Improvements for conversions generator

pkg/conversion/code_generation_test.go

@@ -1,167 +0,0 @@
-/*
-Copyright 2015 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_test
-
-import (
-	"bufio"
-	"bytes"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"os"
-	"testing"
-
-	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
-	"github.com/GoogleCloudPlatform/kubernetes/pkg/conversion"
-
-	"github.com/golang/glog"
-)
-
-func generateConversions(t *testing.T, version string) (bytes.Buffer, bytes.Buffer) {
-	g := conversion.NewGenerator(api.Scheme.Raw())
-	g.OverwritePackage(version, "")
-	g.OverwritePackage("api", "newer")
-	for _, knownType := range api.Scheme.KnownTypes(version) {
-		if err := g.GenerateConversionsForType(version, knownType); err != nil {
-			glog.Errorf("error while generating conversion functions for %v: %v", knownType, err)
-		}
-	}
-
-	var functions bytes.Buffer
-	functionsWriter := bufio.NewWriter(&functions)
-	if err := g.WriteConversionFunctions(functionsWriter); err != nil {
-		t.Fatalf("couldn't generate conversion functions: %v", err)
-	}
-	if err := functionsWriter.Flush(); err != nil {
-		t.Fatalf("error while flushing writer")
-	}
-
-	var names bytes.Buffer
-	namesWriter := bufio.NewWriter(&names)
-	if err := g.WriteConversionFunctionNames(namesWriter); err != nil {
-		t.Fatalf("couldn't generate conversion function names: %v", err)
-	}
-	if err := namesWriter.Flush(); err != nil {
-		t.Fatalf("error while flushing writer")
-	}
-
-	return functions, names
-}
-
-func readLinesUntil(t *testing.T, reader *bufio.Reader, stop string, buffer *bytes.Buffer) error {
-	for {
-		line, err := reader.ReadString('\n')
-		if err == io.EOF {
-			return fmt.Errorf("'%s' line not found", stop)
-		}
-		if err != nil {
-			t.Fatalf("error while reading file: %v", err)
-		}
-		if line == stop {
-			break
-		}
-		if buffer != nil {
-			if _, err := buffer.WriteString(line); err != nil {
-				t.Fatalf("error while buffering line")
-			}
-		}
-	}
-	return nil
-}
-
-func bufferExistingConversions(t *testing.T, fileName string) (bytes.Buffer, bytes.Buffer) {
-	file, err := os.Open(fileName)
-	if err != nil {
-		t.Fatalf("couldn't open file %s", fileName)
-	}
-	defer file.Close()
-
-	reader := bufio.NewReader(file)
-
-	functionsPrefix := "// AUTO-GENERATED FUNCTIONS START HERE\n"
-	functionsSuffix := "// AUTO-GENERATED FUNCTIONS END HERE\n"
-	if err := readLinesUntil(t, reader, functionsPrefix, nil); err != nil {
-		t.Fatalf("error while parsing file: %v", err)
-	}
-	var functions bytes.Buffer
-	if err := readLinesUntil(t, reader, functionsSuffix, &functions); err != nil {
-		t.Fatalf("error while parsing file: %v", err)
-	}
-
-	functionNamesPrefix := "\terr := newer.Scheme.AddGeneratedConversionFuncs(\n"
-	functionNamesSuffix := "\t)\n"
-	if err := readLinesUntil(t, reader, functionNamesPrefix, nil); err != nil {
-		t.Fatalf("error while parsing file: %v", err)
-	}
-	var names bytes.Buffer
-	if err := readLinesUntil(t, reader, functionNamesSuffix, &names); err != nil {
-		t.Fatalf("error while parsing file: %v", err)
-	}
-
-	return functions, names
-}
-
-func compareBuffers(t *testing.T, generatedFile string, existing, generated bytes.Buffer) bool {
-	ok := true
-	for {
-		existingLine, existingErr := existing.ReadString('\n')
-		generatedLine, generatedErr := generated.ReadString('\n')
-		if existingErr == io.EOF && generatedErr == io.EOF {
-			break
-		}
-		if existingErr != generatedErr {
-			ok = false
