Start plugin support and plugin manager

cmd/micro/lua/lua.go

@@ -1,6 +1,7 @@
 package lua
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"io"
@@ -28,10 +29,10 @@ func init() {
 }
 
 // LoadFile loads a lua file
-func LoadFile(module string, file string, data string) error {
-	pluginDef := "local P = {};" + module + " = P;setmetatable(" + module + ", {__index = _G});setfenv(1, P);"
+func LoadFile(module string, file string, data []byte) error {
+	pluginDef := []byte("module(\"" + module + "\", package.seeall)")
 
-	if fn, err := L.Load(strings.NewReader(pluginDef+data), file); err != nil {
+	if fn, err := L.Load(bytes.NewReader(append(pluginDef, data...)), file); err != nil {
 		return err
 	} else {
 		L.Push(fn)

cmd/micro/lua/plugin.go

@@ -0,0 +1,67 @@
+package lua
+
+import (
+	"errors"
+	"io/ioutil"
+	"strings"
+
+	lua "github.com/yuin/gopher-lua"
+)
+
+var ErrNoSuchFunction = errors.New("No such function exists")
+
+type Plugin struct {
+	name  string
+	files []string
+}
+
+func NewPluginFromDir(name string, dir string) (*Plugin, error) {
+	files, err := ioutil.ReadDir(dir)
+	if err != nil {
+		return nil, err
+	}
+
+	p := new(Plugin)
+	p.name = name
+
+	for _, f := range files {
+		if strings.HasSuffix(f.Name(), ".lua") {
+			p.files = append(p.files, dir+f.Name())
+		}
+	}
+
+	return p, nil
+}
+
+func (p *Plugin) Load() error {
+	for _, f := range p.files {
+		dat, err := ioutil.ReadFile(f)
+		if err != nil {
+			return err
+		}
+		err = LoadFile(p.name, f, dat)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (p *Plugin) Call(fn string, args ...lua.LValue) (lua.LValue, error) {
+	plug := L.GetGlobal(p.name)
+	luafn := L.GetField(plug, fn)
+	if luafn == lua.LNil {
+		return nil, ErrNoSuchFunction
+	}
+	err := L.CallByParam(lua.P{
+		Fn:      luafn,
+		NRet:    1,
+		Protect: true,
+	}, args...)
+	if err != nil {
+		return nil, err
+	}
+	ret := L.Get(-1)
+	L.Pop(1)
+	return ret, nil
+}