gob: add support for complex numbers

R=rsc
CC=golang-dev
http://codereview.appspot.com/1708048

4 files changed, 224 insertions, 69 deletions

diff --git a/src/pkg/gob/codec_test.go b/src/pkg/gob/codec_test.go
index dad0ac48c..d8bdf2d2f 100644
--- a/src/pkg/gob/codec_test.go
+++ b/src/pkg/gob/codec_test.go
@@ -112,7 +112,9 @@ var boolResult = []byte{0x07, 0x01}
 var signedResult = []byte{0x07, 2 * 17}
 var unsignedResult = []byte{0x07, 17}
 var floatResult = []byte{0x07, 0xFE, 0x31, 0x40}
-// The result of encoding "hello" with field number 6
+// The result of encoding a number 17+19i with field number 7
+var complexResult = []byte{0x07, 0xFE, 0x31, 0x40, 0xFE, 0x33, 0x40}
+// The result of encoding "hello" with field number 7
 var bytesResult = []byte{0x07, 0x05, 'h', 'e', 'l', 'l', 'o'}
 
 func newencoderState(b *bytes.Buffer) *encoderState {
@@ -537,6 +539,45 @@ func TestScalarDecInstructions(t *testing.T) {
 		}
 	}
 
+	// complex
+	{
+		var data struct {
+			a complex
+		}
+		instr := &decInstr{decOpMap[reflect.Complex], 6, 0, 0, ovfl}
+		state := newDecodeStateFromData(complexResult)
+		execDec("complex", instr, state, t, unsafe.Pointer(&data))
+		if data.a != 17+19i {
+			t.Errorf("complex a = %v not 17+19i", data.a)
+		}
+	}
+
+	// complex64
+	{
+		var data struct {
+			a complex64
+		}
+		instr := &decInstr{decOpMap[reflect.Complex64], 6, 0, 0, ovfl}
+		state := newDecodeStateFromData(complexResult)
+		execDec("complex", instr, state, t, unsafe.Pointer(&data))
+		if data.a != 17+19i {
+			t.Errorf("complex a = %v not 17+19i", data.a)
+		}
+	}
+
+	// complex128
+	{
+		var data struct {
+			a complex128
+		}
+		instr := &decInstr{decOpMap[reflect.Complex128], 6, 0, 0, ovfl}
+		state := newDecodeStateFromData(complexResult)
+		execDec("complex", instr, state, t, unsafe.Pointer(&data))
+		if data.a != 17+19i {
+			t.Errorf("complex a = %v not 17+19i", data.a)
+		}
+	}
+
 	// bytes == []uint8
 	{
 		var data struct {
@@ -576,6 +617,7 @@ func TestEndToEnd(t *testing.T) {
 		n       *[3]float
 		strs    *[2]string
 		int64s  *[]int64
+		ri      complex64
 		s       string
 		y       []byte
 		t       *T2
@@ -590,6 +632,7 @@ func TestEndToEnd(t *testing.T) {
 		n:      &[3]float{1.5, 2.5, 3.5},
 		strs:   &[2]string{s1, s2},
 		int64s: &[]int64{77, 89, 123412342134},
+		ri:     17 - 23i,
 		s:      "Now is the time",
 		y:      []byte("hello, sailor"),
 		t:      &T2{"this is T2"},
@@ -616,6 +659,8 @@ func TestOverflow(t *testing.T) {
 		maxu uint64
 		maxf float64
 		minf float64
+		maxc complex128
+		minc complex128
 	}
 	var it inputT
 	var err os.Error
@@ -758,6 +803,22 @@ func TestOverflow(t *testing.T) {
 	if err == nil || err.String() != `value for "maxf" out of range` {
 		t.Error("wrong overflow error for float32:", err)
 	}
+
+	// complex64
+	b.Reset()
+	it = inputT{
+		maxc: cmplx(math.MaxFloat32*2, math.MaxFloat32*2),
+	}
+	type outc64 struct {
+		maxc complex64
+		minc complex64
+	}
+	var o8 outc64
+	enc.Encode(it)
+	err = dec.Decode(&o8)
+	if err == nil || err.String() != `value for "maxc" out of range` {
+		t.Error("wrong overflow error for complex64:", err)
+	}
 }
 
