1// Copyright 2013 Dario Castañé. All rights reserved.
2// Copyright 2009 The Go Authors. All rights reserved.
3// Use of this source code is governed by a BSD-style
4// license that can be found in the LICENSE file.
5
6// Based on src/pkg/reflect/deepequal.go from official
7// golang's stdlib.
8
9package mergo
10
11import (
12	"errors"
13	"reflect"
14)
15
16// Errors reported by Mergo when it finds invalid arguments.
17var (
18	ErrNilArguments                = errors.New("src and dst must not be nil")
19	ErrDifferentArgumentsTypes     = errors.New("src and dst must be of same type")
20	ErrNotSupported                = errors.New("only structs and maps are supported")
21	ErrExpectedMapAsDestination    = errors.New("dst was expected to be a map")
22	ErrExpectedStructAsDestination = errors.New("dst was expected to be a struct")
23	ErrNonPointerAgument           = errors.New("dst must be a pointer")
24)
25
26// During deepMerge, must keep track of checks that are
27// in progress.  The comparison algorithm assumes that all
28// checks in progress are true when it reencounters them.
29// Visited are stored in a map indexed by 17 * a1 + a2;
30type visit struct {
31	ptr  uintptr
32	typ  reflect.Type
33	next *visit
34}
35
36// From src/pkg/encoding/json/encode.go.
37func isEmptyValue(v reflect.Value) bool {
38	switch v.Kind() {
39	case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
40		return v.Len() == 0
41	case reflect.Bool:
42		return !v.Bool()
43	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
44		return v.Int() == 0
45	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
46		return v.Uint() == 0
47	case reflect.Float32, reflect.Float64:
48		return v.Float() == 0
49	case reflect.Interface, reflect.Ptr:
50		if v.IsNil() {
51			return true
52		}
53		return isEmptyValue(v.Elem())
54	case reflect.Func:
55		return v.IsNil()
56	case reflect.Invalid:
57		return true
58	}
59	return false
60}
61
62func resolveValues(dst, src interface{}) (vDst, vSrc reflect.Value, err error) {
63	if dst == nil || src == nil {
64		err = ErrNilArguments
65		return
66	}
67	vDst = reflect.ValueOf(dst).Elem()
68	if vDst.Kind() != reflect.Struct && vDst.Kind() != reflect.Map {
69		err = ErrNotSupported
70		return
71	}
72	vSrc = reflect.ValueOf(src)
73	// We check if vSrc is a pointer to dereference it.
74	if vSrc.Kind() == reflect.Ptr {
75		vSrc = vSrc.Elem()
76	}
77	return
78}
79