akashi

README

灯 - Akashi

akashi is a Go library that provides a utility to compute and display the differences between two Go values. The core functionality is exposed through the DiffString function.

Features

• Compares two Go values of any type.
• Returns a human-readable string representing the differences.
• Supports the fmt.Stringer interface for readable output. For example, time.Time values are displayed as time.Time("2025-02-03 23:03:15 +0000 UTC").

Installation

To install akashi, use go get:

go get github.com/seiyab/akashi

Usage

The primary function in this library is DiffString. It takes two interface{} values and an optional list of Options.

package main

import (
	"fmt"
	"github.com/seiyab/akashi"
)

func main() {
	type User struct {
		ID           string
		Name         string
		RegisteredAt time.Time
	}

	obj1 := User{
		ID:           "123",
		Name:         "Alice",
		RegisteredAt: time.Date(2025, 2, 3, 23, 3, 15, 0, time.UTC),
	}
	obj2 := User{
		ID:           "123",
		Name:         "Alice",
		RegisteredAt: time.Date(2024, 12, 19, 5, 45, 50, 0, jst),
	}

	diff = akashi.DiffString(obj1, obj2)

	fmt.Println(diff)
	// Output:
	//   akashi_test.User{
	//     ID: "123",
	//     Name: "Alice",
	// -   RegisteredAt: time.Time("2025-02-03 23:03:15 +0000 UTC"),
	// +   RegisteredAt: time.Time("2024-12-19 05:45:50 +0900 JST"),
	//   }
}

DiffString

func DiffString(x, y interface{}, options ...Option) string

DiffString returns a string that represents the difference between x and y. You can pass Options to customize the diffing process and output.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the LICENSE file.

Documentation

Overview

Example

package main

import (
	"fmt"
	"time"

	"github.com/seiyab/akashi"
)

type User struct {
	ID           string
	Name         string
	RegisteredAt time.Time
}

func main() {
	s := akashi.DiffString(
		User{
			ID:           "123",
			Name:         "Alice",
			RegisteredAt: time.Date(2025, 2, 3, 23, 3, 15, 0, time.UTC),
		},
		User{
			ID:           "123",
			Name:         "Alice",
			RegisteredAt: time.Date(2024, 12, 19, 5, 45, 50, 0, jst),
		},
	)

	fmt.Println(s)

}

Output:
  akashi_test.User{
    ID: "123",
    Name: "Alice",
-   RegisteredAt: time.Time("2025-02-03 23:03:15 +0000 UTC"),
+   RegisteredAt: time.Time("2024-12-19 05:45:50 +0900 JST"),
  }

Example (Slice)

package main

import (
	"fmt"

	"github.com/seiyab/akashi"
)

func main() {
	s := akashi.DiffString(
		[]string{"a", "b", "c", "d"},
		[]string{"a", "c", "d", "e"},
	)

	fmt.Println(s)

}

Output:
  []string{
    "a",
-   "b",
    "c",
    "d",
+   "e",
  }

Index

• Variables
• func DiffString(x, y interface{}, options ...Option) string
• type ColorProfile
• type Option
  • func WithColor(profile ...ColorProfile) Option
  • func WithFormat(fn interface{}) Option
  • func WithReflectEqual(fn func(v1, v2 reflect.Value) bool) Option

Examples

• Package
• Package (Slice)
• WithFormat

Variables

var DefaultColorProfile = ColorProfile{
	Left:    "\x1b[31m",
	Right:   "\x1b[32m",
	Neutral: "",
	Reset:   "\x1b[0m",
}

Functions

func DiffString

func DiffString(x, y interface{}, options ...Option) string

DiffString returns a string that represents the difference between x and y.

Types

type ColorProfile

type ColorProfile = doc.ColorProfile

type Option

type Option func(*differ) *differ

Option is an option for DiffString.

func WithColor

func WithColor(profile ...ColorProfile) Option

func WithFormat

func WithFormat(fn interface{}) Option

WithFormat sets a function to format a value.

Example

package main

import (
	"fmt"
	"time"

	"github.com/seiyab/akashi"
)

func main() {
	s := akashi.DiffString(
		time.Date(2025, 2, 3, 23, 3, 15, 0, time.UTC),
		time.Date(2024, 12, 19, 5, 45, 50, 0, time.UTC),
		akashi.WithFormat(
			func(t time.Time) string {
				return t.Format(time.RFC3339)
			},
		),
	)

	fmt.Println(s)

}

Output:
- time.Time("2025-02-03T23:03:15Z")
+ time.Time("2024-12-19T05:45:50Z")

func WithReflectEqual

func WithReflectEqual(fn func(v1, v2 reflect.Value) bool) Option

WithReflectEqual sets a function to compare reflect.Value.