 
diff --git a/src/pkg/gob/decode.go b/src/pkg/gob/decode.go
index 8f5c383ea..0dbf81488 100644
--- a/src/pkg/gob/decode.go
+++ b/src/pkg/gob/decode.go
@@ -151,6 +151,11 @@ func ignoreUint(i *decInstr, state *decodeState, p unsafe.Pointer) {
 	decodeUint(state)
 }
 
+func ignoreTwoUints(i *decInstr, state *decodeState, p unsafe.Pointer) {
+	decodeUint(state)
+	decodeUint(state)
+}
+
 func decBool(i *decInstr, state *decodeState, p unsafe.Pointer) {
 	if i.indir > 0 {
 		if *(*unsafe.Pointer)(p) == nil {
@@ -286,25 +291,30 @@ func floatFromBits(u uint64) float64 {
 	return math.Float64frombits(v)
 }
 
-func decFloat32(i *decInstr, state *decodeState, p unsafe.Pointer) {
-	if i.indir > 0 {
-		if *(*unsafe.Pointer)(p) == nil {
-			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(float32))
-		}
-		p = *(*unsafe.Pointer)(p)
-	}
+func storeFloat32(i *decInstr, state *decodeState, p unsafe.Pointer) {
 	v := floatFromBits(decodeUint(state))
 	av := v
 	if av < 0 {
 		av = -av
 	}
-	if math.MaxFloat32 < av { // underflow is OK
+	// +Inf is OK in both 32- and 64-bit floats.  Underflow is always OK.
+	if math.MaxFloat32 < av && av <= math.MaxFloat64 {
 		state.err = i.ovfl
 	} else {
 		*(*float32)(p) = float32(v)
 	}
 }
 
+func decFloat32(i *decInstr, state *decodeState, p unsafe.Pointer) {
+	if i.indir > 0 {
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(float32))
+		}
+		p = *(*unsafe.Pointer)(p)
+	}
+	storeFloat32(i, state, p)
+}
+
 func decFloat64(i *decInstr, state *decodeState, p unsafe.Pointer) {
 	if i.indir > 0 {
 		if *(*unsafe.Pointer)(p) == nil {
@@ -315,6 +325,30 @@ func decFloat64(i *decInstr, state *decodeState, p unsafe.Pointer) {
 	*(*float64)(p) = floatFromBits(uint64(decodeUint(state)))
 }
 
+// Complex numbers are just a pair of floating-point numbers, real part first.
+func decComplex64(i *decInstr, state *decodeState, p unsafe.Pointer) {
+	if i.indir > 0 {
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(complex64))
+		}
+		p = *(*unsafe.Pointer)(p)
+	}
+	storeFloat32(i, state, p)
+	storeFloat32(i, state, unsafe.Pointer(uintptr(p)+uintptr(unsafe.Sizeof(float(0)))))
+}
+
+func decComplex128(i *decInstr, state *decodeState, p unsafe.Pointer) {
+	if i.indir > 0 {
+		if *(*unsafe.Pointer)(p) == nil {
+			*(*unsafe.Pointer)(p) = unsafe.Pointer(new(complex128))
+		}
+		p = *(*unsafe.Pointer)(p)
+	}
+	real := floatFromBits(uint64(decodeUint(state)))
+	imag := floatFromBits(uint64(decodeUint(state)))
+	*(*complex128)(p) = cmplx(real, imag)
+}
+
 // uint8 arrays are encoded as an unsigned count followed by the raw bytes.
 func decUint8Array(i *decInstr, state *decodeState, p unsafe.Pointer) {
 	if i.indir > 0 {
@@ -540,21 +574,25 @@ func ignoreSlice(state *decodeState, elemOp decOp) os.Error {
 	return ignoreArrayHelper(state, elemOp, int(decodeUint(state)))
 }
 
