/\ \                                                       
 __  __    ___    \_\ \     __   _ __   ____    ___    ___   _ __    __	         __     ___
/\ \/\ \ /' _ `\  /'_  \  /'__`\/\  __\/ ,__\  / ___\ / __`\/\  __\/'__`\      /'_ `\  / __`\
\ \ \_\ \/\ \/\ \/\ \ \ \/\  __/\ \ \//\__, `\/\ \__//\ \ \ \ \ \//\  __/  __ /\ \L\ \/\ \L\ \
 \ \____/\ \_\ \_\ \___,_\ \____\\ \_\\/\____/\ \____\ \____/\ \_\\ \____\/\_\\ \____ \ \____/
  \/___/  \/_/\/_/\/__,_ /\/____/ \/_/ \/___/  \/____/\/___/  \/_/ \/____/\/_/ \/___L\ \/___/
                                                                                 /\____/
                                                                                 \_/__/

Underscore.go

like underscore.js and C# LINQ, but for Go

Installation

$ go get github.com/ahl5esoft/golang-underscore

Update

$ go get -u github.com/ahl5esoft/golang-underscore

Lack

• Concat/ThenBy

Documentation

API

• Aggregate
• All, AllBy
• Any, AnyBy
• Chain
• Count
• Distinct, DistinctBy
• Each
• Field, FieldValue
• Filter, FilterBy
• Find, FindBy
• FindIndex, FindIndexBy
• First
• Group, GroupBy
• Index, IndexBy
• IsArray
• IsMatch
• Keys
• Last
• Map, MapBy
• MapMany, MapManyBy
• Object
• Order, OrderBy
• Range
• Reduce
• Reject, RejectBy
• Reverse, ReverseBy
• Select, SelectBy
• SelectMany, SelectManyBy
• Size
• Skip
• Sort, SortBy
• Take
• Uniq, UniqBy
• Value
• Values
• Where, WhereBy

Aggregate(memo, fn) IEnumerable

Arguments

• iterator - func(element or value, key or index, memo) memo
• memo - anyType

Examples

var res []int
Chain([]int{1, 2}).Aggregate(
	func(memo []int, n, _ int) []int {
		memo = append(memo, n)
		memo = append(memo, n+10)
		return memo
	},
	make([]int, 0),
).Value(&res)
// res = [1 11 2 12]

Same

• Reduce

All(predicate) bool

Arguments

• predicate - func(element, index or key) bool

Return

• bool - all the values that pass a truth test predicate

Examples

ok := Chain([]testModel{
	{ID: 1, Name: "one"},
	{ID: 1, Name: "two"},
	{ID: 1, Name: "three"},
}).All(func(r testModel, _ int) bool {
	return r.ID == 1
})
// ok == true

AllBy(fields) bool

Arguments

• fields - map[string]interface{}

Return

• bool - all the values that pass a truth test predicate

Examples

ok := Chain([]testModel{
	{ID: 1, Name: "one"},
	{ID: 2, Name: "one"},
	{ID: 3, Name: "one"},
}).AllBy(map[string]interface{}{
	"name": "one",
})
// ok == true

Any(predicate) bool

Arguments

• predicate - func(element or value, index or key) bool

Return

• bool - any of the values that pass a truth test predicate

Examples

ok := Chain([]testModel{
	{ID: 1, Name: "one"},
	{ID: 2, Name: "two"},
	{ID: 3, Name: "three"},
}).Any(func(r testModel, _ int) bool {
	return r.ID == 0
})
// ok == false

AnyBy(fields) bool

Arguments

• fields - map[string]interface{}

Return

• bool

Examples

ok := Chain([]testModel{
	{ID: 1, Name: "one"},
	{ID: 2, Name: "two"},
	{ID: 3, Name: "three"},
}).AnyBy(map[string]interface{}{
	"name": "two",
})
// ok == true

Chain(source) IEnumerable

Arguments

• source - array or map

Examples

var dst int
Range(1, benchmarkSize, 1).Select(func(r, _ int) int {
	return -r
}).Where(func(r, _ int) bool {
	return r < -20
}).First().Value(&dst)
// dst = -21

