encoding/binary: add bool support

This change adds support for decoding and encoding the bool type. The
encoding is a single byte, with a zero value for false and a non-zero
value for true.

Closes #16856.

Change-Id: I1d1114b320263691473bb100cad0f380e0204186
Reviewed-on: https://go-review.googlesource.com/28514
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

src/encoding/binary/binary.go

@@ -169,6 +169,8 @@ func Read(r io.Reader, order ByteOrder, data interface{}) error {
 			return err
 		}
 		switch data := data.(type) {
+		case *bool:
+			*data = b[0] != 0
 		case *int8:
 			*data = int8(b[0])
 		case *uint8:
@@ -185,8 +187,12 @@ func Read(r io.Reader, order ByteOrder, data interface{}) error {
 			*data = int64(order.Uint64(bs))
 		case *uint64:
 			*data = order.Uint64(bs)
-		case []int8:
+		case []bool:
 			for i, x := range bs { // Easier to loop over the input for 8-bit values.
+				data[i] = x != 0
+			}
+		case []int8:
+			for i, x := range bs {
 				data[i] = int8(x)
 			}
 		case []uint8:
@@ -258,6 +264,26 @@ func Write(w io.Writer, order ByteOrder, data interface{}) error {
 			bs = b[:n]
 		}
 		switch v := data.(type) {
+		case *bool:
+			if *v {
+				b[0] = 1
+			} else {
+				b[0] = 0
+			}
+		case bool:
+			if v {
+				b[0] = 1
+			} else {
+				b[0] = 0
+			}
+		case []bool:
+			for i, x := range v {
+				if x {
+					bs[i] = 1
+				} else {
+					bs[i] = 0
+				}
+			}
 		case *int8:
 			b[0] = byte(*v)
 		case int8:
@@ -378,7 +404,8 @@ func sizeof(t reflect.Type) int {
 		}
 		return sum
 
-	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
+	case reflect.Bool,
+		reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
 		reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
 		reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
 		return int(t.Size())
@@ -395,6 +422,21 @@ type coder struct {
 type decoder coder
 type encoder coder
 
+func (d *decoder) bool() bool {
+	x := d.buf[0]
+	d.buf = d.buf[1:]
+	return x != 0
+}
+
+func (e *encoder) bool(x bool) {
+	if x {
+		e.buf[0] = 1
+	} else {
+		e.buf[0] = 0
+	}
+	e.buf = e.buf[1:]
+}
+
 func (d *decoder) uint8() uint8 {
 	x := d.buf[0]
 	d.buf = d.buf[1:]
@@ -485,6 +527,9 @@ func (d *decoder) value(v reflect.Value) {
 			d.value(v.Index(i))
 		}
 
+	case reflect.Bool:
+		v.SetBool(d.bool())
+
 	case reflect.Int8:
 		v.SetInt(int64(d.int8()))
 	case reflect.Int16:
@@ -547,6 +592,9 @@ func (e *encoder) value(v reflect.Value) {
 			e.value(v.Index(i))
 		}
 
+	case reflect.Bool:
+		e.bool(v.Bool())
+
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		switch v.Type().Kind() {
 		case reflect.Int8:
@@ -609,7 +657,7 @@ func (e *encoder) skip(v reflect.Value) {
 // It returns zero if the type cannot be implemented by the fast path in Read or Write.
 func intDataSize(data interface{}) int {
 	switch data := data.(type) {
-	case int8, uint8, *int8, *uint8:
+	case bool, int8, uint8, *bool, *int8, *uint8:
 		return 1
 	case []int8:
 		return len(data)

src/encoding/binary/binary_test.go

@@ -27,6 +27,8 @@ type Struct struct {
 	Complex64  complex64
 	Complex128 complex128
 	Array      [4]uint8
+	Bool       bool
+	BoolArray  [4]bool
 }
 
 type T struct {
@@ -58,6 +60,9 @@ var s = Struct{
 	),
 
 	[4]uint8{0x43, 0x44, 0x45, 0x46},
+
+	true,
+	[4]bool{true, false, true, false},
 }
 
 var big = []byte{
@@ -76,6 +81,9 @@ var big = []byte{
 	51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66,
 
 	67, 68, 69, 70,
+
+	1,
+	1, 0, 1, 0,
 }
 
 var little = []byte{
@@ -94,6 +102,9 @@ var little = []byte{
 	58, 57, 56, 55, 54, 53, 52, 51, 66, 65, 64, 63, 62, 61, 60, 59,
 
 	67, 68, 69, 70,
+
+	1,
+	1, 0, 1, 0,
 }
 
 var src = []byte{1, 2, 3, 4, 5, 6, 7, 8}
@@ -141,6 +152,25 @@ func TestWriteSlice(t *testing.T) {
 	checkResult(t, "WriteSlice", BigEndian, err, buf.Bytes(), src)
 }
 
+func TestReadBool(t *testing.T) {
+	var res bool
+	var err error
+	err = Read(bytes.NewReader([]byte{0}), BigEndian, &res)
+	checkResult(t, "ReadBool", BigEndian, err, res, false)
+	res = false
+	err = Read(bytes.NewReader([]byte{1}), BigEndian, &res)
+	checkResult(t, "ReadBool", BigEndian, err, res, true)
+	res = false
+	err = Read(bytes.NewReader([]byte{2}), BigEndian, &res)
+	checkResult(t, "ReadBool", BigEndian, err, res, true)
+}
+
+func TestReadBoolSlice(t *testing.T) {
+	slice := make([]bool, 4)
+	err := Read(bytes.NewReader([]byte{0, 1, 2, 255}), BigEndian, slice)
+	checkResult(t, "ReadBoolSlice", BigEndian, err, slice, []bool{false, true, true, true})
+}
+
 // Addresses of arrays are easier to manipulate with reflection than are slices.
 var intArrays = []interface{}{
 	&[100]int8{},
@@ -422,16 +452,15 @@ func BenchmarkReadInts(b *testing.B) {
 		Read(r, BigEndian, &ls.Uint32)
 		Read(r, BigEndian, &ls.Uint64)
 	}
-
+	b.StopTimer()
 	want := s
 	want.Float32 = 0
 	want.Float64 = 0
 	want.Complex64 = 0
 	want.Complex128 = 0
-	for i := range want.Array {
-		want.Array[i] = 0
-	}
-	b.StopTimer()
+	want.Array = [4]uint8{0, 0, 0, 0}
+	want.Bool = false
+	want.BoolArray = [4]bool{false, false, false, false}
 	if b.N > 0 && !reflect.DeepEqual(ls, want) {
 		b.Fatalf("struct doesn't match:\ngot  %v;\nwant %v", ls, want)
 	}