Use interface to get bytes (#309)

Use interface to detect bytes.Byffer.
Move generator.

flate/gen_inflate.go → flate/_gen/gen_inflate.go

@@ -1,6 +1,6 @@
 // +build generate
 
-//go:generate go run $GOFILE && gofmt -w inflate_gen.go
+//go:generate go run $GOFILE && gofmt -w ../inflate_gen.go
 
 package main
 
@@ -10,7 +10,7 @@ import (
 )
 
 func main() {
-	f, err := os.Create("inflate_gen.go")
+	f, err := os.Create("../inflate_gen.go")
 	if err != nil {
 		panic(err)
 	}

s2/encode.go

@@ -399,6 +399,13 @@ func (w *Writer) ReadFrom(r io.Reader) (n int64, err error) {
 			return 0, err
 		}
 	}
+	if br, ok := r.(byter); ok {
+		buf := br.Bytes()
+		if err := w.EncodeBuffer(buf); err != nil {
+			return 0, err
+		}
+		return int64(len(buf)), w.Flush()
+	}
 	for {
 		inbuf := w.buffers.Get().([]byte)[:w.blockSize+obufHeaderLen]
 		n2, err := io.ReadFull(r, inbuf[obufHeaderLen:])

s2/s2.go

@@ -35,6 +35,7 @@
 package s2
 
 import (
+	"bytes"
 	"hash/crc32"
 )
 
@@ -127,3 +128,9 @@ func literalExtraSize(n int64) int64 {
 		return 5
 	}
 }
+
+type byter interface {
+	Bytes() []byte
+}
+
+var _ byter = &bytes.Buffer{}

zstd/decoder.go

@@ -5,7 +5,6 @@
 package zstd
 
 import (
-	"bytes"
 	"errors"
 	"io"
 	"sync"
@@ -179,11 +178,13 @@ func (d *Decoder) Reset(r io.Reader) error {
 	}
 
 	// If bytes buffer and < 1MB, do sync decoding anyway.
-	if bb, ok := r.(*bytes.Buffer); ok && bb.Len() < 1<<20 {
+	if bb, ok := r.(byter); ok && bb.Len() < 1<<20 {
+		var bb2 byter
+		bb2 = bb
 		if debug {
 			println("*bytes.Buffer detected, doing sync decode, len:", bb.Len())
 		}
-		b := bb.Bytes()
+		b := bb2.Bytes()
 		var dst []byte
 		if cap(d.current.b) > 0 {
 			dst = d.current.b

zstd/zstd.go

@@ -4,6 +4,7 @@
 package zstd
 
 import (
+	"bytes"
 	"errors"
 	"log"
 	"math"
@@ -146,3 +147,10 @@ func load64(b []byte, i int) uint64 {
 	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
 		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
 }
+
+type byter interface {
+	Bytes() []byte
+	Len() int
+}
+
+var _ byter = &bytes.Buffer{}