support luajit 2.1

1 files changed, 420 insertions, 0 deletions

diff --git a/luajit.go b/luajit.go
new file mode 100644
index 0000000..2ee8b55
--- /dev/null
+++ b/luajit.go
@@ -0,0 +1,420 @@
+//go:build jit
+
+package main
+
+/*
+#cgo LDFLAGS: -lluajit-5.1
+#include <stdlib.h>
+#include <stdint.h>
+#include <luajit-2.1/lua.h>
+#include <luajit-2.1/lualib.h>
+#include <luajit-2.1/lauxlib.h>
+
+extern int luna_run_go_func(uintptr_t);
+
+static inline int luna_run(lua_State *l) {
+	return luna_run_go_func(lua_tonumber(l, lua_upvalueindex(1)));
+}
+
+static inline void luna_push_function(lua_State *l, uintptr_t f) {
+	lua_pushinteger(l, f);
+	lua_pushcclosure(l, luna_run, 1);
+}
+*/
+import "C"
+import (
+	"errors"
+	"fmt"
+	"reflect"
+	"runtime/cgo"
+	"slices"
+	"time"
+	"unsafe"
+)
+
+type LuaRef C.longlong
+// Lua is a wrapper around C Lua state with several conveniences.
+type Lua struct {
+	l *C.lua_State
+}
+
+//export luna_run_go_func
+// luna_run_go_func calls a Go function from C/Lua.
+func luna_run_go_func(f C.uintptr_t) C.int {
+	fn := cgo.Handle(f).Value().(func() int)
+	return C.int(fn())
+}
+
+// Start opens the Lua context with all built-in libraries.
+func (l *Lua) Start() {
+	l.l = C.luaL_newstate()
+	C.luaL_openlibs(l.l)
+}
+
+// Close closes the Lua context.
+func (l *Lua) Close() {
+	C.lua_close(l.l)
+}
+
+// Require loads and executes the file pushing results onto the Lua stack.
+func (l *Lua) Require(file string) error {
+	if !l.LoadFile(file) {
+		errMsg := l.ToString(-1)
+		l.Pop(1)
+		return errors.New("could not open the file:\n" + errMsg)
+	}
+	err := l.PCall(0, C.LUA_MULTRET)
+	if err != nil {
+		return errors.New("could not execute the file:\n" + err.Error())
+	}
+	return nil
+}
+
+// PCall calls a function with the stack index (-nargs-1) expecting nresults
+// number of results.
+func (l *Lua) PCall(nargs int, nresults int) error {
+	res := C.lua_pcall(l.l, C.int(nargs), C.int(nresults), 0)
+	if res != C.LUA_OK {
+		errMsg := l.ToString(-1)
+		l.Pop(1)
+		return errors.New(errMsg)
+	}
+	return nil
+}
+
+// LoadFile loads the file code in the current Lua context.
+func (l *Lua) LoadFile(file string) bool {
+	cstr := C.CString(file)
+	defer C.free(unsafe.Pointer(cstr))
+	res := C.luaL_loadfilex(l.l, cstr, nil)
+	return res == C.LUA_OK
+}
+
+// StackLen returns the length of the Lua stack.
+func (l *Lua) StackLen() int {
+	return int(C.lua_gettop(l.l))
+}
+
+// ToInt converts a stack value with stack index into a string.
+func (l *Lua) ToString(index int) string {
+	return C.GoString(C.lua_tolstring(l.l, C.int(index), nil))
+}
+
+// ToInt converts a stack value with stack index -1 into a number.
+func (l *Lua) ToInt(index int) int {
+	return int(C.lua_tonumberx(l.l, C.int(index), nil))
+}
+
+// PopToRef pops the item (stack offset -1) from the stack and then stores it
+// in the registry.
+func (l *Lua) PopToRef() LuaRef {
+	return LuaRef(C.luaL_ref(l.l, C.LUA_REGISTRYINDEX))
+}
+
+// Pop pops N items from the Lua stack.
+func (l *Lua) Pop(n int) {
+	C.lua_settop(l.l, C.int(-n - 1))
+}
+
+// PushNumber pushes tnil onto the Lua stack.
+func (l *Lua) PushNil() {
+	C.lua_pushnil(l.l)
+}
+
+// PushNumber pushes the number onto the Lua stack.
+func (l *Lua) PushNumber(num int) {
+	C.lua_pushnumber(l.l, C.double(num))
+}
+
+// PushNumber pushes the number onto the Lua stack.
+func (l *Lua) PushFloatNumber(num float64) {
+	C.lua_pushnumber(l.l, C.double(num))
+}
+
+// PushString pushes the string onto the Lua stack.
