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// 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.
// Package reflect is a fork of go's standard library reflection package, which
// allows for deep equal with equality functions defined.
package reflect
import (
"fmt"
"reflect"
"strings"
)
// Equalities is a map from type to a function comparing two values of
// that type.
type Equalities map[reflect.Type]reflect.Value
// For convenience, panics on errors
func EqualitiesOrDie(funcs ...interface{}) Equalities {
e := Equalities{}
if err := e.AddFuncs(funcs...); err != nil {
panic(err)
}
return e
}
// AddFuncs is a shortcut for multiple calls to AddFunc.
func (e Equalities) AddFuncs(funcs ...interface{}) error {
for _, f := range funcs {
if err := e.AddFunc(f); err != nil {
return err
}
}
return nil
}
// AddFunc uses func as an equality function: it must take
// two parameters of the same type, and return a boolean.
func (e Equalities) AddFunc(eqFunc interface{}) error {
fv := reflect.ValueOf(eqFunc)
ft := fv.Type()
if ft.Kind() != reflect.Func {
return fmt.Errorf("expected func, got: %v", ft)
}
if ft.NumIn() != 2 {
return fmt.Errorf("expected two 'in' params, got: %v", ft)
}
if ft.NumOut() != 1 {
return fmt.Errorf("expected one 'out' param, got: %v", ft)
}
if ft.In(0) != ft.In(1) {
return fmt.Errorf("expected arg 1 and 2 to have same type, but got %v", ft)
}
var forReturnType bool
boolType := reflect.TypeOf(forReturnType)
if ft.Out(0) != boolType {
return fmt.Errorf("expected bool return, got: %v", ft)
}
e[ft.In(0)] = fv
return nil
}
// Below here is forked from go's reflect/deepequal.go
// 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
}
// unexportedTypePanic is thrown when you use this DeepEqual on something that has an
// unexported type. It indicates a programmer error, so should not occur at runtime,
// which is why it's not public and thus impossible to catch.
type unexportedTypePanic []reflect.Type
func (u unexportedTypePanic) Error() string { return u.String() }
func (u unexportedTypePanic) String() string {
strs := make([]string, len(u))
for i, t := range u {
strs[i] = fmt.Sprintf("%v", t)
}
return "an unexported field was encountered, nested like this: " + strings.Join(strs, " -> ")
}
func makeUsefulPanic(v reflect.Value) {
if x := recover(); x != nil {
if u, ok := x.(unexportedTypePanic); ok {
u = append(unexportedTypePanic{v.Type()}, u...)
x = u
}
panic(x)
}
}
// Tests for deep equality using reflected types. The map argument tracks
// comparisons that have already been seen, which allows short circuiting on
// recursive types.
// equateNilAndEmpty controls whether empty maps/slices are equivalent to nil
func (e Equalities) deepValueEqual(v1, v2 reflect.Value, visited map[visit]bool, equateNilAndEmpty bool, depth int) bool {
defer makeUsefulPanic(v1)
if !v1.IsValid() || !v2.IsValid() {
return v1.IsValid() == v2.IsValid()
}
if v1.Type() != v2.Type() {
return false
}
if fv, ok := e[v1.Type()]; ok {
return fv.Call([]reflect.Value{v1, v2})[0].Bool()
}
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:
// We don't need to check length here because length is part of
// an array's type, which has already been filtered for.
for i := 0; i < v1.Len(); i++ {
if !e.deepValueEqual(v1.Index(i), v2.Index(i), visited, equateNilAndEmpty, depth+1) {
return false
}
}
return true
case reflect.Slice:
if equateNilAndEmpty {
if (v1.IsNil() || v1.Len() == 0) != (v2.IsNil() || v2.Len() == 0) {
return false
}
if v1.IsNil() || v1.Len() == 0 {
return true
}
} else {
if v1.IsNil() != v2.IsNil() {
return false
}
// Optimize nil and empty cases
// Two lists that are BOTH nil are equal
// No need to check v2 is nil since v1.IsNil == v2.IsNil from above
if v1.IsNil() {
return true
}
// Two lists that are both empty and both non nil are equal
if v1.Len() == 0 || v2.Len() == 0 {
return true
}
}
if v1.Len() != v2.Len() {
return false
}
if v1.Pointer() == v2.Pointer() {
return true
}
for i := 0; i < v1.Len(); i++ {
if !e.deepValueEqual(v1.Index(i), v2.Index(i), visited, equateNilAndEmpty, depth+1) {
return false
}
}
return true
case reflect.Interface:
if v1.IsNil() || v2.IsNil() {
return v1.IsNil() == v2.IsNil()
}
return e.deepValueEqual(v1.Elem(), v2.Elem(), visited, equateNilAndEmpty, depth+1)
case reflect.Ptr:
return e.deepValueEqual(v1.Elem(), v2.Elem(), visited, equateNilAndEmpty, depth+1)
case reflect.Struct:
for i, n := 0, v1.NumField(); i < n; i++ {
if !e.deepValueEqual(v1.Field(i), v2.Field(i), visited, equateNilAndEmpty, depth+1) {
return false
}
}
return true
case reflect.Map:
if equateNilAndEmpty {
if (v1.IsNil() || v1.Len() == 0) != (v2.IsNil() || v2.Len() == 0) {
return false
}
if v1.IsNil() || v1.Len() == 0 {
return true
}
} else {
if v1.IsNil() != v2.IsNil() {
return false
}
// Optimize nil and empty cases
// Two maps that are BOTH nil are equal
// No need to check v2 is nil since v1.IsNil == v2.IsNil from above
if v1.IsNil() {
return true
}
// Two maps that are both empty and both non nil are equal
if v1.Len() == 0 || v2.Len() == 0 {
return true
}
}
if v1.Len() != v2.Len() {
return false
}
if v1.Pointer() == v2.Pointer() {
return true
}
for _, k := range v1.MapKeys() {
if !e.deepValueEqual(v1.MapIndex(k), v2.MapIndex(k), visited, equateNilAndEmpty, depth+1) {
return false
}
}
return true
case reflect.Func:
if v1.IsNil() && v2.IsNil() {
return true
}
// Can't do better than this:
return false
default:
// Normal equality suffices
if !v1.CanInterface() || !v2.CanInterface() {
panic(unexportedTypePanic{})
}
return v1.Interface() == v2.Interface()
}
}
// DeepEqual is like reflect.DeepEqual, but focused on semantic equality
// instead of memory equality.