-			t.Errorf("reading errors: existing %v generated %v", existingErr, generatedErr)
-			return ok
-		}
-		if existingErr != nil {
-			ok = false
-			t.Errorf("error while reading: %v", existingErr)
-		}
-		if existingLine != generatedLine {
-			ok = false
-			diff := fmt.Sprintf("first difference: expected %s, got %s", generatedLine, existingLine)
-			t.Errorf("please update conversion functions; generated: %s; diff: %s", generatedFile, diff)
-			return ok
-		}
-	}
-	return ok
-}
-
-func TestNoManualChangesToGenerateConversions(t *testing.T) {
-	versions := []string{"v1beta3"}
-
-	for _, version := range versions {
-		fileName := fmt.Sprintf("../../pkg/api/%s/conversion_generated.go", version)
-
-		existingFunctions, existingNames := bufferExistingConversions(t, fileName)
-		generatedFunctions, generatedNames := generateConversions(t, version)
-
-		functionsTxt := fmt.Sprintf("%s.functions.txt", version)
-		ioutil.WriteFile(functionsTxt, generatedFunctions.Bytes(), os.FileMode(0644))
-
-		namesTxt := fmt.Sprintf("%s.names.txt", version)
-		ioutil.WriteFile(namesTxt, generatedNames.Bytes(), os.FileMode(0644))
-
-		if ok := compareBuffers(t, functionsTxt, existingFunctions, generatedFunctions); ok {
-			os.Remove(functionsTxt)
-		}
-		if ok := compareBuffers(t, namesTxt, existingNames, generatedNames); ok {
-			os.Remove(namesTxt)
-		}
-	}
-}

pkg/conversion/generator.go

@@ -1,705 +0,0 @@
-/*
-Copyright 2015 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"
-	"io"
-	"reflect"
-	"sort"
-	"strings"
-)
-
-type Generator interface {
-	GenerateConversionsForType(version string, reflection reflect.Type) error
-	WriteConversionFunctions(w io.Writer) error
-	WriteConversionFunctionNames(w io.Writer) error
-	OverwritePackage(pkg, overwrite string)
-}
-
-func NewGenerator(scheme *Scheme) Generator {
-	return &generator{
-		scheme:        scheme,
-		convertibles:  make(map[reflect.Type]reflect.Type),
-		pkgOverwrites: make(map[string]string),
-	}
-}
-
-var complexTypes []reflect.Kind = []reflect.Kind{reflect.Map, reflect.Ptr, reflect.Slice, reflect.Interface, reflect.Struct}
-
-type generator struct {
-	scheme       *Scheme
-	convertibles map[reflect.Type]reflect.Type
-	// If pkgOverwrites is set for a given package name, that package name
-	// will be replaced while writing conversion function. If empty, package
-	// name will be omitted.
-	pkgOverwrites map[string]string
-}
-
-func (g *generator) GenerateConversionsForType(version string, reflection reflect.Type) error {
-	kind := reflection.Name()
-	internalObj, err := g.scheme.NewObject(g.scheme.InternalVersion, kind)
-	if err != nil {
-		return fmt.Errorf("cannot create an object of type %v in internal version", kind)
-	}
-	internalObjType := reflect.TypeOf(internalObj)
-	if internalObjType.Kind() != reflect.Ptr {
-		return fmt.Errorf("created object should be of type Ptr: ", internalObjType.Kind())
-	}
-	return g.generateConversionsBetween(reflection, internalObjType.Elem())
-}
-
-func (g *generator) generateConversionsBetween(inType, outType reflect.Type) error {
-	existingConversion := g.scheme.Converter().HasConversionFunc(inType, outType) && g.scheme.Converter().HasConversionFunc(outType, inType)
-
-	// Avoid processing the same type multiple times.
-	if value, found := g.convertibles[inType]; found {
-		if value != outType {
-			return fmt.Errorf("multiple possible convertibles for %v", inType)
-		}
-		return nil
-	}
-	if inType == outType {
-		// Don't generate conversion methods for the same type.
