ignore missing structs

R=rsc
DELTA=113  (74 added, 14 deleted, 25 changed)
OCL=31776
CL=31776

src/pkg/gob/codec_test.go

@@ -703,6 +703,7 @@ type IT0 struct {
 	ignore_f bool;
 	ignore_g string;
 	ignore_h []byte;
+	ignore_i *RT1;
 	c float;
 }
 
@@ -718,13 +719,17 @@ func TestIgnoredFields(t *testing.T) {
 	it0.ignore_f = true;
 	it0.ignore_g = "pay no attention";
 	it0.ignore_h = strings.Bytes("to the curtain");
+	it0.ignore_i = &RT1{ 3.1, "hi", 7, "hello" };
 
 	b := new(bytes.Buffer);
 	encode(b, it0);
 	rt0Id := getTypeInfo(reflect.Typeof(it0)).typeId;
 	var rt1 RT1;
 	// Wire type is IT0, local type is RT1.
-	decode(b, rt0Id, &rt1);
+	err := decode(b, rt0Id, &rt1);
+	if err != nil {
+		t.Error("error: ", err);
+	}
 	if int(it0.a) != rt1.a || it0.b != rt1.b || it0.c != rt1.c {
 		t.Errorf("rt1->rt0: expected %v; got %v", it0, rt1);
 	}

src/pkg/gob/decode.go

@@ -361,6 +361,31 @@ func decodeStruct(engine *decEngine, rtyp *reflect.StructType, b *bytes.Buffer,
 	return state.err
 }
 
+func ignoreStruct(engine *decEngine, b *bytes.Buffer) os.Error {
+	state := new(decodeState);
+	state.b = b;
+	state.fieldnum = -1;
+	for state.err == nil {
+		delta := int(decodeUint(state));
+		if delta < 0 {
+			state.err = os.ErrorString("gob ignore decode: corrupted data: negative delta");
+			break
+		}
+		if state.err != nil || delta == 0 {	// struct terminator is zero delta fieldnum
+			break
+		}
+		fieldnum := state.fieldnum + delta;
+		if fieldnum >= len(engine.instr) {
+			state.err = ErrRange;
+			break;
+		}
+		instr := &engine.instr[fieldnum];
+		instr.op(instr, state, unsafe.Pointer(nil));
+		state.fieldnum = fieldnum;
+	}
+	return state.err
+}
+
 func decodeArrayHelper(state *decodeState, p uintptr, elemOp decOp, elemWid uintptr, length, elemIndir int) os.Error {
 	instr := &decInstr{elemOp, 0, elemIndir, 0};
 	for i := 0; i < length && state.err == nil; i++ {
@@ -459,6 +484,7 @@ var decIgnoreOpMap = map[TypeId] decOp {
 }
 
 func getDecEnginePtr(wireId TypeId, rt reflect.Type) (enginePtr **decEngine, err os.Error)
+func getIgnoreEnginePtr(wireId TypeId) (enginePtr **decEngine, err os.Error)
 
 // Return the decoding op for the base type under rt and
 // the indirection count to reach it.
@@ -499,7 +525,7 @@ func decOpFor(wireId TypeId, rt reflect.Type) (decOp, int, os.Error) {
 				return nil, 0, err
 			}
 			op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
-				// indirect through info to delay evaluation for recursive structs
+				// indirect through enginePtr to delay evaluation for recursive structs
 				state.err = decodeStruct(*enginePtr, t, state.b, uintptr(p), i.indir)
 			};
 		}
@@ -537,7 +563,15 @@ func decIgnoreOpFor(wireId TypeId) (decOp, os.Error) {
 			};
 
 		case *structType:
-			// TODO: write an ignore engine for structs
+			// Generate a closure that calls out to the engine for the nested type.
+			enginePtr, err := getIgnoreEnginePtr(wireId);
+			if err != nil {
+				return nil, err
+			}
+			op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
+				// indirect through enginePtr to delay evaluation for recursive structs
+				state.err = ignoreStruct(*enginePtr, state.b)
+			};
 		}
 	}
 	if op == nil {
@@ -547,7 +581,8 @@ func decIgnoreOpFor(wireId TypeId) (decOp, os.Error) {
 }
 
