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// Copied with small adaptations from the reflect package in the
// Go source tree.
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Deep equality test via reflection
package checkers
import "reflect"
// During deepValueEqual, must keep track of checks that are
// in progress. The comparison algorithm assumes that all
// checks in progress are true when it reencounters them.
// Visited comparisons are stored in a map indexed by visit.
type visit struct {
a1 uintptr
a2 uintptr
typ reflect.Type
}
// Tests for deep equality using reflected types. The map argument tracks
// comparisons that have already been seen, which allows short circuiting on
// recursive types.
func deepValueEqual(v1, v2 reflect.Value, visited map[visit]bool, depth int) bool {
if !v1.IsValid() || !v2.IsValid() {
return v1.IsValid() == v2.IsValid()
}
if v1.Type() != v2.Type() {
return false
}
// if depth > 10 { panic("deepValueEqual") } // for debugging
hard := func(k reflect.Kind) bool {
switch k {
case reflect.Array, reflect.Map, reflect.Slice, reflect.Struct:
return true
}
return false
}
if v1.CanAddr() && v2.CanAddr() && hard(v1.Kind()) {
addr1 := v1.UnsafeAddr()
addr2 := v2.UnsafeAddr()
if addr1 > addr2 {
// Canonicalize order to reduce number of entries in visited.
addr1, addr2 = addr2, addr1
}
// Short circuit if references are identical ...
if addr1 == addr2 {
return true
}
// ... or already seen
typ := v1.Type()
v := visit{addr1, addr2, typ}
if visited[v] {
return true
}
// Remember for later.
visited[v] = true
}
switch v1.Kind() {
case reflect.Array:
if v1.Len() != v2.Len() {
return false
}
for i := 0; i < v1.Len(); i++ {
if !deepValueEqual(v1.Index(i), v2.Index(i), visited, depth+1) {
return false
}
}
return true
case reflect.Slice:
// No check for nil == nil here.
if v1.Len() != v2.Len() {
return false
}
if v1.Pointer() == v2.Pointer() {
return true
}
for i := 0; i < v1.Len(); i++ {
if !deepValueEqual(v1.Index(i), v2.Index(i), visited, depth+1) {
return false
}
}
return true
case reflect.Interface:
if v1.IsNil() || v2.IsNil() {
return v1.IsNil() == v2.IsNil()
}
return deepValueEqual(v1.Elem(), v2.Elem(), visited, depth+1)
case reflect.Ptr:
return deepValueEqual(v1.Elem(), v2.Elem(), visited, depth+1)
case reflect.Struct:
for i, n := 0, v1.NumField(); i < n; i++ {
if !deepValueEqual(v1.Field(i), v2.Field(i), visited, depth+1) {
return false
}
}
return true
case reflect.Map:
// No check for nil == nil here.
if v1.Len() != v2.Len() {
return false
}
if v1.Pointer() == v2.Pointer() {
return true
}
for _, k := range v1.MapKeys() {
if !deepValueEqual(v1.MapIndex(k), v2.MapIndex(k), visited, depth+1) {
return false
}
}
return true
case reflect.Func:
if v1.IsNil() && v2.IsNil() {
return true
}
// Can't do better than this:
return false
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return v1.Int() == v2.Int()
case reflect.Uint, reflect.Uintptr, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
return v1.Uint() == v2.Uint()
case reflect.Float32, reflect.Float64:
return v1.Float() == v2.Float()
case reflect.Complex64, reflect.Complex128:
return v1.Complex() == v2.Complex()
case reflect.Bool:
return v1.Bool() == v2.Bool()
case reflect.String:
return v1.String() == v2.String()
case reflect.Chan, reflect.UnsafePointer:
return v1.Pointer() == v2.Pointer()
default:
panic("unexpected type " + v1.Type().String())
}
}
// DeepEqual tests for deep equality. It uses normal == equality where
// possible but will scan elements of arrays, slices, maps, and fields of
// structs. In maps, keys are compared with == but elements use deep
// equality. DeepEqual correctly handles recursive types. Functions are equal
// only if they are both nil.
// DeepEqual differs from reflect.DeepEqual in that an empty
// slice is equal to a nil slice, and an empty map is equal to a nil map.
func DeepEqual(a1, a2 interface{}) bool {
if a1 == nil || a2 == nil {
return a1 == a2
}
v1 := reflect.ValueOf(a1)
v2 := reflect.ValueOf(a2)
if v1.Type() != v2.Type() {
return false
}
return deepValueEqual(v1, v2, make(map[visit]bool), 0)
}
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