-		return nil
-	}
-
-	if inType.Kind() != outType.Kind() {
-		return fmt.Errorf("cannot convert types of different kinds: %v %v", inType, outType)
-	}
-	// We should be able to generate conversions both sides.
-	switch inType.Kind() {
-	case reflect.Map:
-		inErr := g.generateConversionsForMap(inType, outType)
-		outErr := g.generateConversionsForMap(outType, inType)
-		if !existingConversion && (inErr != nil || outErr != nil) {
-			return inErr
-		}
-		// We don't add it to g.convertibles - maps should be handled correctly
-		// inside appropriate conversion functions.
-		return nil
-	case reflect.Ptr:
-		inErr := g.generateConversionsBetween(inType.Elem(), outType.Elem())
-		outErr := g.generateConversionsBetween(outType.Elem(), inType.Elem())
-		if !existingConversion && (inErr != nil || outErr != nil) {
-			return inErr
-		}
-		// We don't add it to g.convertibles - maps should be handled correctly
-		// inside appropriate conversion functions.
-		return nil
-	case reflect.Slice:
-		inErr := g.generateConversionsForSlice(inType, outType)
-		outErr := g.generateConversionsForSlice(outType, inType)
-		if !existingConversion && (inErr != nil || outErr != nil) {
-			return inErr
-		}
-		// We don't add it to g.convertibles - slices should be handled correctly
-		// inside appropriate conversion functions.
-		return nil
-	case reflect.Interface:
-		// TODO(wojtek-t): Currently we don't support converting interfaces.
-		return fmt.Errorf("interfaces are not supported")
-	case reflect.Struct:
-		inErr := g.generateConversionsForStruct(inType, outType)
-		outErr := g.generateConversionsForStruct(outType, inType)
-		if !existingConversion && (inErr != nil || outErr != nil) {
-			return inErr
-		}
-		if !existingConversion {
-			if _, found := g.convertibles[outType]; !found {
-				g.convertibles[inType] = outType
-			}
-		}
-		return nil
-	default:
-		// All simple types should be handled correctly with default conversion.
-		return nil
-	}
-	panic("This should never happen")
-}
-
-func isComplexType(reflection reflect.Type) bool {
-	for _, complexType := range complexTypes {
-		if complexType == reflection.Kind() {
-			return true
-		}
-	}
-	return false
-}
-
-func (g *generator) generateConversionsForMap(inType, outType reflect.Type) error {
-	inKey := inType.Key()
-	outKey := outType.Key()
-	if err := g.generateConversionsBetween(inKey, outKey); err != nil {
-		return err
-	}
-	inValue := inType.Elem()
-	outValue := outType.Elem()
-	if err := g.generateConversionsBetween(inValue, outValue); err != nil {
-		return err
-	}
-	return nil
-}
-
-func (g *generator) generateConversionsForSlice(inType, outType reflect.Type) error {
-	inElem := inType.Elem()
-	outElem := outType.Elem()
-	if err := g.generateConversionsBetween(inElem, outElem); err != nil {
-		return err
-	}
-	return nil
-}
-
-func (g *generator) generateConversionsForStruct(inType, outType reflect.Type) error {
-	for i := 0; i < inType.NumField(); i++ {
-		inField := inType.Field(i)
-		outField, found := outType.FieldByName(inField.Name)
-		if !found {
-			return fmt.Errorf("couldn't find a corresponding field %v in %v", inField.Name, outType)
-		}
-		if inField.Type.Kind() != outField.Type.Kind() {
-			return fmt.Errorf("cannot convert types of different kinds: %v %v", inField, outField)
-		}
-		if isComplexType(inField.Type) {
-			if err := g.generateConversionsBetween(inField.Type, outField.Type); err != nil {
-				return err
-			}
-		}
-	}
-	return nil
-}
-
-type byName []reflect.Type
-
-func (s byName) Len() int {
-	return len(s)
-}
-
-func (s byName) Less(i, j int) bool {
-	return s[i].Name() < s[j].Name()
-}
-
-func (s byName) Swap(i, j int) {
-	s[i], s[j] = s[j], s[i]
-}
-
-func (g *generator) WriteConversionFunctions(w io.Writer) error {
-	// It's desired to print conversion functions always in the same order
-	// (e.g. for better tracking of what has really been added).
