<13> go collection-func

集合的操作：

import (
    "fmt"
    "strings"
)
// 返回数组下标，找不到返回－1
func Index(vs []string, t string) int {
    for i, v := range vs {
        if v == t {
            return i
        }
    }
    return -1
}
// 是否包含t字符串
func Include(vs []string, t string) bool {
    return Index(vs, t) >= 0
}
// 任何一个字串符合f即返回true
func Any(vs []string, f func(string) bool) bool {
    for _, v := range vs {
        if f(v) {
            return true
        }
    }
    return false
}
// 所有字符串符合f才返回true
func All(vs []string, f func(string) bool) bool {
    for _, v := range vs {
        if !f(v) {
            return false
        }
    }
    return true
}
// 过滤掉f符合的字符串
func Filter(vs []string, f func(string) bool) []string {
    vsf := make([]string, 0)
    for _, v := range vs {
        if f(v) {
            vsf = append(vsf, v)
        }
    }
    return vsf
}

func Map(vs []string, f func(string) string) []string {
    vsm := make([]string, len(vs))
    for i, v := range vs {
        vsm[i] = f(v)
    }
    return vsm
}

func main() {
    var strs = []string{"peach", "apple", "pear", "plum"}
    fmt.Println(Index(strs, "pear"))
    fmt.Println(Include(strs, "grape"))
    fmt.Println(Any(strs, func(v string) bool {
        return strings.HasPrefix(v, "p")
    }))
    fmt.Println(All(strs, func(v string) bool {
        return strings.HasPrefix(v, "p")
    }))
    fmt.Println(Filter(strs, func(v string) bool {
        return strings.Contains(v, "e")
    }))

    fmt.Println(Map(strs, strings.ToUpper))
}
// 输出：
// 2
// false
// true
// false
// [peach apple pear]
// [PEACH APPLE PEAR PLUM]