githaven/vendor/github.com/smartystreets/assertions/internal/oglematchers/identical_to.go

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// Copyright 2012 Aaron Jacobs. All Rights Reserved.
// Author: aaronjjacobs@gmail.com (Aaron Jacobs)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package oglematchers
import (
"errors"
"fmt"
"reflect"
)
// Is the type comparable according to the definition here?
//
// http://weekly.golang.org/doc/go_spec.html#Comparison_operators
//
func isComparable(t reflect.Type) bool {
switch t.Kind() {
case reflect.Array:
return isComparable(t.Elem())
case reflect.Struct:
for i := 0; i < t.NumField(); i++ {
if !isComparable(t.Field(i).Type) {
return false
}
}
return true
case reflect.Slice, reflect.Map, reflect.Func:
return false
}
return true
}
// Should the supplied type be allowed as an argument to IdenticalTo?
func isLegalForIdenticalTo(t reflect.Type) (bool, error) {
// Allow the zero type.
if t == nil {
return true, nil
}
// Reference types are always okay; we compare pointers.
switch t.Kind() {
case reflect.Slice, reflect.Map, reflect.Func, reflect.Chan:
return true, nil
}
// Reject other non-comparable types.
if !isComparable(t) {
return false, errors.New(fmt.Sprintf("%v is not comparable", t))
}
return true, nil
}
// IdenticalTo(x) returns a matcher that matches values v with type identical
// to x such that:
//
// 1. If v and x are of a reference type (slice, map, function, channel), then
// they are either both nil or are references to the same object.
//
// 2. Otherwise, if v and x are not of a reference type but have a valid type,
// then v == x.
//
// If v and x are both the invalid type (which results from the predeclared nil
// value, or from nil interface variables), then the matcher is satisfied.
//
// This function will panic if x is of a value type that is not comparable. For
// example, x cannot be an array of functions.
func IdenticalTo(x interface{}) Matcher {
t := reflect.TypeOf(x)
// Reject illegal arguments.
if ok, err := isLegalForIdenticalTo(t); !ok {
panic("IdenticalTo: " + err.Error())
}
return &identicalToMatcher{x}
}
type identicalToMatcher struct {
x interface{}
}
func (m *identicalToMatcher) Description() string {
t := reflect.TypeOf(m.x)
return fmt.Sprintf("identical to <%v> %v", t, m.x)
}
func (m *identicalToMatcher) Matches(c interface{}) error {
// Make sure the candidate's type is correct.
t := reflect.TypeOf(m.x)
if ct := reflect.TypeOf(c); t != ct {
return NewFatalError(fmt.Sprintf("which is of type %v", ct))
}
// Special case: two values of the invalid type are always identical.
if t == nil {
return nil
}
// Handle reference types.
switch t.Kind() {
case reflect.Slice, reflect.Map, reflect.Func, reflect.Chan:
xv := reflect.ValueOf(m.x)
cv := reflect.ValueOf(c)
if xv.Pointer() == cv.Pointer() {
return nil
}
return errors.New("which is not an identical reference")
}
// Are the values equal?
if m.x == c {
return nil
}
return errors.New("")
}