698 lines
18 KiB
Go
698 lines
18 KiB
Go
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package copier
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import (
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"database/sql"
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"database/sql/driver"
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"errors"
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"fmt"
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"reflect"
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"strings"
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"unicode"
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)
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// These flags define options for tag handling
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const (
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// Denotes that a destination field must be copied to. If copying fails then a panic will ensue.
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tagMust uint8 = 1 << iota
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// Denotes that the program should not panic when the must flag is on and
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// value is not copied. The program will return an error instead.
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tagNoPanic
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// Ignore a destination field from being copied to.
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tagIgnore
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// Denotes that the value as been copied
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hasCopied
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// Some default converter types for a nicer syntax
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String string = ""
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Bool bool = false
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Int int = 0
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Float32 float32 = 0
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Float64 float64 = 0
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)
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// Option sets copy options
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type Option struct {
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// setting this value to true will ignore copying zero values of all the fields, including bools, as well as a
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// struct having all it's fields set to their zero values respectively (see IsZero() in reflect/value.go)
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IgnoreEmpty bool
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DeepCopy bool
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Converters []TypeConverter
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}
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type TypeConverter struct {
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SrcType interface{}
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DstType interface{}
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Fn func(src interface{}) (interface{}, error)
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}
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type converterPair struct {
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SrcType reflect.Type
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DstType reflect.Type
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}
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// Tag Flags
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type flags struct {
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BitFlags map[string]uint8
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SrcNames tagNameMapping
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DestNames tagNameMapping
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}
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// Field Tag name mapping
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type tagNameMapping struct {
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FieldNameToTag map[string]string
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TagToFieldName map[string]string
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}
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// Copy copy things
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func Copy(toValue interface{}, fromValue interface{}) (err error) {
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return copier(toValue, fromValue, Option{})
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}
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// CopyWithOption copy with option
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func CopyWithOption(toValue interface{}, fromValue interface{}, opt Option) (err error) {
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return copier(toValue, fromValue, opt)
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}
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func copier(toValue interface{}, fromValue interface{}, opt Option) (err error) {
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var (
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isSlice bool
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amount = 1
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from = indirect(reflect.ValueOf(fromValue))
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to = indirect(reflect.ValueOf(toValue))
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converters map[converterPair]TypeConverter
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)
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// save convertes into map for faster lookup
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for i := range opt.Converters {
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if converters == nil {
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converters = make(map[converterPair]TypeConverter)
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}
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pair := converterPair{
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SrcType: reflect.TypeOf(opt.Converters[i].SrcType),
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DstType: reflect.TypeOf(opt.Converters[i].DstType),
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}
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converters[pair] = opt.Converters[i]
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}
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if !to.CanAddr() {
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return ErrInvalidCopyDestination
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}
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// Return is from value is invalid
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if !from.IsValid() {
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return ErrInvalidCopyFrom
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}
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fromType, isPtrFrom := indirectType(from.Type())
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toType, _ := indirectType(to.Type())
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if fromType.Kind() == reflect.Interface {
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fromType = reflect.TypeOf(from.Interface())
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}
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if toType.Kind() == reflect.Interface {
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toType, _ = indirectType(reflect.TypeOf(to.Interface()))
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oldTo := to
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to = reflect.New(reflect.TypeOf(to.Interface())).Elem()
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defer func() {
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oldTo.Set(to)
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}()
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}
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// Just set it if possible to assign for normal types
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if from.Kind() != reflect.Slice && from.Kind() != reflect.Struct && from.Kind() != reflect.Map && (from.Type().AssignableTo(to.Type()) || from.Type().ConvertibleTo(to.Type())) {
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if !isPtrFrom || !opt.DeepCopy {
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to.Set(from.Convert(to.Type()))
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} else {
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fromCopy := reflect.New(from.Type())
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fromCopy.Set(from.Elem())
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to.Set(fromCopy.Convert(to.Type()))
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}
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return
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}