-	var keys []reflect.Type
-	for key := range g.convertibles {
-		keys = append(keys, key)
-	}
-	sort.Sort(byName(keys))
-
-	indent := 0
-	for _, inType := range keys {
-		outType := g.convertibles[inType]
-		// All types in g.convertibles are structs.
-		if inType.Kind() != reflect.Struct {
-			return fmt.Errorf("non-struct conversions are not-supported")
-		}
-		if err := g.writeConversionForType(w, inType, outType, indent); err != nil {
-			return err
-		}
-		if err := g.writeConversionForType(w, outType, inType, indent); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func (g *generator) WriteConversionFunctionNames(w io.Writer) error {
-	// Write conversion function names alphabetically ordered.
-	var names []string
-	for inType, outType := range g.convertibles {
-		names = append(names, conversionFunctionName(inType, outType))
-		names = append(names, conversionFunctionName(outType, inType))
-	}
-	sort.Strings(names)
-
-	indent := 2
-	for _, name := range names {
-		if err := writeLine(w, indent, fmt.Sprintf("%s,\n", name)); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func (g *generator) typeName(inType reflect.Type) string {
-	switch inType.Kind() {
-	case reflect.Map:
-		return fmt.Sprintf("map[%s]%s", g.typeName(inType.Key()), g.typeName(inType.Elem()))
-	case reflect.Slice:
-		return fmt.Sprintf("[]%s", g.typeName(inType.Elem()))
-	case reflect.Ptr:
-		return fmt.Sprintf("*%s", g.typeName(inType.Elem()))
-	default:
-		typeWithPkg := fmt.Sprintf("%s", inType)
-		slices := strings.Split(typeWithPkg, ".")
-		if len(slices) == 1 {
-			// Default package.
-			return slices[0]
-		}
-		if len(slices) == 2 {
-			pkg := slices[0]
-			if val, found := g.pkgOverwrites[pkg]; found {
-				pkg = val
-			}
-			if pkg != "" {
-				pkg = pkg + "."
-			}
-			return pkg + slices[1]
-		}
-		panic("Incorrect type name: " + typeWithPkg)
-	}
-}
-
-func (g *generator) writeDefaultingFunc(w io.Writer, inType reflect.Type, indent int) error {
-	getStmt := "if defaulting, found := s.DefaultingInterface(reflect.TypeOf(*in)); found {\n"
-	if err := writeLine(w, indent, getStmt); err != nil {
-		return err
-	}
-	callFormat := "defaulting.(func(*%s))(in)\n"
-	callStmt := fmt.Sprintf(callFormat, g.typeName(inType))
-	if err := writeLine(w, indent+1, callStmt); err != nil {
-		return err
-	}
-	if err := writeLine(w, indent, "}\n"); err != nil {
-		return err
-	}
-	return nil
-}
-
-func packageForName(inType reflect.Type) string {
-	if inType.PkgPath() == "" {
-		return ""
-	}
-	slices := strings.Split(inType.PkgPath(), "/")
-	return slices[len(slices)-1]
-}
-
-func conversionFunctionName(inType, outType reflect.Type) string {
-	funcNameFormat := "convert_%s_%s_To_%s_%s"
-	inPkg := packageForName(inType)
-	outPkg := packageForName(outType)
-	funcName := fmt.Sprintf(funcNameFormat, inPkg, inType.Name(), outPkg, outType.Name())
-	return funcName
-}
-
