Your IP : 172.28.240.42
// Copyright 2021 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.
package slices
import (
"cmp"
"internal/race"
"internal/testenv"
"math"
"strings"
"testing"
)
var equalIntTests = []struct {
s1, s2 []int
want bool
}{
{
[]int{1},
nil,
false,
},
{
[]int{},
nil,
true,
},
{
[]int{1, 2, 3},
[]int{1, 2, 3},
true,
},
{
[]int{1, 2, 3},
[]int{1, 2, 3, 4},
false,
},
}
var equalFloatTests = []struct {
s1, s2 []float64
wantEqual bool
wantEqualNaN bool
}{
{
[]float64{1, 2},
[]float64{1, 2},
true,
true,
},
{
[]float64{1, 2, math.NaN()},
[]float64{1, 2, math.NaN()},
false,
true,
},
}
func TestEqual(t *testing.T) {
for _, test := range equalIntTests {
if got := Equal(test.s1, test.s2); got != test.want {
t.Errorf("Equal(%v, %v) = %t, want %t", test.s1, test.s2, got, test.want)
}
}
for _, test := range equalFloatTests {
if got := Equal(test.s1, test.s2); got != test.wantEqual {
t.Errorf("Equal(%v, %v) = %t, want %t", test.s1, test.s2, got, test.wantEqual)
}
}
}
// equal is simply ==.
func equal[T comparable](v1, v2 T) bool {
return v1 == v2
}
// equalNaN is like == except that all NaNs are equal.
func equalNaN[T comparable](v1, v2 T) bool {
isNaN := func(f T) bool { return f != f }
return v1 == v2 || (isNaN(v1) && isNaN(v2))
}
// offByOne returns true if integers v1 and v2 differ by 1.
func offByOne(v1, v2 int) bool {
return v1 == v2+1 || v1 == v2-1
}
func TestEqualFunc(t *testing.T) {
for _, test := range equalIntTests {
if got := EqualFunc(test.s1, test.s2, equal[int]); got != test.want {
t.Errorf("EqualFunc(%v, %v, equal[int]) = %t, want %t", test.s1, test.s2, got, test.want)
}
}
for _, test := range equalFloatTests {
if got := EqualFunc(test.s1, test.s2, equal[float64]); got != test.wantEqual {
t.Errorf("Equal(%v, %v, equal[float64]) = %t, want %t", test.s1, test.s2, got, test.wantEqual)
}
if got := EqualFunc(test.s1, test.s2, equalNaN[float64]); got != test.wantEqualNaN {
t.Errorf("Equal(%v, %v, equalNaN[float64]) = %t, want %t", test.s1, test.s2, got, test.wantEqualNaN)
}
}
s1 := []int{1, 2, 3}
s2 := []int{2, 3, 4}
if EqualFunc(s1, s1, offByOne) {
t.Errorf("EqualFunc(%v, %v, offByOne) = true, want false", s1, s1)
}
if !EqualFunc(s1, s2, offByOne) {
t.Errorf("EqualFunc(%v, %v, offByOne) = false, want true", s1, s2)
}
s3 := []string{"a", "b", "c"}
s4 := []string{"A", "B", "C"}
if !EqualFunc(s3, s4, strings.EqualFold) {
t.Errorf("EqualFunc(%v, %v, strings.EqualFold) = false, want true", s3, s4)
}
cmpIntString := func(v1 int, v2 string) bool {
return string(rune(v1)-1+'a') == v2
}
if !EqualFunc(s1, s3, cmpIntString) {
t.Errorf("EqualFunc(%v, %v, cmpIntString) = false, want true", s1, s3)
}
}
func BenchmarkEqualFunc_Large(b *testing.B) {
type Large [4 * 1024]byte
xs := make([]Large, 1024)
ys := make([]Large, 1024)
for i := 0; i < b.N; i++ {
_ = EqualFunc(xs, ys, func(x, y Large) bool { return x == y })
}
}
var compareIntTests = []struct {
s1, s2 []int
want int
}{
{
[]int{1},
[]int{1},
0,
},
{
[]int{1},
[]int{},
1,
},
{
[]int{},
[]int{1},
-1,