Count() int

Examples

src := []string{"a", "b", "c"}
dst := Chain(src).Count()
// dst = 3

Same

• Size

Distinct(selector) IEnumerable

Arguments

• selector - nil or func(element or value, index or key) anyType

Examples

src := []int{1, 2, 1, 4, 1, 3}
dst := make([]int, 0)
Chain(src).Distinct(func(n, _ int) (int, error) {
	return n % 2, nil
}).Value(&dst)
// dst = [1 2]

Same

• Uniq

DistinctBy(fieldName) IEnumerable

Arguments

• fieldName - string

Examples

src := []testModel{
	{ID: 1, Name: "a"},
	{ID: 2, Name: "a"},
	{ID: 3, Name: "a"},
}
dst := make([]testModel, 0)
Chain(src).DistinctBy("name").Value(&dst)
// dst = [{1 a}]

Same

• UniqBy

Each(iterator)

Arguments

• iterator - func(element or value, index or key)

Examples

arr := []testModel{
	{ID: 1, Name: "one"},
	{ID: 1, Name: "two"},
	{ID: 1, Name: "three"},
}
Chain(arr).Each(func(r testModel, i int) {
	if !(r.ID == arr[i].ID && r.Name == arr[i].Name) {
		// wrong
	}
})

Field(name)

Arguments

• name - field name

Return

• func(interface{}) interface{}

Examples

item := testModel{ 1, "one" }

getAge := Field("age")
_, err := getAge(item)
// err != nil

getName := Field("name")
name, err := getName(item)
// name = "one"

FieldValue(name)

Arguments

• name - field name

Return

• func(interface{}) reflect.Value

Examples

item := testModel{ 1, "one" }

getAgeValue := FieldValue("age")
res := getAgeValue(item)
// res != reflect.Value(nil)

getNameValue := FieldValue("name")
nameValue, err := getNameValue(item)
// nameValue = reflect.ValueOf("one")

Find(predicate) IEnumerable

Arguments

• predicate - func(element or value, index or key) bool

Examples

var dst int
Chain([]int{1, 2, 3}).Find(func(r, _ int) bool {
	return r == 2
}).Value(&dst)
// dst == 2
// or
var dst int
Chain([][]int{
	[]int{1, 3, 5, 7},
	[]int{2, 4, 6, 8},
}).Find(func(r []int, _ int) bool {
	return r[0]%2 == 0
}).Find(func(r, _ int) bool {
	return r > 6
}).Value(&dst)
// dst == 8

FindBy(fields) IEnumerable

Arguments

• fields - map[string]interface{}

Examples

src := []testModel{
	{ID: 1, Name: "one"},
	{ID: 2, Name: "two"},
	{ID: 3, Name: "three"},
}
var dst testModel
Chain(src).FindBy(map[string]interface{}{
	"id": 2,
}).Value(&dst)
// dst == src[1]

FindIndex(predicate) int

Arguments

• predicate - func(element or value, index or key) bool

Return

• int - index

Examples

src := []testModel{
	{ID: 1, Name: "one"},
	{ID: 2, Name: "two"},
	{ID: 3, Name: "three"},
}
index := Chain(src).FindIndex(func(r testModel, _ int) bool {
	return r.Name == src[1].Name
})
// i == 1

FindIndexBy(fields) int

Arguments

• fields - map[string]interface{}

Return

• int - index

Examples

src := []testModel{
	{ID: 1, Name: "one"},
	{ID: 2, Name: "two"},
	{ID: 3, Name: "three"},
}
index := Chain(src).FindIndexBy(map[string]interface{}{
	"id": 1,
})
// index == 0

First() IEnumerable

Arguments

• predicate - func(element or value, index or key) bool

Examples

var dst int
Chain([]int{1, 2, 3}).First().Value(&dst)
// dst == 1
// or
var dst int
Chain([][]int{
	[]int{1, 3, 5, 7},
	[]int{2, 4, 6, 8},
}).First().First().Value(&dst)
// dst == 1

