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// Copyright 2014 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"
"unicode"
"unicode/utf8"
)
func changeInitialCase(s string, mapper func(rune) rune) string {
if s == "" {
return s
}
r, n := utf8.DecodeRuneInString(s)
return string(mapper(r)) + s[n:]
}
func isExported(field reflect.StructField) bool {
r, _ := utf8.DecodeRuneInString(field.Name)
return r >= 'A' && r <= 'Z'
}
// 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 deepMap(dst, src reflect.Value, visited map[uintptr]*visit, depth int, overwrite bool) (err error) {
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{addr, typ, seen}
}
zeroValue := reflect.Value{}
switch dst.Kind() {
case reflect.Map:
dstMap := dst.Interface().(map[string]interface{})
for i, n := 0, src.NumField(); i < n; i++ {
srcType := src.Type()
field := srcType.Field(i)
if !isExported(field) {
continue
}
fieldName := field.Name
fieldName = changeInitialCase(fieldName, unicode.ToLower)
if v, ok := dstMap[fieldName]; !ok || (isEmptyValue(reflect.ValueOf(v)) || overwrite) {
dstMap[fieldName] = src.Field(i).Interface()
}
}
case reflect.Struct:
srcMap := src.Interface().(map[string]interface{})
for key := range srcMap {
srcValue := srcMap[key]
fieldName := changeInitialCase(key, unicode.ToUpper)
dstElement := dst.FieldByName(fieldName)
if dstElement == zeroValue {
// We discard it because the field doesn't exist.
continue
}
srcElement := reflect.ValueOf(srcValue)
dstKind := dstElement.Kind()
srcKind := srcElement.Kind()
if srcKind == reflect.Ptr && dstKind != reflect.Ptr {
srcElement = srcElement.Elem()
srcKind = reflect.TypeOf(srcElement.Interface()).Kind()
} else if dstKind == reflect.Ptr {
// Can this work? I guess it can't.
if srcKind != reflect.Ptr && srcElement.CanAddr() {
srcPtr := srcElement.Addr()
srcElement = reflect.ValueOf(srcPtr)
srcKind = reflect.Ptr
}
}
if !srcElement.IsValid() {
continue
}
if srcKind == dstKind {
if err = deepMerge(dstElement, srcElement, visited, depth+1, overwrite); err != nil {
return
}
} else {
if srcKind == reflect.Map {
if err = deepMap(dstElement, srcElement, visited, depth+1, overwrite); err != nil {
return
}
} else {
return fmt.Errorf("type mismatch on %s field: found %v, expected %v", fieldName, srcKind, dstKind)
}
}
}
}
return
}
// Map sets fields' values in dst from src.
// src can be a map with string keys or a struct. dst must be the opposite:
// if src is a map, dst must be a valid pointer to struct. If src is a struct,
// dst must be map[string]interface{}.
// It won't merge unexported (private) fields and will do recursively
// any exported field.
// If dst is a map, keys will be src fields' names in lower camel case.
// Missing key in src that doesn't match a field in dst will be skipped. This
// doesn't apply if dst is a map.
// This is separated method from Merge because it is cleaner and it keeps sane
// semantics: merging equal types, mapping different (restricted) types.
func Map(dst, src interface{}) error {
return _map(dst, src, false)
}
// MapWithOverwrite will do the same as Map except that non-empty dst attributes will be overriden by
// non-empty src attribute values.
func MapWithOverwrite(dst, src interface{}) error {
return _map(dst, src, true)
}
func _map(dst, src interface{}, overwrite bool) error {
var (
vDst, vSrc reflect.Value
err error
)
if vDst, vSrc, err = resolveValues(dst, src); err != nil {
return err
}
// To be friction-less, we redirect equal-type arguments
// to deepMerge. Only because arguments can be anything.
if vSrc.Kind() == vDst.Kind() {
return deepMerge(vDst, vSrc, make(map[uintptr]*visit), 0, overwrite)
}
switch vSrc.Kind() {
case reflect.Struct:
if vDst.Kind() != reflect.Map {
return ErrExpectedMapAsDestination
}
case reflect.Map:
if vDst.Kind() != reflect.Struct {
return ErrExpectedStructAsDestination
}
default:
return ErrNotSupported
}
return deepMap(vDst, vSrc, make(map[uintptr]*visit), 0, overwrite)
}
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