Deep-copy functions autogeneration.

pkg/conversion/cloner.go

@@ -0,0 +1,226 @@
+/*
+Copyright 2014 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package conversion
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// Cloner knows how to copy one type to another.
+type Cloner struct {
+	// Map from the type to a function which can do the deep copy.
+	deepCopyFuncs          map[reflect.Type]reflect.Value
+	generatedDeepCopyFuncs map[reflect.Type]reflect.Value
+}
+
+// NewCloner creates a new Cloner object.
+func NewCloner() *Cloner {
+	c := &Cloner{
+		deepCopyFuncs:          map[reflect.Type]reflect.Value{},
+		generatedDeepCopyFuncs: map[reflect.Type]reflect.Value{},
+	}
+	if err := c.RegisterDeepCopyFunc(byteSliceDeepCopy); err != nil {
+		// If one of the deep-copy functions is malformed, detect it immediately.
+		panic(err)
+	}
+	return c
+}
+
+// Prevent recursing into every byte...
+func byteSliceDeepCopy(in []byte, out *[]byte, c *Cloner) error {
+	*out = make([]byte, len(in))
+	copy(*out, in)
+	return nil
+}
+
+// Verifies whether a deep-copy function has a correct signature.
+func verifyDeepCopyFunctionSignature(ft reflect.Type) error {
+	if ft.Kind() != reflect.Func {
+		return fmt.Errorf("expected func, got: %v", ft)
+	}
+	if ft.NumIn() != 3 {
+		return fmt.Errorf("expected three 'in' params, got $v", ft)
+	}
+	if ft.NumOut() != 1 {
+		return fmt.Errorf("expected one 'out' param, got %v", ft)
+	}
+	if ft.In(1).Kind() != reflect.Ptr {
+		return fmt.Errorf("expected pointer arg for 'in' param 1, got: %v", ft)
+	}
+	if ft.In(1).Elem() != ft.In(0) {
+		return fmt.Errorf("expected 'in' param 0 the same as param 1, got: %v", ft)
+	}
+	var forClonerType Cloner
+	if expected := reflect.TypeOf(&forClonerType); ft.In(2) != expected {
+		return fmt.Errorf("expected '%v' arg for 'in' param 2, got: '%v'", expected, ft.In(2))
+	}
+	var forErrorType error
+	// This convolution is necessary, otherwise TypeOf picks up on the fact
+	// that forErrorType is nil
+	errorType := reflect.TypeOf(&forErrorType).Elem()
+	if ft.Out(0) != errorType {
+		return fmt.Errorf("expected error return, got: %v", ft)
+	}
+	return nil
+}
+
+// RegisterGeneratedDeepCopyFunc registers a copying func with the Cloner.
+// deepCopyFunc must take two parameters: a type and a pointer to Cloner
+// and return an element of the same type and an error.
+//
+// Example:
+// c.RegisterGeneratedDeepCopyFunc(
+//         func(in Pod, c *Cloner) (Pod, error) {
+//                 // deep copy logic...
+//                 return copy, nil
+//          })
+func (c *Cloner) RegisterDeepCopyFunc(deepCopyFunc interface{}) error {
+	fv := reflect.ValueOf(deepCopyFunc)
+	ft := fv.Type()
+	if err := verifyDeepCopyFunctionSignature(ft); err != nil {
+		return err
+	}
+	c.deepCopyFuncs[ft.In(0)] = fv
+	return nil
+}
+
+// Similar to RegisterDeepCopyFunc, but registers deep copy function that were
+// automatically generated.
+func (c *Cloner) RegisterGeneratedDeepCopyFunc(deepCopyFunc interface{}) error {
+	fv := reflect.ValueOf(deepCopyFunc)
+	ft := fv.Type()
+	if err := verifyDeepCopyFunctionSignature(ft); err != nil {
+		return err
+	}
+	c.generatedDeepCopyFuncs[ft.In(0)] = fv
+	return nil
+}
+
+// DeepCopy will perform a deep copy of a given object.
+func (c *Cloner) DeepCopy(in interface{}) (interface{}, error) {
+	inValue := reflect.ValueOf(in)
+	outValue, err := c.deepCopy(inValue)
+	if err != nil {
+		return nil, err
+	}
+	return outValue.Interface(), nil
+}
+
+func (c *Cloner) deepCopy(src reflect.Value) (reflect.Value, error) {
+	inType := src.Type()
+
+	if fv, ok := c.deepCopyFuncs[inType]; ok {
+		return c.customDeepCopy(src, fv)
+	}
+	if fv, ok := c.generatedDeepCopyFuncs[inType]; ok {
+		return c.customDeepCopy(src, fv)
+	}
+	return c.defaultDeepCopy(src)
+}
+
+func (c *Cloner) customDeepCopy(src, fv reflect.Value) (reflect.Value, error) {
+	outValue := reflect.New(src.Type())
+	args := []reflect.Value{src, outValue, reflect.ValueOf(c)}
+	result := fv.Call(args)[0].Interface()
+	// This convolution is necessary because nil interfaces won't convert
+	// to error.
+	if result == nil {
+		return outValue.Elem(), nil
+	}
+	return outValue.Elem(), result.(error)
+}
+
+func (c *Cloner) defaultDeepCopy(src reflect.Value) (reflect.Value, error) {
+	switch src.Kind() {
+	case reflect.Chan, reflect.Func, reflect.UnsafePointer, reflect.Uintptr:
+		return src, fmt.Errorf("cannot deep copy kind: %s", src.Kind())
+	case reflect.Array:
+		dst := reflect.New(src.Type())
+		for i := 0; i < src.Len(); i++ {
+			copyVal, err := c.deepCopy(src.Index(i))
+			if err != nil {
+				return src, err
+			}
+			dst.Elem().Index(i).Set(copyVal)
+		}
+		return dst.Elem(), nil
+	case reflect.Interface:
+		if src.IsNil() {
+			return src, nil
+		}
+		return c.deepCopy(src.Elem())
+	case reflect.Map:
+		if src.IsNil() {
+			return src, nil
+		}
+		dst := reflect.MakeMap(src.Type())
+		for _, k := range src.MapKeys() {
+			copyVal, err := c.deepCopy(src.MapIndex(k))
+			if err != nil {
+				return src, err
+			}
+			dst.SetMapIndex(k, copyVal)
+		}
+		return dst, nil
+	case reflect.Ptr:
+		if src.IsNil() {
+			return src, nil
+		}
+		dst := reflect.New(src.Type().Elem())
+		copyVal, err := c.deepCopy(src.Elem())
+		if err != nil {
+			return src, err
+		}
+		dst.Elem().Set(copyVal)
+		return dst, nil
+	case reflect.Slice:
+		if src.IsNil() {
+			return src, nil
+		}
+		dst := reflect.MakeSlice(src.Type(), 0, src.Len())
+		for i := 0; i < src.Len(); i++ {
+			copyVal, err := c.deepCopy(src.Index(i))
+			if err != nil {
+				return src, err
+			}
+			dst = reflect.Append(dst, copyVal)
+		}
+		return dst, nil
+	case reflect.Struct:
+		dst := reflect.New(src.Type())
+		for i := 0; i < src.NumField(); i++ {
+			if !dst.Elem().Field(i).CanSet() {
+				// Can't set private fields. At this point, the
+				// best we can do is a shallow copy. For
+				// example, time.Time is a value type with
+				// private members that can be shallow copied.
+				return src, nil
+			}
+			copyVal, err := c.deepCopy(src.Field(i))
+			if err != nil {
+				return src, err
+			}
+			dst.Elem().Field(i).Set(copyVal)
+		}
+		return dst.Elem(), nil
+
+	default:
+		// Value types like numbers, booleans, and strings.
+		return src, nil
+	}
+}

