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package main
/*
#cgo LDFLAGS: -llua
#include <stdlib.h>
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
*/
import "C"
import (
"errors"
"unsafe"
"log"
)
type LuaRef C.longlong
type Lua struct {
l *C.lua_State
}
func (l *Lua) Start() {
l.l = C.luaL_newstate()
C.luaL_openlibs(l.l)
}
func (l *Lua) Close() {
C.lua_close(l.l)
C.free(unsafe.Pointer(l.l))
}
func (l *Lua) Require(file string) (LuaRef, error) {
if !l.LoadFile(file) {
errMsg := l.ToString(-1)
l.Pop(1)
return 0, errors.New("could not open the file:\n" + errMsg)
}
if !l.PCall(0, C.LUA_MULTRET) {
errMsg := l.ToString(-1)
l.Pop(1)
return 0, errors.New("could not execute the file:\n" + errMsg)
}
if !l.IsTable(-1) {
return 0, errors.New("module did not return a table")
}
return l.PopToRef(), nil
}
func (l *Lua) PCall(nargs int, nresults int) bool {
res := C.lua_pcallk(l.l, C.int(nargs), C.int(nresults), 0, 0, nil)
return res == C.LUA_OK
}
func (l *Lua) LoadFile(file string) bool {
cfile := C.CString(file)
defer C.free(unsafe.Pointer(cfile))
res := C.luaL_loadfilex(l.l, cfile, nil)
return res == C.LUA_OK
}
func (l *Lua) StackLen() int {
return int(C.lua_gettop(l.l))
}
func (l *Lua) ToString(index int) string {
return C.GoString(C.lua_tolstring(l.l, C.int(index), nil))
}
func (l *Lua) ToInt(index int) int {
return int(C.lua_tonumberx(l.l, C.int(index), nil))
}
func (l *Lua) PopToRef() LuaRef {
return LuaRef(C.luaL_ref(l.l, C.LUA_REGISTRYINDEX))
}
func (l *Lua) Pop(n int) {
C.lua_settop(l.l, C.int(-n - 1))
}
func (l *Lua) PushNil() {
C.lua_pushnil(l.l)
}
func (l *Lua) PushString(str string) {
cstr := C.CString(str)
defer C.free(unsafe.Pointer(cstr))
C.lua_pushstring(l.l, cstr)
}
func (l *Lua) PushTable(table map[string]string) {
C.lua_createtable(l.l, 0, C.int(len(table)))
for k, v := range table {
l.PushString(v)
C.lua_setfield(l.l, -2, C.CString(k))
}
}
func (l *Lua) PushFromRef(ref LuaRef) {
C.lua_rawgeti(l.l, C.LUA_REGISTRYINDEX, C.longlong(ref));
}
func (l *Lua) IsString(index int) bool {
return C.lua_isstring(l.l, C.int(index)) == 1
}
func (l *Lua) IsNumber(index int) bool {
return C.lua_isnumber(l.l, C.int(index)) == 1
}
func (l *Lua) IsFunction(index int) bool {
return C.lua_type(l.l, C.int(index)) == C.LUA_TFUNCTION
}
func (l *Lua) IsTable(index int) bool {
return C.lua_type(l.l, C.int(index)) == C.LUA_TTABLE
}
func (l *Lua) Next() bool {
return C.lua_next(l.l, -2) != 0
}
func (l *Lua) LoadString(code string) error {
cstr := C.CString(code)
defer C.free(unsafe.Pointer(cstr))
if C.luaL_loadstring(l.l, cstr) != C.LUA_OK {
errMsg := l.ToString(-1)
l.Pop(1)
return errors.New(errMsg)
}
if !l.PCall(0, 0) {
errMsg := l.ToString(-1)
l.Pop(1)
return errors.New(errMsg)
}
l.Pop(l.StackLen())
return nil
}
func (l *Lua) PushTableItem(key string) {
ckey := C.CString(key)
defer C.free(unsafe.Pointer(ckey))
C.lua_pushstring(l.l, ckey);
C.lua_gettable(l.l, -2);
}
func (l *Lua) RestoreStackFunc() func () {
before := l.StackLen()
return func () {
after := l.StackLen()
diff := after - before
if diff == 0 {
return
} else if diff < 0 {
log.Fatalf(
"too many stack pops: len before: %d, after: %d\n",
before,
after,
)
}
C.lua_settop(l.l, C.int(before))
}
}
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