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if from.Kind() != reflect.Slice && fromType.Kind() == reflect.Map && toType.Kind() == reflect.Map {
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if !fromType.Key().ConvertibleTo(toType.Key()) {
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return ErrMapKeyNotMatch
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}
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if to.IsNil() {
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to.Set(reflect.MakeMapWithSize(toType, from.Len()))
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}
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for _, k := range from.MapKeys() {
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toKey := indirect(reflect.New(toType.Key()))
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if !set(toKey, k, opt.DeepCopy, converters) {
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return fmt.Errorf("%w map, old key: %v, new key: %v", ErrNotSupported, k.Type(), toType.Key())
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}
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elemType := toType.Elem()
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if elemType.Kind() != reflect.Slice {
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elemType, _ = indirectType(elemType)
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}
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toValue := indirect(reflect.New(elemType))
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if !set(toValue, from.MapIndex(k), opt.DeepCopy, converters) {
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if err = copier(toValue.Addr().Interface(), from.MapIndex(k).Interface(), opt); err != nil {
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return err
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}
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}
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for {
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if elemType == toType.Elem() {
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to.SetMapIndex(toKey, toValue)
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break
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}
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elemType = reflect.PtrTo(elemType)
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toValue = toValue.Addr()
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}
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}
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return
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}
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if from.Kind() == reflect.Slice && to.Kind() == reflect.Slice && fromType.ConvertibleTo(toType) {
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if to.IsNil() {
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slice := reflect.MakeSlice(reflect.SliceOf(to.Type().Elem()), from.Len(), from.Cap())
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to.Set(slice)
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}
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for i := 0; i < from.Len(); i++ {
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if to.Len() < i+1 {
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to.Set(reflect.Append(to, reflect.New(to.Type().Elem()).Elem()))
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}
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if !set(to.Index(i), from.Index(i), opt.DeepCopy, converters) {
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// ignore error while copy slice element
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err = copier(to.Index(i).Addr().Interface(), from.Index(i).Interface(), opt)
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if err != nil {
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continue
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}
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}
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}
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return
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}
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if fromType.Kind() != reflect.Struct || toType.Kind() != reflect.Struct {
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// skip not supported type
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return
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}
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if from.Kind() == reflect.Slice || to.Kind() == reflect.Slice {
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isSlice = true
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if from.Kind() == reflect.Slice {
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amount = from.Len()
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}
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}
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for i := 0; i < amount; i++ {
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var dest, source reflect.Value
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if isSlice {
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// source
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if from.Kind() == reflect.Slice {
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source = indirect(from.Index(i))
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} else {
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source = indirect(from)
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}
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// dest
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dest = indirect(reflect.New(toType).Elem())
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} else {
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source = indirect(from)
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dest = indirect(to)
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}
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destKind := dest.Kind()
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initDest := false
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if destKind == reflect.Interface {
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initDest = true
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dest = indirect(reflect.New(toType))
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}
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// Get tag options
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flgs, err := getFlags(dest, source, toType, fromType)
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if err != nil {
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return err
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}
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// check source
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if source.IsValid() {
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copyUnexportedStructFields(dest, source)
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// Copy from source field to dest field or method
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fromTypeFields := deepFields(fromType)
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for _, field := range fromTypeFields {
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name := field.Name
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// Get bit flags for field
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fieldFlags, _ := flgs.BitFlags[name]
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// Check if we should ignore copying
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if (fieldFlags & tagIgnore) != 0 {
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continue
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}
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srcFieldName, destFieldName := getFieldName(name, flgs)
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if fromField := source.FieldByName(srcFieldName); fromField.IsValid() && !shouldIgnore(fromField, opt.IgnoreEmpty) {
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// process for nested anonymous field
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destFieldNotSet := false
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if f, ok := dest.Type().FieldByName(destFieldName); ok {
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for idx := range f.Index {
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destField := dest.FieldByIndex(f.Index[:idx+1])
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if destField.Kind() != reflect.Ptr {
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continue
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}
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if !destField.IsNil() {
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continue
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}
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if !destField.CanSet() {
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destFieldNotSet = true