pkg/conversion/scheme.go

@@ -40,6 +40,10 @@ type Scheme struct {
 	// default coverting behavior.
 	converter *Converter
 
+	// cloner stores all registered copy functions. It also has default
+	// deep copy behavior.
+	cloner *Cloner
+
 	// Indent will cause the JSON output from Encode to be indented, iff it is true.
 	Indent bool
 
@@ -60,6 +64,7 @@ func NewScheme() *Scheme {
 		typeToVersion:   map[reflect.Type]string{},
 		typeToKind:      map[reflect.Type][]string{},
 		converter:       NewConverter(),
+		cloner:          NewCloner(),
 		InternalVersion: "",
 		MetaFactory:     DefaultMetaFactory,
 	}
@@ -212,6 +217,29 @@ func (s *Scheme) AddGeneratedConversionFuncs(conversionFuncs ...interface{}) err
 	return nil
 }
 
+// AddDeepCopyFuncs adds functions to the list of deep copy functions.
+// Note that to copy sub-objects, you can use the conversion.Cloner object that
+// will be passed to your deep-copy function.
+func (s *Scheme) AddDeepCopyFuncs(deepCopyFuncs ...interface{}) error {
+	for _, f := range deepCopyFuncs {
+		if err := s.cloner.RegisterDeepCopyFunc(f); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Similar to AddDeepCopyFuncs, but registers deep copy functions that were
+// automatically generated.
+func (s *Scheme) AddGeneratedDeepCopyFuncs(deepCopyFuncs ...interface{}) error {
+	for _, f := range deepCopyFuncs {
+		if err := s.cloner.RegisterGeneratedDeepCopyFunc(f); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // AddStructFieldConversion allows you to specify a mechanical copy for a moved
 // or renamed struct field without writing an entire conversion function. See
 // the comment in Converter.SetStructFieldCopy for parameter details.
@@ -262,6 +290,11 @@ func (s *Scheme) RegisterInputDefaults(in interface{}, fn FieldMappingFunc, defa
 	return s.converter.RegisterInputDefaults(in, fn, defaultFlags)
 }
 
+// Performs a deep copy of the given object.
+func (s *Scheme) DeepCopy(in interface{}) (interface{}, error) {
+	return s.cloner.DeepCopy(in)
+}
+
 // Convert will attempt to convert in into out. Both must be pointers. For easy
 // testing of conversion functions. Returns an error if the conversion isn't
 // possible. You can call this with types that haven't been registered (for example,