Source: optional.go in package cloud.google.com/go/internal/optional

Copyright 2016 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 optional provides versions of primitive types that can be nil. These are useful in methods that update some of an API object's fields.

package optional

import (
	"fmt"
	"strings"
	"time"
)

Bool is either a bool or nil.

	Bool interface{}

String is either a string or nil.

	String interface{}

Int is either an int or nil.

	Int interface{}

Uint is either a uint or nil.

	Uint interface{}

Float64 is either a float64 or nil.

	Float64 interface{}

Duration is either a time.Duration or nil.

	Duration interface{}
)

ToBool returns its argument as a bool. It panics if its argument is nil or not a bool.

func ToBool(v Bool) bool {
	x, ok := v.(bool)
	if !ok {
		doPanic("Bool", v)
	}
	return x
}

ToString returns its argument as a string. It panics if its argument is nil or not a string.

func ToString(v String) string {
	x, ok := v.(string)
	if !ok {
		doPanic("String", v)
	}
	return x
}

ToInt returns its argument as an int. It panics if its argument is nil or not an int.

func ToInt(v Int) int {
	x, ok := v.(int)
	if !ok {
		doPanic("Int", v)
	}
	return x
}

ToUint returns its argument as a uint. It panics if its argument is nil or not a uint.

func ToUint(v Uint) uint {
	x, ok := v.(uint)
	if !ok {
		doPanic("Uint", v)
	}
	return x
}

ToFloat64 returns its argument as a float64. It panics if its argument is nil or not a float64.

func ToFloat64(v Float64) float64 {
	x, ok := v.(float64)
	if !ok {
		doPanic("Float64", v)
	}
	return x
}

ToDuration returns its argument as a time.Duration. It panics if its argument is nil or not a time.Duration.

func ToDuration(v Duration) time.Duration {
	x, ok := v.(time.Duration)
	if !ok {
		doPanic("Duration", v)
	}
	return x
}

func doPanic(capType string, v interface{}) {
	panic(fmt.Sprintf("optional.%s value should be %s, got %T", capType, strings.ToLower(capType), v))