytes - b.bytes,
                .chars = a.chars - b.chars,
        };
 
        return res;
}
 
static inline gp_utf8_pos gp_utf8_pos_add(gp_utf8_pos a, gp_utf8_pos b)
{
        gp_utf8_pos res = {
                .bytes = a.bytes + b.bytes,
                .chars = a.chars + b.chars,
        };
 
        return res;
}
 
static inline gp_utf8_pos gp_utf8_pos_min(gp_utf8_pos a, gp_utf8_pos b)
{
        if (a.bytes < b.bytes)
                return a;
        else
                return b;
}
 
static inline gp_utf8_pos gp_utf8_pos_max(gp_utf8_pos a, gp_utf8_pos b)
{
        if (a.bytes > b.bytes)
                return a;
        else
                return b;
}
 
static inline ssize_t gp_utf8_pos_move(const char *str, gp_utf8_pos *cur_pos, ssize_t dir)
{
        ssize_t dirs = dir;
 
        if (dir > 0) {
                while (dir > 0) {
                        int8_t chsz = gp_utf8_next_chsz(str, cur_pos->bytes);
 
                        if (chsz <= 0)
                                return dirs - dir;
 
                        cur_pos->bytes += chsz;
                        cur_pos->chars++;
 
                        dir--;
                }
 
                return dirs;
        }
 
        if (dir < 0) {
                while (dir < 0) {
                        int8_t chsz = gp_utf8_prev_chsz(str, cur_pos->bytes);
 
                        if (chsz <= 0)
                                return dir - dirs;
 
                        cur_pos->bytes -= chsz;
                        cur_pos->chars--;
 
                        dir++;
                }
 
                return -dirs;
        }
 
        return 0;
}
 
static inline uint32_t gp_utf8_pos_prev(const char *str, gp_utf8_pos *pos) {
        int8_t chsz;
 
        if (!pos->bytes)
                return 0;
 
        chsz = gp_utf8_prev_chsz(str, pos->bytes);
        if (chsz <= 0)
                return 0;
 
        pos->bytes -= chsz;
        pos->chars--;
 
        str += pos->bytes;
 
        return gp_utf8_next(&str);
}
 
static inline uint32_t gp_utf8_pos_next(const char *str, gp_utf8_pos *pos)
{
        int8_t chsz;
 
        chsz = gp_utf8_next_chsz(str, pos->bytes);
        if (chsz <= 0)
                return 0;
 
        str += pos->bytes;
 
        pos->bytes += chsz;
        pos->chars++;
 
        return gp_utf8_next(&str);
}
 
#endif /* UTILS_GP_UTF_POS_H */