+func (l *Lua) PushString(str string) {
+	cstr := C.CString(str)
+	defer C.free(unsafe.Pointer(cstr))
+	C.lua_pushstring(l.l, cstr)
+}
+
+// PushGoFunction pushes a Go function onto the Lua stack so it's possible to
+// call it from Lua. You may need to delete returned handle with .Delete()
+// method later.
+func (l *Lua) PushGoFunction(f func (l *Lua) int) cgo.Handle {
+	h := cgo.NewHandle(func () int {
+		return f(l)
+	})
+	C.luna_push_function(l.l, C.uintptr_t(h))
+	return h
+}
+
+// CreateTable pushes a new Lua table onto the stack.
+func (l *Lua) CreateTable(len int) {
+	C.lua_createtable(l.l, 0, C.int(len))
+}
+
+// SetTableItem adds a value (stack offset -1) to a table (offset -2) under
+// the specified key.
+func (l *Lua) SetTableItem(key string) {
+	cstr := C.CString(key)
+	defer C.free(unsafe.Pointer(cstr))
+	C.lua_setfield(l.l, -2, C.CString(key))
+}
+
+// PushAny pushes value v onto the stack.
+func (l *Lua) PushAny(v any) error {
+	switch v.(type) {
+	case string:
+		v, _ := v.(string)
+		l.PushString(v)
+	case func (l *Lua) int:
+		v, _ := v.(func (l *Lua) int)
+		l.PushGoFunction(v)
+	case int:
+		v, _ := v.(int)
+		l.PushNumber(v)
+	case int64:
+		v, _ := v.(int64)
+		l.PushNumber(int(v))
+	case float64:
+		v, _ := v.(float64)
+		l.PushFloatNumber(v)
+	case map[string]any:
+		v, _ := v.(map[string]any)
+		l.PushObject(v)
+	case []any:
+		v, _ := v.([]any)
+		l.PushArray(v)
+	case time.Time:
+		v, _ := v.(time.Time)
+		l.PushString(v.Format(time.DateTime))
+	default:
+		return fmt.Errorf("unsupported value type: %T", v)
+	}
+	return nil
+}
+
+// PushObject recursively pushes string->any Go table onto the stack.
+func (l *Lua) PushObject(table map[string]any) error {
+	l.CreateTable(len(table))
+	for k, v := range table {
+		err := l.PushAny(v)
+		if err != nil {
+			return err
+		}
+		l.SetTableItem(k)
+	}
+	return nil
+}
+
+// PushArray recursively pushes an array of Go values onto the stack.
+func (l *Lua) PushArray(array []any) error {
+	l.CreateTable(len(array))
+	for k, v := range array {
+		l.PushNumber(k + 1)
+		err := l.PushAny(v)
+		if err != nil {
+			return err
+		}
+		C.lua_settable(l.l, C.int(-3))
+	}
+	return nil
+}
+
+// PushFromRef pushes a value from registry ref onto the stack.
+func (l *Lua) PushFromRef(ref LuaRef) {
+	C.lua_rawgeti(l.l, C.LUA_REGISTRYINDEX, C.int(ref));
+}
+
+// Type returns type of the value sitting at n index on the stack.
+func (l *Lua) Type(n int) int {
+	return int(C.lua_type(l.l, C.int(n)))
+}
+
+// IsNil checks if the stack contains nil under the given index.
+func (l *Lua) IsNil(index int) bool {
+	return C.lua_type(l.l, C.int(index)) == C.LUA_TNIL
+}
+
+// IsString checks if the stack contains a string under the given index.
+func (l *Lua) IsString(index int) bool {
+	return C.lua_isstring(l.l, C.int(index)) == 1
+}
+
+// IsNumber checks if the stack contains a number (both int and float) under
+// the given index.
+func (l *Lua) IsNumber(index int) bool {
+	return C.lua_isnumber(l.l, C.int(index)) == 1
+}
+
+// IsFunction checks if the stack contains a function under the given index.
+func (l *Lua) IsFunction(index int) bool {
+	return C.lua_type(l.l, C.int(index)) == C.LUA_TFUNCTION
+}
+
+// IsTable checks if the stack contains a table under the given index.
+func (l *Lua) IsTable(index int) bool {
+	return C.lua_type(l.l, C.int(index)) == C.LUA_TTABLE
+}
+
+// Next advances a table iterator at the stack index -2.
+func (l *Lua) Next() bool {
+	return C.lua_next(l.l, -2) != 0
+}
+
+// LoadString loads and executes the code in the current Lua context.
