Function Info

debug.go:313–391

Info gets information about a specific function or function invocation. To get information about a function invocation, the parameter where must be a valid activation record that was filled by a previous call to Stack or given as an argument to a hook (see Hook). To get information about a functio

(l *State, what string, where Frame)

//
// This function returns false on error (for instance, an invalid option in what).
func Info(l *State, what string, where Frame) (d Debug, ok bool) {
	var f closure
	var fun value
	if what[0] == '>' {
		where = nil
		fun = l.stack[l.top-1]
		switch fun := fun.(type) {
		case closure:
			f = fun
		case *goFunction:
		default:
			panic("function expected")
		}
		what = what[1:] // skip the '>'
		l.top--         // pop function
	} else {
		fun = l.stack[where.function]
		switch fun := fun.(type) {
		case closure:
			f = fun
		case *goFunction:
		default:
			l.assert(false)
		}
	}
	ok, hasL, hasF := true, false, false
	d.callInfo = where
	ci := d.callInfo
	for _, r := range what {
		switch r {
		case 'S':
			d = functionInfo(d, f)
		case 'l':
			d.CurrentLine = -1
			if where != nil && ci.isLua() {
				d.CurrentLine = l.currentLine(where)
			}
		case 'u':
			if f == nil {
				d.UpValueCount = 0
			} else {
				d.UpValueCount = f.upValueCount()
			}
			if lf, ok := f.(*luaClosure); !ok {
				d.IsVarArg = true
				d.ParameterCount = 0
			} else {
				d.IsVarArg = lf.prototype.isVarArg
				d.ParameterCount = lf.prototype.parameterCount
			}
		case 't':
			d.IsTailCall = where != nil && ci.isCallStatus(callStatusTail)
		case 'n':
			// calling function is a known Lua function?
			if where != nil && !ci.isCallStatus(callStatusTail) && where.previous.isLua() {
				d.Name, d.NameKind = l.functionName(where.previous)
			} else {
				d.NameKind = ""