-func indentLine(w io.Writer, indent int) error {
-	indentation := ""
-	for i := 0; i < indent; i++ {
-		indentation = indentation + "\t"
-	}
-	_, err := io.WriteString(w, indentation)
-	return err
-}
-
-func writeLine(w io.Writer, indent int, line string) error {
-	if err := indentLine(w, indent); err != nil {
-		return err
-	}
-	if _, err := io.WriteString(w, line); err != nil {
-		return err
-	}
-	return nil
-}
-
-func writeHeader(w io.Writer, name, inType, outType string, indent int) error {
-	format := "func %s(in *%s, out *%s, s conversion.Scope) error {\n"
-	stmt := fmt.Sprintf(format, name, inType, outType)
-	return writeLine(w, indent, stmt)
-}
-
-func writeFooter(w io.Writer, indent int) error {
-	if err := writeLine(w, indent+1, "return nil\n"); err != nil {
-		return err
-	}
-	if err := writeLine(w, indent, "}\n"); err != nil {
-		return err
-	}
-	return nil
-}
-
-func (g *generator) writeConversionForMap(w io.Writer, inField, outField reflect.StructField, indent int) error {
-	ifFormat := "if in.%s != nil {\n"
-	ifStmt := fmt.Sprintf(ifFormat, inField.Name)
-	if err := writeLine(w, indent, ifStmt); err != nil {
-		return err
-	}
-	makeFormat := "out.%s = make(%s)\n"
-	makeStmt := fmt.Sprintf(makeFormat, outField.Name, g.typeName(outField.Type))
-	if err := writeLine(w, indent+1, makeStmt); err != nil {
-		return err
-	}
-	forFormat := "for key, val := range in.%s {\n"
-	forStmt := fmt.Sprintf(forFormat, inField.Name)
-	if err := writeLine(w, indent+1, forStmt); err != nil {
-		return err
-	}
-	// Whether we need to explicitly create a new value.
-	newValue := false
-	if isComplexType(inField.Type.Elem()) || !inField.Type.Elem().ConvertibleTo(outField.Type.Elem()) {
-		newValue = true
-		newFormat := "newVal := %s{}\n"
-		newStmt := fmt.Sprintf(newFormat, g.typeName(outField.Type.Elem()))
-		if err := writeLine(w, indent+2, newStmt); err != nil {
-			return err
-		}
-		convertStmt := "if err := s.Convert(&val, &newVal, 0); err != nil {\n"
-		if err := writeLine(w, indent+2, convertStmt); err != nil {
-			return err
-		}
-		if err := writeLine(w, indent+3, "return err\n"); err != nil {
-			return err
-		}
-		if err := writeLine(w, indent+2, "}\n"); err != nil {
-			return err
-		}
-	}
-	if inField.Type.Key().ConvertibleTo(outField.Type.Key()) {
-		value := "val"
-		if newValue {
-			value = "newVal"
-		}
-		assignStmt := ""
-		if inField.Type.Key().AssignableTo(outField.Type.Key()) {
-			assignStmt = fmt.Sprintf("out.%s[key] = %s\n", outField.Name, value)
-		} else {
-			assignStmt = fmt.Sprintf("out.%s[%s(key)] = %s\n", outField.Name, g.typeName(outField.Type.Key()), value)
-		}
-		if err := writeLine(w, indent+2, assignStmt); err != nil {
-			return err
-		}
-	} else {
-		// TODO(wojtek-t): Support maps with keys that are non-convertible to each other.
-		return fmt.Errorf("conversions between unconvertible keys in map are not supported.")
