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