redigo/redis/reply.go

// Copyright 2012 Gary Burd
//
// Licensed under the Apache License, Version 2.0 (the "License"): you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.

package redis

import (
	"errors"
	"fmt"
	"strconv"
)

var ErrNil = errors.New("redigo: nil returned")

// Int is a helper that converts a command reply to an integer. If err is not
// equal to nil, then Int returns 0, err. Otherwise, Int converts the
// reply to an int as follows:
//
//  Reply type    Result
//  integer       int(reply), nil
//  bulk          strconv.ParseInt(reply, 10, 0)
//  nil           0, ErrNil
//  other         0, error
func Int(reply interface{}, err error) (int, error) {
	if err != nil {
		return 0, err
	}
	switch reply := reply.(type) {
	case int64:
		x := int(reply)
		if int64(x) != reply {
			return 0, strconv.ErrRange
		}
		return x, nil
	case []byte:
		n, err := strconv.ParseInt(string(reply), 10, 0)
		return int(n), err
	case nil:
		return 0, ErrNil
	case Error:
		return 0, reply
	}
	return 0, fmt.Errorf("redigo: unexpected type for Int, got type %T", reply)
}

// String is a helper that converts a command reply to a string. If err is not
// equal to nil, then String returns "", err. Otherwise String converts the
// reply to a string as follows:
//
//  Reply type      Result
//  bulk            string(reply), nil
//  string          reply, nil
//  nil             "",  ErrNil
//  other           "",  error
func String(reply interface{}, err error) (string, error) {
	if err != nil {
		return "", err
	}
	switch reply := reply.(type) {
	case []byte:
		return string(reply), nil
	case string:
		return reply, nil
	case nil:
		return "", ErrNil
	case Error:
		return "", reply
	}
	return "", fmt.Errorf("redigo: unexpected type for String, got type %T", reply)
}

// Bytes is a helper that converts a command reply to a slice of bytes. If err
// is not equal to nil, then Bytes returns nil, err. Otherwise Bytes converts
// the reply to a slice of bytes as follows:
//
//  Reply type      Result
//  bulk            reply, nil
//  string          []byte(reply), nil
//  nil             nil, ErrNil
//  other           nil, error
func Bytes(reply interface{}, err error) ([]byte, error) {
	if err != nil {
		return nil, err
	}
	switch reply := reply.(type) {
	case []byte:
		return reply, nil
	case string:
		return []byte(reply), nil
	case nil:
		return nil, ErrNil
	case Error:
		return nil, reply
	}
	return nil, fmt.Errorf("redigo: unexpected type for Bytes, got type %T", reply)
}

// Bool is a helper that converts a command reply to a boolean. If err is not
// equal to nil, then Bool returns false, err. Otherwise Bool converts the
// reply to boolean as follows:
//
//  Reply type      Result
//  integer         value != 0, nil
//  bulk            strconv.ParseBool(reply)
//  nil             false, ErrNil
//  other           false, error
func Bool(reply interface{}, err error) (bool, error) {
	if err != nil {
		return false, err
	}
	switch reply := reply.(type) {
	case int64:
		return reply != 0, nil
	case []byte:
		return strconv.ParseBool(string(reply))
	case nil:
		return false, ErrNil
	case Error:
		return false, reply
	}
	return false, fmt.Errorf("redigo: unexpected type for Bool, got type %T", reply)
}

// MultiBulk is deprecated. Use Values.
func MultiBulk(reply interface{}, err error) ([]interface{}, error) { return Values(reply, err) }

// Values is a helper that converts a multi-bulk command reply to a
// []interface{}. If err is not equal to nil, then Values returns nil, err.
// Otherwise, Multi converts the reply as follows:
//
//  Reply type      Result
//  multi-bulk      reply, nil
//  nil             nil, ErrNil
//  other           nil, error
func Values(reply interface{}, err error) ([]interface{}, error) {
	if err != nil {
		return nil, err
	}
	switch reply := reply.(type) {
	case []interface{}:
		return reply, nil
	case nil:
		return nil, ErrNil
	case Error:
		return nil, reply
	}
	return nil, fmt.Errorf("redigo: unexpected type for Multi, got type %T", reply)
}