golang中规则引擎的一种查询语言类似于SQL中的where部分

YQL(Yet another-Query-Language)

where

Install

go get github.com/caibirdme/yql

Exmaple

yql_test.go

	rawYQL := `name='deen' and age>=23 and (hobby in ('soccer', 'swim') or score>90))`
	result, _ := yql.Match(rawYQL, map[string]interface{}{
		"name":  "deen",
		"age":   int64(23),
		"hobby": "basketball",
		"score": int64(100),
	})
	fmt.Println(result)
	rawYQL = `score ∩ (7,1,9,5,3)`
	result, _ = yql.Match(rawYQL, map[string]interface{}{
		"score": []int64{3, 100, 200},
	})
	fmt.Println(result)
	rawYQL = `score in (7,1,9,5,3)`
	result, _ = yql.Match(rawYQL, map[string]interface{}{
		"score": []int64{3, 5, 2},
	})
	fmt.Println(result)
	rawYQL = `score.sum() > 10`
	result, _ = yql.Match(rawYQL, map[string]interface{}{
		"score": []int{1, 2, 3, 4, 5},
	})
	fmt.Println(result)
	//Output:
	//true
	//true
	//false
	//true

RuleMatch

	rawYQL := `name='deen' and age>=23 and (hobby in ('soccer', 'swim') or score>90)`
	ruler,_ := yql.Rule(rawYQL)

	result, _ := ruler.Match(map[string]interface{}{
		"name":  "deen",
		"age":   23,
		"hobby": "basketball",
		"score": int64(100),
	})
	fmt.Println(result)
	result, _ = ruler.Match(map[string]interface{}{
		"name":  "deen",
		"age":   23,
		"hobby": "basketball",
		"score": int64(90),
	})
	fmt.Println(result)
	//Output:
	//true
	//false

map[string]interface{}

• int
• int64
• float64
• string
• bool

Helpers

score.sum() > 10sum

This repo is in the early stage, so now there are just a few helpers, feel free to create an issue about your needs. Supported helpers are listed below:

float64(total)/float64(len(slice))

Usage scenario

Obviously, it's easy to use in rule engine.

var handlers = map[int]func(map[string]interface{}){
	1: sendEmail,
	2: sendMessage,
	3: alertBoss,
}

data := resolvePostParamsFromRequest(request)
rules := getRulesFromDB(sql)

for _,rule := range rules {
	if success,_ := yql.Match(rule.YQL, data); success {
		handler := handlers[rule.ID]
		handler(data)
		break
	}
}

if else

func isVIP(user User) bool {
	rule := fmt.Sprintf("monthly_vip=true and now<%s or eternal_vip=1 or ab_test!=false", user.ExpireTime)
	ok,_ := yql.Match(rule, map[string]interface{}{
		"monthly_vip": user.IsMonthlyVIP,
		"now": time.Now().Unix(),
		"eternal_vip": user.EternalFlag,
		"ab_test": isABTestMatched(user),
	})
	return ok
}

json.Marshal

Syntax

Compatibility promise

Match

Further Trial

Though it's kinder difficult to create a robust new Go compiler, there're still some interesting things could do. For example, bringing lambda function in Go which maybe look like:

var scores = []int{1,2,3,4,5,6,7,8,9,10}
newSlice := yql.Filter(`(v) => v % 2 == 0`).Map(`(v) => v*v`).Call(scores).Interface()
//[]int{4,16,36,64,100}

If the lambda function won't change all time, it can be cached like opcode, which is as fast as the compiled code. And in most cases, who care?(pythoner?)

It's not easy but interesting, isn't it? Welcome to join me, open some issues and talk about your ideas with me. Maybe one day it can become a pre-compile tool like babel in javascript.

Attention

Lambda expression

You can take a quick preview in test case

type Student struct {
	Age  int
	Name string
}

var students = []Student{
	Student{
		Name: "deen",
		Age:  24,
	},
	Student{
		Name: "bob",
		Age:  22,
	},
	Student{
		Name: "alice",
		Age:  23,
	},
	Student{
		Name: "tom",
		Age:  25,
	},
	Student{
		Name: "jerry",
		Age:  20,
	},
}

t = yql.Filter(`(v) => v.Age > 23 || v.Name == "alice"`).Call(students).Interface()
res,_ := t.([]Student)
// res: Student{"deen",24} Student{"alice", 23} Student{"tom", 25}

Chainable

dst := []int{1, 2, 3, 4, 5, 6, 7}
r := Filter(`(v) => v > 3 && v <= 7`).Map(`(v) =>  v << 2`).Filter(`(v) => v % 8 == 0`).Call(dst)
s, err := r.Interface()
ass := assert.New(t)
ass.NoError(err)
ass.Equal([]int{16, 24}, s)