Group(keySelector) IEnumerable

Arguments

• keySelector - func(element or value, index or key) anyType

Examples

dst := make(map[string][]int)
Chain([]int{1, 2, 3, 4, 5}).Group(func(n, _ int) string {
	if n%2 == 0 {
		return "even"
	}
	return "odd"
}).Value(&dst)
// dst = map[odd:[1 3 5] even:[2 4]]

GroupBy(fieldName) IEnumerable

Arguments

• fieldName - field name

Examples

dst := make(map[string][]testModel)
Chain([]testModel{
	{ID: 1, Name: "a"},
	{ID: 2, Name: "a"},
	{ID: 3, Name: "b"},
	{ID: 4, Name: "b"},
}).GroupBy("Name").Value(&dst)
// dst = map[a:[{1 a} {2 a}] b:[{3 b} {4 b}]]

Index(indexSelector) IEnumerable

Arguments

• indexSelector - func(element or value, index or key) anyType

Examples

src := []string{"a", "b"}
res := make(map[string]string)
Chain(src).Index(func(item string, _ int) string {
	return item
}).Value(&res)
// res = map[a:a b:b]

IndexBy(property) IEnumerable

Arguments

• property - string

Examples

arr := []testModel{
	{ID: 1, Name: "a"},
	{ID: 2, Name: "a"},
	{ID: 3, Name: "b"},
	{ID: 4, Name: "b"},
}
res := make(map[string]testModel)
Chain(arr).IndexBy("id").Value(&res)
// res = map[1:{{0} 1 a} 2:{{0} 2 a} 3:{{0} 3 b} 4:{{0} 4 b}]

IsArray(element) bool

Arguments

• element - object

Examples

if !IsArray([]int{}) {
	// wrong
}

if IsArray(map[string]int{}) {
	// wrong
}

IsMatch(element, fields) bool

Arguments

• element - object
• fields - map[string]interface{}

Examples

m := testModel{ 1, "one" }
ok := IsMatch(nil, nil)
// ok = false

ok = IsMatch(m, nil)
// ok = false

ok = IsMatch(m, map[string]interface{}{
	"id": m.Id,
	"name": "a",
})
// ok = false

ok = IsMatch(m, map[string]interface{}{
	"id": m.Id,
	"name": m.Name,
})
// ok = true

Keys() IEnumerable

Examples

src := []string{"aa", "bb", "cc"}
dst := make([]int, 0)
Chain(src).Keys().Value(&dst)
// dst = [0 1 2]

src := map[int]string{
	1: "a",
	2: "b",
	3: "c",
	4: "d",
}
dst := make([]int, 0)
Chain(src).Keys().Value(&dst)
// dst = [1 2 3 4]

Last() IEnumerable

Examples

arr := []int{1, 2, 3}
var res int
chain(arr).Last().Value(&res)
// res = 3

var res []int
src := [][]int{
	{1, 2, 3, 4},
	{5, 6},
}
Chain(src).Last().Map(func(r, _ int) int {
	return r + 5
}).Value(&res)
// res = [10, 11]

Object() IEnumerable

Examples

src := [][]interface{}{
	[]interface{}{"a", 1},
	[]interface{}{"b", 2},
}
dst := make(map[string]int)
Chain(src).Object().Value(&dst)
// dst = map[a:1 b:2]

Order(selector) IEnumerable

Arguments

• selector - func(element, key or index) anyType

Examples

arr := []testModel{
	{ID: 2, Name: "two"},
	{ID: 1, Name: "one"},
	{ID: 3, Name: "three"},
}
var res []testModel
Chain(arr).Order(func(n testModel, _ int) int {
	return n.ID
}).Value(&res)
// res = [{{0} 1 one} {{0} 2 two} {{0} 3 three}]

