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resp.go
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resp.go
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package main
import (
"net"
"strconv"
"errors"
"io"
"bufio"
)
// Constants representing the RESP types
const (
STRING = '+'
ERROR = '-'
INTEGER = ':'
BULK = '$'
ARRAY = '*'
)
// Value struct to represent RESP types
type Value struct {
typ string
str string
num int
bulk string
array []Value
}
// Marshal method to convert Value to RESP format
func (v Value) Marshal() []byte {
switch v.typ {
case "array":
return v.marshalArray()
case "bulk":
return v.marshalBulk()
case "string":
return v.marshalString()
case "null":
return v.marshallNull()
case "error":
return v.marshallError()
default:
return []byte{}
}
}
// marshalString converts a simple string value to RESP format
func (v Value) marshalString() []byte {
var bytes []byte
bytes = append(bytes, STRING)
bytes = append(bytes, v.str...)
bytes = append(bytes, '\r', '\n')
return bytes
}
// marshalBulk converts a bulk string value to RESP format
func (v Value) marshalBulk() []byte {
var bytes []byte
bytes = append(bytes, BULK)
bytes = append(bytes, strconv.Itoa(len(v.bulk))...)
bytes = append(bytes, '\r', '\n')
bytes = append(bytes, v.bulk...)
bytes = append(bytes, '\r', '\n')
return bytes
}
// marshalArray converts an array value to RESP format
func (v Value) marshalArray() []byte {
len := len(v.array)
var bytes []byte
bytes = append(bytes, ARRAY)
bytes = append(bytes, strconv.Itoa(len)...)
bytes = append(bytes, '\r', '\n')
for i := 0; i < len; i++ {
bytes = append(bytes, v.array[i].Marshal()...)
}
return bytes
}
// marshallError converts an error value to RESP format
func (v Value) marshallError() []byte {
var bytes []byte
bytes = append(bytes, ERROR)
bytes = append(bytes, v.str...)
bytes = append(bytes, '\r', '\n')
return bytes
}
// marshallNull converts a null value to RESP format
func (v Value) marshallNull() []byte {
return []byte("$-1\r\n")
}
// NewResp initializes a new RESP connection
type NewResp struct {
conn net.Conn
}
// Read reads a RESP message from the connection
func (r *NewResp) Read() (Value, error) {
// Read the first byte to determine the type
var buf [1]byte
_, err := r.conn.Read(buf[:])
if err != nil {
return Value{}, err
}
typ := buf[0]
switch typ {
case STRING:
return r.readString()
case ERROR:
return r.readError()
case INTEGER:
return r.readInteger()
case BULK:
return r.readBulk()
case ARRAY:
return r.readArray()
default:
return Value{}, errors.New("unknown RESP type")
}
}
// readString reads a string from the RESP format
func (r *NewResp) readString() (Value, error) {
return r.readValue(STRING)
}
// readError reads an error from the RESP format
func (r *NewResp) readError() (Value, error) {
return r.readValue(ERROR)
}
// readInteger reads an integer from the RESP format
func (r *NewResp) readInteger() (Value, error) {
return r.readValue(INTEGER)
}
// readBulk reads a bulk string from the RESP format
func (r *NewResp) readBulk() (Value, error) {
var lengthBuf [32]byte
// Read length of bulk string
n, err := r.conn.Read(lengthBuf[:])
if err != nil {
return Value{}, err
}
lengthStr := string(lengthBuf[:n])
length, err := strconv.Atoi(lengthStr[:n-2]) // Remove CRLF
if err != nil {
return Value{}, err
}
if length == -1 {
return Value{typ: "null"}, nil // Handle null bulk string
}
// Read the bulk string
bulkData := make([]byte, length+2) // +2 for CRLF
_, err = io.ReadFull(r.conn, bulkData)
if err != nil {
return Value{}, err
}
// Return the bulk string
return Value{typ: "bulk", bulk: string(bulkData[:length])}, nil
}
// readArray reads an array from the RESP format
func (r *NewResp) readArray() (Value, error) {
var lengthBuf [32]byte
// Read length of array
n, err := r.conn.Read(lengthBuf[:])
if err != nil {
return Value{}, err
}
lengthStr := string(lengthBuf[:n])
length, err := strconv.Atoi(lengthStr[:n-2]) // Remove CRLF
if err != nil {
return Value{}, err
}
array := make([]Value, length)
for i := 0; i < length; i++ {
value, err := r.Read() // Read each value in the array
if err != nil {
return Value{}, err
}
array[i] = value
}
return Value{typ: "array", array: array}, nil
}
// readValue reads a RESP value based on the provided type
func (r *NewResp) readValue(typ byte) (Value, error) {
// Read until CRLF and parse the value
buf := bufio.NewReader(r.conn)
valueBytes, err := buf.ReadBytes('\n')
if err != nil {
return Value{}, err
}
valueStr := string(valueBytes[:len(valueBytes)-2]) // Remove CRLF
switch typ {
case STRING:
return Value{typ: "string", str: valueStr}, nil
case ERROR:
return Value{typ: "error", str: valueStr}, nil
case INTEGER:
num, err := strconv.Atoi(valueStr)
if err != nil {
return Value{}, err
}
return Value{typ: "integer", num: num}, nil
default:
return Value{}, errors.New("unknown type")
}
}