//
// It will use e's equality functions if it finds types that match.
//
// An empty slice *is* equal to a nil slice for our purposes; same for maps.
//
// Unexported field members cannot be compared and will cause an informative panic; you must add an Equality
// function for these types.
func (e Equalities) DeepEqual(a1, a2 interface{}) bool {
return e.deepEqual(a1, a2, true)
}
func (e Equalities) DeepEqualWithNilDifferentFromEmpty(a1, a2 interface{}) bool {
return e.deepEqual(a1, a2, false)
}
func (e Equalities) deepEqual(a1, a2 interface{}, equateNilAndEmpty bool) 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 e.deepValueEqual(v1, v2, make(map[visit]bool), equateNilAndEmpty, 0)
}
func (e Equalities) deepValueDerive(v1, v2 reflect.Value, visited map[visit]bool, depth int) bool {
defer makeUsefulPanic(v1)
if !v1.IsValid() || !v2.IsValid() {
return v1.IsValid() == v2.IsValid()
}
if v1.Type() != v2.Type() {
return false
}
if fv, ok := e[v1.Type()]; ok {
return fv.Call([]reflect.Value{v1, v2})[0].Bool()
}
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:
// We don't need to check length here because length is part of
// an array's type, which has already been filtered for.
for i := 0; i < v1.Len(); i++ {
if !e.deepValueDerive(v1.Index(i), v2.Index(i), visited, depth+1) {
return false
}
}
return true
case reflect.Slice:
if v1.IsNil() || v1.Len() == 0 {
return true
}
if v1.Len() > v2.Len() {
return false
}
if v1.Pointer() == v2.Pointer() {
return true
}
for i := 0; i < v1.Len(); i++ {
if !e.deepValueDerive(v1.Index(i), v2.Index(i), visited, depth+1) {
return false
}
}
return true
case reflect.String:
if v1.Len() == 0 {
return true
}
if v1.Len() > v2.Len() {
return false
}
return v1.String() == v2.String()
case reflect.Interface:
if v1.IsNil() {
return true
}
return e.deepValueDerive(v1.Elem(), v2.Elem(), visited, depth+1)
case reflect.Pointer:
if v1.IsNil() {
return true
}
return e.deepValueDerive(v1.Elem(), v2.Elem(), visited, depth+1)
case reflect.Struct:
for i, n := 0, v1.NumField(); i < n; i++ {
if !e.deepValueDerive(v1.Field(i), v2.Field(i), visited, depth+1) {
return false
}
}
return true
case reflect.Map:
if v1.IsNil() || v1.Len() == 0 {
return true
}
if v1.Len() > v2.Len() {
return false
}
if v1.Pointer() == v2.Pointer() {
return true
}
for _, k := range v1.MapKeys() {
if !e.deepValueDerive(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
default:
// Normal equality suffices
if !v1.CanInterface() || !v2.CanInterface() {
panic(unexportedTypePanic{})
}
return v1.Interface() == v2.Interface()
}
}
// DeepDerivative is similar to DeepEqual except that unset fields in a1 are
// ignored (not compared). This allows us to focus on the fields that matter to
// the semantic comparison.
//
// The unset fields include a nil pointer and an empty string.
func (e Equalities) DeepDerivative(a1, a2 interface{}) bool {
if a1 == nil {
return true
}
v1 := reflect.ValueOf(a1)
v2 := reflect.ValueOf(a2)
if v1.Type() != v2.Type() {
return false
}
return e.deepValueDerive(v1, v2, make(map[visit]bool), 0)
}