Same

• Sort

OrderBy(fieldName) IEnumerable

Arguments

• fieldName - string

Examples

arr := []testModel{
	{ID: 2, Name: "two"},
	{ID: 1, Name: "one"},
	{ID: 3, Name: "three"},
}
var res []testModel
Chain(arr).OrderBy("id").Value(&res)
// res = [{{0} 1 one} {{0} 2 two} {{0} 3 three}]

Same

• SortBy

Range(start, stop, step) IEnumerable

Arguments

• start - int
• stop - int
• step - int

Examples

var res []int
Range2(0, 0, 1).Value(&res)
// res = []

var res []int
Range2(0, 10, 0).Value(&res)
// panic

var res []int
Range2(4, 0, -1).Value(&res)
// res = [4 3 2 1]

var res []int
Range2(0, 2, 1).Value(&res)
// res = [0 1]

var res []int
Range2(0, 3, 2).Value(&res)
// res = [0 2]

Reject(predicate) IEnumerable

Arguments

• predicate - func(element or value, index or key) bool

Examples

arr := []int{1, 2, 3, 4}
var res []int
Chain(arr).Reject(func(n, i int) bool {
	return n%2 == 0
}).Value(&res)
// res = [1, 3]

Same

• Except

RejectBy(fields) IEnumerable

Arguments

• fields - map[string]interface{}

Examples

arr := []testModel{
	{ID: 1, Name: "one"},
	{ID: 2, Name: "two"},
	{ID: 3, Name: "three"},
}
var res []testModel
Chain(arr).RejectBy(map[string]interface{}{
	"Id": 1,
}).Value(&res)
// res = []testModel{ {ID: 2, Name: "two"}, {ID: 3, Name: "three"} }

Same

• ExceptBy

Reverse(selector) IEnumerable

Arguments

• selector - func(element, index or key) anyType

Examples

src := []testModel{
	{ID: 2, Name: "two"},
	{ID: 1, Name: "one"},
	{ID: 3, Name: "three"},
}
var res []testModel
Chain(src).Reverse(func(r testModel, _ int) int {
	return r.ID
}).Value(&res)
// res = []testModel{ {ID: 3, Name: "three"}, {ID: 2, Name: "two"}, {ID: 1, Name: "one"} }

ReverseBy(fieldName) IEnumerable

Arguments

• fieldName - string

Examples

src := []testModel{
	{ID: 2, Name: "two"},
	{ID: 1, Name: "one"},
	{ID: 3, Name: "three"},
}
var res []testModel
Chain(src).ReverseBy("id").Value(&res)
// res = []testModel{ {ID: 3, Name: "three"}, {ID: 2, Name: "two"}, {ID: 1, Name: "one"} }

Select(selector) IEnumerable

Arguments

• selector - func(element, index or key) anyType

Examples

src := []string{"11", "12", "13"}
dst := make([]int, 0)
Chain(src).Select(func(s string, _ int) int {
	n, _ := strconv.Atoi(s)
	return n
}).Value(&dst)
// dst = [11 12 13]

Same

• Map

SelectBy(fieldName) IEnumerable

Arguments

• fieldName - string

Examples

src := []testModel{
	{ID: 1, Name: "one"},
	{ID: 2, Name: "two"},
	{ID: 3, Name: "three"},
}
dst := make([]string, 0)
Chain(src).SelectBy("name").Value(&dst)
// dst = [one two three]

Same

• MapBy

SelectMany(selector) IEnumerable

Arguments

• selector - func(element, index or key) anyType with array or slice

Examples

src := [2]int{1, 2}
var dst []int
Chain(src).SelectMany(func(r, _ int) []int {
	return []int{r - 1, r + 1}
}).Value(&dst)
// dst = [0 2 1 3]

Same

• MapMany

SelectManyBy(property) IEnumerable

Arguments

• property - string

Examples

src := []testSelectManyModel{
	{Array: [2]int{1, 2}},
	{Array: [2]int{3, 4}},
}
var dst []int
Chain(src).SelectManyBy("Array").Value(&dst)
// res = [1 2 3 4]

Same

• MapManyBy

Skip(count) IEnumerable

Arguments

• count - int

Examples

src := []int{1, 2, 3}
dst := make([]int, 0)
Chain(src).Skip(2).Value(&dst)
// dst = [3]

