Go Slice Tricks Cheat Sheet、Go 切片使用小妙招

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If the type of the element is a pointer or a struct with pointer fields, which need to be garbage collected, the above implementations of Cut and Delete have a potential memory leak problem: some elements with values are still referenced by slice a and thus can not be collected.

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AppendVector

---

a = append(a, b...)

Copy

b = make([]T, len(a))
copy(b, a)

---

b = append([]T(nil), a...)

---

b = append(a[:0:0], a...)

Cut

a = append(a[:i], a[j:]...)

Delete

a = append(a[:i], a[i+1:]...)

---

a = a[:i+copy(a[i:], a[i+1:])]

Delete without preserving order

a[i] = a[len(a)-1] 
a = a[:len(a)-1]

Cut (GC)

copy(a[i:], a[j:])
for k, n := len(a)-j+i, len(a); k < n; k++ {
 a[k] = nil // or the zero value of T
}
a = a[:len(a)-j+i]

Delete (GC)

if i < len(a)-1 {
  copy(a[i:], a[i+1:])
}
a[len(a)-1] = nil // or the zero value of T
a = a[:len(a)-1]

Delete without preserving order (GC)

a[i] = a[len(a)-1]
a[len(a)-1] = nil
a = a[:len(a)-1]

Expand

a = append(a[:i], append(make([]T, j), a[i:]...)...)

Extend

a = append(a, make([]T, j)...)

Filter (in place)

n := 0
for _, x := range a {
 if keep(x) {
  a[n] = x
  n++
 }
}
a = a[:n]

Insert

a = append(a[:i], append([]T{x}, a[i:]...)...)

InsertVector

a = append(a[:i], append(b, a[i:]...)...)

Push

a = append(a, x)

Pop

x, a = a[len(a)-1], a[:len(a)-1]

Push Front/Unshift

a = append([]T{x}, a...)

Pop Front/Shift

x, a = a[0], a[1:]

Go Slice Tricks Cheat Sheet (ueokande.github.io)