go append 源码
golang append 代码
文件路径：/test/append.go
// run
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Semi-exhaustive test for the append predeclared function.
package main
import (
"fmt"
"reflect"
)
func verify(name string, result, expected interface{}) {
if !reflect.DeepEqual(result, expected) {
panic(name)
}
}
func main() {
for _, t := range tests {
verify(t.name, t.result, t.expected)
}
verifyStruct()
verifyInterface()
verifyType()
}
var (
zero int = 0
one int = 1
)
var tests = []struct {
name string
result, expected interface{}
}{
{"bool a", append([]bool{}), []bool{}},
{"bool b", append([]bool{}, true), []bool{true}},
{"bool c", append([]bool{}, true, false, true, true), []bool{true, false, true, true}},
{"bool d", append([]bool{true, false, true}), []bool{true, false, true}},
{"bool e", append([]bool{true, false, true}, false), []bool{true, false, true, false}},
{"bool f", append([]bool{true, false, true}, false, false, false), []bool{true, false, true, false, false, false}},
{"bool g", append([]bool{}, []bool{true}...), []bool{true}},
{"bool h", append([]bool{}, []bool{true, false, true, false}...), []bool{true, false, true, false}},
{"bool i", append([]bool{true, false, true}, []bool{true}...), []bool{true, false, true, true}},
{"bool j", append([]bool{true, false, true}, []bool{true, true, true}...), []bool{true, false, true, true, true, true}},
{"byte a", append([]byte{}), []byte{}},
{"byte b", append([]byte{}, 0), []byte{0}},
{"byte c", append([]byte{}, 0, 1, 2, 3), []byte{0, 1, 2, 3}},
{"byte d", append([]byte{0, 1, 2}), []byte{0, 1, 2}},
{"byte e", append([]byte{0, 1, 2}, 3), []byte{0, 1, 2, 3}},
{"byte f", append([]byte{0, 1, 2}, 3, 4, 5), []byte{0, 1, 2, 3, 4, 5}},
{"byte g", append([]byte{}, []byte{0}...), []byte{0}},
{"byte h", append([]byte{}, []byte{0, 1, 2, 3}...), []byte{0, 1, 2, 3}},
{"byte i", append([]byte{0, 1, 2}, []byte{3}...), []byte{0, 1, 2, 3}},
{"byte j", append([]byte{0, 1, 2}, []byte{3, 4, 5}...), []byte{0, 1, 2, 3, 4, 5}},
{"bytestr a", append([]byte{}, "0"...), []byte("0")},
{"bytestr b", append([]byte{}, "0123"...), []byte("0123")},
{"bytestr c", append([]byte("012"), "3"...), []byte("0123")},
{"bytestr d", append([]byte("012"), "345"...), []byte("012345")},
{"int16 a", append([]int16{}), []int16{}},
{"int16 b", append([]int16{}, 0), []int16{0}},
{"int16 c", append([]int16{}, 0, 1, 2, 3), []int16{0, 1, 2, 3}},
{"int16 d", append([]int16{0, 1, 2}), []int16{0, 1, 2}},
{"int16 e", append([]int16{0, 1, 2}, 3), []int16{0, 1, 2, 3}},
{"int16 f", append([]int16{0, 1, 2}, 3, 4, 5), []int16{0, 1, 2, 3, 4, 5}},
{"int16 g", append([]int16{}, []int16{0}...), []int16{0}},
{"int16 h", append([]int16{}, []int16{0, 1, 2, 3}...), []int16{0, 1, 2, 3}},
{"int16 i", append([]int16{0, 1, 2}, []int16{3}...), []int16{0, 1, 2, 3}},
{"int16 j", append([]int16{0, 1, 2}, []int16{3, 4, 5}...), []int16{0, 1, 2, 3, 4, 5}},
{"uint32 a", append([]uint32{}), []uint32{}},
{"uint32 b", append([]uint32{}, 0), []uint32{0}},
