enum

README

Enum

Auto generate your types and implement various interfaces by only creating constants. All you need to do is add a go generate line above your constant group.

//go:generate go-enum --trim "Post" --format snake
const (
    PostCreate PostType = 0
    PostRead   PostType = 2
    PostUpdate PostType = 4
    PostDelete PostType = 8
)

If you just want an enum and don't care about the value, use Go's iota.

//go:generate go-enum --trim "Direction" --format upper
const (
    DirectionUp Direction = iota
    DirectionDown
    DirectionLeft
    DirectionRight
)

If you want to use the actual constant and it's value but treat it as an enum to support validation and conversion from a fixed type, set the value to a string. The Stringer() interface will be implemented just like other enums but by adding --with-value you implement Value() which returns the constants actual value.

//go:generate go-enum --trim "Answer" --format capitalize-first --no-json --with-value
const (
	AnswerYes   YesOrNo = "Y"
	AnswerNo    YesOrNo = "N"
	AnswerMaybe YesOrNo = "M"
)

You can now create types from either the constant value or the trimmed constant name and also validate the type if created manually. If the constnat value is needed, e.g. while storing you can use Value() but for printing String() will return the full name.

func main() {
	var (
		y, _ = YesOrNoFromString("Y")     // AnswerYes
		m, _ = YesOrNoFromString("Maybe") // AnswerMaybe
		bad  = YesOrNo("Bad")
	)

	fmt.Println(y.String())   // Yes
	fmt.Println(m.Value())    // M
	fmt.Println(m.Valid())    // True
	fmt.Println(bad.Valid())  // False
	fmt.Println(bad.String()) // ""
	fmt.Println(bad.Value())  // ""
}

See the example folder for example generated code.

Installation

go get -u github.com/bombsimon/enum/...

Interfaces

The current interfaces that will be implemented are

• FromString - Convert a string to the enum type
• String - Get the string value for the enum
• Value - Get the actual value of the enum
• Valid - Returns true or false if the enum is valid
• MarshalJSON - JSON marshal interface
• UnmarshalJSON - JSON unmarshal interface

Flags

The following flags can be used.

• json - Don't generate JSON interface by setting to false
• value - Set to true to generate Value() and allow FromString() to accept the enums actual value as well
• format - The way to format the constant.
• trim - What part of the constant to trim.

Format functions

The string representation of the enum can beformatted in multiple ways. The value will be the name of the constant mins the part that's been trimmed off by setting --trim. Below are examples assuming --trim is set to Prefix.

Method	Flag name	Constant	String() value
Snake case	snake	PrefixThisString	this_string
Camel case	camel	PrefixSomeValue	SomeValue
Upper	upper	PrefixMyValue	MYVALUE
Lower	lower	PrefixMoreConstants	moreconstants
First letter	first	PrefixJustFirstLetter	J (will preserve casing)
First letter upper	first-upper	PrefixSomeValue	S (will convert to upper)
First letter lower	first-lower	PrefixAnotherValue	a (will convert to lower)
Capitalize first word	capitalize-first	PrefixThisIsWords	This is words
Capitalzie all words	capitalize-all	PrefixThisIsAlsoWords	This Is Also Words

Documentation

Index

• func CapitalizeAll(s string) string
• func CapitalizeFirst(s string) string
• func FirstLetter(s string) string
• func FirstLetterLower(s string) string
• func FirstLetterUpper(s string) string
• func FormatFuncs() map[string]func(s string) string
• type Enum
• type FormatFunc
• type Parser
  • func New(file, trimPrefix string, lineStart int, json, value bool, ff FormatFunc) *Parser
  • func (ep *Parser) CreateFile() error
  • func (ep *Parser) GetEnum(fileData []byte) error
  • func (ep *Parser) GetEnumFromFile() error

Functions

func CapitalizeAll

func CapitalizeAll(s string) string

func CapitalizeFirst

func CapitalizeFirst(s string) string

func FirstLetter

func FirstLetter(s string) string

func FirstLetterLower

func FirstLetterLower(s string) string

func FirstLetterUpper

func FirstLetterUpper(s string) string

func FormatFuncs

func FormatFuncs() map[string]func(s string) string

Types

type Enum

type Enum struct {
	Int    int
	Value  string
	Name   string
	String string
}

Enum is one enum with a number mapped to a string. The name of the enun will be the constant value.

type FormatFunc

type FormatFunc func(string) string

FormatFunc is the function to format the string value of the enum.

type Parser

type Parser struct {
	Enums       []Enum
	File        string
	Format      FormatFunc
	LineStart   int
	Package     string
	TrimPrefix  string
	TypeName    string
	ValueType   string
	WithJSON    bool
	WithValue   bool
	GeneratedAt string
}

Parser is the parser that will search a file for constants and add each constant as an enum.

func New

func New(file, trimPrefix string, lineStart int, json, value bool, ff FormatFunc) *Parser

New will create a new parser to use for a given file.

func (*Parser) CreateFile

func (ep *Parser) CreateFile() error

CreateFile will create a file on disk with the enum found.

func (*Parser) GetEnum

func (ep *Parser) GetEnum(fileData []byte) error

GetEnum will find all enum in one const block starting from the parsers LineStart.

func (*Parser) GetEnumFromFile

func (ep *Parser) GetEnumFromFile() error

GetEnumFromFile will read a file and pass the content to GetEnum()