mapgen

README

mapgen

mapgen is a Go code generation tool for creating utility functions and maps for constants defined in a specific type. It dynamically generates helper functions to simplify working with constants, such as converting them to strings, extracting keys, and validating values.

Installation

To install mapgen, use the following command:

go install github.com/c9s/mapgen@latest

This will install the mapgen binary to your $GOPATH/bin directory.

Usage

The mapgen tool takes a type name and generates utility functions and maps for constants of that type.

Command-Line Flags

Flag	Description
-type	The name of the type for which constants are to be processed (required).
-output	Output file name. Defaults to <type>map.go.
-stdout	Print the generated code to standard output instead of writing to a file.

Examples

Generate Code for PrivateChannel

Suppose you have a type PrivateChannel with several constants:

type PrivateChannel string

const (
    PrivateChannelOrder PrivateChannel = "order"
    PrivateChannelTrade PrivateChannel = "trade"
    // @group Margin
    PrivateChannelMarginOrder PrivateChannel = "margin_order"
)

Run mapgen as follows:

mapgen -type PrivateChannel

This will generate a file privatechannelmap.go with the following content:

// Code generated by mapgen; DO NOT EDIT.
package main

var AllPrivateChannel = map[PrivateChannel]struct{}{
    PrivateChannelOrder: {},
    PrivateChannelTrade: {},
    PrivateChannelMarginOrder: {},
}

var AllMarginPrivateChannel = map[PrivateChannel]struct{}{
    PrivateChannelMarginOrder: {},
}

// PrivateChannelStrings converts a slice of PrivateChannel to a slice of string
func PrivateChannelStrings(slice []PrivateChannel) (out []string) {
    for _, el := range slice {
        out = append(out, string(el))
    }
    return out
}

// PrivateChannelKeys converts a map of PrivateChannel to a slice of PrivateChannel
func PrivateChannelKeys(values map[PrivateChannel]struct{}) (slice []PrivateChannel) {
    for k := range values {
        slice = append(slice, k)
    }
    return slice
}

// ValidatePrivateChannel validates a value of type PrivateChannel
func ValidatePrivateChannel(ch PrivateChannel) bool {
    _, ok := AllPrivateChannel[ch]
    return ok
}

Use -stdout to Print Generated Code

To print the generated code to the terminal instead of writing it to a file, use the -stdout flag:

mapgen -type PrivateChannel -stdout

Custom Output File

To specify a custom output file name, use the -output flag:

mapgen -type PrivateChannel -output custom_file.go

Features

• Dynamically generates:

  • A map of all constants for the type.
  • Grouped maps based on @group annotations in comments.
  • Utility functions:
    • Convert constants to strings (TypeStrings).
    • Extract keys from maps (TypeKeys).
    • Validate values (ValidateType).

• Supports grouping constants using @group annotations.

License

mapgen is released under the MIT License. See LICENSE for more details.