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, maps, and slices 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	ErrNonPointerArgument          = 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	typ  reflect.Type
32	next *visit
33	ptr  uintptr
34}
35
36// From src/pkg/encoding/json/encode.go.
37func isEmptyValue(v reflect.Value, shouldDereference bool) 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		if shouldDereference {
54			return isEmptyValue(v.Elem(), shouldDereference)
55		}
56		return false
57	case reflect.Func:
58		return v.IsNil()
59	case reflect.Invalid:
60		return true
61	}
62	return false
63}
64
65func resolveValues(dst, src interface{}) (vDst, vSrc reflect.Value, err error) {
66	if dst == nil || src == nil {
67		err = ErrNilArguments
68		return
69	}
70	vDst = reflect.ValueOf(dst).Elem()
71	if vDst.Kind() != reflect.Struct && vDst.Kind() != reflect.Map && vDst.Kind() != reflect.Slice {
72		err = ErrNotSupported
73		return
74	}
75	vSrc = reflect.ValueOf(src)
76	// We check if vSrc is a pointer to dereference it.
77	if vSrc.Kind() == reflect.Ptr {
78		vSrc = vSrc.Elem()
79	}
80	return
81}