 // Are these two gob Types compatible?
-// Answers the question for basic types, arrays, and slices.  Defers for structs.
+// Answers the question for basic types, arrays, and slices.
+// Structs are considered ok; fields will be checked later.
 func compatibleType(fr reflect.Type, fw TypeId) bool {
 	for {
 		if pt, ok := fr.(*reflect.PtrType); ok {
@@ -592,8 +627,6 @@ func compatibleType(fr reflect.Type, fw TypeId) bool {
 		return fw == tFloat;
 	case *reflect.StringType:
 		return fw == tString;
-	case *reflect.StructType:
-		return true;	// defer for now
 	case *reflect.ArrayType:
 		aw, ok := fw.gobType().(*arrayType);
 		return ok && t.Len() == aw.Len && compatibleType(t.Elem(), aw.Elem);
@@ -604,7 +637,10 @@ func compatibleType(fr reflect.Type, fw TypeId) bool {
 			return fw == tBytes
 		}
 		sw, ok := fw.gobType().(*sliceType);
-		return ok && compatibleType(t.Elem(), sw.Elem);
+		elem, _ := indirect(t.Elem());
+		return ok && compatibleType(elem, sw.Elem);
+	case *reflect.StructType:
+		return true;
 	}
 	return true;
 }
@@ -624,7 +660,6 @@ func compileDec(wireId TypeId, rt reflect.Type) (engine *decEngine, err os.Error
 		localField, present := srt.FieldByName(wireField.name);
 		// TODO(r): anonymous names
 		if !present || localField.Anonymous {
-			println("no matching field", wireField.name, "in type", wireId.String());
 			op, err := decIgnoreOpFor(wireField.typeId);
 			if err != nil {
 				return nil, err
@@ -633,7 +668,7 @@ func compileDec(wireId TypeId, rt reflect.Type) (engine *decEngine, err os.Error
 			continue;
 		}
 		if !compatibleType(localField.Type, wireField.typeId) {
-			return nil, os.ErrorString("gob: TODO: wrong type for field " + wireField.name + " in type " + wireId.String());
+			return nil, os.ErrorString("gob: wrong type for field " + wireField.name + " in type " + wireId.Name());
 		}
 		op, indir, err := decOpFor(wireField.typeId, localField.Type);
 		if err != nil {
@@ -645,22 +680,42 @@ func compileDec(wireId TypeId, rt reflect.Type) (engine *decEngine, err os.Error
 	return;
 }
 
+var decoderCache = make(map[reflect.Type] map[TypeId] **decEngine)
+var ignorerCache = make(map[TypeId] **decEngine)
 
 // typeLock must be held.
 func getDecEnginePtr(wireId TypeId, rt reflect.Type) (enginePtr **decEngine, err os.Error) {
-	info := getTypeInfo(rt);	// TODO: eliminate this; creates a gobType you don't need.
-	var ok bool;
-	if enginePtr, ok = info.decoderPtr[wireId]; !ok {
-		if info.typeId.gobType() == nil {
-			_pkg, name := rt.Name();
-			info.typeId = newType(name, rt).id();
+	decoderMap, ok := decoderCache[rt];
+	if !ok {
+		decoderMap = make(map[TypeId] **decEngine);
+		decoderCache[rt] = decoderMap;
 	}
-		// mark this engine as underway before compiling to handle recursive types.
+	if enginePtr, ok = decoderMap[wireId]; !ok {
+		// To handle recursive types, mark this engine as underway before compiling.
 		enginePtr = new(*decEngine);
-		info.decoderPtr[wireId] = enginePtr;
+		decoderMap[wireId] = enginePtr;
 		*enginePtr, err = compileDec(wireId, rt);
 		if err != nil {
-			info.decoderPtr[wireId] = nil, false;
+			decoderMap[wireId] = nil, false;
+		}
+	}
+	return
+}
+
+// When ignoring data, in effect we compile it into this type
+type emptyStruct struct {}
+var emptyStructType = reflect.Typeof(emptyStruct{})
+
+// typeLock must be held.
+func getIgnoreEnginePtr(wireId TypeId) (enginePtr **decEngine, err os.Error) {
+	var ok bool;
+	if enginePtr, ok = ignorerCache[wireId]; !ok {
+		// To handle recursive types, mark this engine as underway before compiling.
+		enginePtr = new(*decEngine);
+		ignorerCache[wireId] = enginePtr;
+		*enginePtr, err = compileDec(wireId, emptyStructType);
+		if err != nil {
+			ignorerCache[wireId] = nil, false;
 		}
 	}
 	return
@@ -685,9 +740,9 @@ func decode(b *bytes.Buffer, wireId TypeId, e interface{}) os.Error {
 		return err
 	}
 	engine := *enginePtr;
-	if engine.numInstr == 0 && st.NumField() > 0 {
+	if engine.numInstr == 0 && st.NumField() > 0 && len(wireId.gobType().(*structType).field) > 0 {
 		path, name := rt.Name();
-		return os.ErrorString("type mismatch: no fields matched compiling decoder for " + name)
+		return os.ErrorString("gob: type mismatch: no fields matched compiling decoder for " + name)
 	}
 	return decodeStruct(engine, rt.(*reflect.StructType), b, uintptr(v.Addr()), 0);
 }

