lancet/docs/api/packages/function.md

Function

function 函数包控制函数执行流程，包含部分函数式编程。

源码:

• https://github.com/duke-git/lancet/blob/main/function/function.go
• https://github.com/duke-git/lancet/blob/main/function/watcher.go

用法:

import (
    "github.com/duke-git/lancet/v2/function"
)

目录

• After
• Before
• CurryFn
• Compose
• Debounced
• Delay
• Schedule
• Pipeline
• Watcher

文档

After

创建一个函数，当他被调用n或更多次之后将马上触发fn

函数签名:

func After(n int, fn any) func(args ...any) []reflect.Value

示例:运行

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/function"
)

func main() {
    fn := function.After(2, func() {
        fmt.Println("hello")
    })

    fn()
    fn()

    // Output:
    // hello
}

Before

创建一个函数，调用次数不超过n次，之后再调用这个函数，将返回一次最后调用fn的结果

函数签名:

func Before(n int, fn any) func(args ...any) []reflect.Value

示例:运行

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/function"
)

func main() {
    fn := function.Before(2, func() {
        fmt.Println("hello")
    })

    fn()
    fn()
    fn()
    fn()

    // Output:
    // hello
    // hello
}

CurryFn

创建柯里化函数

函数签名:

type CurryFn[T any] func(...T) T
func (cf CurryFn[T]) New(val T) func(...T) T

示例:运行

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/function"
)

func main() {
    add := func(a, b int) int {
        return a + b
    }

    var addCurry function.CurryFn[int] = func(values ...int) int {
        return add(values[0], values[1])
    }
    add1 := addCurry.New(1)

    result := add1(2)

    fmt.Println(result)

    // Output:
    // 3
}

Compose

从右至左组合函数列表fnList，返回组合后的函数

函数签名:

func Compose[T any](fnList ...func(...T) T) func(...T) T

示例:运行

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/function"
)

func main() {
    toUpper := func(strs ...string) string {
        return strings.ToUpper(strs[0])
    }
    toLower := func(strs ...string) string {
        return strings.ToLower(strs[0])
    }
    transform := function.Compose(toUpper, toLower)

    result := transform("aBCde")

    fmt.Println(result)

    // Output:
    // ABCDE
}

Debounced

创建一个debounced函数，该函数延迟调用fn直到自上次调用debounced函数后等待持续时间过去。

函数签名:

func Debounced(fn func(), duration time.Duration) func()

示例:运行

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/function"
)

func main() {
    count := 0

    add := func() {
        count++
    }

    debouncedAdd := function.Debounced(add, 50*time.Microsecond)

    debouncedAdd()
    debouncedAdd()
    debouncedAdd()
    debouncedAdd()

    time.Sleep(100 * time.Millisecond)

    fmt.Println(count)

    debouncedAdd()

    time.Sleep(100 * time.Millisecond)

    fmt.Println(count)

    // Output:
    // 1
    // 2
}

Delay

延迟delay时间后调用函数

函数签名:

func Delay(delay time.Duration, fn any, args ...any)

示例:运行

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/function"
)

func main() {
    var print = func(s string) {
        fmt.Println(s)
    }

    function.Delay(2*time.Second, print, "hello")

    // Output:
    // hello
}

Schedule

每次持续时间调用函数，直到关闭返回的 bool chan

函数签名:

func Schedule(d time.Duration, fn any, args ...any) chan bool

示例:运行

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/function"
)

func main() {
    count := 0

    increase := func() {
        count++
    }

    stop := function.Schedule(2*time.Second, increase)

    time.Sleep(2 * time.Second)
    close(stop)

    fmt.Println(count)

    // Output:
    // 2
}

Pipeline

执行函数pipeline.

函数签名:

func Pipeline[T any](funcs ...func(T) T) func(T) T

示例:运行

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/function"
)

func main() {
    addOne := func(x int) int {
        return x + 1
    }
    double := func(x int) int {
        return 2 * x
    }
    square := func(x int) int {
        return x * x
    }

    fn := function.Pipeline(addOne, double, square)

    result := fn(2)

    fmt.Println(result)

    // Output:
    // 36
}

Watcher

Watcher用于记录代码执行时间。可以启动/停止/重置手表定时器。获取函数执行的时间。

函数签名:

type Watcher struct {
    startTime int64
    stopTime  int64
    excuting  bool
}
func NewWatcher() *Watcher
func (w *Watcher) Start()
func (w *Watcher) Stop()
func (w *Watcher) Reset()
func (w *Watcher) GetElapsedTime() time.Duration

示例:运行

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/function"
)

func main() {
    w := function.NewWatcher()

    w.Start()

    longRunningTask()

    fmt.Println(w.excuting) //true

    w.Stop()

    eapsedTime := w.GetElapsedTime().Milliseconds()

    fmt.Println(eapsedTime)

    w.Reset()

}

func longRunningTask() {
    var slice []int64
    for i := 0; i < 10000000; i++ {
        slice = append(slice, int64(i))
    }
}