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break
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}
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// destField is a nil pointer that can be set
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newValue := reflect.New(destField.Type().Elem())
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destField.Set(newValue)
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}
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}
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if destFieldNotSet {
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break
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}
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toField := dest.FieldByName(destFieldName)
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if toField.IsValid() {
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if toField.CanSet() {
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if !set(toField, fromField, opt.DeepCopy, converters) {
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if err := copier(toField.Addr().Interface(), fromField.Interface(), opt); err != nil {
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return err
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}
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}
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if fieldFlags != 0 {
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// Note that a copy was made
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flgs.BitFlags[name] = fieldFlags | hasCopied
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}
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}
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} else {
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// try to set to method
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var toMethod reflect.Value
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if dest.CanAddr() {
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toMethod = dest.Addr().MethodByName(destFieldName)
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} else {
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toMethod = dest.MethodByName(destFieldName)
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}
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if toMethod.IsValid() && toMethod.Type().NumIn() == 1 && fromField.Type().AssignableTo(toMethod.Type().In(0)) {
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toMethod.Call([]reflect.Value{fromField})
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}
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}
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}
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}
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// Copy from from method to dest field
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for _, field := range deepFields(toType) {
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name := field.Name
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srcFieldName, destFieldName := getFieldName(name, flgs)
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var fromMethod reflect.Value
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if source.CanAddr() {
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fromMethod = source.Addr().MethodByName(srcFieldName)
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} else {
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fromMethod = source.MethodByName(srcFieldName)
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}
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if fromMethod.IsValid() && fromMethod.Type().NumIn() == 0 && fromMethod.Type().NumOut() == 1 && !shouldIgnore(fromMethod, opt.IgnoreEmpty) {
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if toField := dest.FieldByName(destFieldName); toField.IsValid() && toField.CanSet() {
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values := fromMethod.Call([]reflect.Value{})
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if len(values) >= 1 {
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set(toField, values[0], opt.DeepCopy, converters)
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}
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}
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}
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}
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}
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if isSlice && to.Kind() == reflect.Slice {
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if dest.Addr().Type().AssignableTo(to.Type().Elem()) {
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if to.Len() < i+1 {
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to.Set(reflect.Append(to, dest.Addr()))
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} else {
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if !set(to.Index(i), dest.Addr(), opt.DeepCopy, converters) {
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// ignore error while copy slice element
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err = copier(to.Index(i).Addr().Interface(), dest.Addr().Interface(), opt)
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if err != nil {
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continue
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}
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}
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}
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} else if dest.Type().AssignableTo(to.Type().Elem()) {
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if to.Len() < i+1 {
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to.Set(reflect.Append(to, dest))
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} else {
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if !set(to.Index(i), dest, opt.DeepCopy, converters) {
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// ignore error while copy slice element
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err = copier(to.Index(i).Addr().Interface(), dest.Interface(), opt)
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if err != nil {
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continue
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}
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}
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}
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}
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} else if initDest {
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to.Set(dest)
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}
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err = checkBitFlags(flgs.BitFlags)
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}
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return
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}
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func copyUnexportedStructFields(to, from reflect.Value) {
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if from.Kind() != reflect.Struct || to.Kind() != reflect.Struct || !from.Type().AssignableTo(to.Type()) {
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return
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}
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// create a shallow copy of 'to' to get all fields
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tmp := indirect(reflect.New(to.Type()))
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tmp.Set(from)
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// revert exported fields
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for i := 0; i < to.NumField(); i++ {
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if tmp.Field(i).CanSet() {
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tmp.Field(i).Set(to.Field(i))
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}
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}
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to.Set(tmp)
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}
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func shouldIgnore(v reflect.Value, ignoreEmpty bool) bool {
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if !ignoreEmpty {
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return false
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}
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return v.IsZero()
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}
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|
|
|
||
|
|
func deepFields(reflectType reflect.Type) []reflect.StructField {
|
||
|
|
if reflectType, _ = indirectType(reflectType); reflectType.Kind() == reflect.Struct {
|
||
|
|
fields := make([]reflect.StructField, 0, reflectType.NumField())
|
||
|
|
|
||
|
|
for i := 0; i < reflectType.NumField(); i++ {
|
||
|
|
v := reflectType.Field(i)
|
||
|
|
// PkgPath is the package path that qualifies a lower case (unexported)
|
||
|
|
// field name. It is empty for upper case (exported) field names.