+// Index by Go types.
 var decOpMap = []decOp{
-	reflect.Bool:    decBool,
-	reflect.Int8:    decInt8,
-	reflect.Int16:   decInt16,
-	reflect.Int32:   decInt32,
-	reflect.Int64:   decInt64,
-	reflect.Uint8:   decUint8,
-	reflect.Uint16:  decUint16,
-	reflect.Uint32:  decUint32,
-	reflect.Uint64:  decUint64,
-	reflect.Float32: decFloat32,
-	reflect.Float64: decFloat64,
-	reflect.String:  decString,
-}
-
+	reflect.Bool:       decBool,
+	reflect.Int8:       decInt8,
+	reflect.Int16:      decInt16,
+	reflect.Int32:      decInt32,
+	reflect.Int64:      decInt64,
+	reflect.Uint8:      decUint8,
+	reflect.Uint16:     decUint16,
+	reflect.Uint32:     decUint32,
+	reflect.Uint64:     decUint64,
+	reflect.Float32:    decFloat32,
+	reflect.Float64:    decFloat64,
+	reflect.Complex64:  decComplex64,
+	reflect.Complex128: decComplex128,
+	reflect.String:     decString,
+}
+
+// Indexed by gob types.  tComplex will be added during type.init().
 var decIgnoreOpMap = map[typeId]decOp{
 	tBool:   ignoreUint,
 	tInt:    ignoreUint,
@@ -652,6 +690,8 @@ func (dec *Decoder) decIgnoreOpFor(wireId typeId) (decOp, os.Error) {
 		// Special cases
 		wire := dec.wireType[wireId]
 		switch {
+		case wire == nil:
+			panic("internal error: can't find ignore op for type " + wireId.string())
 		case wire.arrayT != nil:
 			elemId := wire.arrayT.Elem
 			elemOp, err := dec.decIgnoreOpFor(elemId)
@@ -728,6 +768,8 @@ func (dec *Decoder) compatibleType(fr reflect.Type, fw typeId) bool {
 		return fw == tUint
 	case *reflect.FloatType:
 		return fw == tFloat
+	case *reflect.ComplexType:
+		return fw == tComplex
 	case *reflect.StringType:
 		return fw == tString
 	case *reflect.ArrayType:
@@ -866,39 +908,39 @@ func (dec *Decoder) decode(wireId typeId, e interface{}) os.Error {
 }
 
 func init() {
-	// We assume that the size of float is sufficient to tell us whether it is
-	// equivalent to float32 or to float64.   This is very unlikely to be wrong.
-	var op decOp
-	switch unsafe.Sizeof(float(0)) {
-	case unsafe.Sizeof(float32(0)):
-		op = decFloat32
-	case unsafe.Sizeof(float64(0)):
-		op = decFloat64
+	var fop, cop decOp
+	switch reflect.Typeof(float(0)).Bits() {
+	case 32:
+		fop = decFloat32
+		cop = decComplex64
+	case 64:
+		fop = decFloat64
+		cop = decComplex128
 	default:
 		panic("gob: unknown size of float")
 	}
-	decOpMap[reflect.Float] = op
+	decOpMap[reflect.Float] = fop
+	decOpMap[reflect.Complex] = cop
 
-	// A similar assumption about int and uint.  Also assume int and uint have the same size.
-	var uop decOp
-	switch unsafe.Sizeof(int(0)) {
-	case unsafe.Sizeof(int32(0)):
-		op = decInt32
+	var iop, uop decOp
+	switch reflect.Typeof(int(0)).Bits() {
+	case 32:
+		iop = decInt32
 		uop = decUint32
-	case unsafe.Sizeof(int64(0)):
-		op = decInt64
+	case 64:
+		iop = decInt64
 		uop = decUint64
 	default:
 		panic("gob: unknown size of int/uint")
 	}
-	decOpMap[reflect.Int] = op
+	decOpMap[reflect.Int] = iop
 	decOpMap[reflect.Uint] = uop
 
