terraform/vendor/github.com/imdario/mergo/merge.go

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