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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 (
"errors"
"reflect"
)
// Errors reported by Mergo when it finds invalid arguments.
var (
ErrNilArguments = errors.New("src and dst must not be nil")
ErrDifferentArgumentsTypes = errors.New("src and dst must be of same type")
ErrNotSupported = errors.New("only structs and maps are supported")
ErrExpectedMapAsDestination = errors.New("dst was expected to be a map")
ErrExpectedStructAsDestination = errors.New("dst was expected to be a struct")
)
// During deepMerge, must keep track of checks that are
// in progress. The comparison algorithm assumes that all
// checks in progress are true when it reencounters them.
// Visited are stored in a map indexed by 17 * a1 + a2;
type visit struct {
ptr uintptr
typ reflect.Type
next *visit
}
// From src/pkg/encoding/json/encode.go.
func isEmptyValue(v reflect.Value) bool {
switch v.Kind() {
case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
return v.Len() == 0
case reflect.Bool:
return !v.Bool()
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return v.Int() == 0
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return v.Uint() == 0
case reflect.Float32, reflect.Float64:
return v.Float() == 0
case reflect.Interface, reflect.Ptr:
if v.IsNil() {
return true
}
return isEmptyValue(v.Elem())
case reflect.Func:
return v.IsNil()
case reflect.Invalid:
return true
}
return false
}
func resolveValues(dst, src interface{}) (vDst, vSrc reflect.Value, err error) {
if dst == nil || src == nil {
err = ErrNilArguments
return
}
vDst = reflect.ValueOf(dst).Elem()
if vDst.Kind() != reflect.Struct && vDst.Kind() != reflect.Map {
err = ErrNotSupported
return
}
vSrc = reflect.ValueOf(src)
// We check if vSrc is a pointer to dereference it.
if vSrc.Kind() == reflect.Ptr {
vSrc = vSrc.Elem()
}
return
}
// 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 deeper(dst, src reflect.Value, visited map[uintptr]*visit, depth int) (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}
}
return // TODO refactor
}
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