512 lines
17 KiB
Go
512 lines
17 KiB
Go
// Copyright 2015 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package proptools
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import (
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"fmt"
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"reflect"
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)
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// AppendProperties appends the values of properties in the property struct src to the property
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// struct dst. dst and src must be the same type, and both must be pointers to structs.
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//
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// The filter function can prevent individual properties from being appended by returning false, or
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// abort AppendProperties with an error by returning an error. Passing nil for filter will append
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// all properties.
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//
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// An error returned by AppendProperties that applies to a specific property will be an
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// *ExtendPropertyError, and can have the property name and error extracted from it.
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//
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// The append operation is defined as appending strings and slices of strings normally, OR-ing bool
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// values, replacing non-nil pointers to booleans or strings, and recursing into
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// embedded structs, pointers to structs, and interfaces containing
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// pointers to structs. Appending the zero value of a property will always be a no-op.
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func AppendProperties(dst interface{}, src interface{}, filter ExtendPropertyFilterFunc) error {
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return extendProperties(dst, src, filter, OrderAppend)
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}
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// PrependProperties prepends the values of properties in the property struct src to the property
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// struct dst. dst and src must be the same type, and both must be pointers to structs.
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//
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// The filter function can prevent individual properties from being prepended by returning false, or
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// abort PrependProperties with an error by returning an error. Passing nil for filter will prepend
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// all properties.
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//
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// An error returned by PrependProperties that applies to a specific property will be an
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// *ExtendPropertyError, and can have the property name and error extracted from it.
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//
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// The prepend operation is defined as prepending strings, and slices of strings normally, OR-ing
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// bool values, replacing non-nil pointers to booleans or strings, and recursing into
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// embedded structs, pointers to structs, and interfaces containing
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// pointers to structs. Prepending the zero value of a property will always be a no-op.
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func PrependProperties(dst interface{}, src interface{}, filter ExtendPropertyFilterFunc) error {
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return extendProperties(dst, src, filter, OrderPrepend)
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}
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// AppendMatchingProperties appends the values of properties in the property struct src to the
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// property structs in dst. dst and src do not have to be the same type, but every property in src
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// must be found in at least one property in dst. dst must be a slice of pointers to structs, and
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// src must be a pointer to a struct.
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//
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// The filter function can prevent individual properties from being appended by returning false, or
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// abort AppendProperties with an error by returning an error. Passing nil for filter will append
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// all properties.
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//
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// An error returned by AppendMatchingProperties that applies to a specific property will be an
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// *ExtendPropertyError, and can have the property name and error extracted from it.
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//
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// The append operation is defined as appending strings, and slices of strings normally, OR-ing bool
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// values, replacing pointers to booleans or strings whether they are nil or not, and recursing into
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// embedded structs, pointers to structs, and interfaces containing
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// pointers to structs. Appending the zero value of a property will always be a no-op.
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func AppendMatchingProperties(dst []interface{}, src interface{},
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filter ExtendPropertyFilterFunc) error {
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return extendMatchingProperties(dst, src, filter, OrderAppend)
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}
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// PrependMatchingProperties prepends the values of properties in the property struct src to the
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// property structs in dst. dst and src do not have to be the same type, but every property in src
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// must be found in at least one property in dst. dst must be a slice of pointers to structs, and
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// src must be a pointer to a struct.
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//
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// The filter function can prevent individual properties from being prepended by returning false, or
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// abort PrependProperties with an error by returning an error. Passing nil for filter will prepend
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// all properties.
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//
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// An error returned by PrependProperties that applies to a specific property will be an
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// *ExtendPropertyError, and can have the property name and error extracted from it.
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//
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// The prepend operation is defined as prepending strings, and slices of strings normally, OR-ing
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// bool values, replacing nil pointers to booleans or strings, and recursing into
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// embedded structs, pointers to structs, and interfaces containing
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// pointers to structs. Prepending the zero value of a property will always be a no-op.
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func PrependMatchingProperties(dst []interface{}, src interface{},
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filter ExtendPropertyFilterFunc) error {
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return extendMatchingProperties(dst, src, filter, OrderPrepend)
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}
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// ExtendProperties appends or prepends the values of properties in the property struct src to the
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// property struct dst. dst and src must be the same type, and both must be pointers to structs.
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//
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// The filter function can prevent individual properties from being appended or prepended by
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// returning false, or abort ExtendProperties with an error by returning an error. Passing nil for
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// filter will append or prepend all properties.
