GitHub - alexpantyukhin/go-pattern-match: Pattern matchings for Go.

Go pattern matching

It's just another implementation of pattern matching in Go. I have been inspired by Python pattern matching, that's why I wanted to try writing something similar in Go :) For now the following matching are implemented :

Simple types (like int, int64, float, float64, bool..).
Struct type.
Slices (with HEAD, TAIL, OneOf patterns).
Dictionary (with ANY, OneOf pattern).
Regexp.
Additional custom matching (ability to add special matching for some, structs for example).

Usages

Fibonacci example:

func fib(n int) int {
	_, res := match.Match(n).
		When(1, 1).
		When(2, 1).
		When(match.ANY, func() int { return fib(n-1) + fib(n-2) }).
		Result()

	return res.(int)
}

Simple types:

isMatched, mr := match.Match(42).
                When(42, 10).
                Result()
// isMatched - true, mr - 10

With Structs:

Simple check value by type

val := TestStruct{1}

isMatched, _ := Match(val).
    When(func(TestStruct) {},  1).
    Result()

Check value by type and condition

val := TestStruct{1}

isMatched, _ := Match(val).
	When(func(ts TestStruct) bool { return ts.value == 42 }, 1).
	When(func(ts AnotherStruct) bool { return ts.stringValue == "hello" }, 2).
	Result()

With Maps:

isMatched, mr := match.Match(map[string]int{
                	"rsc": 3711,
                	"r":   2138,
                	"gri": 1908,
                	"adg": 912,
                }).
        	    When(map[string]interface{}{
                	"rsc": 3711,
                	"r":   2138,
                	"gri": 1908,
                	"adg": match.ANY,
            	}, true).
            	Result()

With Slices:

isMatched, mr := match.Match([]int{1, 2, 3, 4, 5, 6}).
            	When([]interface{}{match.HEAD, 3, match.OneOf(3, 4), 5, 6}, 125).
            	Result()

With regexps:

isMatched, mr := match.Match("gophergopher").
            	When("gophergopher", func() interface{} { return true }).
            	Result()

Without result:

func main() {
	Match(val).
	When(42, func() { fmt.Println("You found the answer to life, universe and everything!") }).
	When(ANY, func() { fmt.Println("No.. It's not an answer.") }).
	Result()
}

Installation

Just go get this repository in the following way:

go get github.com/alexpantyukhin/go-pattern-match

Full example

package main

import (
    "fmt"
    "github.com/alexpantyukhin/go-pattern-match"
)

func main() {
    isMatched, mr := match.Match([]int{1, 2, 3}).
        When(42, false).
        When([]interface{}{match.HEAD, 2, 3}, true).
        Result()


    if isMatched {
        fmt.Println(mr)
    }
}