// GoLuaFunc converts an arbitrary Go function into a Lua-compatible GoFunction.
// There are special optimized cases for functions that go from strings to strings,
// and doubles to doubles, but otherwise Go
// reflection is used to provide a generic wrapper function
func GoLuaFunc(L *lua.State, fun interface{}) lua.LuaGoFunction {
switch f := fun.(type) {
case func(*lua.State) int:
return f
case func(string) string:
return func(L *lua.State) int {
L.PushString(f(L.ToString(1)))
return 1
}
case func(float64) float64:
return func(L *lua.State) int {
L.PushNumber(f(L.ToNumber(1)))
return 1
}
default:
}
var funv reflect.Value
switch ff := fun.(type) {
case reflect.Value:
funv = ff
default:
funv = valueOf(fun)
}
funt := funv.Type()
targs, tout := functionArgRetTypes(funt)
return func(L *lua.State) int {
var lastT reflect.Type
isVariadic := funt.IsVariadic()
if isVariadic {
lastT = targs[len(targs)-1].Elem()
targs = targs[0 : len(targs)-1]
}
args := make([]reflect.Value, len(targs))
for i, t := range targs {
val := LuaToGo(L, t, i+1)
args[i] = valueOf(val)
}
if isVariadic {
n := L.GetTop()
for i := len(targs) + 1; i <= n; i++ {
val := valueOf(LuaToGo(L, lastT, i))
args = append(args, val)
}
}
resv := funv.Call(args)
for i, val := range resv {
GoToLua(L, tout[i], val)
}
return len(resv)
}
}
// Convert a Lua value 'idx' on the stack to the Go value of desired type 't'. Handles
// numerical and string types in a straightforward way, and will convert tables to
// either map or slice types.
func LuaToGo(L *lua.State, t reflect.Type, idx int) interface{} {
var value interface{}
var kind reflect.Kind
if t == nil { // let the Lua type drive the conversion...
switch L.Type(idx) {
case lua.LUA_TNIL:
return nil // well, d'oh
case lua.LUA_TBOOLEAN:
kind = reflect.Bool
case lua.LUA_TSTRING:
kind = reflect.String
case lua.LUA_TTABLE:
kind = reflect.Interface
default:
return NewLuaObject(L, idx)
}
} else if t.Kind() == reflect.Ptr {
kind = t.Elem().Kind()
} else {
kind = t.Kind()
}
switch kind {
// various numerical types are tedious but straightforward
case reflect.Float64:
{
ptr := new(float64)
*ptr = L.ToNumber(idx)
value = *ptr
}
case reflect.Float32:
{
ptr := new(float32)
*ptr = float32(L.ToNumber(idx))
value = *ptr
}
case reflect.Int:
{
ptr := new(int)
*ptr = int(L.ToNumber(idx))
value = *ptr
}
case reflect.Int8:
{
ptr := new(byte)
*ptr = byte(L.ToNumber(idx))
value = *ptr
}
case reflect.String:
{
tos := L.ToString(idx)
ptr := new(string)
*ptr = tos
value = *ptr
}
case reflect.Bool:
{
ptr := new(bool)
*ptr = bool(L.ToBoolean(idx))
value = *ptr
}
case reflect.Slice:
{
// if we get a table, then copy its values to a new slice
if L.IsTable(idx) {
value = CopyTableToSlice(L, t, idx)
} else {
value = unwrapProxy(L, idx)
}
}
case reflect.Map:
{
if L.IsTable(idx) {
value = CopyTableToMap(L, t, idx)
} else {
value = unwrapProxy(L, idx)
}
}
case reflect.Struct:
{
if L.IsTable(idx) {
value = CopyTableToStruct(L, t, idx)
} else {
value = unwrapProxy(L, idx)
}
}
case reflect.Interface:
{
if L.IsTable(idx) {
// have to make an executive decision here: tables with non-zero
// length are assumed to be slices!
if L.ObjLen(idx) > 0 {
value = CopyTableToSlice(L, nil, idx)
} else {
value = CopyTableToMap(L, nil, idx)
}
} else if L.IsNumber(idx) {
value = L.ToNumber(idx)
} else if L.IsString(idx) {
value = L.ToString(idx)
} else if L.IsBoolean(idx) {
value = L.ToBoolean(idx)
} else {
value = unwrapProxy(L, idx)
}
}
default:
{
fmt.Println("unhandled type", t)
value = 20
}
}
return value
}
