kitty/kitty/text-cache.c

/*
 * text-cache.c
 * Copyright (C) 2024 Kovid Goyal <kovid at kovidgoyal.net>
 *
 * Distributed under terms of the GPL3 license.
 */

#include "data-types.h"
typedef struct Chars {
    size_t count;
    const char_type *chars;
} Chars;

#define NAME chars_map
#define KEY_TY Chars
#define VAL_TY char_type
static uint64_t hash_chars(Chars k);
static bool cmpr_chars(Chars a, Chars b);
#define HASH_FN hash_chars
#define CMPR_FN cmpr_chars
#include "kitty-verstable.h"

typedef struct TextCache {
    struct { Chars *items; size_t capacity; char_type count; } array;
    chars_map map;
    unsigned refcnt;
} TextCache;
static uint64_t hash_chars(Chars k) { return vt_hash_bytes(k.chars, sizeof(k.chars[0]) * k.count); }
static bool cmpr_chars(Chars a, Chars b) { return a.count == b.count && memcmp(a.chars, b.chars, sizeof(a.chars[0]) * a.count) == 0; }

#define TEXT_CACHE_IMPLEMENTATION
#include "text-cache.h"

TextCache*
tc_alloc(void) {
    TextCache *ans = calloc(1, sizeof(TextCache));
    if (!ans) return NULL;
    ans->array.capacity = 256;
    ans->array.items = malloc(ans->array.capacity * sizeof(ans->array.items[0]));
    if (!ans->array.items) { free(ans); ans = NULL; return ans; }
    vt_init(&ans->map);
    ans->refcnt = 1;
    return ans;
}

void
tc_clear(TextCache *ans) {
    ans->array.count = 0;
    vt_cleanup(&ans->map);
}

static void
free_text_cache(TextCache *self) {
    vt_cleanup(&self->map);
    for (char_type i = 0; i < self->array.count; i++) free((char_type*)self->array.items[i].chars);
    free(self->array.items);
    free(self);
}

TextCache*
tc_incref(TextCache *self) { if (self) { self->refcnt++; } return self; }

TextCache*
tc_decref(TextCache *self) {
    if (self) {
        if (self->refcnt < 2) free_text_cache(self);
        else self->refcnt--;
    }
    return NULL;
}

char_type
tc_first_char_at_index(const TextCache *self, char_type idx) {
    if (self->array.count > idx) return self->array.items[idx].chars[0];
    return 0;
}

char_type
tc_last_char_at_index(const TextCache *self, char_type idx) {
    if (self->array.count > idx) return self->array.items[idx].chars[self->array.items[idx].count-1];
    return 0;
}


void
tc_chars_at_index(const TextCache *self, char_type idx, ListOfChars *ans) {
    if (self->array.count > idx) {
        ensure_space_for_chars(ans, self->array.items[idx].count);
        ans->count = self->array.items[idx].count;
        memcpy(ans->chars, self->array.items[idx].chars, sizeof(ans->chars[0]) * ans->count);
    } else {
        ans->count = 0;
    }
}

bool
tc_chars_at_index_without_alloc(const TextCache *self, char_type idx, ListOfChars *ans) {
    if (self->array.count > idx) {
        ans->count = self->array.items[idx].count;
        if (ans->capacity < ans->count) return false;
        memcpy(ans->chars, self->array.items[idx].chars, sizeof(ans->chars[0]) * ans->count);
    } else {
        ans->count = 0;
    }
    return true;
}


unsigned
tc_num_codepoints(const TextCache *self, char_type idx) {
     return self->array.count > idx ? self->array.items[idx].count : 0;
}

unsigned
tc_chars_at_index_ansi(const TextCache *self, char_type idx, ANSIBuf *output) {
    unsigned count = 0;
    if (self->array.count > idx) {
        count = self->array.items[idx].count;
        // we ensure space for one extra byte for ANSI escape code trailer if multicell
        ensure_space_for(output, buf, output->buf[0], output->len + count + 1, capacity, 2048, false);
        memcpy(output->buf + output->len, self->array.items[idx].chars, sizeof(output->buf[0]) * count);
        output->len += count;
    }
    return count;
}

static char_type
copy_and_insert(TextCache *self, const Chars key) {
    if (self->array.count > MAX_CHAR_TYPE_VALUE) fatal("Too many items in TextCache");
    ensure_space_for(&(self->array), items, Chars, self->array.count + 1, capacity, 256, false);
    char_type *copy = malloc(key.count * sizeof(key.chars[0]));
    if (!copy) fatal("Out of memory");
    memcpy(copy, key.chars, key.count * sizeof(key.chars[0]));
    char_type ans = self->array.count;
    Chars *k = self->array.items + self->array.count++;
    k->count = key.count; k->chars = copy;
    chars_map_itr i = vt_insert(&self->map, *k, ans);
    if (vt_is_end(i)) fatal("Out of memory");
    return ans;
}

char_type
tc_get_or_insert_chars(TextCache *self, const ListOfChars *chars) {
    Chars key = {.count=chars->count, .chars=chars->chars};
    chars_map_itr i = vt_get(&self->map, key);
    if (vt_is_end(i)) return copy_and_insert(self, key);
    return i.data->val;
}