},
{
[]int{},
[]int{},
0,
},
{
[]int{1, 2, 3},
[]int{1, 2, 3},
0,
},
{
[]int{1, 2, 3},
[]int{1, 2, 3, 4},
-1,
},
{
[]int{1, 2, 3, 4},
[]int{1, 2, 3},
+1,
},
{
[]int{1, 2, 3},
[]int{1, 4, 3},
-1,
},
{
[]int{1, 4, 3},
[]int{1, 2, 3},
+1,
},
{
[]int{1, 4, 3},
[]int{1, 2, 3, 8, 9},
+1,
},
}
var compareFloatTests = []struct {
s1, s2 []float64
want int
}{
{
[]float64{},
[]float64{},
0,
},
{
[]float64{1},
[]float64{1},
0,
},
{
[]float64{math.NaN()},
[]float64{math.NaN()},
0,
},
{
[]float64{1, 2, math.NaN()},
[]float64{1, 2, math.NaN()},
0,
},
{
[]float64{1, math.NaN(), 3},
[]float64{1, math.NaN(), 4},
-1,
},
{
[]float64{1, math.NaN(), 3},
[]float64{1, 2, 4},
-1,
},
{
[]float64{1, math.NaN(), 3},
[]float64{1, 2, math.NaN()},
-1,
},
{
[]float64{1, 2, 3},
[]float64{1, 2, math.NaN()},
+1,
},
{
[]float64{1, 2, 3},
[]float64{1, math.NaN(), 3},
+1,
},
{
[]float64{1, math.NaN(), 3, 4},
[]float64{1, 2, math.NaN()},
-1,
},
}
func TestCompare(t *testing.T) {
intWant := func(want bool) string {
if want {
return "0"
}
return "!= 0"
}
for _, test := range equalIntTests {
if got := Compare(test.s1, test.s2); (got == 0) != test.want {
t.Errorf("Compare(%v, %v) = %d, want %s", test.s1, test.s2, got, intWant(test.want))
}
}
for _, test := range equalFloatTests {
if got := Compare(test.s1, test.s2); (got == 0) != test.wantEqualNaN {
t.Errorf("Compare(%v, %v) = %d, want %s", test.s1, test.s2, got, intWant(test.wantEqualNaN))
}
}
for _, test := range compareIntTests {
if got := Compare(test.s1, test.s2); got != test.want {
t.Errorf("Compare(%v, %v) = %d, want %d", test.s1, test.s2, got, test.want)
}
}
for _, test := range compareFloatTests {
if got := Compare(test.s1, test.s2); got != test.want {
t.Errorf("Compare(%v, %v) = %d, want %d", test.s1, test.s2, got, test.want)
}
}
}
func equalToCmp[T comparable](eq func(T, T) bool) func(T, T) int {
return func(v1, v2 T) int {
if eq(v1, v2) {
return 0
}
return 1
}
}
func TestCompareFunc(t *testing.T) {
intWant := func(want bool) string {
if want {
return "0"
}
return "!= 0"
}
for _, test := range equalIntTests {
if got := CompareFunc(test.s1, test.s2, equalToCmp(equal[int])); (got == 0) != test.want {
t.Errorf("CompareFunc(%v, %v, equalToCmp(equal[int])) = %d, want %s", test.s1, test.s2, got, intWant(test.want))
}
}
for _, test := range equalFloatTests {
if got := CompareFunc(test.s1, test.s2, equalToCmp(equal[float64])); (got == 0) != test.wantEqual {
t.Errorf("CompareFunc(%v, %v, equalToCmp(equal[float64])) = %d, want %s", test.s1, test.s2, got, intWant(test.wantEqual))
}
}
for _, test := range compareIntTests {
if got := CompareFunc(test.s1, test.s2, cmp.Compare[int]); got != test.want {
t.Errorf("CompareFunc(%v, %v, cmp[int]) = %d, want %d", test.s1, test.s2, got, test.want)
}
}
for _, test := range compareFloatTests {
if got := CompareFunc(test.s1, test.s2, cmp.Compare[float64]); got != test.want {
t.Errorf("CompareFunc(%v, %v, cmp[float64]) = %d, want %d", test.s1, test.s2, got, test.want)
}
}
s1 := []int{1, 2, 3}
s2 := []int{2, 3, 4}