+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)
+	}
+	err := l.PCall(0, 0)
+	if err != nil {
+		return err
+	}
+	l.Pop(l.StackLen())
+	return nil
+}
+
+// Scan scans values from the Lua stack into vars according to their types.
+func (l *Lua) Scan(vars ...any) error {
+	slices.Reverse(vars)
+	for i, v := range vars {
+		t := reflect.TypeOf(v)
+		// unwrap pointers
+		for t.Kind() == reflect.Ptr {
+			t = t.Elem()
+		}
+		tk := t.Kind()
+		if t.Name() == "LuaRef" {
+			if l.IsFunction(-1) == false {
+				return fmt.Errorf(
+					"passed arg #%d must be function",
+					len(vars)-i,
+				)
+			}
+			*v.(*LuaRef) = l.PopToRef()
+		} else if t.String() == "cgo.Handle" {
+			if l.IsNumber(-1) == false {
+				return fmt.Errorf(
+					"passed arg #%d must be Go handler",
+					len(vars)-i,
+				)
+			}
+			*v.(*cgo.Handle) = cgo.Handle(uintptr(l.ToInt(-1)))
+			l.Pop(1)
+		} else if tk == reflect.String {
+			if l.IsString(-1) == false {
+				return fmt.Errorf(
+					"passed arg #%d must be string",
+					len(vars)-i,
+				)
+			}
+			*v.(*string) = l.ToString(-1)
+			l.Pop(1)
+		} else if tk == reflect.Int {
+			if l.IsNumber(-1) == false {
+				return fmt.Errorf(
+					"passed arg #%d must be number",
+					len(vars)-i,
+				)
+			}
+			*v.(*int) = l.ToInt(-1)
+			l.Pop(1)
+		} else if tk == reflect.Map && t.Key().Kind() == reflect.String {
+			// TODO: should be possible to use maps with any types
+			// of value, not only strings.
+			vm, _ := v.(*map[string]string)
+			l.PushNil()
+			for l.Next() {
+				if !l.IsString(-1) {
+					return fmt.Errorf(
+						"map arg #%d must only have string values",
+						len(vars)-i,
+					)
+				}
+				if !l.IsString(-2) {
+					return fmt.Errorf(
+						"map arg #%d must only have string keys",
+						len(vars)-i,
+					)
+				}
+				v := l.ToString(-1)
+				l.Pop(1)
+				// We must not pop the item key from the stack
+				// because otherwise C.lua_next won't work
+				// properly.
+				k := l.ToString(-1)
+				(*vm)[k] = v
+			}
+			l.Pop(1)
+		} else if tk == reflect.Slice &&
+			t.Elem().Kind() == reflect.Interface {
+			if !l.IsTable(-1) {
+				return fmt.Errorf(
+					"passed arg #%d must be a table",
+					len(vars)-i,
+				)
+			}
+			va, _ := v.(*[]any)
+			l.PushNil()
+			for l.Next() {
+				var v any = nil
+				if l.IsString(-1) {
+					v = l.ToString(-1)
+				} else if l.IsNumber(-1) {
+					v = l.ToInt(-1)
+				} else if l.IsNil(-1) {
+					v = nil
+				} else {
+					return fmt.Errorf("unknown value in array")
+				}
+				l.Pop(1)
+				(*va) = append((*va), v)
+			}
+			l.Pop(1)
+		} else {
+			return fmt.Errorf("unknown var type: %s", t)
+		}
+	}
+	return nil
+}
+
+// RestoreStackFunc remembers the Lua stack size and then restores it when a
+// returned function is called. It's a helper function to avoid stack leakage.
+func (l *Lua) RestoreStackFunc() func () {
+	before := l.StackLen()
+	return func () {
+		after := l.StackLen()
+		diff := after - before
+		if diff == 0 {
+			return
+		} else if diff < 0 {
+			msg := fmt.Sprintf(
+				"too many stack pops: len before: %d, after: %d\n",
+				before,
+				after,
+			)
+			panic(msg)
+		}
+		C.lua_settop(l.l, C.int(before))
+	}
+}
+
+// SetGlobal sets a global value at the -1 stack index with the name.
+func (l *Lua) SetGlobal(name string) {
+	cstr := C.CString(name)
+	defer C.free(unsafe.Pointer(cstr))
+	C.lua_setfield(l.l, C.LUA_GLOBALSINDEX, cstr)
+}
+
+// GetGlobal gets a global value under the name.
+func (l *Lua) GetGlobal(name string) {
+	cstr := C.CString(name)
+	defer C.free(unsafe.Pointer(cstr))
+	C.lua_getfield(l.l, C.LUA_GLOBALSINDEX, cstr)
+}