mirror of https://github.com/cheat/cheat.git
410 lines
12 KiB
Go
410 lines
12 KiB
Go
// 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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)
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func hasMergeableFields(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 field.Anonymous && dst.Field(i).Kind() == reflect.Struct {
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exported = exported || hasMergeableFields(dst.Field(i))
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} else if isExportedComponent(&field) {
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exported = exported || len(field.PkgPath) == 0
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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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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 := field.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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Transformers Transformers
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Overwrite bool
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ShouldNotDereference bool
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AppendSlice bool
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TypeCheck bool
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overwriteWithEmptyValue bool
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overwriteSliceWithEmptyValue bool
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sliceDeepCopy bool
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debug 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(dst, src reflect.Value, visited map[uintptr]*visit, depth int, config *Config) (err error) {
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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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sliceDeepCopy := config.sliceDeepCopy
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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 nil
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}
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}
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// Remember, remember...
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visited[h] = &visit{typ, seen, addr}
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}
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if config.Transformers != nil && !isReflectNil(dst) && dst.IsValid() {
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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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switch dst.Kind() {
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case reflect.Struct:
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if hasMergeableFields(dst) {
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for i, n := 0, dst.NumField(); i < n; i++ {
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if err = deepMerge(dst.Field(i), src.Field(i), visited, depth+1, config); err != nil {
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return
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}
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}
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} else {
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if dst.CanSet() && (isReflectNil(dst) || overwrite) && (!isEmptyValue(src, !config.ShouldNotDereference) || overwriteWithEmptySrc) {
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dst.Set(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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if src.Kind() != reflect.Map {
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if overwrite && dst.CanSet() {
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dst.Set(src)
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}
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return
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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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if !srcElement.IsValid() {
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continue
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}
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dstElement := dst.MapIndex(key)
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switch srcElement.Kind() {
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case reflect.Chan, reflect.Func, reflect.Map, reflect.Interface, reflect.Slice:
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if srcElement.IsNil() {
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if overwrite {
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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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fallthrough
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default:
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if !srcElement.CanInterface() {
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continue
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}
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switch reflect.TypeOf(srcElement.Interface()).Kind() {
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case reflect.Struct:
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fallthrough
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case reflect.Ptr:
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fallthrough
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case reflect.Map:
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srcMapElm := srcElement
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dstMapElm := dstElement
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if srcMapElm.CanInterface() {
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srcMapElm = reflect.ValueOf(srcMapElm.Interface())
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if dstMapElm.IsValid() {
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dstMapElm = reflect.ValueOf(dstMapElm.Interface())
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}
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}
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if err = deepMerge(dstMapElm, srcMapElm, visited, depth+1, config); err != nil {
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return
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}
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case reflect.Slice:
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srcSlice := reflect.ValueOf(srcElement.Interface())
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var dstSlice reflect.Value
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if !dstElement.IsValid() || dstElement.IsNil() {
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dstSlice = reflect.MakeSlice(srcSlice.Type(), 0, srcSlice.Len())
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} else {
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dstSlice = reflect.ValueOf(dstElement.Interface())
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}
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if (!isEmptyValue(src, !config.ShouldNotDereference) || overwriteWithEmptySrc || overwriteSliceWithEmptySrc) && (overwrite || isEmptyValue(dst, !config.ShouldNotDereference)) && !config.AppendSlice && !sliceDeepCopy {
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if typeCheck && srcSlice.Type() != dstSlice.Type() {
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return fmt.Errorf("cannot override two slices with different type (%s, %s)", srcSlice.Type(), dstSlice.Type())
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}
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dstSlice = srcSlice
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} else if config.AppendSlice {
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if srcSlice.Type() != dstSlice.Type() {
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return fmt.Errorf("cannot append two slices with different type (%s, %s)", srcSlice.Type(), dstSlice.Type())
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}
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dstSlice = reflect.AppendSlice(dstSlice, srcSlice)
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} else if sliceDeepCopy {
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i := 0
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for ; i < srcSlice.Len() && i < dstSlice.Len(); i++ {
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srcElement := srcSlice.Index(i)
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dstElement := dstSlice.Index(i)
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if srcElement.CanInterface() {
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srcElement = reflect.ValueOf(srcElement.Interface())
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}
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if dstElement.CanInterface() {
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dstElement = reflect.ValueOf(dstElement.Interface())
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}
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if err = deepMerge(dstElement, srcElement, visited, depth+1, config); err != nil {
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return
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}
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}
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}
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dst.SetMapIndex(key, dstSlice)
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}
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}
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if dstElement.IsValid() && !isEmptyValue(dstElement, !config.ShouldNotDereference) {
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if reflect.TypeOf(srcElement.Interface()).Kind() == reflect.Slice {
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continue
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}
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if reflect.TypeOf(srcElement.Interface()).Kind() == reflect.Map && reflect.TypeOf(dstElement.Interface()).Kind() == reflect.Map {
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continue
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}
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}
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if srcElement.IsValid() && ((srcElement.Kind() != reflect.Ptr && overwrite) || !dstElement.IsValid() || isEmptyValue(dstElement, !config.ShouldNotDereference)) {
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if dst.IsNil() {
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dst.Set(reflect.MakeMap(dst.Type()))
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}
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dst.SetMapIndex(key, srcElement)
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}
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}
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// Ensure that all keys in dst are deleted if they are not in src.