if got := CompareFunc(s1, s2, equalToCmp(offByOne)); got != 0 {
t.Errorf("CompareFunc(%v, %v, offByOne) = %d, want 0", s1, s2, got)
}
s3 := []string{"a", "b", "c"}
s4 := []string{"A", "B", "C"}
if got := CompareFunc(s3, s4, strings.Compare); got != 1 {
t.Errorf("CompareFunc(%v, %v, strings.Compare) = %d, want 1", s3, s4, got)
}
compareLower := func(v1, v2 string) int {
return strings.Compare(strings.ToLower(v1), strings.ToLower(v2))
}
if got := CompareFunc(s3, s4, compareLower); got != 0 {
t.Errorf("CompareFunc(%v, %v, compareLower) = %d, want 0", s3, s4, got)
}
cmpIntString := func(v1 int, v2 string) int {
return strings.Compare(string(rune(v1)-1+'a'), v2)
}
if got := CompareFunc(s1, s3, cmpIntString); got != 0 {
t.Errorf("CompareFunc(%v, %v, cmpIntString) = %d, want 0", s1, s3, got)
}
}
var indexTests = []struct {
s []int
v int
want int
}{
{
nil,
0,
-1,
},
{
[]int{},
0,
-1,
},
{
[]int{1, 2, 3},
2,
1,
},
{
[]int{1, 2, 2, 3},
2,
1,
},
{
[]int{1, 2, 3, 2},
2,
1,
},
}
func TestIndex(t *testing.T) {
for _, test := range indexTests {
if got := Index(test.s, test.v); got != test.want {
t.Errorf("Index(%v, %v) = %d, want %d", test.s, test.v, got, test.want)
}
}
}
func equalToIndex[T any](f func(T, T) bool, v1 T) func(T) bool {
return func(v2 T) bool {
return f(v1, v2)
}
}
func BenchmarkIndex_Large(b *testing.B) {
type Large [4 * 1024]byte
ss := make([]Large, 1024)
for i := 0; i < b.N; i++ {
_ = Index(ss, Large{1})
}
}
func TestIndexFunc(t *testing.T) {
for _, test := range indexTests {
if got := IndexFunc(test.s, equalToIndex(equal[int], test.v)); got != test.want {
t.Errorf("IndexFunc(%v, equalToIndex(equal[int], %v)) = %d, want %d", test.s, test.v, got, test.want)
}
}
s1 := []string{"hi", "HI"}
if got := IndexFunc(s1, equalToIndex(equal[string], "HI")); got != 1 {
t.Errorf("IndexFunc(%v, equalToIndex(equal[string], %q)) = %d, want %d", s1, "HI", got, 1)
}
if got := IndexFunc(s1, equalToIndex(strings.EqualFold, "HI")); got != 0 {
t.Errorf("IndexFunc(%v, equalToIndex(strings.EqualFold, %q)) = %d, want %d", s1, "HI", got, 0)
}
}
func BenchmarkIndexFunc_Large(b *testing.B) {
type Large [4 * 1024]byte
ss := make([]Large, 1024)
for i := 0; i < b.N; i++ {
_ = IndexFunc(ss, func(e Large) bool {
return e == Large{1}
})
}
}
func TestContains(t *testing.T) {
for _, test := range indexTests {
if got := Contains(test.s, test.v); got != (test.want != -1) {
t.Errorf("Contains(%v, %v) = %t, want %t", test.s, test.v, got, test.want != -1)
}
}
}
func TestContainsFunc(t *testing.T) {
for _, test := range indexTests {
if got := ContainsFunc(test.s, equalToIndex(equal[int], test.v)); got != (test.want != -1) {
t.Errorf("ContainsFunc(%v, equalToIndex(equal[int], %v)) = %t, want %t", test.s, test.v, got, test.want != -1)
}
}
s1 := []string{"hi", "HI"}
if got := ContainsFunc(s1, equalToIndex(equal[string], "HI")); got != true {
t.Errorf("ContainsFunc(%v, equalToContains(equal[string], %q)) = %t, want %t", s1, "HI", got, true)
}
if got := ContainsFunc(s1, equalToIndex(equal[string], "hI")); got != false {
