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/*jshint esversion: 6 */
"use strict";
const lua = require('./lua.js');
const CT = lua.constant_types;
const LUA_MULTRET = lua.LUA_MULTRET;
const lobject = require('./lobject.js');
const TValue = lobject.TValue;
const lstate = require('./lstate.js');
const CallInfo = lstate.CallInfo;
const llimit = require('./llimit.js');
const ltm = require('./ltm.js');
const TMS = ltm.TMS;
const nil = new TValue(CT.LUA_TNIL, null);
const luaD_precall = function(L, off, nresults) {
let func = L.stack[off];
let ci;
switch(func.type) {
case CT.LUA_TCCL: // JS function ?
throw new Error("LUA_TCCL not implemeted yet");
case CT.LUA_TLCF: // still JS function ?
throw new Error("LUA_TLCF not implemeted yet");
case CT.LUA_TLCL: {
let p = func.p;
let n = L.top - off - 1;
let fsize = p.maxstacksize;
let base;
if (p.is_vararg) {
base = adjust_varargs(L, p, n);
} else {
for (; n < p.numparams; n++)
L.stack[L.top++] = nil; // complete missing arguments
base = off + 1;
}
// next_ci
if (L.ci.next) {
L.ci = L.ci.next;
ci = L.ci;
} else {
ci = new CallInfo(off);
L.ci.next = ci;
ci.previous = L.ci;
ci.next = null;
L.ci = ci;
L.ciOff++;
}
ci.nresults = nresults;
ci.func = func;
ci.funcOff = off;
ci.u.l.base = base;
ci.top = base + fsize;
L.top = ci.top;
ci.u.l.savedpc = p.code;
ci.pcOff = 0;
ci.callstatus = lstate.CIST_LUA;
return false;
}
default:
tryfuncTM(L, off, func);
return luaD_precall(L, off, nresults);
}
};
const luaD_poscall = function(L, ci, firstResult, nres) {
let wanted = ci.nresults;
let res = ci.funcOff;
L.ci = ci.previous;
L.ciOff--;
return moveresults(L, firstResult, res, nres, wanted);
};
const moveresults = function(L, firstResult, res, nres, wanted) {
switch (wanted) {
case 0:
break;
case 1: {
if (nres === 0)
firstResult = nil;
L.stack[res] = L.stack[firstResult];
break;
}
case LUA_MULTRET: {
for (let i = 0; i < nres; i++)
L.stack[res + i] = L.stack[firstResult + i];
L.top = res + nres;
return false;
}
default: {
let i;
if (wanted <= nres) {
for (i = 0; i < wanted; i++) {
L.stack[res + i] = L.stack[firstResult + i];
}
} else {
for (i = 0; i < nres; i++)
L.stack[res + i] = L.stack[firstResult + i];
for (; i < wanted; i++)
L.stack[res + i] = nil;
}
break;
}
}
L.top = res + wanted; /* top points after the last result */
return true;
};
const adjust_varargs = function(L, p, actual) {
let nfixargs = p.numparams;
/* move fixed parameters to final position */
let fixed = L.top - actual; /* first fixed argument */
let base = L.top; /* final position of first argument */
let i;
for (i = 0; i < nfixargs && i < actual; i++) {
L.stack[L.top++] = L.stack[fixed + i];
L.stack[fixed + i] = nil;
}
for (; i < nfixargs; i++)
L.stack[L.top++] = nil;
return base;
};
const tryfuncTM = function(L, off, func) {
let tm = ltm.luaT_gettmbyobj(L, func, TMS.TM_CALL);
if (!tm.ttisfunction(tm))
throw new Error("__call metatable member is not a function"); // TODO: luaG_typeerror
/* Open a hole inside the stack at 'func' */
for (let p = L.top; p > off; p--)
L.stack[p] = L.stack[p-1];
L.top++; /* slot ensured by caller */
L.stack[off] = tm; /* tag method is the new function to be called */
};
module.exports = {
nil: nil,
luaD_precall: luaD_precall,
luaD_poscall: luaD_poscall,
moveresults: moveresults,
adjust_varargs: adjust_varargs,
tryfuncTM: tryfuncTM
};
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