在Go中对多个结构字段进行排序[重复]

Question

This question already has an answer here:

• How to sort struct with multiple sort parameters? 6 answers

I have an array/slice of members:

type SomeType struct {
    timeStamp time
    typeName string
    other variables...
}

And there are 3 methods on this structure based on typeName, like:

isTypeA(): returns bool
isTypeB(): returns bool
isTypeC(): returns bool

Now this is how my sorting needs to work: - Sort based on timeStamp in ascending order - If the timeStamp is same, then typeA's should come before typeB's which should come before typeC's. (type A, B, C is not really alphabetical)

I am using sort.Slice to sort on timeStamp, but I am not sure how to do the type A,B,C sorting.

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Answer 1

Translate the arbitrary type values into something that is sortable in the way your requirements ask.

func ThingTypeSortable(thing *Thing) int {
    if thing == nil {
        return 0
    }

    if thing.isTypeA() {
        return 1
    }
    if thing.isTypeB() {
        return 2
    }
    if thing.isTypeC() {
        return 3
    }

    return 0
}

...then it's just another thing to sort by if the timestamps are equal.

sort.Slice(inputs, func(i, j int) bool {
    if inputs[i].t.UTC() != inputs[j].t.UTC() {
        return inputs[i].t.Before(inputs[j].t)
    }

    return ThingTypeSortable(inputs[i]) < ThingTypeSortable(inputs[j])
})