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98 lines
2.8 KiB
Go
98 lines
2.8 KiB
Go
// Copyright 2013 Dario Castañé. All rights reserved.
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Based on src/pkg/reflect/deepequal.go from official
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// golang's stdlib.
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package mergo
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import (
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"errors"
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"reflect"
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)
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// Errors reported by Mergo when it finds invalid arguments.
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var (
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ErrNilArguments = errors.New("src and dst must not be nil")
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ErrDifferentArgumentsTypes = errors.New("src and dst must be of same type")
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ErrNotSupported = errors.New("only structs and maps are supported")
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ErrExpectedMapAsDestination = errors.New("dst was expected to be a map")
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ErrExpectedStructAsDestination = errors.New("dst was expected to be a struct")
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)
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// During deepMerge, must keep track of checks that are
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// in progress. The comparison algorithm assumes that all
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// checks in progress are true when it reencounters them.
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// Visited are stored in a map indexed by 17 * a1 + a2;
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type visit struct {
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ptr uintptr
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typ reflect.Type
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next *visit
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}
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// From src/pkg/encoding/json/encode.go.
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func isEmptyValue(v reflect.Value) bool {
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switch v.Kind() {
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case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
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return v.Len() == 0
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case reflect.Bool:
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return !v.Bool()
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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return v.Int() == 0
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
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return v.Uint() == 0
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case reflect.Float32, reflect.Float64:
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return v.Float() == 0
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case reflect.Interface, reflect.Ptr:
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if v.IsNil() {
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return true
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}
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return isEmptyValue(v.Elem())
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case reflect.Func:
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return v.IsNil()
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case reflect.Invalid:
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return true
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}
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return false
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}
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func resolveValues(dst, src interface{}) (vDst, vSrc reflect.Value, err error) {
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if dst == nil || src == nil {
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err = ErrNilArguments
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return
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}
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vDst = reflect.ValueOf(dst).Elem()
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if vDst.Kind() != reflect.Struct && vDst.Kind() != reflect.Map {
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err = ErrNotSupported
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return
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}
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vSrc = reflect.ValueOf(src)
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// We check if vSrc is a pointer to dereference it.
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if vSrc.Kind() == reflect.Ptr {
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vSrc = vSrc.Elem()
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}
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return
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}
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// Traverses recursively both values, assigning src's fields values to dst.
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// The map argument tracks comparisons that have already been seen, which allows
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// short circuiting on recursive types.
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func deeper(dst, src reflect.Value, visited map[uintptr]*visit, depth int) (err error) {
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if dst.CanAddr() {
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addr := dst.UnsafeAddr()
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h := 17 * addr
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seen := visited[h]
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typ := dst.Type()
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for p := seen; p != nil; p = p.next {
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if p.ptr == addr && p.typ == typ {
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return nil
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}
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}
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// Remember, remember...
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visited[h] = &visit{addr, typ, seen}
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}
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return // TODO refactor
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}
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