 	// Finally uintptr
-	switch unsafe.Sizeof(uintptr(0)) {
-	case unsafe.Sizeof(uint32(0)):
+	switch reflect.Typeof(uintptr(0)).Bits() {
+	case 32:
 		uop = decUint32
-	case unsafe.Sizeof(uint64(0)):
+	case 64:
 		uop = decUint64
 	default:
 		panic("gob: unknown size of uintptr")
diff --git a/src/pkg/gob/encode.go b/src/pkg/gob/encode.go
index 76032389e..b48c1f698 100644
--- a/src/pkg/gob/encode.go
+++ b/src/pkg/gob/encode.go
@@ -467,7 +467,7 @@ func floatBits(f float64) uint64 {
 }
 
 func encFloat(i *encInstr, state *encoderState, p unsafe.Pointer) {
-	f := float(*(*float)(p))
+	f := *(*float)(p)
 	if f != 0 || state.inArray {
 		v := floatBits(float64(f))
 		state.update(i)
@@ -476,7 +476,7 @@ func encFloat(i *encInstr, state *encoderState, p unsafe.Pointer) {
 }
 
 func encFloat32(i *encInstr, state *encoderState, p unsafe.Pointer) {
-	f := float32(*(*float32)(p))
+	f := *(*float32)(p)
 	if f != 0 || state.inArray {
 		v := floatBits(float64(f))
 		state.update(i)
@@ -493,6 +493,40 @@ func encFloat64(i *encInstr, state *encoderState, p unsafe.Pointer) {
 	}
 }
 
+// Complex numbers are just a pair of floating-point numbers, real part first.
+func encComplex(i *encInstr, state *encoderState, p unsafe.Pointer) {
+	c := *(*complex)(p)
+	if c != 0+0i || state.inArray {
+		rpart := floatBits(float64(real(c)))
+		ipart := floatBits(float64(imag(c)))
+		state.update(i)
+		encodeUint(state, rpart)
+		encodeUint(state, ipart)
+	}
+}
+
+func encComplex64(i *encInstr, state *encoderState, p unsafe.Pointer) {
+	c := *(*complex64)(p)
+	if c != 0+0i || state.inArray {
+		rpart := floatBits(float64(real(c)))
+		ipart := floatBits(float64(imag(c)))
+		state.update(i)
+		encodeUint(state, rpart)
+		encodeUint(state, ipart)
+	}
+}
+
+func encComplex128(i *encInstr, state *encoderState, p unsafe.Pointer) {
+	c := *(*complex128)(p)
+	if c != 0+0i || state.inArray {
+		rpart := floatBits(real(c))
+		ipart := floatBits(imag(c))
+		state.update(i)
+		encodeUint(state, rpart)
+		encodeUint(state, ipart)
+	}
+}
+
 // Byte arrays are encoded as an unsigned count followed by the raw bytes.
 func encUint8Array(i *encInstr, state *encoderState, p unsafe.Pointer) {
 	b := *(*[]byte)(p)
@@ -602,22 +636,25 @@ func encodeMap(b *bytes.Buffer, rt reflect.Type, p uintptr, keyOp, elemOp encOp,
 }
 
 var encOpMap = []encOp{
-	reflect.Bool:    encBool,
-	reflect.Int:     encInt,
-	reflect.Int8:    encInt8,
-	reflect.Int16:   encInt16,
-	reflect.Int32:   encInt32,
-	reflect.Int64:   encInt64,
-	reflect.Uint:    encUint,
-	reflect.Uint8:   encUint8,
-	reflect.Uint16:  encUint16,
-	reflect.Uint32:  encUint32,
-	reflect.Uint64:  encUint64,
-	reflect.Uintptr: encUintptr,
-	reflect.Float:   encFloat,
-	reflect.Float32: encFloat32,
-	reflect.Float64: encFloat64,
-	reflect.String:  encString,
+	reflect.Bool:       encBool,
+	reflect.Int:        encInt,
+	reflect.Int8:       encInt8,
+	reflect.Int16:      encInt16,
+	reflect.Int32:      encInt32,
+	reflect.Int64:      encInt64,
+	reflect.Uint:       encUint,
+	reflect.Uint8:      encUint8,
+	reflect.Uint16:     encUint16,
+	reflect.Uint32:     encUint32,
+	reflect.Uint64:     encUint64,
+	reflect.Uintptr:    encUintptr,
+	reflect.Float:      encFloat,
+	reflect.Float32:    encFloat32,
+	reflect.Float64:    encFloat64,
+	reflect.Complex:    encComplex,
+	reflect.Complex64:  encComplex64,
+	reflect.Complex128: encComplex128,
+	reflect.String:     encString,
 }
 