t.Errorf("ContainsFunc(%v, equalToContains(strings.EqualFold, %q)) = %t, want %t", s1, "hI", got, false)
}
if got := ContainsFunc(s1, equalToIndex(strings.EqualFold, "hI")); got != true {
t.Errorf("ContainsFunc(%v, equalToContains(strings.EqualFold, %q)) = %t, want %t", s1, "hI", got, true)
}
}
var insertTests = []struct {
s []int
i int
add []int
want []int
}{
{
[]int{1, 2, 3},
0,
[]int{4},
[]int{4, 1, 2, 3},
},
{
[]int{1, 2, 3},
1,
[]int{4},
[]int{1, 4, 2, 3},
},
{
[]int{1, 2, 3},
3,
[]int{4},
[]int{1, 2, 3, 4},
},
{
[]int{1, 2, 3},
2,
[]int{4, 5},
[]int{1, 2, 4, 5, 3},
},
}
func TestInsert(t *testing.T) {
s := []int{1, 2, 3}
if got := Insert(s, 0); !Equal(got, s) {
t.Errorf("Insert(%v, 0) = %v, want %v", s, got, s)
}
for _, test := range insertTests {
copy := Clone(test.s)
if got := Insert(copy, test.i, test.add...); !Equal(got, test.want) {
t.Errorf("Insert(%v, %d, %v...) = %v, want %v", test.s, test.i, test.add, got, test.want)
}
}
if !testenv.OptimizationOff() && !race.Enabled {
// Allocations should be amortized.
const count = 50
n := testing.AllocsPerRun(10, func() {
s := []int{1, 2, 3}
for i := 0; i < count; i++ {
s = Insert(s, 0, 1)
}
})
if n > count/2 {
t.Errorf("too many allocations inserting %d elements: got %v, want less than %d", count, n, count/2)
}
}
}
func TestInsertOverlap(t *testing.T) {
const N = 10
a := make([]int, N)
want := make([]int, 2*N)
for n := 0; n <= N; n++ { // length
for i := 0; i <= n; i++ { // insertion point
for x := 0; x <= N; x++ { // start of inserted data
for y := x; y <= N; y++ { // end of inserted data
for k := 0; k < N; k++ {
a[k] = k
}
want = want[:0]
want = append(want, a[:i]...)
want = append(want, a[x:y]...)
want = append(want, a[i:n]...)
got := Insert(a[:n], i, a[x:y]...)
if !Equal(got, want) {
t.Errorf("Insert with overlap failed n=%d i=%d x=%d y=%d, got %v want %v", n, i, x, y, got, want)
}
}
}
}
}
}
var deleteTests = []struct {
s []int
i, j int
want []int
}{
{
[]int{1, 2, 3},
0,
0,
[]int{1, 2, 3},
},
{
[]int{1, 2, 3},
0,
1,
[]int{2, 3},
},
{
[]int{1, 2, 3},
3,
3,
[]int{1, 2, 3},
},
{
[]int{1, 2, 3},
0,
2,
[]int{3},
},
{
[]int{1, 2, 3},
0,
3,
[]int{},
},
}
func TestDelete(t *testing.T) {
for _, test := range deleteTests {
copy := Clone(test.s)
if got := Delete(copy, test.i, test.j); !Equal(got, test.want) {
t.Errorf("Delete(%v, %d, %d) = %v, want %v", test.s, test.i, test.j, got, test.want)
}
}
}
var deleteFuncTests = []struct {
s []int
fn func(int) bool
want []int
}{
{
nil,
func(int) bool { return true },
nil,
},
{
[]int{1, 2, 3},
func(int) bool { return true },
nil,
},
{
[]int{1, 2, 3},
func(int) bool { return false },
[]int{1, 2, 3},
},
{
[]int{1, 2, 3},
func(i int) bool { return i > 2 },
[]int{1, 2},
},
{
[]int{1, 2, 3},
func(i int) bool { return i < 2 },
[]int{2, 3},
},
{
[]int{10, 2, 30},
func(i int) bool { return i >= 10 },
[]int{2},
},
}
func TestDeleteFunc(t *testing.T) {
for i, test := range deleteFuncTests {
copy := Clone(test.s)
if got := DeleteFunc(copy, test.fn); !Equal(got, test.want) {
