339 lines
8.9 KiB
Go
339 lines
8.9 KiB
Go
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// Copyright 2013 Dario Castañé. All rights reserved.
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Based on src/pkg/reflect/deepequal.go from official
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// golang's stdlib.
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package mergo
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import (
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"fmt"
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"reflect"
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"unsafe"
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)
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func hasExportedField(dst reflect.Value) (exported bool) {
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for i, n := 0, dst.NumField(); i < n; i++ {
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field := dst.Type().Field(i)
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if isExportedComponent(&field) {
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return true
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}
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}
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return
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}
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func isExportedComponent(field *reflect.StructField) bool {
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name := field.Name
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pkgPath := field.PkgPath
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if len(pkgPath) > 0 {
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return false
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}
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c := name[0]
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if 'a' <= c && c <= 'z' || c == '_' {
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return false
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}
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return true
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}
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type Config struct {
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Overwrite bool
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AppendSlice bool
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TypeCheck bool
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Transformers Transformers
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overwriteWithEmptyValue bool
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overwriteSliceWithEmptyValue bool
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}
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type Transformers interface {
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Transformer(reflect.Type) func(dst, src reflect.Value) error
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}
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// Traverses recursively both values, assigning src's fields values to dst.
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// The map argument tracks comparisons that have already been seen, which allows
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// short circuiting on recursive types.
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func deepMerge(dstIn, src reflect.Value, visited map[uintptr]*visit, depth int, config *Config) (dst reflect.Value, err error) {
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dst = dstIn
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overwrite := config.Overwrite
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typeCheck := config.TypeCheck
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overwriteWithEmptySrc := config.overwriteWithEmptyValue
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overwriteSliceWithEmptySrc := config.overwriteSliceWithEmptyValue
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if !src.IsValid() {
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return
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}
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if dst.CanAddr() {
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addr := dst.UnsafeAddr()
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h := 17 * addr
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seen := visited[h]
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typ := dst.Type()
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for p := seen; p != nil; p = p.next {
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if p.ptr == addr && p.typ == typ {
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return dst, nil
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}
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}
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// Remember, remember...
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visited[h] = &visit{addr, typ, seen}
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}
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if config.Transformers != nil && !isEmptyValue(dst) {
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if fn := config.Transformers.Transformer(dst.Type()); fn != nil {
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err = fn(dst, src)
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return
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}
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}
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if dst.IsValid() && src.IsValid() && src.Type() != dst.Type() {
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err = fmt.Errorf("cannot append two different types (%s, %s)", src.Kind(), dst.Kind())
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return
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}
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switch dst.Kind() {
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case reflect.Struct:
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if hasExportedField(dst) {
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dstCp := reflect.New(dst.Type()).Elem()
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for i, n := 0, dst.NumField(); i < n; i++ {
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dstField := dst.Field(i)
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structField := dst.Type().Field(i)
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// copy un-exported struct fields
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if !isExportedComponent(&structField) {
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rf := dstCp.Field(i)
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rf = reflect.NewAt(rf.Type(), unsafe.Pointer(rf.UnsafeAddr())).Elem() //nolint:gosec
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dstRF := dst.Field(i)
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if !dst.Field(i).CanAddr() {
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continue
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}
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dstRF = reflect.NewAt(dstRF.Type(), unsafe.Pointer(dstRF.UnsafeAddr())).Elem() //nolint:gosec
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rf.Set(dstRF)
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continue
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}
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dstField, err = deepMerge(dstField, src.Field(i), visited, depth+1, config)
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if err != nil {
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return
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}
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dstCp.Field(i).Set(dstField)
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}
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if dst.CanSet() {
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dst.Set(dstCp)
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} else {
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dst = dstCp
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}
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return
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} else {
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if (isReflectNil(dst) || overwrite) && (!isEmptyValue(src) || overwriteWithEmptySrc) {
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dst = src
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}
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}
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case reflect.Map:
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if dst.IsNil() && !src.IsNil() {
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if dst.CanSet() {
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dst.Set(reflect.MakeMap(dst.Type()))
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} else {
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dst = src
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return
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}
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}
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for _, key := range src.MapKeys() {
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srcElement := src.MapIndex(key)
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dstElement := dst.MapIndex(key)
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if !srcElement.IsValid() {
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continue
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}
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if dst.MapIndex(key).IsValid() {
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k := dstElement.Interface()
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dstElement = reflect.ValueOf(k)
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}
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if isReflectNil(srcElement) {
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if overwrite || isReflectNil(dstElement) {
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dst.SetMapIndex(key, srcElement)
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}
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continue
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}
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if !srcElement.CanInterface() {
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continue
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}
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if srcElement.CanInterface() {
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srcElement = reflect.ValueOf(srcElement.Interface())
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if dstElement.IsValid() {
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dstElement = reflect.ValueOf(dstElement.Interface())
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}
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}
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dstElement, err = deepMerge(dstElement, srcElement, visited, depth+1, config)
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if err != nil {
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return
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}
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dst.SetMapIndex(key, dstElement)
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}
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case reflect.Slice:
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newSlice := dst
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if (!isEmptyValue(src) || overwriteWithEmptySrc || overwriteSliceWithEmptySrc) && (overwrite || isEmptyValue(dst)) && !config.AppendSlice {