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//
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// The order function is called on each non-filtered property to determine if it should be appended
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// or prepended.
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//
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// An error returned by ExtendProperties that applies to a specific property will be an
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// *ExtendPropertyError, and can have the property name and error extracted from it.
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//
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// The append operation is defined as appending strings and slices of strings normally, OR-ing bool
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// values, replacing non-nil pointers to booleans or strings, and recursing into
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// embedded structs, pointers to structs, and interfaces containing
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// pointers to structs. Appending or prepending the zero value of a property will always be a
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// no-op.
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func ExtendProperties(dst interface{}, src interface{}, filter ExtendPropertyFilterFunc,
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order ExtendPropertyOrderFunc) error {
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return extendProperties(dst, src, filter, order)
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}
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// ExtendMatchingProperties appends or prepends the values of properties in the property struct src
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// to the property structs in dst. dst and src do not have to be the same type, but every property
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// in src must be found in at least one property in dst. dst must be a slice of pointers to
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// structs, and src must be a pointer to a struct.
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//
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// The filter function can prevent individual properties from being appended or prepended by
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// returning false, or abort ExtendMatchingProperties with an error by returning an error. Passing
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// nil for filter will append or prepend all properties.
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//
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// The order function is called on each non-filtered property to determine if it should be appended
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// or prepended.
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//
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// An error returned by ExtendMatchingProperties that applies to a specific property will be an
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// *ExtendPropertyError, and can have the property name and error extracted from it.
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//
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// The append operation is defined as appending strings, and slices of strings normally, OR-ing bool
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// values, replacing non-nil pointers to booleans or strings, and recursing into
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// embedded structs, pointers to structs, and interfaces containing
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// pointers to structs. Appending or prepending the zero value of a property will always be a
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// no-op.
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func ExtendMatchingProperties(dst []interface{}, src interface{},
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filter ExtendPropertyFilterFunc, order ExtendPropertyOrderFunc) error {
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return extendMatchingProperties(dst, src, filter, order)
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}
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type Order int
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const (
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Append Order = iota
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Prepend
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Replace
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)
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type ExtendPropertyFilterFunc func(property string,
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dstField, srcField reflect.StructField,
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dstValue, srcValue interface{}) (bool, error)
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type ExtendPropertyOrderFunc func(property string,
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dstField, srcField reflect.StructField,
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dstValue, srcValue interface{}) (Order, error)
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func OrderAppend(property string,
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dstField, srcField reflect.StructField,
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dstValue, srcValue interface{}) (Order, error) {
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return Append, nil
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}
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func OrderPrepend(property string,
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dstField, srcField reflect.StructField,
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dstValue, srcValue interface{}) (Order, error) {
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return Prepend, nil
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}
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func OrderReplace(property string,
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dstField, srcField reflect.StructField,
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dstValue, srcValue interface{}) (Order, error) {
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return Replace, nil
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}
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type ExtendPropertyError struct {
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Err error
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Property string
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}
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func (e *ExtendPropertyError) Error() string {
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return fmt.Sprintf("can't extend property %q: %s", e.Property, e.Err)
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}
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func extendPropertyErrorf(property string, format string, a ...interface{}) *ExtendPropertyError {
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return &ExtendPropertyError{
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Err: fmt.Errorf(format, a...),
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Property: property,
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}
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}
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func extendProperties(dst interface{}, src interface{}, filter ExtendPropertyFilterFunc,
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order ExtendPropertyOrderFunc) error {
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srcValue, err := getStruct(src)
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if err != nil {
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if _, ok := err.(getStructEmptyError); ok {
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return nil
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}
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return err
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}
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dstValue, err := getOrCreateStruct(dst)
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if err != nil {
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return err
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}
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if dstValue.Type() != srcValue.Type() {
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return fmt.Errorf("expected matching types for dst and src, got %T and %T", dst, src)
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}
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dstValues := []reflect.Value{dstValue}
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return extendPropertiesRecursive(dstValues, srcValue, "", filter, true, order)
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}
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func extendMatchingProperties(dst []interface{}, src interface{}, filter ExtendPropertyFilterFunc,
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order ExtendPropertyOrderFunc) error {
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srcValue, err := getStruct(src)
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if err != nil {
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if _, ok := err.(getStructEmptyError); ok {
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return nil
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}
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return err
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}
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dstValues := make([]reflect.Value, len(dst))
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for i := range dst {
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var err error
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dstValues[i], err = getOrCreateStruct(dst[i])
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if err != nil {
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return err
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}
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}
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return extendPropertiesRecursive(dstValues, srcValue, "", filter, false, order)
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}
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func extendPropertiesRecursive(dstValues []reflect.Value, srcValue reflect.Value,
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prefix string, filter ExtendPropertyFilterFunc, sameTypes bool,
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orderFunc ExtendPropertyOrderFunc) error {
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srcType := srcValue.Type()
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for i, srcField := range typeFields(srcType) {
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if srcField.PkgPath != "" {
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// The field is not exported so just skip it.
