99 lines
2.5 KiB
Go
99 lines
2.5 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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"reflect"
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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) (err error) {
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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{addr, typ, seen}
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}
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switch dst.Kind() {
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case reflect.Struct:
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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); err != nil {
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return
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}
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}
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case reflect.Map:
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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 reflect.TypeOf(srcElement.Interface()).Kind() {
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case reflect.Struct:
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fallthrough
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case reflect.Map:
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if err = deepMerge(dstElement, srcElement, visited, depth+1); err != nil {
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return
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}
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}
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if !dstElement.IsValid() {
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dst.SetMapIndex(key, srcElement)
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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 src.IsNil() {
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break
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} else if dst.IsNil() {
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if dst.CanSet() && isEmptyValue(dst) {
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dst.Set(src)
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}
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} else if err = deepMerge(dst.Elem(), src.Elem(), visited, depth+1); err != nil {
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return
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}
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default:
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if dst.CanSet() && !isEmptyValue(src) {
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dst.Set(src)
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}
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}
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return
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}
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// Merge sets fields' values in dst from src if they have a zero
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// value of their type.
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// dst and src must be valid same-type structs and dst must be
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// a pointer to struct.
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// It won't merge unexported (private) fields and will do recursively
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// any exported field.
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func Merge(dst, src interface{}) 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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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)
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}
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