go-enum
An enum generator for go
How it works
The goal of go-enum is to create an easy to use enum generator that will take a decorated type declaration like type EnumName int and create the associated constant values and funcs that will make life a little easier for adding new values. It's not perfect, but I think it's useful.
I took the output of the Stringer command as the String() method, and added a way to parse a string value.
Command options
go-enum --help
Options:
-h, --help display help information
-f, --file *The file(s) to generate enums. Use more than one flag for more files.
--noprefix Prevents the constants generated from having the Enum as a prefix.
--lower Adds lowercase variants of the enum strings for lookup.
--marshal Adds text (and inherently json) marshalling functions.
--sql Adds SQL database scan and value functions.
--flag Adds golang flag functions.
--prefix Replaces the prefix with a user one.
--names Generates a 'Names() []string' function, and adds the possible enum values in the error response during parsing
--nocamel Removes the snake_case to CamelCase name changing
Syntax
The parser looks for comments on your type defs and parse the enum declarations from it. The parser will look for ENUM( and continue to look for comma separated values until it finds a ). You can put values on the same line, or on multiple lines.
If you need to have a specific value jump in the enum, you can now specify that by adding =numericValue to the enum declaration. Keep in mind, this resets the data for all following values. So if you specify 50 in the middle of an enum, each value after that will be 51, 52, 53...
Comments
You can use comments inside enum that start with //
The comment must be at the end of the same line as the comment value, only then it will be added as a comment to the generated constant.
// Commented is an enumeration of commented values
/*
ENUM(
value1 // Commented value 1
value2
value3 // Commented value 3
)
*/
type Commented int
The generated comments in code will look something like:
...
const (
// CommentedValue1 is a Commented of type Value1
// Commented value 1
CommentedValue1 Commented = iota
// CommentedValue2 is a Commented of type Value2
CommentedValue2
// CommentedValue3 is a Commented of type Value3
// Commented value 3
CommentedValue3
)
...
Example
There are a few examples in the example directory. I've included one here for easy access, but can't guarantee it's up to date.
// Color is an enumeration of colors that are allowed.
/* ENUM(
Black, White, Red
Green = 33 // Green starts with 33
*/
// Blue
// grey=
// yellow
// blue-green
// red-orange
// yellow_green
// red-orange-blue
// )
type Color int32
The generated code will look something like:
// Code generated by go-enum
// DO NOT EDIT!
package example
import (
"fmt"
"strings"
)
const (
// ColorBlack is a Color of type Black
ColorBlack Color = iota
// ColorWhite is a Color of type White
ColorWhite
// ColorRed is a Color of type Red
ColorRed
// ColorGreen is a Color of type Green
// Green starts with 33
ColorGreen Color = iota + 30
// ColorBlue is a Color of type Blue
ColorBlue
// ColorGrey is a Color of type Grey
ColorGrey
// ColorYellow is a Color of type Yellow
ColorYellow
// ColorBlueGreen is a Color of type Blue-Green
ColorBlueGreen
// ColorRedOrange is a Color of type Red-Orange
ColorRedOrange
// ColorYellowGreen is a Color of type Yellow_green
ColorYellowGreen
// ColorRedOrangeBlue is a Color of type Red-Orange-Blue
ColorRedOrangeBlue
)
const _ColorName = "BlackWhiteRedGreenBluegreyyellowblue-greenred-orangeyellow_greenred-orange-blue"
var _ColorMap = map[Color]string{
0: _ColorName[0:5],
1: _ColorName[5:10],
2: _ColorName[10:13],
33: _ColorName[13:18],
34: _ColorName[18:22],
35: _ColorName[22:26],
36: _ColorName[26:32],
37: _ColorName[32:42],
38: _ColorName[42:52],
39: _ColorName[52:64],
40: _ColorName[64:79],
}
// String implements the Stringer interface.
func (x Color) String() string {
if str, ok := _ColorMap[x]; ok {
return str
}
return fmt.Sprintf("Color(%d)", x)
}
var _ColorValue = map[string]Color{
_ColorName[0:5]: 0,
strings.ToLower(_ColorName[0:5]): 0,
_ColorName[5:10]: 1,
strings.ToLower(_ColorName[5:10]): 1,
_ColorName[10:13]: 2,
strings.ToLower(_ColorName[10:13]): 2,
_ColorName[13:18]: 33,
strings.ToLower(_ColorName[13:18]): 33,
_ColorName[18:22]: 34,
strings.ToLower(_ColorName[18:22]): 34,
_ColorName[22:26]: 35,
strings.ToLower(_ColorName[22:26]): 35,
_ColorName[26:32]: 36,
strings.ToLower(_ColorName[26:32]): 36,
_ColorName[32:42]: 37,
strings.ToLower(_ColorName[32:42]): 37,
_ColorName[42:52]: 38,
strings.ToLower(_ColorName[42:52]): 38,
_ColorName[52:64]: 39,
strings.ToLower(_ColorName[52:64]): 39,
_ColorName[64:79]: 40,
strings.ToLower(_ColorName[64:79]): 40,
}
// ParseColor attempts to convert a string to a Color
func ParseColor(name string) (Color, error) {
if x, ok := _ColorValue[name]; ok {
return x, nil
}
return Color(0), fmt.Errorf("%s is not a valid Color", name)
}
// MarshalText implements the text marshaller method
func (x Color) MarshalText() ([]byte, error) {
return []byte(x.String()), nil
}
// UnmarshalText implements the text unmarshaller method
func (x *Color) UnmarshalText(text []byte) error {
name := string(text)
tmp, err := ParseColor(name)
if err != nil {
return err
}
*x = tmp
return nil
}
Adding it to your project
go get github.com/abice/go-enum- Add a go:generate line to your file like so...
//go:generate go-enum -f=$GOFILE --marshal - Run go generate like so
go generate ./... - Enjoy your newly created Enumeration
