127 lines
3.1 KiB
Go
127 lines
3.1 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) (b bool) {
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if !v1.IsValid() || !v2.IsValid() {
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return v1.IsValid() == v2.IsValid()
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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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if v1.CanAddr() && v2.CanAddr() {
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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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}
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switch v1.Kind() {
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case Array:
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if v1.Len() != v2.Len() {
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return false
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}
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for i := 0; i < v1.Len(); i++ {
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if !deepValueEqual(v1.Index(i), v2.Index(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 Slice:
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if v1.Len() != v2.Len() {
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return false
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}
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for i := 0; i < v1.Len(); i++ {
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if !deepValueEqual(v1.Index(i), v2.Index(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 Interface:
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if v1.IsNil() || v2.IsNil() {
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return v1.IsNil() == v2.IsNil()
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}
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return deepValueEqual(v1.Elem(), v2.Elem(), visited, depth+1)
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case Ptr:
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return deepValueEqual(v1.Elem(), v2.Elem(), visited, depth+1)
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case Struct:
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for i, n := 0, v1.NumField(); i < n; i++ {
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if !deepValueEqual(v1.Field(i), v2.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 Map:
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if v1.Len() != v2.Len() {
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return false
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}
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for _, k := range v1.MapKeys() {
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if !deepValueEqual(v1.MapIndex(k), v2.MapIndex(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 := ValueOf(a1)
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v2 := ValueOf(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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