{"uint32 c", append([]uint32{}, 0, 1, 2, 3), []uint32{0, 1, 2, 3}},
{"uint32 d", append([]uint32{0, 1, 2}), []uint32{0, 1, 2}},
{"uint32 e", append([]uint32{0, 1, 2}, 3), []uint32{0, 1, 2, 3}},
{"uint32 f", append([]uint32{0, 1, 2}, 3, 4, 5), []uint32{0, 1, 2, 3, 4, 5}},
{"uint32 g", append([]uint32{}, []uint32{0}...), []uint32{0}},
{"uint32 h", append([]uint32{}, []uint32{0, 1, 2, 3}...), []uint32{0, 1, 2, 3}},
{"uint32 i", append([]uint32{0, 1, 2}, []uint32{3}...), []uint32{0, 1, 2, 3}},
{"uint32 j", append([]uint32{0, 1, 2}, []uint32{3, 4, 5}...), []uint32{0, 1, 2, 3, 4, 5}},
{"float64 a", append([]float64{}), []float64{}},
{"float64 b", append([]float64{}, 0), []float64{0}},
{"float64 c", append([]float64{}, 0, 1, 2, 3), []float64{0, 1, 2, 3}},
{"float64 d", append([]float64{0, 1, 2}), []float64{0, 1, 2}},
{"float64 e", append([]float64{0, 1, 2}, 3), []float64{0, 1, 2, 3}},
{"float64 f", append([]float64{0, 1, 2}, 3, 4, 5), []float64{0, 1, 2, 3, 4, 5}},
{"float64 g", append([]float64{}, []float64{0}...), []float64{0}},
{"float64 h", append([]float64{}, []float64{0, 1, 2, 3}...), []float64{0, 1, 2, 3}},
{"float64 i", append([]float64{0, 1, 2}, []float64{3}...), []float64{0, 1, 2, 3}},
{"float64 j", append([]float64{0, 1, 2}, []float64{3, 4, 5}...), []float64{0, 1, 2, 3, 4, 5}},
{"complex128 a", append([]complex128{}), []complex128{}},
{"complex128 b", append([]complex128{}, 0), []complex128{0}},
{"complex128 c", append([]complex128{}, 0, 1, 2, 3), []complex128{0, 1, 2, 3}},
{"complex128 d", append([]complex128{0, 1, 2}), []complex128{0, 1, 2}},
{"complex128 e", append([]complex128{0, 1, 2}, 3), []complex128{0, 1, 2, 3}},
{"complex128 f", append([]complex128{0, 1, 2}, 3, 4, 5), []complex128{0, 1, 2, 3, 4, 5}},
{"complex128 g", append([]complex128{}, []complex128{0}...), []complex128{0}},
{"complex128 h", append([]complex128{}, []complex128{0, 1, 2, 3}...), []complex128{0, 1, 2, 3}},
{"complex128 i", append([]complex128{0, 1, 2}, []complex128{3}...), []complex128{0, 1, 2, 3}},
{"complex128 j", append([]complex128{0, 1, 2}, []complex128{3, 4, 5}...), []complex128{0, 1, 2, 3, 4, 5}},
{"string a", append([]string{}), []string{}},
{"string b", append([]string{}, "0"), []string{"0"}},
{"string c", append([]string{}, "0", "1", "2", "3"), []string{"0", "1", "2", "3"}},
{"string d", append([]string{"0", "1", "2"}), []string{"0", "1", "2"}},
{"string e", append([]string{"0", "1", "2"}, "3"), []string{"0", "1", "2", "3"}},
{"string f", append([]string{"0", "1", "2"}, "3", "4", "5"), []string{"0", "1", "2", "3", "4", "5"}},
{"string g", append([]string{}, []string{"0"}...), []string{"0"}},
{"string h", append([]string{}, []string{"0", "1", "2", "3"}...), []string{"0", "1", "2", "3"}},
{"string i", append([]string{"0", "1", "2"}, []string{"3"}...), []string{"0", "1", "2", "3"}},
{"string j", append([]string{"0", "1", "2"}, []string{"3", "4", "5"}...), []string{"0", "1", "2", "3", "4", "5"}},
{"make a", append([]string{}, make([]string, 0)...), []string{}},
