Scott Baker | e7144bc | 2019-10-01 14:16:47 -0700 | [diff] [blame^] | 1 | // Copyright 2014 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 | |
| 9 | package mergo |
| 10 | |
| 11 | import ( |
| 12 | "fmt" |
| 13 | "reflect" |
| 14 | "unicode" |
| 15 | "unicode/utf8" |
| 16 | ) |
| 17 | |
| 18 | func changeInitialCase(s string, mapper func(rune) rune) string { |
| 19 | if s == "" { |
| 20 | return s |
| 21 | } |
| 22 | r, n := utf8.DecodeRuneInString(s) |
| 23 | return string(mapper(r)) + s[n:] |
| 24 | } |
| 25 | |
| 26 | func isExported(field reflect.StructField) bool { |
| 27 | r, _ := utf8.DecodeRuneInString(field.Name) |
| 28 | return r >= 'A' && r <= 'Z' |
| 29 | } |
| 30 | |
| 31 | // Traverses recursively both values, assigning src's fields values to dst. |
| 32 | // The map argument tracks comparisons that have already been seen, which allows |
| 33 | // short circuiting on recursive types. |
| 34 | func deepMap(dst, src reflect.Value, visited map[uintptr]*visit, depth int, config *Config) (err error) { |
| 35 | overwrite := config.Overwrite |
| 36 | if dst.CanAddr() { |
| 37 | addr := dst.UnsafeAddr() |
| 38 | h := 17 * addr |
| 39 | seen := visited[h] |
| 40 | typ := dst.Type() |
| 41 | for p := seen; p != nil; p = p.next { |
| 42 | if p.ptr == addr && p.typ == typ { |
| 43 | return nil |
| 44 | } |
| 45 | } |
| 46 | // Remember, remember... |
| 47 | visited[h] = &visit{addr, typ, seen} |
| 48 | } |
| 49 | zeroValue := reflect.Value{} |
| 50 | switch dst.Kind() { |
| 51 | case reflect.Map: |
| 52 | dstMap := dst.Interface().(map[string]interface{}) |
| 53 | for i, n := 0, src.NumField(); i < n; i++ { |
| 54 | srcType := src.Type() |
| 55 | field := srcType.Field(i) |
| 56 | if !isExported(field) { |
| 57 | continue |
| 58 | } |
| 59 | fieldName := field.Name |
| 60 | fieldName = changeInitialCase(fieldName, unicode.ToLower) |
| 61 | if v, ok := dstMap[fieldName]; !ok || (isEmptyValue(reflect.ValueOf(v)) || overwrite) { |
| 62 | dstMap[fieldName] = src.Field(i).Interface() |
| 63 | } |
| 64 | } |
| 65 | case reflect.Ptr: |
| 66 | if dst.IsNil() { |
| 67 | v := reflect.New(dst.Type().Elem()) |
| 68 | dst.Set(v) |
| 69 | } |
| 70 | dst = dst.Elem() |
| 71 | fallthrough |
| 72 | case reflect.Struct: |
| 73 | srcMap := src.Interface().(map[string]interface{}) |
| 74 | for key := range srcMap { |
| 75 | config.overwriteWithEmptyValue = true |
| 76 | srcValue := srcMap[key] |
| 77 | fieldName := changeInitialCase(key, unicode.ToUpper) |
| 78 | dstElement := dst.FieldByName(fieldName) |
| 79 | if dstElement == zeroValue { |
| 80 | // We discard it because the field doesn't exist. |
| 81 | continue |
| 82 | } |
| 83 | srcElement := reflect.ValueOf(srcValue) |
| 84 | dstKind := dstElement.Kind() |
| 85 | srcKind := srcElement.Kind() |
| 86 | if srcKind == reflect.Ptr && dstKind != reflect.Ptr { |
| 87 | srcElement = srcElement.Elem() |
| 88 | srcKind = reflect.TypeOf(srcElement.Interface()).Kind() |
| 89 | } else if dstKind == reflect.Ptr { |
| 90 | // Can this work? I guess it can't. |
| 91 | if srcKind != reflect.Ptr && srcElement.CanAddr() { |
| 92 | srcPtr := srcElement.Addr() |
| 93 | srcElement = reflect.ValueOf(srcPtr) |