t.Errorf("DeleteFunc case %d: got %v, want %v", i, got, test.want)
}
}
}
func panics(f func()) (b bool) {
defer func() {
if x := recover(); x != nil {
b = true
}
}()
f()
return false
}
func TestDeletePanics(t *testing.T) {
for _, test := range []struct {
name string
s []int
i, j int
}{
{"with negative first index", []int{42}, -2, 1},
{"with negative second index", []int{42}, 1, -1},
{"with out-of-bounds first index", []int{42}, 2, 3},
{"with out-of-bounds second index", []int{42}, 0, 2},
{"with invalid i>j", []int{42}, 1, 0},
} {
if !panics(func() { Delete(test.s, test.i, test.j) }) {
t.Errorf("Delete %s: got no panic, want panic", test.name)
}
}
}
func TestClone(t *testing.T) {
s1 := []int{1, 2, 3}
s2 := Clone(s1)
if !Equal(s1, s2) {
t.Errorf("Clone(%v) = %v, want %v", s1, s2, s1)
}
s1[0] = 4
want := []int{1, 2, 3}
if !Equal(s2, want) {
t.Errorf("Clone(%v) changed unexpectedly to %v", want, s2)
}
if got := Clone([]int(nil)); got != nil {
t.Errorf("Clone(nil) = %#v, want nil", got)
}
if got := Clone(s1[:0]); got == nil || len(got) != 0 {
t.Errorf("Clone(%v) = %#v, want %#v", s1[:0], got, s1[:0])
}
}
var compactTests = []struct {
name string
s []int
want []int
}{
{
"nil",
nil,
nil,
},
{
"one",
[]int{1},
[]int{1},
},
{
"sorted",
[]int{1, 2, 3},
[]int{1, 2, 3},
},
{
"1 item",
[]int{1, 1, 2},
[]int{1, 2},
},
{
"unsorted",
[]int{1, 2, 1},
[]int{1, 2, 1},
},
{
"many",
[]int{1, 2, 2, 3, 3, 4},
[]int{1, 2, 3, 4},
},
}
func TestCompact(t *testing.T) {
for _, test := range compactTests {
copy := Clone(test.s)
if got := Compact(copy); !Equal(got, test.want) {
t.Errorf("Compact(%v) = %v, want %v", test.s, got, test.want)
}
}
}
func BenchmarkCompact(b *testing.B) {
for _, c := range compactTests {
b.Run(c.name, func(b *testing.B) {
ss := make([]int, 0, 64)
for k := 0; k < b.N; k++ {
ss = ss[:0]
ss = append(ss, c.s...)
_ = Compact(ss)
}
})
}
}
func BenchmarkCompact_Large(b *testing.B) {
type Large [4 * 1024]byte
ss := make([]Large, 1024)
for i := 0; i < b.N; i++ {
_ = Compact(ss)
}
}
func TestCompactFunc(t *testing.T) {
for _, test := range compactTests {
copy := Clone(test.s)
if got := CompactFunc(copy, equal[int]); !Equal(got, test.want) {
t.Errorf("CompactFunc(%v, equal[int]) = %v, want %v", test.s, got, test.want)
}
}
s1 := []string{"a", "a", "A", "B", "b"}
copy := Clone(s1)
want := []string{"a", "B"}
if got := CompactFunc(copy, strings.EqualFold); !Equal(got, want) {
t.Errorf("CompactFunc(%v, strings.EqualFold) = %v, want %v", s1, got, want)
}
}
func BenchmarkCompactFunc_Large(b *testing.B) {
type Large [4 * 1024]byte
ss := make([]Large, 1024)
for i := 0; i < b.N; i++ {
_ = CompactFunc(ss, func(a, b Large) bool { return a == b })
}
}
func TestGrow(t *testing.T) {
s1 := []int{1, 2, 3}
copy := Clone(s1)
s2 := Grow(copy, 1000)
if !Equal(s1, s2) {
t.Errorf("Grow(%v) = %v, want %v", s1, s2, s1)
}
if cap(s2) < 1000+len(s1) {
t.Errorf("after Grow(%v) cap = %d, want >= %d", s1, cap(s2), 1000+len(s1))
}
// Test mutation of elements between length and capacity.