-	}
-	if err := writeLine(w, indent+1, "}\n"); err != nil {
-		return err
-	}
-	if err := writeLine(w, indent, "} else {\n"); err != nil {
-		return err
-	}
-	nilFormat := "out.%s = nil\n"
-	nilStmt := fmt.Sprintf(nilFormat, outField.Name)
-	if err := writeLine(w, indent+1, nilStmt); err != nil {
-		return err
-	}
-	if err := writeLine(w, indent, "}\n"); err != nil {
-		return err
-	}
-	return nil
-}
-
-func (g *generator) writeConversionForSlice(w io.Writer, inField, outField reflect.StructField, indent int) error {
-	ifFormat := "if in.%s != nil {\n"
-	ifStmt := fmt.Sprintf(ifFormat, inField.Name)
-	if err := writeLine(w, indent, ifStmt); err != nil {
-		return err
-	}
-
-	makeFormat := "out.%s = make(%s, len(in.%s))\n"
-	makeStmt := fmt.Sprintf(makeFormat, outField.Name, g.typeName(outField.Type), inField.Name)
-	if err := writeLine(w, indent+1, makeStmt); err != nil {
-		return err
-	}
-	forFormat := "for i := range in.%s {\n"
-	forStmt := fmt.Sprintf(forFormat, inField.Name)
-	if err := writeLine(w, indent+1, forStmt); err != nil {
-		return err
-	}
-	assigned := false
-	switch inField.Type.Elem().Kind() {
-	case reflect.Map, reflect.Ptr, reflect.Slice, reflect.Interface, reflect.Struct:
-		// Don't copy these via assignment/conversion!
-	default:
-		// This should handle all simple types.
-		if inField.Type.Elem().AssignableTo(outField.Type.Elem()) {
-			assignFormat := "out.%s[i] = in.%s[i]\n"
-			assignStmt := fmt.Sprintf(assignFormat, outField.Name, inField.Name)
-			if err := writeLine(w, indent+2, assignStmt); err != nil {
-				return err
-			}
-			assigned = true
-		} else if inField.Type.Elem().ConvertibleTo(outField.Type.Elem()) {
-			assignFormat := "out.%s[i] = %s(in.%s[i])\n"
-			assignStmt := fmt.Sprintf(assignFormat, outField.Name, g.typeName(outField.Type.Elem()), inField.Name)
-			if err := writeLine(w, indent+2, assignStmt); err != nil {
-				return err
-			}
-			assigned = true
-		}
-	}
-	if !assigned {
-		assignStmt := ""
-		if g.existsConvertionFunction(inField.Type.Elem(), outField.Type.Elem()) {
-			assignFormat := "if err := %s(&in.%s[i], &out.%s[i], s); err != nil {\n"
-			funcName := conversionFunctionName(inField.Type.Elem(), outField.Type.Elem())
-			assignStmt = fmt.Sprintf(assignFormat, funcName, inField.Name, outField.Name)
-		} else {
-			assignFormat := "if err := s.Convert(&in.%s[i], &out.%s[i], 0); err != nil {\n"
-			assignStmt = fmt.Sprintf(assignFormat, inField.Name, outField.Name)
-		}
-		if err := writeLine(w, indent+2, assignStmt); err != nil {
-			return err
-		}
-		if err := writeLine(w, indent+3, "return err\n"); err != nil {
-			return err
-		}
-		if err := writeLine(w, indent+2, "}\n"); err != nil {
-			return err
-		}
-	}
-	if err := writeLine(w, indent+1, "}\n"); err != nil {
-		return err
-	}
-	if err := writeLine(w, indent, "} else {\n"); err != nil {
-		return err
-	}
-	nilFormat := "out.%s = nil\n"
-	nilStmt := fmt.Sprintf(nilFormat, outField.Name)
-	if err := writeLine(w, indent+1, nilStmt); err != nil {
-		return err
-	}
-	if err := writeLine(w, indent, "}\n"); err != nil {
-		return err
-	}
-	return nil
-}
-
-func (g *generator) writeConversionForPtr(w io.Writer, inField, outField reflect.StructField, indent int) error {
-	switch inField.Type.Elem().Kind() {
-	case reflect.Map, reflect.Ptr, reflect.Slice, reflect.Interface, reflect.Struct:
-		// Don't copy these via assignment/conversion!
-	default:
-		// This should handle pointers to all simple types.