Take(count) IEnumerable

Arguments

• count - int

Examples

src := []int{1, 2, 3}
dst := make([]int, 0)
Chain(src).Take(1).Value(&dst)
// res = [1]

Value(res interface{})

Arguments

• res - array or slice or reflect.Value(array) or reflect.Value(map)

Examples

resValue := reflect.New(
	reflect.SliceOf(
		reflect.TypeOf(1),
	),
)
Chain([]string{"a", "b"}).Map(func(_ string, i int) int {
	return i
}).Value(resValue)
// resValue = &[0 1]

src := []testModel{
	{ID: 1, Name: "a"},
	{ID: 2, Name: "a"},
	{ID: 3, Name: "b"},
	{ID: 4, Name: "b"},
}
resValue := reflect.New(
	reflect.MapOf(
		reflect.TypeOf(src[0].Name),
		reflect.TypeOf(src),
	),
)
Chain(src).GroupBy("name").Value(resValue)
// res = &map[even:[2 4] odd:[1 3 5]]

Values() IEnumerable

Examples

src := []string{"a", "b"}
dst := make([]string, 0)
Chain(src).Values().Value(&dst)
// dst = [a b]

src := map[int]string{
	1: "a",
	2: "b",
	3: "c",
	4: "d",
}
dst := make([]string, 0)
Chain(src).Values().Value(&dst)
// dst = [a b c d]

Where(predicate) IEnumerable

Arguments

• predicate - func(element or value, index or key) bool

Examples

src := []testModel{
	{ID: 1, Name: "one"},
	{ID: 2, Name: "one"},
	{ID: 3, Name: "three"},
	{ID: 4, Name: "three"},
}
dst := make([]testModel, 0)
Chain(src).Where(func(r testModel, _ int) bool {
	return r.ID%2 == 0
}).Value(&dst)
// len(dst) == 2 && dst[0] == src[1] && dst[1] == src[3])

Same

• Filter

WhereBy(fields) IEnumerable

Arguments

• fields - map[string]interface{}

Examples

src := []testModel{
	{ID: 1, Name: "one"},
	{ID: 2, Name: "one"},
	{ID: 3, Name: "three"},
	{ID: 4, Name: "three"},
}
dst := make([]testModel, 0)
Chain(src).WhereBy(map[string]interface{}{
	"Name": "one",
}).Value(&dst)
// len(dst) == 2 && dst[0] == src[0] && dst[1] == src[1]

Same

• FilterBy

Release Notes

v2.1.0 (2020-11-17)
* IEnumerable增加Order、OrderBy、Sort、SortBy
* IEnumerable.Aggregate(memo interface{}, fn interface{}) -> IEnumerable.Aggregate(fn interface{}, memo interface{})

v2.0.0 (2019-06-27)
* 删除IQuery
* IEnumerable增加MapMany、MapManyBy、SelectMany、SelectManyBy

v1.6.0 (2019-06-21)
* IEnumerable增加Count、Size
* 删除FindLastIndex

v1.5.0 (2019-06-18)
* 增加Chain Benchmark
* IEnumerable增加Group、GroupBy
* 优化IEnumerable的Distinct、Enumerator、Index、Property、Select、Where

v1.4.0 (2019-06-15)
* Reduce、Take支持IEnumerable
* IEnumerable增加Aggregate、Skip
* IQuery删除Clone
* 优化IEnumerable的First、Index、Values

v1.3.0 (2019-06-09)
* FindIndex、FindIndexBy、Keys、Map、MapBy、Object、Uniq、UniqBy、Values支持IEnumerable
* IEnumerable增加Distinct、DistinctBy、Select、SelectBy

v1.2.0 (2019-06-04)
* Each、Filter、Where支持IEnumerable

v1.1.0 (2019-06-02)
* 增加IEnumerable、IEnumerator
* All、Any、Chain、Find、First、Range2、Value支持IEnumerable

v1.0.0 (2019-04-23)
* first edition