copy = Clone(s1)
s3 := Grow(copy[:1], 2)[:3]
if !Equal(s1, s3) {
t.Errorf("Grow should not mutate elements between length and capacity")
}
s3 = Grow(copy[:1], 1000)[:3]
if !Equal(s1, s3) {
t.Errorf("Grow should not mutate elements between length and capacity")
}
// Test number of allocations.
if n := testing.AllocsPerRun(100, func() { Grow(s2, cap(s2)-len(s2)) }); n != 0 {
t.Errorf("Grow should not allocate when given sufficient capacity; allocated %v times", n)
}
if n := testing.AllocsPerRun(100, func() { Grow(s2, cap(s2)-len(s2)+1) }); n != 1 {
errorf := t.Errorf
if race.Enabled || testenv.OptimizationOff() {
errorf = t.Logf // this allocates multiple times in race detector mode
}
errorf("Grow should allocate once when given insufficient capacity; allocated %v times", n)
}
// Test for negative growth sizes.
var gotPanic bool
func() {
defer func() { gotPanic = recover() != nil }()
Grow(s1, -1)
}()
if !gotPanic {
t.Errorf("Grow(-1) did not panic; expected a panic")
}
}
func TestClip(t *testing.T) {
s1 := []int{1, 2, 3, 4, 5, 6}[:3]
orig := Clone(s1)
if len(s1) != 3 {
t.Errorf("len(%v) = %d, want 3", s1, len(s1))
}
if cap(s1) < 6 {
t.Errorf("cap(%v[:3]) = %d, want >= 6", orig, cap(s1))
}
s2 := Clip(s1)
if !Equal(s1, s2) {
t.Errorf("Clip(%v) = %v, want %v", s1, s2, s1)
}
if cap(s2) != 3 {
t.Errorf("cap(Clip(%v)) = %d, want 3", orig, cap(s2))
}
}
func TestReverse(t *testing.T) {
even := []int{3, 1, 4, 1, 5, 9} // len = 6
Reverse(even)
if want := []int{9, 5, 1, 4, 1, 3}; !Equal(even, want) {
t.Errorf("Reverse(even) = %v, want %v", even, want)
}
odd := []int{3, 1, 4, 1, 5, 9, 2} // len = 7
Reverse(odd)
if want := []int{2, 9, 5, 1, 4, 1, 3}; !Equal(odd, want) {
t.Errorf("Reverse(odd) = %v, want %v", odd, want)
}
words := strings.Fields("one two three")
Reverse(words)
if want := strings.Fields("three two one"); !Equal(words, want) {
t.Errorf("Reverse(words) = %v, want %v", words, want)
}
singleton := []string{"one"}
Reverse(singleton)
if want := []string{"one"}; !Equal(singleton, want) {
t.Errorf("Reverse(singeleton) = %v, want %v", singleton, want)
}
Reverse[[]string](nil)
}
// naiveReplace is a baseline implementation to the Replace function.
func naiveReplace[S ~[]E, E any](s S, i, j int, v ...E) S {
s = Delete(s, i, j)
s = Insert(s, i, v...)
return s
}
func TestReplace(t *testing.T) {
for _, test := range []struct {
s, v []int
i, j int
}{
{}, // all zero value
{
s: []int{1, 2, 3, 4},
v: []int{5},
i: 1,
j: 2,
},
{
s: []int{1, 2, 3, 4},
v: []int{5, 6, 7, 8},
i: 1,
j: 2,
},
{
s: func() []int {
s := make([]int, 3, 20)
s[0] = 0
s[1] = 1
s[2] = 2
return s
}(),
v: []int{3, 4, 5, 6, 7},
i: 0,
j: 1,
},
} {
ss, vv := Clone(test.s), Clone(test.v)
want := naiveReplace(ss, test.i, test.j, vv...)
got := Replace(test.s, test.i, test.j, test.v...)
