Add Lua script helper.

script.go

@@ -0,0 +1,45 @@
+package redis
+
+import (
+	"crypto/sha1"
+	"encoding/hex"
+	"io"
+	"strings"
+)
+
+type Script struct {
+	src, hash string
+}
+
+func NewScript(src string) *Script {
+	h := sha1.New()
+	io.WriteString(h, src)
+	return &Script{
+		src:  src,
+		hash: hex.EncodeToString(h.Sum(nil)),
+	}
+}
+
+func (s *Script) Load(c *Client) *StringReq {
+	return c.ScriptLoad(s.src)
+}
+
+func (s *Script) Exists(c *Client) *BoolSliceReq {
+	return c.ScriptExists(s.src)
+}
+
+func (s *Script) Eval(c *Client, keys []string, args []string) *IfaceReq {
+	return c.Eval(s.src, keys, args)
+}
+
+func (s *Script) EvalSha(c *Client, keys []string, args []string) *IfaceReq {
+	return c.EvalSha(s.hash, keys, args)
+}
+
+func (s *Script) Run(c *Client, keys []string, args []string) *IfaceReq {
+	r := s.EvalSha(c, keys, args)
+	if err := r.Err(); err != nil && strings.HasPrefix(err.Error(), "NOSCRIPT ") {
+		return s.Eval(c, keys, args)
+	}
+	return r
+}