go slice compare

by · 2018年12月19日 · 252 Words · ~2min reading time | Improve on


原文链接： go slice compare
package main

import "reflect"

func main(){
    
}

func CompareSlices_Reflect(a, b []int) bool {
    return reflect.DeepEqual(a, b)
}

func CompareSlices_General(a, b []int) bool {
    if len(a) != len(b) {
        return false
    }

    if (a == nil) != (b == nil) {
        return false
    }

    for i, v := range a {
        if v != b[i] {
            return false
        }
    }

    return true
}

func CompareSlices_BCE(a, b []int) bool {
    if len(a) != len(b) {
        return false
    }

    if (a == nil) != (b == nil) {
        return false
    }

    b = b[:len(a)] // this line is the key
    for i, v := range a {
        if v != b[i] { // here is no bounds checking for b[i]
            return false
        }
    }

    return true
}

func CompareSlices_Pointer(a, b []int) bool {
    if len(a) != len(b) {
        return false
    }

    if (a == nil) != (b == nil) {
        return false
    }

    if len(a) == 0 {
        return true
    }

    if &a[0] == &b[0] {
        return true // early exit
    }

    for i, v := range a {
        if v != b[i] {
            return false
        }
    }

    return true
}

func CompareSlices_PointerAndBCE(a, b []int) bool {
    if len(a) != len(b) {
        return false
    }

    if (a == nil) != (b == nil) {
        return false
    }

    if len(a) == 0 {
        return true
    }

    b = b[:len(a)]
    if &a[0] == &b[0] {
        return true
    }

    for i, v := range a {
        if v != b[i] {
            return false
        }
    }

    return true
}

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