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/* jshint esversion: 6 */
"use strict";
const assert = require('assert');
const lua = require('./lua.js');
const lapi = require('./lapi.js');
const lauxlib = require('./lauxlib.js');
const lstate = require('./lstate.js');
const ldo = require('./ldo.js');
const ldebug = require('./ldebug.js');
const CT = lua.constant_types;
const TS = lua.thread_status;
/*
** Operations that an object must define to mimic a table
** (some functions only need some of them)
*/
const TAB_R = 1; /* read */
const TAB_W = 2; /* write */
const TAB_L = 4; /* length */
const TAB_RW = (TAB_R | TAB_W); /* read/write */
const checkfield = function(L, key, n) {
lapi.lua_pushstring(L, key);
return lapi.lua_rawget(L, -n) !== CT.LUA_TNIL;
};
/*
** Check that 'arg' either is a table or can behave like one (that is,
** has a metatable with the required metamethods)
*/
const checktab = function(L, arg, what) {
if (lapi.lua_type(L, arg) !== CT.LUA_TTABLE) { /* is it not a table? */
let n = 1;
if (lapi.lua_getmetatable(L, arg) && /* must have metatable */
(!(what & TAB_R) || checkfield(L, "__index", ++n)) &&
(!(what & TAB_W) || checkfield(L, "__newindex", ++n)) &&
(!(what & TAB_L) || checkfield(L, "__len", ++n))) {
lapi.lua_pop(L, n); /* pop metatable and tested metamethods */
}
else
lauxlib.luaL_checktype(L, arg, CT.LUA_TTABLE); /* force an error */
}
};
const aux_getn = function(L, n, w) {
checktab(L, n, w | TAB_L);
lauxlib.luaL_len(L, n);
};
const addfield = function(L, b, i) {
lapi.lua_geti(L, 1, i);
if (!lapi.lua_isstring(L, -1))
lauxlib.luaL_error(L, `invalid value (${lauxlib.luaL_typename(L, -1)}) at index ${i} in table for 'concat'`);
lauxlib.luaL_addvalue(b);
};
const tconcat = function(L) {
let last = aux_getn(L, 1, TAB_R);
let sep = lauxlib.luaL_optlstring(L, 2, "");
let i = lauxlib.luaL_optinteger(L, 3, 1);
last = lauxlib.luaL_optinteger(L, 4, last);
let b = new lauxlib.luaL_Buffer();
lauxlib.luaL_buffinit(L, b);
for (; i < last; i++) {
addfield(L, b, i);
lauxlib.luaL_addlstring(b, sep);
}
if (i === last)
addfield(L, b, i);
lauxlib.luaL_pushresult(b);
return 1;
};
const pack = function(L) {
let n = lapi.lua_gettop(L); /* number of elements to pack */
lapi.lua_createtable(L, n, 1); /* create result table */
lapi.lua_insert(L, 1); /* put it at index 1 */
for (let i = n; i >= 1; i--) /* assign elements */
lapi.lua_seti(L, 1, i);
lapi.lua_pushinteger(L, n);
lapi.lua_setfield(L, 1, "n"); /* t.n = number of elements */
return 1; /* return table */
};
const unpack = function(L) {
let i = lauxlib.luaL_optinteger(L, 2, 1);
let e = lauxlib.luaL_opt(L, lauxlib.luaL_checkinteger, 3, lapi.lua_len(L, 1));
if (i > e) return 0; /* empty range */
let n = e - i; /* number of elements minus 1 (avoid overflows) */
if (n >= Number.MAX_SAFE_INTEGER || !lapi.lua_checkstack(L, ++n))
return lauxlib.luaL_error(L, "too many results to unpack");
for (; i < e; i++) /* push arg[i..e - 1] (to avoid overflows) */
lapi.lua_geti(L, 1, i);
lapi.lua_geti(L, 1, e); /* push last element */
return n;
};
const tab_funcs = {
"concat": tconcat,
"pack": pack,
"unpack": unpack,
};
const luaopen_table = function(L) {
lauxlib.luaL_newlib(L, tab_funcs);
return 1;
};
module.exports.luaopen_table = luaopen_table;
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