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if typeCheck && src.Type() != dst.Type() {
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return dst, fmt.Errorf("cannot override two slices with different type (%s, %s)", src.Type(), dst.Type())
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}
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newSlice = src
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} else if config.AppendSlice {
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if typeCheck && src.Type() != dst.Type() {
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err = fmt.Errorf("cannot append two slice with different type (%s, %s)", src.Type(), dst.Type())
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return
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}
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newSlice = reflect.AppendSlice(dst, src)
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}
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if dst.CanSet() {
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dst.Set(newSlice)
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} else {
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dst = newSlice
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}
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case reflect.Ptr, reflect.Interface:
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if isReflectNil(src) {
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break
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}
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if dst.Kind() != reflect.Ptr && src.Type().AssignableTo(dst.Type()) {
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if dst.IsNil() || overwrite {
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if overwrite || isEmptyValue(dst) {
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if dst.CanSet() {
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dst.Set(src)
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} else {
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dst = src
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}
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}
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}
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break
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}
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if src.Kind() != reflect.Interface {
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if dst.IsNil() || (src.Kind() != reflect.Ptr && overwrite) {
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if dst.CanSet() && (overwrite || isEmptyValue(dst)) {
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dst.Set(src)
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}
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} else if src.Kind() == reflect.Ptr {
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if dst, err = deepMerge(dst.Elem(), src.Elem(), visited, depth+1, config); err != nil {
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return
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}
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dst = dst.Addr()
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} else if dst.Elem().Type() == src.Type() {
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if dst, err = deepMerge(dst.Elem(), src, visited, depth+1, config); err != nil {
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return
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}
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} else {
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return dst, ErrDifferentArgumentsTypes
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}
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break
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}
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if dst.IsNil() || overwrite {
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if (overwrite || isEmptyValue(dst)) && (overwriteWithEmptySrc || !isEmptyValue(src)) {
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if dst.CanSet() {
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dst.Set(src)
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} else {
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dst = src
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}
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}
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} else if _, err = deepMerge(dst.Elem(), src.Elem(), visited, depth+1, config); err != nil {
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return
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}
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default:
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overwriteFull := (!isEmptyValue(src) || overwriteWithEmptySrc) && (overwrite || isEmptyValue(dst))
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if overwriteFull {
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if dst.CanSet() {
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dst.Set(src)
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} else {
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dst = src
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}
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}
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}
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return
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}
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// Merge will fill any empty for value type attributes on the dst struct using corresponding
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// src attributes if they themselves are not empty. dst and src must be valid same-type structs
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// and dst must be a pointer to struct.
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// It won't merge unexported (private) fields and will do recursively any exported field.
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func Merge(dst, src interface{}, opts ...func(*Config)) error {
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return merge(dst, src, opts...)
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}
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// MergeWithOverwrite will do the same as Merge except that non-empty dst attributes will be overridden by
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// non-empty src attribute values.
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// Deprecated: use Merge(…) with WithOverride
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func MergeWithOverwrite(dst, src interface{}, opts ...func(*Config)) error {
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return merge(dst, src, append(opts, WithOverride)...)
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}
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// WithTransformers adds transformers to merge, allowing to customize the merging of some types.
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func WithTransformers(transformers Transformers) func(*Config) {
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return func(config *Config) {
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config.Transformers = transformers
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}
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}
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// WithOverride will make merge override non-empty dst attributes with non-empty src attributes values.
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func WithOverride(config *Config) {
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config.Overwrite = true
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}
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// WithOverwriteWithEmptyValue will make merge override non empty dst attributes with empty src attributes values.
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func WithOverwriteWithEmptyValue(config *Config) {
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config.overwriteWithEmptyValue = true
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}
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// WithOverrideEmptySlice will make merge override empty dst slice with empty src slice.
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func WithOverrideEmptySlice(config *Config) {
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config.overwriteSliceWithEmptyValue = true
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}
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// WithAppendSlice will make merge append slices instead of overwriting it.
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func WithAppendSlice(config *Config) {
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config.AppendSlice = true
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}
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// WithTypeCheck will make merge check types while overwriting it (must be used with WithOverride).
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func WithTypeCheck(config *Config) {
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config.TypeCheck = true
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}
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func merge(dst, src interface{}, opts ...func(*Config)) error {
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var (
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vDst, vSrc reflect.Value
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err error
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)
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config := &Config{}
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for _, opt := range opts {
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opt(config)
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}
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if vDst, vSrc, err = resolveValues(dst, src); err != nil {
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return err
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}
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if !vDst.CanSet() {
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return fmt.Errorf("cannot set dst, needs reference")
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}
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if vDst.Type() != vSrc.Type() {
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return ErrDifferentArgumentsTypes
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}
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_, err = deepMerge(vDst, vSrc, make(map[uintptr]*visit), 0, config)
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return err
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}
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// IsReflectNil is the reflect value provided nil
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func isReflectNil(v reflect.Value) bool {
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k := v.Kind()
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switch k {
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case reflect.Interface, reflect.Slice, reflect.Chan, reflect.Func, reflect.Map, reflect.Ptr:
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// Both interface and slice are nil if first word is 0.
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// Both are always bigger than a word; assume flagIndir.
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return v.IsNil()
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default:
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return false
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}
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}
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