1 // Copyright 2013 Dario Castañé. All rights reserved.
2 // Copyright 2009 The Go Authors. All rights reserved.
3 // Use of this source code is governed by a BSD-style
4 // license that can be found in the LICENSE file.
6 // Based on src/pkg/reflect/deepequal.go from official
16 func hasExportedField(dst reflect.Value) (exported bool) {
17 for i, n := 0, dst.NumField(); i < n; i++ {
18 field := dst.Type().Field(i)
19 if field.Anonymous && dst.Field(i).Kind() == reflect.Struct {
20 exported = exported || hasExportedField(dst.Field(i))
22 exported = exported || len(field.PkgPath) == 0
31 Transformers Transformers
32 overwriteWithEmptyValue bool
35 type Transformers interface {
36 Transformer(reflect.Type) func(dst, src reflect.Value) error
39 // Traverses recursively both values, assigning src's fields values to dst.
40 // The map argument tracks comparisons that have already been seen, which allows
41 // short circuiting on recursive types.
42 func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, config *Config) (err error) {
43 overwrite := config.Overwrite
44 overwriteWithEmptySrc := config.overwriteWithEmptyValue
45 config.overwriteWithEmptyValue = false
51 addr := dst.UnsafeAddr()
55 for p := seen; p != nil; p = p.next {
56 if p.ptr == addr && p.typ == typ {
60 // Remember, remember...
61 visited[h] = &visit{addr, typ, seen}
64 if config.Transformers != nil && !isEmptyValue(dst) {
65 if fn := config.Transformers.Transformer(dst.Type()); fn != nil {
73 if hasExportedField(dst) {
74 for i, n := 0, dst.NumField(); i < n; i++ {
75 if err = deepMerge(dst.Field(i), src.Field(i), visited, depth+1, config); err != nil {
80 if dst.CanSet() && (!isEmptyValue(src) || overwriteWithEmptySrc) && (overwrite || isEmptyValue(dst)) {
85 if dst.IsNil() && !src.IsNil() {
86 dst.Set(reflect.MakeMap(dst.Type()))
88 for _, key := range src.MapKeys() {
89 srcElement := src.MapIndex(key)
90 if !srcElement.IsValid() {
93 dstElement := dst.MapIndex(key)
94 switch srcElement.Kind() {
95 case reflect.Chan, reflect.Func, reflect.Map, reflect.Interface, reflect.Slice:
96 if srcElement.IsNil() {
101 if !srcElement.CanInterface() {
104 switch reflect.TypeOf(srcElement.Interface()).Kind() {
110 srcMapElm := srcElement
111 dstMapElm := dstElement
112 if srcMapElm.CanInterface() {
113 srcMapElm = reflect.ValueOf(srcMapElm.Interface())
114 if dstMapElm.IsValid() {
115 dstMapElm = reflect.ValueOf(dstMapElm.Interface())
118 if err = deepMerge(dstMapElm, srcMapElm, visited, depth+1, config); err != nil {
122 srcSlice := reflect.ValueOf(srcElement.Interface())
124 var dstSlice reflect.Value
125 if !dstElement.IsValid() || dstElement.IsNil() {
126 dstSlice = reflect.MakeSlice(srcSlice.Type(), 0, srcSlice.Len())
128 dstSlice = reflect.ValueOf(dstElement.Interface())
131 if (!isEmptyValue(src) || overwriteWithEmptySrc) && (overwrite || isEmptyValue(dst)) && !config.AppendSlice {
133 } else if config.AppendSlice {
134 if srcSlice.Type() != dstSlice.Type() {
135 return fmt.Errorf("cannot append two slice with different type (%s, %s)", srcSlice.Type(), dstSlice.Type())
137 dstSlice = reflect.AppendSlice(dstSlice, srcSlice)
139 dst.SetMapIndex(key, dstSlice)
142 if dstElement.IsValid() && !isEmptyValue(dstElement) && (reflect.TypeOf(srcElement.Interface()).Kind() == reflect.Map || reflect.TypeOf(srcElement.Interface()).Kind() == reflect.Slice) {
146 if srcElement.IsValid() && (overwrite || (!dstElement.IsValid() || isEmptyValue(dstElement))) {
148 dst.Set(reflect.MakeMap(dst.Type()))
150 dst.SetMapIndex(key, srcElement)
157 if (!isEmptyValue(src) || overwriteWithEmptySrc) && (overwrite || isEmptyValue(dst)) && !config.AppendSlice {
159 } else if config.AppendSlice {
160 if src.Type() != dst.Type() {
161 return fmt.Errorf("cannot append two slice with different type (%s, %s)", src.Type(), dst.Type())
163 dst.Set(reflect.AppendSlice(dst, src))
167 case reflect.Interface:
171 if src.Kind() != reflect.Interface {
172 if dst.IsNil() || overwrite {
173 if dst.CanSet() && (overwrite || isEmptyValue(dst)) {
176 } else if src.Kind() == reflect.Ptr {
177 if err = deepMerge(dst.Elem(), src.Elem(), visited, depth+1, config); err != nil {
180 } else if dst.Elem().Type() == src.Type() {
181 if err = deepMerge(dst.Elem(), src, visited, depth+1, config); err != nil {
185 return ErrDifferentArgumentsTypes
189 if dst.IsNil() || overwrite {
190 if dst.CanSet() && (overwrite || isEmptyValue(dst)) {
193 } else if err = deepMerge(dst.Elem(), src.Elem(), visited, depth+1, config); err != nil {
197 if dst.CanSet() && (!isEmptyValue(src) || overwriteWithEmptySrc) && (overwrite || isEmptyValue(dst)) {
204 // Merge will fill any empty for value type attributes on the dst struct using corresponding
205 // src attributes if they themselves are not empty. dst and src must be valid same-type structs
206 // and dst must be a pointer to struct.
207 // It won't merge unexported (private) fields and will do recursively any exported field.
208 func Merge(dst, src interface{}, opts ...func(*Config)) error {
209 return merge(dst, src, opts...)
212 // MergeWithOverwrite will do the same as Merge except that non-empty dst attributes will be overriden by
213 // non-empty src attribute values.
214 // Deprecated: use Merge(…) with WithOverride
215 func MergeWithOverwrite(dst, src interface{}, opts ...func(*Config)) error {
216 return merge(dst, src, append(opts, WithOverride)...)
219 // WithTransformers adds transformers to merge, allowing to customize the merging of some types.
220 func WithTransformers(transformers Transformers) func(*Config) {
221 return func(config *Config) {
222 config.Transformers = transformers
226 // WithOverride will make merge override non-empty dst attributes with non-empty src attributes values.
227 func WithOverride(config *Config) {
228 config.Overwrite = true
231 // WithAppendSlice will make merge append slices instead of overwriting it
232 func WithAppendSlice(config *Config) {
233 config.AppendSlice = true
236 func merge(dst, src interface{}, opts ...func(*Config)) error {
238 vDst, vSrc reflect.Value
244 for _, opt := range opts {
248 if vDst, vSrc, err = resolveValues(dst, src); err != nil {
251 if vDst.Type() != vSrc.Type() {
252 return ErrDifferentArgumentsTypes
254 return deepMerge(vDst, vSrc, make(map[uintptr]*visit), 0, config)