Update Go library to r60.

From-SVN: r178910

1 files changed, 31 insertions, 16 deletions

diff --git a/libgo/go/gob/encode.go b/libgo/go/gob/encode.go
index f9e691a..317014e 100644
--- a/libgo/go/gob/encode.go
+++ b/libgo/go/gob/encode.go
@@ -11,7 +11,7 @@ import (
 	"unsafe"
 )
 
-const uint64Size = unsafe.Sizeof(uint64(0))
+const uint64Size = int(unsafe.Sizeof(uint64(0)))
 
 // encoderState is the global execution state of an instance of the encoder.
 // Field numbers are delta encoded and always increase. The field
@@ -62,7 +62,7 @@ func (state *encoderState) encodeUint(x uint64) {
 	var n, m int
 	m = uint64Size
 	for n = 1; x > 0; n++ {
-		state.buf[m] = uint8(x & 0xFF)
+		state.buf[m] = uint8(x)
 		x >>= 8
 		m--
 	}
@@ -466,9 +466,30 @@ func (enc *Encoder) encodeInterface(b *bytes.Buffer, iv reflect.Value) {
 	enc.freeEncoderState(state)
 }
 
+// isZero returns whether the value is the zero of its type.
+func isZero(val reflect.Value) bool {
+	switch val.Kind() {
+	case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
+		return val.Len() == 0
+	case reflect.Bool:
+		return !val.Bool()
+	case reflect.Complex64, reflect.Complex128:
+		return val.Complex() == 0
+	case reflect.Chan, reflect.Func, reflect.Ptr:
+		return val.IsNil()
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return val.Int() == 0
+	case reflect.Float32, reflect.Float64:
+		return val.Float() == 0
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return val.Uint() == 0
+	}
+	panic("unknown type in isZero " + val.Type().String())
+}
+
 // encGobEncoder encodes a value that implements the GobEncoder interface.
 // The data is sent as a byte array.
-func (enc *Encoder) encodeGobEncoder(b *bytes.Buffer, v reflect.Value, index int) {
+func (enc *Encoder) encodeGobEncoder(b *bytes.Buffer, v reflect.Value) {
 	// TODO: should we catch panics from the called method?
 	// We know it's a GobEncoder, so just call the method directly.
 	data, err := v.Interface().(GobEncoder).GobEncode()
@@ -557,7 +578,9 @@ func (enc *Encoder) encOpFor(rt reflect.Type, inProgress map[reflect.Type]*encOp
 				// the iteration.
 				v := reflect.ValueOf(unsafe.Unreflect(t, unsafe.Pointer(p)))
 				mv := reflect.Indirect(v)
-				if !state.sendZero && mv.Len() == 0 {
+				// We send zero-length (but non-nil) maps because the
+				// receiver might want to use the map.  (Maps don't use append.)
+				if !state.sendZero && mv.IsNil() {
 					return
 				}
 				state.update(i)
@@ -592,17 +615,6 @@ func (enc *Encoder) encOpFor(rt reflect.Type, inProgress map[reflect.Type]*encOp
 	return &op, indir
 }
 
-// methodIndex returns which method of rt implements the method.
-func methodIndex(rt reflect.Type, method string) int {
-	for i := 0; i < rt.NumMethod(); i++ {
-		if rt.Method(i).Name == method {
-			return i
-		}
-	}
-	errorf("internal error: can't find method %s", method)
-	return 0
-}
-
 // gobEncodeOpFor returns the op for a type that is known to implement
 // GobEncoder.
 func (enc *Encoder) gobEncodeOpFor(ut *userTypeInfo) (*encOp, int) {
@@ -623,8 +635,11 @@ func (enc *Encoder) gobEncodeOpFor(ut *userTypeInfo) (*encOp, int) {
 		} else {
 			v = reflect.ValueOf(unsafe.Unreflect(rt, p))
 		}
+		if !state.sendZero && isZero(v) {
+			return
+		}
 		state.update(i)
-		state.enc.encodeGobEncoder(state.b, v, methodIndex(rt, gobEncodeMethodName))
+		state.enc.encodeGobEncoder(state.b, v)
 	}
 	return &op, int(ut.encIndir) // encIndir: op will get called with p == address of receiver.
 }