|
||
|
|
// See https://golang.org/ref/spec#Uniqueness_of_identifiers
|
||
|
|
if v.PkgPath == "" {
|
||
|
|
fields = append(fields, v)
|
||
|
|
if v.Anonymous {
|
||
|
|
// also consider fields of anonymous fields as fields of the root
|
||
|
|
fields = append(fields, deepFields(v.Type)...)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return fields
|
||
|
|
}
|
||
|
|
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func indirect(reflectValue reflect.Value) reflect.Value {
|
||
|
|
for reflectValue.Kind() == reflect.Ptr {
|
||
|
|
reflectValue = reflectValue.Elem()
|
||
|
|
}
|
||
|
|
return reflectValue
|
||
|
|
}
|
||
|
|
|
||
|
|
func indirectType(reflectType reflect.Type) (_ reflect.Type, isPtr bool) {
|
||
|
|
for reflectType.Kind() == reflect.Ptr || reflectType.Kind() == reflect.Slice {
|
||
|
|
reflectType = reflectType.Elem()
|
||
|
|
isPtr = true
|
||
|
|
}
|
||
|
|
return reflectType, isPtr
|
||
|
|
}
|
||
|
|
|
||
|
|
func set(to, from reflect.Value, deepCopy bool, converters map[converterPair]TypeConverter) bool {
|
||
|
|
if from.IsValid() {
|
||
|
|
if ok, err := lookupAndCopyWithConverter(to, from, converters); err != nil {
|
||
|
|
return false
|
||
|
|
} else if ok {
|
||
|
|
return true
|
||
|
|
}
|
||
|
|
|
||
|
|
if to.Kind() == reflect.Ptr {
|
||
|
|
// set `to` to nil if from is nil
|
||
|
|
if from.Kind() == reflect.Ptr && from.IsNil() {
|
||
|
|
to.Set(reflect.Zero(to.Type()))
|
||
|
|
return true
|
||
|
|
} else if to.IsNil() {
|
||
|
|
// `from` -> `to`
|
||
|
|
// sql.NullString -> *string
|
||
|
|
if fromValuer, ok := driverValuer(from); ok {
|
||
|
|
v, err := fromValuer.Value()
|
||
|
|
if err != nil {
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
// if `from` is not valid do nothing with `to`
|
||
|
|
if v == nil {
|
||
|
|
return true
|
||
|
|
}
|
||
|
|
}
|
||
|
|
// allocate new `to` variable with default value (eg. *string -> new(string))
|
||
|
|
to.Set(reflect.New(to.Type().Elem()))
|
||
|
|
}
|
||
|
|
// depointer `to`
|
||
|
|
to = to.Elem()
|
||
|
|
}
|
||
|
|
|
||
|
|
if deepCopy {
|
||
|
|
toKind := to.Kind()
|
||
|
|
if toKind == reflect.Interface && to.IsNil() {
|
||
|
|
if reflect.TypeOf(from.Interface()) != nil {
|
||
|
|
to.Set(reflect.New(reflect.TypeOf(from.Interface())).Elem())
|
||
|
|
toKind = reflect.TypeOf(to.Interface()).Kind()
|
||
|
|
}
|
||
|
|
}
|
||
|
|
if from.Kind() == reflect.Ptr && from.IsNil() {
|
||
|
|
return true
|
||
|
|
}
|
||
|
|
if toKind == reflect.Struct || toKind == reflect.Map || toKind == reflect.Slice {
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if from.Type().ConvertibleTo(to.Type()) {
|
||
|
|
to.Set(from.Convert(to.Type()))
|
||
|
|
} else if toScanner, ok := to.Addr().Interface().(sql.Scanner); ok {
|
||
|