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continue
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}
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if HasTag(srcField, "blueprint", "mutated") {
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continue
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}
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propertyName := prefix + PropertyNameForField(srcField.Name)
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srcFieldValue := srcValue.Field(i)
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// Step into source interfaces
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if srcFieldValue.Kind() == reflect.Interface {
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if srcFieldValue.IsNil() {
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continue
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}
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srcFieldValue = srcFieldValue.Elem()
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if srcFieldValue.Kind() != reflect.Ptr {
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return extendPropertyErrorf(propertyName, "interface not a pointer")
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}
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}
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// Step into source pointers to structs
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if isStructPtr(srcFieldValue.Type()) {
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if srcFieldValue.IsNil() {
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continue
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}
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srcFieldValue = srcFieldValue.Elem()
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}
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found := false
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var recurse []reflect.Value
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for _, dstValue := range dstValues {
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dstType := dstValue.Type()
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var dstField reflect.StructField
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dstFields := typeFields(dstType)
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if dstType == srcType {
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dstField = dstFields[i]
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} else {
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var ok bool
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for _, field := range dstFields {
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if field.Name == srcField.Name {
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dstField = field
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ok = true
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}
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}
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if !ok {
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continue
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}
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}
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found = true
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dstFieldValue := dstValue.FieldByIndex(dstField.Index)
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origDstFieldValue := dstFieldValue
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// Step into destination interfaces
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if dstFieldValue.Kind() == reflect.Interface {
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if dstFieldValue.IsNil() {
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return extendPropertyErrorf(propertyName, "nilitude mismatch")
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}
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dstFieldValue = dstFieldValue.Elem()
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if dstFieldValue.Kind() != reflect.Ptr {
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return extendPropertyErrorf(propertyName, "interface not a pointer")
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}
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}
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// Step into destination pointers to structs
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if isStructPtr(dstFieldValue.Type()) {
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if dstFieldValue.IsNil() {
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dstFieldValue = reflect.New(dstFieldValue.Type().Elem())
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origDstFieldValue.Set(dstFieldValue)
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}
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dstFieldValue = dstFieldValue.Elem()
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}
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switch srcFieldValue.Kind() {
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case reflect.Struct:
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if sameTypes && dstFieldValue.Type() != srcFieldValue.Type() {
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return extendPropertyErrorf(propertyName, "mismatched types %s and %s",
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dstFieldValue.Type(), srcFieldValue.Type())
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}
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// Recursively extend the struct's fields.
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recurse = append(recurse, dstFieldValue)
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continue
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case reflect.Bool, reflect.String, reflect.Slice:
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if srcFieldValue.Type() != dstFieldValue.Type() {
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return extendPropertyErrorf(propertyName, "mismatched types %s and %s",
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dstFieldValue.Type(), srcFieldValue.Type())
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}
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case reflect.Ptr:
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if srcFieldValue.Type() != dstFieldValue.Type() {
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return extendPropertyErrorf(propertyName, "mismatched types %s and %s",
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dstFieldValue.Type(), srcFieldValue.Type())
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}
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switch ptrKind := srcFieldValue.Type().Elem().Kind(); ptrKind {
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case reflect.Bool, reflect.Int64, reflect.String, reflect.Struct:
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// Nothing
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default:
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return extendPropertyErrorf(propertyName, "pointer is a %s", ptrKind)
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}
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default:
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return extendPropertyErrorf(propertyName, "unsupported kind %s",
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srcFieldValue.Kind())
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}
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dstFieldInterface := dstFieldValue.Interface()
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srcFieldInterface := srcFieldValue.Interface()
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if filter != nil {
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b, err := filter(propertyName, dstField, srcField,
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dstFieldInterface, srcFieldInterface)
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if err != nil {
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return &ExtendPropertyError{
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Property: propertyName,
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Err: err,
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}
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}
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if !b {
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continue
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}
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}
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order := Append
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if orderFunc != nil {
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var err error
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order, err = orderFunc(propertyName, dstField, srcField,
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dstFieldInterface, srcFieldInterface)
