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eval.go
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eval.go
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package red
import (
"crypto/sha1"
"encoding/hex"
"github.com/alxarch/red/resp"
)
// Eval evaluates a Lua script
func (conn *Conn) Eval(dest interface{}, script string, numKeys int, args ...string) error {
return conn.DoCommand(dest, evalCmd(script), evalArgs(script, numKeys, args...)...)
}
func evalCmd(script string) string {
cmd := "EVAL"
if isSHA1(script) {
cmd = "EVALSHA"
}
return cmd
}
func isSHA1(str string) bool {
if len(str) == 2*sha1.Size {
var sha1 [2 * sha1.Size]byte
_, err := hex.Decode(sha1[:], []byte(str))
return err == nil
}
return false
}
// WriteEval is a convenience wrapper for WriteCommand
func (conn *Conn) WriteEval(script string, numKeys int, args ...string) error {
return conn.WriteCommand(evalCmd(script), evalArgs(script, numKeys, args...)...)
}
// LoadScript loads a Lua script
func (conn *Conn) LoadScript(script string) (string, error) {
sha1 := resp.BulkString{}
if err := conn.DoCommand(&sha1, "SCRIPT", String("LOAD"), String(script)); err != nil {
return "", err
}
if sha1.Null() {
return "", resp.ErrNull
}
// Store loaded script for EVAL -> EVAL rewrites
conn.scripts[String(script)] = sha1.String
return sha1.String, nil
}
func evalArgs(script string, numKeys int, args ...string) []Arg {
argv := make([]Arg, len(args)+2)
argv[0] = String(script)
argv[1] = Int(numKeys)
for i, arg := range args {
if i < numKeys {
argv[i+2] = Key(arg)
} else {
argv[i+2] = String(arg)
}
}
return argv
}