|
// `from` -> `to`
|
||
|
|
// *string -> sql.NullString
|
||
|
|
if from.Kind() == reflect.Ptr {
|
||
|
|
// if `from` is nil do nothing with `to`
|
||
|
|
if from.IsNil() {
|
||
|
|
return true
|
||
|
|
}
|
||
|
|
// depointer `from`
|
||
|
|
from = indirect(from)
|
||
|
|
}
|
||
|
|
// `from` -> `to`
|
||
|
|
// string -> sql.NullString
|
||
|
|
// set `to` by invoking method Scan(`from`)
|
||
|
|
err := toScanner.Scan(from.Interface())
|
||
|
|
if err != nil {
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
} else if fromValuer, ok := driverValuer(from); ok {
|
||
|
|
// `from` -> `to`
|
||
|
|
// sql.NullString -> string
|
||
|
|
v, err := fromValuer.Value()
|
||
|
|
if err != nil {
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
// if `from` is not valid do nothing with `to`
|
||
|
|
if v == nil {
|
||
|
|
return true
|
||
|
|
}
|
||
|
|
rv := reflect.ValueOf(v)
|
||
|
|
if rv.Type().AssignableTo(to.Type()) {
|
||
|
|
to.Set(rv)
|
||
|
|
}
|
||
|
|
} else if from.Kind() == reflect.Ptr {
|
||
|
|
return set(to, from.Elem(), deepCopy, converters)
|
||
|
|
} else {
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return true
|
||
|
|
}
|
||
|
|
|
||
|
|
// lookupAndCopyWithConverter looks up the type pair, on success the TypeConverter Fn func is called to copy src to dst field.
|
||
|
|
func lookupAndCopyWithConverter(to, from reflect.Value, converters map[converterPair]TypeConverter) (copied bool, err error) {
|
||
|
|
pair := converterPair{
|
||
|
|
SrcType: from.Type(),
|
||
|
|
DstType: to.Type(),
|
||
|
|
}
|
||
|
|
|
||
|
|
if cnv, ok := converters[pair]; ok {
|
||
|
|
result, err := cnv.Fn(from.Interface())
|
||
|
|
|
||
|
|
if err != nil {
|
||
|
|
return false, err
|
||
|
|
}
|
||
|
|
|
||
|
|
if result != nil {
|
||
|
|
to.Set(reflect.ValueOf(result))
|
||
|
|
} else {
|
||
|
|
// in case we've got a nil value to copy
|
||
|
|
to.Set(reflect.Zero(to.Type()))
|
||
|
|
}
|
||
|
|
|
||
|
|
return true, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
return false, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// parseTags Parses struct tags and returns uint8 bit flags.
|
||
|
|
func parseTags(tag string) (flg uint8, name string, err error) {
|
||
|
|
for _, t := range strings.Split(tag, ",") {
|
||
|
|
switch t {
|
||
|
|
case "-":
|
||
|
|
flg = tagIgnore
|
||
|
|
return
|
||
|
|
case "must":
|
||
|
|
flg = flg | tagMust
|
||
|
|
case "nopanic":
|
||
|
|
flg = flg | tagNoPanic
|
||
|
|
default:
|
||
|
|
if unicode.IsUpper([]rune(t)[0]) {
|
||
|
|
name = strings.TrimSpace(t)
|
||
|
|
} else {
|
||
|
|
err = errors.New("copier field name tag must be start upper case")
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
// getTagFlags Parses struct tags for bit flags, field name.