{"make b", append([]string(nil), make([]string, 0)...), []string(nil)},
{"make c", append([]struct{}{}, make([]struct{}, 0)...), []struct{}{}},
{"make d", append([]struct{}{}, make([]struct{}, 2)...), make([]struct{}, 2)},
{"make e", append([]int{0, 1}, make([]int, 0)...), []int{0, 1}},
{"make f", append([]int{0, 1}, make([]int, 2)...), []int{0, 1, 0, 0}},
{"make g", append([]*int{&zero, &one}, make([]*int, 0)...), []*int{&zero, &one}},
{"make h", append([]*int{&zero, &one}, make([]*int, 2)...), []*int{&zero, &one, nil, nil}},
}
func verifyStruct() {
type T struct {
a, b, c string
}
type S []T
e := make(S, 100)
for i := range e {
e[i] = T{"foo", fmt.Sprintf("%d", i), "bar"}
}
verify("struct a", append(S{}), S{})
verify("struct b", append(S{}, e[0]), e[0:1])
verify("struct c", append(S{}, e[0], e[1], e[2]), e[0:3])
verify("struct d", append(e[0:1]), e[0:1])
verify("struct e", append(e[0:1], e[1]), e[0:2])
verify("struct f", append(e[0:1], e[1], e[2], e[3]), e[0:4])
verify("struct g", append(e[0:3]), e[0:3])
verify("struct h", append(e[0:3], e[3]), e[0:4])
verify("struct i", append(e[0:3], e[3], e[4], e[5], e[6]), e[0:7])
for i := range e {
verify("struct j", append(S{}, e[0:i]...), e[0:i])
input := make(S, i)
copy(input, e[0:i])
verify("struct k", append(input, e[i:]...), e)
verify("struct k - input modified", input, e[0:i])
}
s := make(S, 10, 20)
r := make(S, len(s)+len(e))
for i, x := range e {
r[len(s)+i] = x
}
verify("struct l", append(s), s)
verify("struct m", append(s, e...), r)
}
func verifyInterface() {
type T interface{}
type S []T
e := make(S, 100)
for i := range e {
switch i % 4 {
case 0:
e[i] = i
case 1:
e[i] = "foo"
case 2:
e[i] = fmt.Sprintf("%d", i)
case 3:
e[i] = float64(i)
}
}
verify("interface a", append(S{}), S{})
verify("interface b", append(S{}, e[0]), e[0:1])
verify("interface c", append(S{}, e[0], e[1], e[2]), e[0:3])
verify("interface d", append(e[0:1]), e[0:1])
verify("interface e", append(e[0:1], e[1]), e[0:2])
verify("interface f", append(e[0:1], e[1], e[2], e[3]), e[0:4])
verify("interface g", append(e[0:3]), e[0:3])
verify("interface h", append(e[0:3], e[3]), e[0:4])
verify("interface i", append(e[0:3], e[3], e[4], e[5], e[6]), e[0:7])
for i := range e {
verify("interface j", append(S{}, e[0:i]...), e[0:i])
input := make(S, i)
copy(input, e[0:i])
verify("interface k", append(input, e[i:]...), e)
verify("interface k - input modified", input, e[0:i])
}
s := make(S, 10, 20)
r := make(S, len(s)+len(e))
for i, x := range e {
r[len(s)+i] = x
}
verify("interface l", append(s), s)
verify("interface m", append(s, e...), r)
}
type T1 []int
type T2 []int
func verifyType() {
// The second argument to append has type []E where E is the
// element type of the first argument. Test that the compiler
// accepts two slice types that meet that requirement but are
// not assignment compatible. The return type of append is
// the type of the first argument.
t1 := T1{1}
t2 := T2{2}
verify("T1", append(t1, t2...), T1{1, 2})
}
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