| 94 | srcKind = reflect.Ptr |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | if !srcElement.IsValid() { |
| 99 | continue |
| 100 | } |
| 101 | if srcKind == dstKind { |
| 102 | if err = deepMerge(dstElement, srcElement, visited, depth+1, config); err != nil { |
| 103 | return |
| 104 | } |
| 105 | } else if dstKind == reflect.Interface && dstElement.Kind() == reflect.Interface { |
| 106 | if err = deepMerge(dstElement, srcElement, visited, depth+1, config); err != nil { |
| 107 | return |
| 108 | } |
| 109 | } else if srcKind == reflect.Map { |
| 110 | if err = deepMap(dstElement, srcElement, visited, depth+1, config); err != nil { |
| 111 | return |
| 112 | } |
| 113 | } else { |
| 114 | return fmt.Errorf("type mismatch on %s field: found %v, expected %v", fieldName, srcKind, dstKind) |
| 115 | } |
| 116 | } |
| 117 | } |
| 118 | return |
| 119 | } |
| 120 | |
| 121 | // Map sets fields' values in dst from src. |
| 122 | // src can be a map with string keys or a struct. dst must be the opposite: |
| 123 | // if src is a map, dst must be a valid pointer to struct. If src is a struct, |
| 124 | // dst must be map[string]interface{}. |
| 125 | // It won't merge unexported (private) fields and will do recursively |
| 126 | // any exported field. |
| 127 | // If dst is a map, keys will be src fields' names in lower camel case. |
| 128 | // Missing key in src that doesn't match a field in dst will be skipped. This |
| 129 | // doesn't apply if dst is a map. |
| 130 | // This is separated method from Merge because it is cleaner and it keeps sane |
| 131 | // semantics: merging equal types, mapping different (restricted) types. |
| 132 | func Map(dst, src interface{}, opts ...func(*Config)) error { |
| 133 | return _map(dst, src, opts...) |
| 134 | } |
| 135 | |
| 136 | // MapWithOverwrite will do the same as Map except that non-empty dst attributes will be overridden by |
| 137 | // non-empty src attribute values. |
| 138 | // Deprecated: Use Map(…) with WithOverride |
| 139 | func MapWithOverwrite(dst, src interface{}, opts ...func(*Config)) error { |
| 140 | return _map(dst, src, append(opts, WithOverride)...) |
| 141 | } |
| 142 | |
| 143 | func _map(dst, src interface{}, opts ...func(*Config)) error { |
| 144 | var ( |
| 145 | vDst, vSrc reflect.Value |
| 146 | err error |
| 147 | ) |
| 148 | config := &Config{} |
| 149 | |
| 150 | for _, opt := range opts { |
| 151 | opt(config) |
| 152 | } |
| 153 | |
| 154 | if vDst, vSrc, err = resolveValues(dst, src); err != nil { |
| 155 | return err |
| 156 | } |
| 157 | // To be friction-less, we redirect equal-type arguments |
| 158 | // to deepMerge. Only because arguments can be anything. |
| 159 | if vSrc.Kind() == vDst.Kind() { |
| 160 | return deepMerge(vDst, vSrc, make(map[uintptr]*visit), 0, config) |
| 161 | } |
| 162 | switch vSrc.Kind() { |
| 163 | case reflect.Struct: |
| 164 | if vDst.Kind() != reflect.Map { |
| 165 | return ErrExpectedMapAsDestination |
| 166 | } |
| 167 | case reflect.Map: |
| 168 | if vDst.Kind() != reflect.Struct { |
| 169 | return ErrExpectedStructAsDestination |
| 170 | } |
| 171 | default: |
| 172 | return ErrNotSupported |
| 173 | } |
| 174 | return deepMap(vDst, vSrc, make(map[uintptr]*visit), 0, config) |
| 175 | } |