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if overwriteWithEmptySrc {
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for _, key := range dst.MapKeys() {
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srcElement := src.MapIndex(key)
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if !srcElement.IsValid() {
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dst.SetMapIndex(key, reflect.Value{})
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}
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}
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}
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case reflect.Slice:
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if !dst.CanSet() {
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break
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}
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if (!isEmptyValue(src, !config.ShouldNotDereference) || overwriteWithEmptySrc || overwriteSliceWithEmptySrc) && (overwrite || isEmptyValue(dst, !config.ShouldNotDereference)) && !config.AppendSlice && !sliceDeepCopy {
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dst.Set(src)
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} else if config.AppendSlice {
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if src.Type() != dst.Type() {
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return fmt.Errorf("cannot append two slice with different type (%s, %s)", src.Type(), dst.Type())
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}
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dst.Set(reflect.AppendSlice(dst, src))
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} else if sliceDeepCopy {
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for i := 0; i < src.Len() && i < dst.Len(); i++ {
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srcElement := src.Index(i)
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dstElement := dst.Index(i)
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if srcElement.CanInterface() {
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srcElement = reflect.ValueOf(srcElement.Interface())
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}
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if dstElement.CanInterface() {
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dstElement = reflect.ValueOf(dstElement.Interface())
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}
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if err = deepMerge(dstElement, srcElement, visited, depth+1, config); err != nil {
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return
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}
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}
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}
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case reflect.Ptr:
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fallthrough
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case reflect.Interface:
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if isReflectNil(src) {
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if overwriteWithEmptySrc && dst.CanSet() && src.Type().AssignableTo(dst.Type()) {
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dst.Set(src)
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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, !config.ShouldNotDereference)) {
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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 !config.ShouldNotDereference {
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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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} else {
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if overwriteWithEmptySrc || (overwrite && !src.IsNil()) || dst.IsNil() {
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dst.Set(src)
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}
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}
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} else if dst.Elem().Type() == src.Type() {
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if 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 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 dst.CanSet() && (overwrite || isEmptyValue(dst, !config.ShouldNotDereference)) {
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dst.Set(src)
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}
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break
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}
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if dst.Elem().Kind() == src.Elem().Kind() {
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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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break
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}
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default:
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mustSet := (isEmptyValue(dst, !config.ShouldNotDereference) || overwrite) && (!isEmptyValue(src, !config.ShouldNotDereference) || overwriteWithEmptySrc)
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if mustSet {
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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.Overwrite = true
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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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// WithoutDereference prevents dereferencing pointers when evaluating whether they are empty
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// (i.e. a non-nil pointer is never considered empty).
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func WithoutDereference(config *Config) {
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config.ShouldNotDereference = 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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// WithSliceDeepCopy will merge slice element one by one with Overwrite flag.
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func WithSliceDeepCopy(config *Config) {
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config.sliceDeepCopy = true
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config.Overwrite = true
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}
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func merge(dst, src interface{}, opts ...func(*Config)) error {
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if dst != nil && reflect.ValueOf(dst).Kind() != reflect.Ptr {
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return ErrNonPointerArgument
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}
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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.Type() != vSrc.Type() {
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return ErrDifferentArgumentsTypes
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}
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return deepMerge(vDst, vSrc, make(map[uintptr]*visit), 0, config)
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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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