parser: greatly simplify reply parsing.

parser.go

@@ -0,0 +1,170 @@
+package redis
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+
+	"github.com/vmihailenco/bufio"
+)
+
+//------------------------------------------------------------------------------
+
+var Nil = errors.New("(nil)")
+
+//------------------------------------------------------------------------------
+
+var (
+	errReaderTooSmall = errors.New("redis: reader is too small")
+	errValNotSet      = errors.New("redis: value is not set")
+)
+
+//------------------------------------------------------------------------------
+
+func PackReq(args []string) []byte {
+	buf := make([]byte, 0, 1024)
+	buf = append(buf, '*')
+	buf = strconv.AppendUint(buf, uint64(len(args)), 10)
+	buf = append(buf, '\r', '\n')
+	for _, arg := range args {
+		buf = append(buf, '$')
+		buf = strconv.AppendUint(buf, uint64(len(arg)), 10)
+		buf = append(buf, '\r', '\n')
+		buf = append(buf, []byte(arg)...)
+		buf = append(buf, '\r', '\n')
+	}
+	return buf
+}
+
+//------------------------------------------------------------------------------
+
+type ReadLiner interface {
+	ReadLine() ([]byte, bool, error)
+	Peek(n int) ([]byte, error)
+	ReadN(n int) ([]byte, error)
+}
+
+func readLine(rd ReadLiner) ([]byte, error) {
+	line, isPrefix, err := rd.ReadLine()
+	if err != nil {
+		return line, err
+	}
+	if isPrefix {
+		return line, errReaderTooSmall
+	}
+	return line, nil
+}
+
+//------------------------------------------------------------------------------
+
+func ParseReq(rd ReadLiner) ([]string, error) {
+	line, err := readLine(rd)
+	if err != nil {
+		return nil, err
+	}
+
+	if line[0] != '*' {
+		return []string{string(line)}, nil
+	}
+	numReplies, err := strconv.ParseInt(string(line[1:]), 10, 64)
+	if err != nil {
+		return nil, err
+	}
+
+	args := make([]string, 0)
+	for i := int64(0); i < numReplies; i++ {
+		line, err = readLine(rd)
+		if err != nil {
+			return nil, err
+		}
+		if line[0] != '$' {
+			return nil, fmt.Errorf("Expected '$', but got %q", line)
+		}
+
+		line, err = readLine(rd)
+		if err != nil {
+			return nil, err
+		}
+		args = append(args, string(line))
+	}
+	return args, nil
+}
+
+//------------------------------------------------------------------------------
+
+func ParseReply(rd ReadLiner) (interface{}, error) {
+	line, err := readLine(rd)
+	if err != nil {
+		return 0, err
+	}
+
+	switch line[0] {
+	case '-':
+		return nil, errors.New(string(line[1:]))
+	case '+':
+		return string(line[1:]), nil
+	case ':':
+		return strconv.ParseInt(string(line[1:]), 10, 64)
+	case '$':
+		if len(line) == 3 && line[1] == '-' && line[2] == '1' {
+			return "", Nil
+		} else if len(line) == 2 && line[1] == '0' {
+			return "", nil
+		}
+
+		replyLenInt32, err := strconv.ParseInt(string(line[1:]), 10, 32)
+		if err != nil {
+			return "", err
+		}
+		replyLen := int(replyLenInt32) + 2
+
+		line, err = rd.ReadN(replyLen)
+		if err == bufio.ErrBufferFull {
+			buf := make([]byte, replyLen)
+			r := 0
+
+			r += copy(buf, line)
+
+			for err == bufio.ErrBufferFull {
+				line, err = rd.ReadN(replyLen - r)
+				r += copy(buf[r:], line)
+			}
+
+			line = buf
+		} else if err != nil {
+			return "", err
+		}
+
+		return string(line[:len(line)-2]), nil
+	case '*':
+		if len(line) == 3 && line[1] == '-' && line[2] == '1' {
+			return nil, Nil
+		}
+
+		val := make([]interface{}, 0)
+		if len(line) == 2 && line[1] == '0' {
+			return val, nil
+		}
+
+		numReplies, err := strconv.ParseInt(string(line[1:]), 10, 64)
+		if err != nil {
+			return nil, err
+		}
+
+		for i := int64(0); i < numReplies; i++ {
+			v, err := ParseReply(rd)
+			if err == Nil {
+				val = append(val, nil)
+			} else if err != nil {
+				return nil, err
+			} else {
+				val = append(val, v)
+			}
+		}
+
+		return val, nil
+	default:
+		return nil, fmt.Errorf("redis: can't parse %q", line)
+	}
+	panic("not reachable")
+}