lz4: guard Go-1.10 specific API behind build tags

Fixes #24.

block_test.go

@@ -1,3 +1,5 @@
+//+build go1.9
+
 package lz4_test
 
 import (

lz4.go

@@ -10,11 +10,6 @@
 //
 package lz4
 
-import (
-	"fmt"
-	"strings"
-)
-
 const (
 	// Extension is the LZ4 frame file name extension
 	Extension = ".lz4"
@@ -71,24 +66,3 @@ type Header struct {
 	CompressionLevel int    // Compression level (higher is better, use 0 for fastest compression).
 	done             bool   // Header processed flag (Read or Write and checked).
 }
-
-func (h Header) String() string {
-	var s strings.Builder
-
-	s.WriteString(fmt.Sprintf("%T{", h))
-	if h.BlockChecksum {
-		s.WriteString("BlockChecksum: true ")
-	}
-	if h.NoChecksum {
-		s.WriteString("NoChecksum: true ")
-	}
-	if bs := h.BlockMaxSize; bs != 0 && bs != 4<<20 {
-		s.WriteString(fmt.Sprintf("BlockMaxSize: %d ", bs))
-	}
-	if l := h.CompressionLevel; l != 0 {
-		s.WriteString(fmt.Sprintf("CompressionLevel: %d ", l))
-	}
-	s.WriteByte('}')
-
-	return s.String()
-}

lz4_go1.10.go

@@ -0,0 +1,29 @@
+//+build go1.10
+
+package lz4
+
+import (
+	"fmt"
+	"strings"
+)
+
+func (h Header) String() string {
+	var s strings.Builder
+
+	s.WriteString(fmt.Sprintf("%T{", h))
+	if h.BlockChecksum {
+		s.WriteString("BlockChecksum: true ")
+	}
+	if h.NoChecksum {
+		s.WriteString("NoChecksum: true ")
+	}
+	if bs := h.BlockMaxSize; bs != 0 && bs != 4<<20 {
+		s.WriteString(fmt.Sprintf("BlockMaxSize: %d ", bs))
+	}
+	if l := h.CompressionLevel; l != 0 {
+		s.WriteString(fmt.Sprintf("CompressionLevel: %d ", l))
+	}
+	s.WriteByte('}')
+
+	return s.String()
+}

lz4_notgo1.10.go

@@ -0,0 +1,29 @@
+//+build !go1.10
+
+package lz4
+
+import (
+	"bytes"
+	"fmt"
+)
+
+func (h Header) String() string {
+	var s bytes.Buffer
+
+	s.WriteString(fmt.Sprintf("%T{", h))
+	if h.BlockChecksum {
+		s.WriteString("BlockChecksum: true ")
+	}
+	if h.NoChecksum {
+		s.WriteString("NoChecksum: true ")
+	}
+	if bs := h.BlockMaxSize; bs != 0 && bs != 4<<20 {
+		s.WriteString(fmt.Sprintf("BlockMaxSize: %d ", bs))
+	}
+	if l := h.CompressionLevel; l != 0 {
+		s.WriteString(fmt.Sprintf("CompressionLevel: %d ", l))
+	}
+	s.WriteByte('}')
+
+	return s.String()
+}