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if err != nil {
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return &ExtendPropertyError{
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Property: propertyName,
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Err: err,
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}
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}
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}
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ExtendBasicType(dstFieldValue, srcFieldValue, order)
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}
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if len(recurse) > 0 {
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err := extendPropertiesRecursive(recurse, srcFieldValue,
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propertyName+".", filter, sameTypes, orderFunc)
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if err != nil {
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return err
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}
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} else if !found {
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return extendPropertyErrorf(propertyName, "failed to find property to extend")
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}
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}
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return nil
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}
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func ExtendBasicType(dstFieldValue, srcFieldValue reflect.Value, order Order) {
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prepend := order == Prepend
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switch srcFieldValue.Kind() {
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case reflect.Bool:
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// Boolean OR
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dstFieldValue.Set(reflect.ValueOf(srcFieldValue.Bool() || dstFieldValue.Bool()))
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case reflect.String:
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if prepend {
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dstFieldValue.SetString(srcFieldValue.String() +
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dstFieldValue.String())
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} else {
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dstFieldValue.SetString(dstFieldValue.String() +
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srcFieldValue.String())
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}
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case reflect.Slice:
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if srcFieldValue.IsNil() {
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break
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}
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newSlice := reflect.MakeSlice(srcFieldValue.Type(), 0,
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dstFieldValue.Len()+srcFieldValue.Len())
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if prepend {
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newSlice = reflect.AppendSlice(newSlice, srcFieldValue)
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newSlice = reflect.AppendSlice(newSlice, dstFieldValue)
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} else if order == Append {
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newSlice = reflect.AppendSlice(newSlice, dstFieldValue)
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newSlice = reflect.AppendSlice(newSlice, srcFieldValue)
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} else {
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// replace
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newSlice = reflect.AppendSlice(newSlice, srcFieldValue)
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}
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dstFieldValue.Set(newSlice)
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case reflect.Ptr:
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if srcFieldValue.IsNil() {
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break
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}
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switch ptrKind := srcFieldValue.Type().Elem().Kind(); ptrKind {
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case reflect.Bool:
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if prepend {
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if dstFieldValue.IsNil() {
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dstFieldValue.Set(reflect.ValueOf(BoolPtr(srcFieldValue.Elem().Bool())))
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}
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} else {
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// For append, replace the original value.
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dstFieldValue.Set(reflect.ValueOf(BoolPtr(srcFieldValue.Elem().Bool())))
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}
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case reflect.Int64:
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if prepend {
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if dstFieldValue.IsNil() {
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// Int() returns Int64
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dstFieldValue.Set(reflect.ValueOf(Int64Ptr(srcFieldValue.Elem().Int())))
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}
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} else {
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// For append, replace the original value.
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// Int() returns Int64
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dstFieldValue.Set(reflect.ValueOf(Int64Ptr(srcFieldValue.Elem().Int())))
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}
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case reflect.String:
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if prepend {
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if dstFieldValue.IsNil() {
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dstFieldValue.Set(reflect.ValueOf(StringPtr(srcFieldValue.Elem().String())))
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}
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} else {
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// For append, replace the original value.
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dstFieldValue.Set(reflect.ValueOf(StringPtr(srcFieldValue.Elem().String())))
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}
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default:
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panic(fmt.Errorf("unexpected pointer kind %s", ptrKind))
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}
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}
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}
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type getStructEmptyError struct{}
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func (getStructEmptyError) Error() string { return "interface containing nil pointer" }
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func getOrCreateStruct(in interface{}) (reflect.Value, error) {
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value, err := getStruct(in)
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if _, ok := err.(getStructEmptyError); ok {
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value := reflect.ValueOf(in)
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newValue := reflect.New(value.Type().Elem())
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value.Set(newValue)
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}
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return value, err
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}
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func getStruct(in interface{}) (reflect.Value, error) {
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value := reflect.ValueOf(in)
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if !isStructPtr(value.Type()) {
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return reflect.Value{}, fmt.Errorf("expected pointer to struct, got %s", value.Type())
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}
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if value.IsNil() {
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return reflect.Value{}, getStructEmptyError{}
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}
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value = value.Elem()
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return value, nil
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}
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