136 lines
3.2 KiB
Go
136 lines
3.2 KiB
Go
// 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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// Deep equality test via reflection
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package reflect
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// During deepValueEqual, 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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a1 uintptr
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a2 uintptr
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typ Type
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next *visit
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}
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// Tests for deep equality using reflected types. The map argument tracks
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// comparisons that have already been seen, which allows short circuiting on
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// recursive types.
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func deepValueEqual(v1, v2 Value, visited map[uintptr]*visit, depth int) bool {
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if v1 == nil || v2 == nil {
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return v1 == v2
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}
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if v1.Type() != v2.Type() {
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return false
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}
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// if depth > 10 { panic("deepValueEqual") } // for debugging
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addr1 := v1.UnsafeAddr()
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addr2 := v2.UnsafeAddr()
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if addr1 > addr2 {
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// Canonicalize order to reduce number of entries in visited.
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addr1, addr2 = addr2, addr1
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}
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// Short circuit if references are identical ...
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if addr1 == addr2 {
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return true
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}
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// ... or already seen
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h := 17*addr1 + addr2
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seen := visited[h]
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typ := v1.Type()
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for p := seen; p != nil; p = p.next {
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if p.a1 == addr1 && p.a2 == addr2 && p.typ == typ {
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return true
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}
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}
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// Remember for later.
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visited[h] = &visit{addr1, addr2, typ, seen}
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switch v := v1.(type) {
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case *ArrayValue:
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arr1 := v
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arr2 := v2.(*ArrayValue)
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if arr1.Len() != arr2.Len() {
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return false
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}
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for i := 0; i < arr1.Len(); i++ {
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if !deepValueEqual(arr1.Elem(i), arr2.Elem(i), visited, depth+1) {
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return false
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}
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}
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return true
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case *SliceValue:
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arr1 := v
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arr2 := v2.(*SliceValue)
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if arr1.Len() != arr2.Len() {
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return false
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}
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for i := 0; i < arr1.Len(); i++ {
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if !deepValueEqual(arr1.Elem(i), arr2.Elem(i), visited, depth+1) {
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return false
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}
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}
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return true
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case *InterfaceValue:
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i1 := v.Interface()
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i2 := v2.Interface()
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if i1 == nil || i2 == nil {
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return i1 == i2
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}
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return deepValueEqual(NewValue(i1), NewValue(i2), visited, depth+1)
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case *PtrValue:
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return deepValueEqual(v.Elem(), v2.(*PtrValue).Elem(), visited, depth+1)
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case *StructValue:
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struct1 := v
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struct2 := v2.(*StructValue)
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for i, n := 0, v.NumField(); i < n; i++ {
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if !deepValueEqual(struct1.Field(i), struct2.Field(i), visited, depth+1) {
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return false
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}
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}
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return true
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case *MapValue:
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map1 := v
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map2 := v2.(*MapValue)
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if map1.Len() != map2.Len() {
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return false
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}
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for _, k := range map1.Keys() {
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if !deepValueEqual(map1.Elem(k), map2.Elem(k), visited, depth+1) {
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return false
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}
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}
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return true
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default:
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// Normal equality suffices
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return v1.Interface() == v2.Interface()
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}
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panic("Not reached")
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}
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// DeepEqual tests for deep equality. It uses normal == equality where possible
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// but will scan members of arrays, slices, and fields of structs. It correctly
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// handles recursive types.
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func DeepEqual(a1, a2 interface{}) bool {
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if a1 == nil || a2 == nil {
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return a1 == a2
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}
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v1 := NewValue(a1)
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v2 := NewValue(a2)
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if v1.Type() != v2.Type() {
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return false
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}
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return deepValueEqual(v1, v2, make(map[uintptr]*visit), 0)
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}
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