 // Return the encoding op for the base type under rt and
@@ -688,7 +725,7 @@ func encOpFor(rt reflect.Type) (encOp, int, os.Error) {
 		}
 	}
 	if op == nil {
-		return op, indir, os.ErrorString("gob enc: can't happen: encode type" + rt.String())
+		return op, indir, os.ErrorString("gob enc: can't happen: encode type " + rt.String())
 	}
 	return op, indir, nil
 }
diff --git a/src/pkg/gob/type.go b/src/pkg/gob/type.go
index 6a3e6ba65..2ad36ae65 100644
--- a/src/pkg/gob/type.go
+++ b/src/pkg/gob/type.go
@@ -78,12 +78,17 @@ func (t *commonType) Name() string { return t.name }
 // Create and check predefined types
 // The string for tBytes is "bytes" not "[]byte" to signify its specialness.
 
-var tBool = bootstrapType("bool", false, 1)
-var tInt = bootstrapType("int", int(0), 2)
-var tUint = bootstrapType("uint", uint(0), 3)
-var tFloat = bootstrapType("float", float64(0), 4)
-var tBytes = bootstrapType("bytes", make([]byte, 0), 5)
-var tString = bootstrapType("string", "", 6)
+var (
+	// Primordial types, needed during initialization.
+	tBool   = bootstrapType("bool", false, 1)
+	tInt    = bootstrapType("int", int(0), 2)
+	tUint   = bootstrapType("uint", uint(0), 3)
+	tFloat  = bootstrapType("float", float64(0), 4)
+	tBytes  = bootstrapType("bytes", make([]byte, 0), 5)
+	tString = bootstrapType("string", "", 6)
+	// Types added to the language later, not needed during initialization.
+	tComplex typeId
+)
 
 // Predefined because it's needed by the Decoder
 var tWireType = mustGetTypeInfo(reflect.Typeof(wireType{})).id
@@ -94,10 +99,17 @@ func init() {
 	checkId(9, mustGetTypeInfo(reflect.Typeof(commonType{})).id)
 	checkId(11, mustGetTypeInfo(reflect.Typeof(structType{})).id)
 	checkId(12, mustGetTypeInfo(reflect.Typeof(fieldType{})).id)
+
+	// Complex was added after gob was written, so appears after the
+	// fundamental types are built.
+	tComplex = bootstrapType("complex", 0+0i, 15)
+	decIgnoreOpMap[tComplex] = ignoreTwoUints
+
 	builtinIdToType = make(map[typeId]gobType)
 	for k, v := range idToType {
 		builtinIdToType[k] = v
 	}
+
 	// Move the id space upwards to allow for growth in the predefined world
 	// without breaking existing files.
 	if nextId > firstUserId {
@@ -241,6 +253,9 @@ func newTypeObject(name string, rt reflect.Type) (gobType, os.Error) {
 	case *reflect.FloatType:
 		return tFloat.gobType(), nil
 
+	case *reflect.ComplexType:
+		return tComplex.gobType(), nil
+
 	case *reflect.StringType:
 		return tString.gobType(), nil
 
@@ -335,7 +350,7 @@ func bootstrapType(name string, e interface{}, expect typeId) typeId {
 	rt := reflect.Typeof(e)
 	_, present := types[rt]
 	if present {
-		panic("bootstrap type already present: " + name)
+		panic("bootstrap type already present: " + name + ", " + rt.String())
 	}
 	typ := &commonType{name: name}
 	types[rt] = typ