if !Equal(got, want) {
t.Errorf("Replace(%v, %v, %v, %v) = %v, want %v", test.s, test.i, test.j, test.v, got, want)
}
}
}
func TestReplacePanics(t *testing.T) {
for _, test := range []struct {
name string
s, v []int
i, j int
}{
{"indexes out of order", []int{1, 2}, []int{3}, 2, 1},
{"large index", []int{1, 2}, []int{3}, 1, 10},
{"negative index", []int{1, 2}, []int{3}, -1, 2},
} {
ss, vv := Clone(test.s), Clone(test.v)
if !panics(func() { Replace(ss, test.i, test.j, vv...) }) {
t.Errorf("Replace %s: should have panicked", test.name)
}
}
}
func TestReplaceOverlap(t *testing.T) {
const N = 10
a := make([]int, N)
want := make([]int, 2*N)
for n := 0; n <= N; n++ { // length
for i := 0; i <= n; i++ { // insertion point 1
for j := i; j <= n; j++ { // insertion point 2
for x := 0; x <= N; x++ { // start of inserted data
for y := x; y <= N; y++ { // end of inserted data
for k := 0; k < N; k++ {
a[k] = k
}
want = want[:0]
want = append(want, a[:i]...)
want = append(want, a[x:y]...)
want = append(want, a[j:n]...)
got := Replace(a[:n], i, j, a[x:y]...)
if !Equal(got, want) {
t.Errorf("Insert with overlap failed n=%d i=%d j=%d x=%d y=%d, got %v want %v", n, i, j, x, y, got, want)
}
}
}
}
}
}
}
func BenchmarkReplace(b *testing.B) {
cases := []struct {
name string
s, v func() []int
i, j int
}{
{
name: "fast",
s: func() []int {
return make([]int, 100)
},
v: func() []int {
return make([]int, 20)
},
i: 10,
j: 40,
},
{
name: "slow",
s: func() []int {
return make([]int, 100)
},
v: func() []int {
return make([]int, 20)
},
i: 0,
j: 2,
},
}
for _, c := range cases {
b.Run("naive-"+c.name, func(b *testing.B) {
for k := 0; k < b.N; k++ {
s := c.s()
v := c.v()
_ = naiveReplace(s, c.i, c.j, v...)
}
})
b.Run("optimized-"+c.name, func(b *testing.B) {
for k := 0; k < b.N; k++ {
s := c.s()
v := c.v()
_ = Replace(s, c.i, c.j, v...)
}
})
}
}
func TestRotate(t *testing.T) {
const N = 10
s := make([]int, 0, N)
for n := 0; n < N; n++ {
for r := 0; r < n; r++ {
s = s[:0]
for i := 0; i < n; i++ {
s = append(s, i)
}
rotateLeft(s, r)
for i := 0; i < n; i++ {
if s[i] != (i+r)%n {
t.Errorf("expected n=%d r=%d i:%d want:%d got:%d", n, r, i, (i+r)%n, s[i])
}
}
}
}
}
func TestInsertGrowthRate(t *testing.T) {
b := make([]byte, 1)
maxCap := cap(b)
nGrow := 0
const N = 1e6
for i := 0; i < N; i++ {
b = Insert(b, len(b)-1, 0)
if cap(b) > maxCap {
maxCap = cap(b)
nGrow++
}
}
want := int(math.Log(N) / math.Log(1.25)) // 1.25 == growth rate for large slices
if nGrow > want {
t.Errorf("too many grows. got:%d want:%d", nGrow, want)
}
}
func TestReplaceGrowthRate(t *testing.T) {
b := make([]byte, 2)
maxCap := cap(b)
nGrow := 0
const N = 1e6
for i := 0; i < N; i++ {
b = Replace(b, len(b)-2, len(b)-1, 0, 0)
if cap(b) > maxCap {
maxCap = cap(b)
nGrow++
}
}
want := int(math.Log(N) / math.Log(1.25)) // 1.25 == growth rate for large slices
if nGrow > want {
t.Errorf("too many grows. got:%d want:%d", nGrow, want)
}
}
func apply[T any](v T, f func(T)) {
f(v)
}
// Test type inference with a named slice type.
func TestInference(t *testing.T) {
s1 := []int{1, 2, 3}
apply(s1, Reverse)
if want := []int{3, 2, 1}; !Equal(s1, want) {
t.Errorf("Reverse(%v) = %v, want %v", []int{1, 2, 3}, s1, want)
}
type S []int
s2 := S{4, 5, 6}
apply(s2, Reverse)
if want := (S{6, 5, 4}); !Equal(s2, want) {
t.Errorf("Reverse(%v) = %v, want %v", S{4, 5, 6}, s2, want)
}
}