overhaul everything

bencode/bencode.go

@@ -0,0 +1,104 @@
+// Copyright 2013 The Chihaya Authors. All rights reserved.
+// Use of this source code is governed by the BSD 2-Clause license,
+// which can be found in the LICENSE file.
+
+// Package bencode implements bencoding of objects as defined in BEP 3 using
+// type assertion rather than the use of reflection.
+package bencode
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"strconv"
+	"time"
+)
+
+// An Encoder writes Bencoded objects to an output stream.
+type Encoder struct {
+	w io.Writer
+}
+
+// NewEncoder returns a new encoder that writes to w.
+func NewEncoder(w io.Writer) *Encoder {
+	return &Encoder{w: w}
+}
+
+// Encode writes the bencoding of v to the stream.
+func (enc *Encoder) Encode(v interface{}) error {
+	return marshal(enc.w, v)
+}
+
+// Marshal returns the bencoding of v.
+func Marshal(v interface{}) ([]byte, error) {
+	buf := &bytes.Buffer{}
+	err := marshal(buf, v)
+	return buf.Bytes(), err
+}
+
+// Marshaler is the interface implemented by objects that can marshal
+// themselves.
+type Marshaler interface {
+	MarshalBencode() ([]byte, error)
+}
+
+// Marshal writes types bencoded to an io.Writer
+func marshal(w io.Writer, data interface{}) error {
+	switch v := data.(type) {
+	case Marshaler:
+		bencoded, err := v.MarshalBencode()
+		if err != nil {
+			return err
+		}
+		_, err = w.Write(bencoded)
+		if err != nil {
+			return err
+		}
+
+	case string:
+		fmt.Fprintf(w, "%d:%s", len(v), v)
+
+	case int:
+		fmt.Fprintf(w, "i%de", v)
+
+	case uint:
+		fmt.Fprintf(w, "i%se", strconv.FormatUint(uint64(v), 10))
+
+	case int64:
+		fmt.Fprintf(w, "i%se", strconv.FormatInt(v, 10))
+
+	case uint64:
+		fmt.Fprintf(w, "i%se", strconv.FormatUint(v, 10))
+
+	case time.Duration: // Assume seconds
+		fmt.Fprintf(w, "i%se", strconv.FormatInt(int64(v/time.Second), 10))
+
+	case map[string]interface{}:
+		fmt.Fprintf(w, "d")
+		for key, val := range v {
+			fmt.Fprintf(w, "%s:%s", strconv.Itoa(len(key)), key)
+			err := marshal(w, val)
+			if err != nil {
+				return err
+			}
+		}
+
+	case []string:
+		fmt.Fprintf(w, "l")
+		for _, val := range v {
+			err := marshal(w, val)
+			if err != nil {
+				return err
+			}
+		}
+		fmt.Fprintf(w, "e")
+
+	default:
+		// Although not currently necessary,
+		// should handle []interface{} manually; Go can't do it implicitly
+		return errors.New("bencode: attempted to marshal unsupported type")
+	}
+
+	return nil
+}