如何使用将多个结构连接到同一结构

Question

I'm trying to play around with recursive structs, where when I have multiple I can add them together, creating a new struct with those embedded. However, I'm not sure what the proper way to approach this is.

I've included a code snippet below to further illustrate what I mean.

package main

import "fmt"

type Container struct {
    F          int
    Collection []SubContainer
}

type SubContainer struct {
    Key    string
    Value  int
}

func main() {
    commits := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
        "d": 4,
    }

    sc := []SubContainer{}
    c := []Container{}
    count := 0

    for k, v := range commits {
        sc = append(sc, SubContainer{Key: k, Value: v})
        count++

        if len(sc) == 2 {
            c = append(c, Container{Collection: sc, F: count})
            sc = nil
        }
    }

    for _, r := range c {
        fmt.Println(r)
    }
}

Result:

{2 [{a 1} {b 2}]}
{4 [{c 3} {d 4}]}

Desired result:

{6 {2 [{a 1} {b 2}]} {4 [{c 3} {d 4}]}}

Playground link: https://play.golang.org/p/j6rbhgcOoT

One caveat I'm having trouble wrapping my head around is that the commits length may change (I was initially thinking I could just create a different parent struct). Any suggestions would be appreciated... Is doing this somehow with recursive structs the right approach to accomplish this? Thanks!

Answer 1

I attempted to get close to the desired output without being sure about the exact goal, you will find below a modified version of the snippet you provided.

You can use the String() string method on a collection to customize the format.

package main

import "fmt"

type ContainerCollection struct {
    Count int
    List  []Container
}

func (cc ContainerCollection) String() string {
    total := 0
    for _, c := range cc.List {
        total += c.F
    }
    return fmt.Sprintf("{%d %v}", total, cc.List)
}

type Container struct {
    F          int
    Collection []SubContainer
}

type SubContainer struct {
    Key   string
    Value int
}

func main() {
    commits := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
        "d": 4,
    }

    c := ContainerCollection{Count: 0}
    sc := []SubContainer{}

    for k, v := range commits {
        sc = append(sc, SubContainer{Key: k, Value: v})
        c.Count++
        if len(sc) == 2 {
            c.List = append(c.List, Container{Collection: sc, F: c.Count})
            sc = []SubContainer{}
        }
    }
    // Should also cover odd number of commits
    if len(sc) != 0 {
        c.Count++
        c.List = append(c.List, Container{Collection: sc, F: c.Count})
    }

    // for _, r := range c.List { fmt.Println(r) }

    fmt.Println(c)
}

Result:

{6 [{2 [{a 1} {b 2}]} {4 [{c 3} {d 4}]}]}

Playground