-		assignable := inField.Type.Elem().AssignableTo(outField.Type.Elem())
-		convertible := inField.Type.Elem().ConvertibleTo(outField.Type.Elem())
-		if assignable || convertible {
-			ifFormat := "if in.%s != nil {\n"
-			ifStmt := fmt.Sprintf(ifFormat, inField.Name)
-			if err := writeLine(w, indent, ifStmt); err != nil {
-				return err
-			}
-			newFormat := "out.%s = new(%s)\n"
-			newStmt := fmt.Sprintf(newFormat, outField.Name, g.typeName(outField.Type.Elem()))
-			if err := writeLine(w, indent+1, newStmt); err != nil {
-				return err
-			}
-		}
-		if assignable {
-			assignFormat := "*out.%s = *in.%s\n"
-			assignStmt := fmt.Sprintf(assignFormat, outField.Name, inField.Name)
-			if err := writeLine(w, indent+1, assignStmt); err != nil {
-				return err
-			}
-		} else if convertible {
-			assignFormat := "*out.%s = %s(*in.%s)\n"
-			assignStmt := fmt.Sprintf(assignFormat, outField.Name, g.typeName(outField.Type.Elem()), inField.Name)
-			if err := writeLine(w, indent+1, assignStmt); err != nil {
-				return err
-			}
-		}
-		if assignable || convertible {
-			if err := writeLine(w, indent, "} else {\n"); err != nil {
-				return err
-			}
-			nilFormat := "out.%s = nil\n"
-			nilStmt := fmt.Sprintf(nilFormat, outField.Name)
-			if err := writeLine(w, indent+1, nilStmt); err != nil {
-				return err
-			}
-			if err := writeLine(w, indent, "}\n"); err != nil {
-				return err
-			}
-			return nil
-		}
-	}
-
-	ifFormat := "if in.%s != nil {\n"
-	ifStmt := fmt.Sprintf(ifFormat, inField.Name)
-	if err := writeLine(w, indent, ifStmt); err != nil {
-		return err
-	}
-	assignStmt := ""
-	if g.existsConvertionFunction(inField.Type.Elem(), outField.Type.Elem()) {
-		newFormat := "out.%s = new(%s)\n"
-		newStmt := fmt.Sprintf(newFormat, outField.Name, g.typeName(outField.Type.Elem()))
-		if err := writeLine(w, indent+1, newStmt); err != nil {
-			return err
-		}
-		assignFormat := "if err := %s(in.%s, out.%s, s); err != nil {\n"
-		funcName := conversionFunctionName(inField.Type.Elem(), outField.Type.Elem())
-		assignStmt = fmt.Sprintf(assignFormat, funcName, inField.Name, outField.Name)
-	} else {
-		assignFormat := "if err := s.Convert(&in.%s, &out.%s, 0); err != nil {\n"
-		assignStmt = fmt.Sprintf(assignFormat, inField.Name, outField.Name)
-	}
-	if err := writeLine(w, indent+1, assignStmt); err != nil {
-		return err
-	}
-	if err := writeLine(w, indent+2, "return err\n"); err != nil {
-		return err
-	}
-	if err := writeLine(w, indent+1, "}\n"); err != nil {
-		return err
-	}
-	if err := writeLine(w, indent, "} else {\n"); err != nil {
-		return err
-	}
-	nilFormat := "out.%s = nil\n"
-	nilStmt := fmt.Sprintf(nilFormat, outField.Name)
-	if err := writeLine(w, indent+1, nilStmt); err != nil {
-		return err
-	}
-	if err := writeLine(w, indent, "}\n"); err != nil {
-		return err
-	}
-	return nil
-}
-
-func (g *generator) writeConversionForStruct(w io.Writer, inType, outType reflect.Type, indent int) error {
-	for i := 0; i < inType.NumField(); i++ {
-		inField := inType.Field(i)
-		outField, _ := outType.FieldByName(inField.Name)
-
-		if g.scheme.Converter().HasConversionFunc(inField.Type, outField.Type) {
-			// Use the conversion method that is already defined.
