[READ-ONLY] Mirror of https://github.com/darccio/mergo. Mergo: merging Go structs and maps since 2013
go golang hacktoberfest mapping merge structures
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179// 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, config *Config) (err error) { overwrite := config.Overwrite 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{typ, seen, addr} } 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 _, ok := dstMap[fieldName]; !ok || (!isEmptyValue(reflect.ValueOf(src.Field(i).Interface()), !config.ShouldNotDereference) && overwrite) { dstMap[fieldName] = src.Field(i).Interface() } } case reflect.Ptr: if dst.IsNil() { v := reflect.New(dst.Type().Elem()) dst.Set(v) } dst = dst.Elem() fallthrough case reflect.Struct: srcMap := src.Interface().(map[string]interface{}) for key := range srcMap { config.overwriteWithEmptyValue = true 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, config); err != nil { return } } else if dstKind == reflect.Interface && dstElement.Kind() == reflect.Interface { if err = deepMerge(dstElement, srcElement, visited, depth+1, config); err != nil { return } } else if srcKind == reflect.Map { if err = deepMap(dstElement, srcElement, visited, depth+1, config); 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{}, opts ...func(*Config)) error { return _map(dst, src, opts...)}
// MapWithOverwrite will do the same as Map except that non-empty dst attributes will be overridden by// non-empty src attribute values.// Deprecated: Use Map(…) with WithOverridefunc MapWithOverwrite(dst, src interface{}, opts ...func(*Config)) error { return _map(dst, src, append(opts, WithOverride)...)}
func _map(dst, src interface{}, opts ...func(*Config)) error { if dst != nil && reflect.ValueOf(dst).Kind() != reflect.Ptr { return ErrNonPointerArgument } var ( vDst, vSrc reflect.Value err error ) config := &Config{}
for _, opt := range opts { opt(config) }
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, config) } 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, config)}