Function json_append_metadata_string

engine/script/src/luacjson/lua_cjson.c:618–664

DEFOLD

// DEFOLD
static void json_append_metadata_string(lua_State *l, strbuf_t *json, int lindex)
{
    const char *escstr;
    unsigned i;
    const char *str;
    size_t len;

    int top = lua_gettop(l);

    lua_pushvalue(l, lindex);
    // -1: userdata

    lua_getglobal(l, "tostring");
    // -2: userdata
    // -1: tostring

    lua_pushvalue(l, -2);
    // -3: userdata
    // -2: tostring
    // -1: userdata

    lua_pcall(l, 1, 1, 0);
    // -2: userdata
    // -1: string

    str = lua_tolstring(l, -1, &len);

    /* Worst case is len * 6 (all unicode escapes).
     * This buffer is reused constantly for small strings
     * If there are any excess pages, they won't be hit anyway.
     * This gains ~5% speedup. */
    strbuf_ensure_empty_length(json, len * 6 + 2);

    strbuf_append_char_unsafe(json, '\"');
    for (i = 0; i < len; i++) {
        escstr = char2escape[(unsigned char)str[i]];
        if (escstr)
            strbuf_append_string(json, escstr);
        else
            strbuf_append_char_unsafe(json, str[i]);
    }
    strbuf_append_char_unsafe(json, '\"');

    lua_pop(l, 2); // pop the string+userdata

    assert(top == lua_gettop(l));
}
// DEFOLD END