|
||
|
|
func getFlags(dest, src reflect.Value, toType, fromType reflect.Type) (flags, error) {
|
||
|
|
flgs := flags{
|
||
|
|
BitFlags: map[string]uint8{},
|
||
|
|
SrcNames: tagNameMapping{
|
||
|
|
FieldNameToTag: map[string]string{},
|
||
|
|
TagToFieldName: map[string]string{},
|
||
|
|
},
|
||
|
|
DestNames: tagNameMapping{
|
||
|
|
FieldNameToTag: map[string]string{},
|
||
|
|
TagToFieldName: map[string]string{},
|
||
|
|
},
|
||
|
|
}
|
||
|
|
var toTypeFields, fromTypeFields []reflect.StructField
|
||
|
|
if dest.IsValid() {
|
||
|
|
toTypeFields = deepFields(toType)
|
||
|
|
}
|
||
|
|
if src.IsValid() {
|
||
|
|
fromTypeFields = deepFields(fromType)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Get a list dest of tags
|
||
|
|
for _, field := range toTypeFields {
|
||
|
|
tags := field.Tag.Get("copier")
|
||
|
|
if tags != "" {
|
||
|
|
var name string
|
||
|
|
var err error
|
||
|
|
if flgs.BitFlags[field.Name], name, err = parseTags(tags); err != nil {
|
||
|
|
return flags{}, err
|
||
|
|
} else if name != "" {
|
||
|
|
flgs.DestNames.FieldNameToTag[field.Name] = name
|
||
|
|
flgs.DestNames.TagToFieldName[name] = field.Name
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Get a list source of tags
|
||
|
|
for _, field := range fromTypeFields {
|
||
|
|
tags := field.Tag.Get("copier")
|
||
|
|
if tags != "" {
|
||
|
|
var name string
|
||
|
|
var err error
|
||
|
|
if _, name, err = parseTags(tags); err != nil {
|
||
|
|
return flags{}, err
|
||
|
|
} else if name != "" {
|
||
|
|
flgs.SrcNames.FieldNameToTag[field.Name] = name
|
||
|
|
flgs.SrcNames.TagToFieldName[name] = field.Name
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return flgs, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// checkBitFlags Checks flags for error or panic conditions.
|
||
|
|
func checkBitFlags(flagsList map[string]uint8) (err error) {
|
||
|
|
// Check flag conditions were met
|
||
|
|
for name, flgs := range flagsList {
|
||
|
|
if flgs&hasCopied == 0 {
|
||
|
|
switch {
|
||
|
|
case flgs&tagMust != 0 && flgs&tagNoPanic != 0:
|
||
|
|
err = fmt.Errorf("field %s has must tag but was not copied", name)
|
||
|
|
return
|
||
|
|
case flgs&(tagMust) != 0:
|
||
|
|
panic(fmt.Sprintf("Field %s has must tag but was not copied", name))
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
func getFieldName(fieldName string, flgs flags) (srcFieldName string, destFieldName string) {
|
||
|
|
// get dest field name
|
||
|
|
if srcTagName, ok := flgs.SrcNames.FieldNameToTag[fieldName]; ok {
|
||
|
|
destFieldName = srcTagName
|
||
|
|
if destTagName, ok := flgs.DestNames.TagToFieldName[srcTagName]; ok {
|
||
|
|
destFieldName = destTagName
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
if destTagName, ok := flgs.DestNames.TagToFieldName[fieldName]; ok {
|
||
|
|
destFieldName = destTagName
|
||
|
|
}
|
||
|
|
}
|
||
|
|
if destFieldName == "" {
|
||
|
|
destFieldName = fieldName
|
||
|
|
}
|
||
|
|
|
||
|
|
// get source field name
|
||
|
|
if destTagName, ok := flgs.DestNames.FieldNameToTag[fieldName]; ok {
|
||
|
|
srcFieldName = destTagName
|
||
|
|
if srcField, ok := flgs.SrcNames.TagToFieldName[destTagName]; ok {
|
||
|
|
srcFieldName = srcField
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
if srcField, ok := flgs.SrcNames.TagToFieldName[fieldName]; ok {
|
||
|
|
srcFieldName = srcField
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if srcFieldName == "" {
|
||
|
|
srcFieldName = fieldName
|
||
|
|
}
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
func driverValuer(v reflect.Value) (i driver.Valuer, ok bool) {
|
||
|
|
|
||
|
|
if !v.CanAddr() {
|
||
|
|
i, ok = v.Interface().(driver.Valuer)
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
i, ok = v.Addr().Interface().(driver.Valuer)
|
||
|
|
return
|
||
|
|
}
|