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// Copyright 2022 Google LLC
//
// 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 types
import (
"errors"
"fmt"
"reflect"
"github.com/google/cel-go/common/types/ref"
)
var (
// OptionalType indicates the runtime type of an optional value.
OptionalType = NewOpaqueType("optional")
// OptionalNone is a sentinel value which is used to indicate an empty optional value.
OptionalNone = &Optional{}
)
// OptionalOf returns an optional value which wraps a concrete CEL value.
func OptionalOf(value ref.Val) *Optional {
return &Optional{value: value}
}
// Optional value which points to a value if non-empty.
type Optional struct {
value ref.Val
}
// HasValue returns true if the optional has a value.
func (o *Optional) HasValue() bool {
return o.value != nil
}
// GetValue returns the wrapped value contained in the optional.
func (o *Optional) GetValue() ref.Val {
if !o.HasValue() {
return NewErr("optional.none() dereference")
}
return o.value
}
// ConvertToNative implements the ref.Val interface method.
func (o *Optional) ConvertToNative(typeDesc reflect.Type) (any, error) {
if !o.HasValue() {
return nil, errors.New("optional.none() dereference")
}
return o.value.ConvertToNative(typeDesc)
}
// ConvertToType implements the ref.Val interface method.
func (o *Optional) ConvertToType(typeVal ref.Type) ref.Val {
switch typeVal {
case OptionalType:
return o
case TypeType:
return OptionalType
}
return NewErr("type conversion error from '%s' to '%s'", OptionalType, typeVal)
}
// Equal determines whether the values contained by two optional values are equal.
func (o *Optional) Equal(other ref.Val) ref.Val {
otherOpt, isOpt := other.(*Optional)
if !isOpt {
return False
}
if !o.HasValue() {
return Bool(!otherOpt.HasValue())
}
if !otherOpt.HasValue() {
return False
}
return o.value.Equal(otherOpt.value)
}
func (o *Optional) String() string {
if o.HasValue() {
return fmt.Sprintf("optional(%v)", o.GetValue())
}
return "optional.none()"
}
// Type implements the ref.Val interface method.
func (o *Optional) Type() ref.Type {
return OptionalType
}
// Value returns the underlying 'Value()' of the wrapped value, if present.
func (o *Optional) Value() any {
if o.value == nil {
return nil
}
return o.value.Value()
}
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