-			assignFormat := "if err := s.Convert(&in.%s, &out.%s, 0); err != nil {\n"
-			assignStmt := fmt.Sprintf(assignFormat, inField.Name, outField.Name)
-			if err := writeLine(w, indent, assignStmt); err != nil {
-				return err
-			}
-			if err := writeLine(w, indent+1, "return err\n"); err != nil {
-				return err
-			}
-			if err := writeLine(w, indent, "}\n"); err != nil {
-				return err
-			}
-			continue
-		}
-
-		switch inField.Type.Kind() {
-		case reflect.Map, reflect.Ptr, reflect.Slice, reflect.Interface, reflect.Struct:
-			// Don't copy these via assignment/conversion!
-		default:
-			// This should handle all simple types.
-			if inField.Type.AssignableTo(outField.Type) {
-				assignFormat := "out.%s = in.%s\n"
-				assignStmt := fmt.Sprintf(assignFormat, outField.Name, inField.Name)
-				if err := writeLine(w, indent, assignStmt); err != nil {
-					return err
-				}
-				continue
-			}
-			if inField.Type.ConvertibleTo(outField.Type) {
-				assignFormat := "out.%s = %s(in.%s)\n"
-				assignStmt := fmt.Sprintf(assignFormat, outField.Name, g.typeName(outField.Type), inField.Name)
-				if err := writeLine(w, indent, assignStmt); err != nil {
-					return err
-				}
-				continue
-			}
-		}
-
-		// If the field is a slice, copy its elements one by one.
-		if inField.Type.Kind() == reflect.Slice {
-			if err := g.writeConversionForSlice(w, inField, outField, indent); err != nil {
-				return err
-			}
-			continue
-		}
-
-		// If the field is a map, copy its elements one by one.
-		if inField.Type.Kind() == reflect.Map {
-			if err := g.writeConversionForMap(w, inField, outField, indent); err != nil {
-				return err
-			}
-			continue
-		}
-
-		// If the field is a pointer, we can try to assign underlying values.
-		if inField.Type.Kind() == reflect.Ptr {
-			if err := g.writeConversionForPtr(w, inField, outField, indent); err != nil {
-				return err
-			}
-			continue
-		}
-
-		assignStmt := ""
-		if g.existsConvertionFunction(inField.Type, outField.Type) {
-			assignFormat := "if err := %s(&in.%s, &out.%s, s); err != nil {\n"
-			funcName := conversionFunctionName(inField.Type, outField.Type)
-			assignStmt = fmt.Sprintf(assignFormat, funcName, inField.Name, outField.Name)
-		} else {
-			assignFormat := "if err := s.Convert(&in.%s, &out.%s, 0); err != nil {\n"
-			assignStmt = fmt.Sprintf(assignFormat, inField.Name, outField.Name)
-		}
-		if err := writeLine(w, indent, assignStmt); err != nil {
-			return err
-		}
-		if err := writeLine(w, indent+1, "return err\n"); err != nil {
-			return err
-		}
-		if err := writeLine(w, indent, "}\n"); err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-func (g *generator) writeConversionForType(w io.Writer, inType, outType reflect.Type, indent int) error {
-	funcName := conversionFunctionName(inType, outType)
-	if err := writeHeader(w, funcName, g.typeName(inType), g.typeName(outType), indent); err != nil {
-		return err
-	}
-	if err := g.writeDefaultingFunc(w, inType, indent+1); err != nil {
-		return err
-	}
-	switch inType.Kind() {
-	case reflect.Struct:
-		if err := g.writeConversionForStruct(w, inType, outType, indent+1); err != nil {
-			return err
-		}
-	default:
-		return fmt.Errorf("Type not supported: %v", inType)
-	}
-	if err := writeFooter(w, indent); err != nil {
-		return err
-	}
-	if err := writeLine(w, 0, "\n"); err != nil {
-		return err
-	}
-	return nil
-}
-
-func (g *generator) existsConvertionFunction(inType, outType reflect.Type) bool {
-	if val, found := g.convertibles[inType]; found && val == outType {
-		return true
-	}
-	if val, found := g.convertibles[outType]; found && val == inType {
-		return true
-	}
-	return false
-}
-
-func (g *generator) OverwritePackage(pkg, overwrite string) {
-	g.pkgOverwrites[pkg] = overwrite
-}