src/pkg/gob/encoder_test.go

@@ -35,12 +35,7 @@ type ET3 struct {
 type ET4 struct {
 	a int;
 	et2 *ET1;
-	next *ET2;
-}
-
-// Has different type for a self-referencing field compared to ET1
-type ET5 struct {
-	next *ET2;
+	next int;
 }
 
 func TestBasicEncoder(t *testing.T) {
@@ -206,7 +201,8 @@ func TestEncoderDecoder(t *testing.T) {
 }
 
 // Run one value through the encoder/decoder, but use the wrong type.
-func badTypeCheck(e interface{}, msg string, t *testing.T) {
+// Input is always an ET1; we compare it to whatever is under 'e'.
+func badTypeCheck(e interface{}, shouldFail bool, msg string, t *testing.T) {
 	b := new(bytes.Buffer);
 	enc := NewEncoder(b);
 	et1 := new(ET1);
@@ -218,15 +214,17 @@ func badTypeCheck(e interface{}, msg string, t *testing.T) {
 	}
 	dec := NewDecoder(b);
 	dec.Decode(e);
-	if dec.state.err == nil {
+	if shouldFail && (dec.state.err == nil) {
 		t.Error("expected error for", msg);
 	}
+	if !shouldFail && (dec.state.err != nil) {
+		t.Error("unexpected error for", msg);
+	}
 }
 
 // Test that we recognize a bad type the first time.
 func TestWrongTypeDecoder(t *testing.T) {
-	badTypeCheck(new(ET2), "no fields in common", t);
-	badTypeCheck(new(ET3), "different name of field", t);
-	badTypeCheck(new(ET4), "different type of field", t);
-	badTypeCheck(new(ET5), "different type of self-reference field", t);
+	badTypeCheck(new(ET2), true, "no fields in common", t);
+	badTypeCheck(new(ET3), false, "different name of field", t);
+	badTypeCheck(new(ET4), true, "different type of field", t);
 }

src/pkg/gob/type.go

@@ -23,6 +23,7 @@ var typeLock	sync.Mutex	// set while building a type
 type gobType interface {
 	id()	TypeId;
 	setId(id TypeId);
+	Name()	string;
 	String()	string;
 	safeString(seen map[TypeId] bool)	string;
 }
@@ -47,6 +48,10 @@ func (t TypeId) String() string {
 	return t.gobType().String()
 }
 
+func (t TypeId) Name() string {
+	return t.gobType().Name()
+}
+
 // Common elements of all types.
 type commonType struct {
 	name	string;
@@ -236,7 +241,8 @@ func newTypeObject(name string, rt reflect.Type) gobType {
 		if _, ok := t.Elem().(*reflect.Uint8Type); ok {
 			return tBytes.gobType()
 		}
-		return newSliceType(name, newType("", t.Elem()));
+		_, elemName := t.Elem().Name();
+		return newSliceType(name, newType(elemName, t.Elem()));
 
 	case *reflect.StructType:
 		// Install the struct type itself before the fields so recursive
@@ -325,9 +331,6 @@ type decEngine struct	// defined in decode.go
 type encEngine struct	// defined in encode.go
 type typeInfo struct {
 	typeId	TypeId;
-	// Decoder engine to convert TypeId.Type() to this type.  Stored as a pointer to a
-	// pointer to aid construction of recursive types.  Protected by typeLock.
-	decoderPtr	map[TypeId] **decEngine;
 	encoder	*encEngine;
 	wire	*wireType;
 }
@@ -345,7 +348,6 @@ func getTypeInfo(rt reflect.Type) *typeInfo {
 		info = new(typeInfo);
 		path, name := rt.Name();
 		info.typeId = getType(name, rt).id();
-		info.decoderPtr = make(map[TypeId] **decEngine);
 		// assume it's a struct type
 		info.wire = &wireType{info.typeId.gobType().(*structType)};
 		typeInfoMap[rt] = info;