mirror of https://go.googlesource.com/go
148 lines
3.6 KiB
Go
148 lines
3.6 KiB
Go
// Copyright 2023 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime_test
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import (
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"math"
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"strings"
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"testing"
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"unsafe"
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)
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var (
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zero = math.Copysign(0, +1)
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negZero = math.Copysign(0, -1)
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inf = math.Inf(+1)
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negInf = math.Inf(-1)
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nan = math.NaN()
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)
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var tests = []struct{ min, max float64 }{
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{1, 2},
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{-2, 1},
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{negZero, zero},
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{zero, inf},
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{negInf, zero},
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{negInf, inf},
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{1, inf},
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{negInf, 1},
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}
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var all = []float64{1, 2, -1, -2, zero, negZero, inf, negInf, nan}
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func eq(x, y float64) bool {
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return x == y && math.Signbit(x) == math.Signbit(y)
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}
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func TestMinFloat(t *testing.T) {
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for _, tt := range tests {
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if z := min(tt.min, tt.max); !eq(z, tt.min) {
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t.Errorf("min(%v, %v) = %v, want %v", tt.min, tt.max, z, tt.min)
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}
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if z := min(tt.max, tt.min); !eq(z, tt.min) {
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t.Errorf("min(%v, %v) = %v, want %v", tt.max, tt.min, z, tt.min)
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}
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}
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for _, x := range all {
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if z := min(nan, x); !math.IsNaN(z) {
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t.Errorf("min(%v, %v) = %v, want %v", nan, x, z, nan)
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}
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if z := min(x, nan); !math.IsNaN(z) {
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t.Errorf("min(%v, %v) = %v, want %v", nan, x, z, nan)
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}
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}
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}
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func TestMaxFloat(t *testing.T) {
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for _, tt := range tests {
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if z := max(tt.min, tt.max); !eq(z, tt.max) {
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t.Errorf("max(%v, %v) = %v, want %v", tt.min, tt.max, z, tt.max)
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}
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if z := max(tt.max, tt.min); !eq(z, tt.max) {
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t.Errorf("max(%v, %v) = %v, want %v", tt.max, tt.min, z, tt.max)
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}
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}
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for _, x := range all {
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if z := max(nan, x); !math.IsNaN(z) {
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t.Errorf("max(%v, %v) = %v, want %v", nan, x, z, nan)
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}
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if z := max(x, nan); !math.IsNaN(z) {
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t.Errorf("max(%v, %v) = %v, want %v", nan, x, z, nan)
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}
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}
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}
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// testMinMax tests that min/max behave correctly on every pair of
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// values in vals.
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//
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// vals should be a sequence of values in strictly ascending order.
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func testMinMax[T int | uint8 | string](t *testing.T, vals ...T) {
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for i, x := range vals {
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for _, y := range vals[i+1:] {
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if !(x < y) {
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t.Fatalf("values out of order: !(%v < %v)", x, y)
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}
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if z := min(x, y); z != x {
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t.Errorf("min(%v, %v) = %v, want %v", x, y, z, x)
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}
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if z := min(y, x); z != x {
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t.Errorf("min(%v, %v) = %v, want %v", y, x, z, x)
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}
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if z := max(x, y); z != y {
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t.Errorf("max(%v, %v) = %v, want %v", x, y, z, y)
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}
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if z := max(y, x); z != y {
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t.Errorf("max(%v, %v) = %v, want %v", y, x, z, y)
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}
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}
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}
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}
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func TestMinMaxInt(t *testing.T) { testMinMax[int](t, -7, 0, 9) }
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func TestMinMaxUint8(t *testing.T) { testMinMax[uint8](t, 0, 1, 2, 4, 7) }
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func TestMinMaxString(t *testing.T) { testMinMax[string](t, "a", "b", "c") }
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// TestMinMaxStringTies ensures that min(a, b) returns a when a == b.
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func TestMinMaxStringTies(t *testing.T) {
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s := "xxx"
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x := strings.Split(s, "")
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test := func(i, j, k int) {
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if z := min(x[i], x[j], x[k]); unsafe.StringData(z) != unsafe.StringData(x[i]) {
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t.Errorf("min(x[%v], x[%v], x[%v]) = %p, want %p", i, j, k, unsafe.StringData(z), unsafe.StringData(x[i]))
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}
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if z := max(x[i], x[j], x[k]); unsafe.StringData(z) != unsafe.StringData(x[i]) {
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t.Errorf("max(x[%v], x[%v], x[%v]) = %p, want %p", i, j, k, unsafe.StringData(z), unsafe.StringData(x[i]))
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}
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}
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test(0, 1, 2)
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test(0, 2, 1)
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test(1, 0, 2)
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test(1, 2, 0)
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test(2, 0, 1)
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test(2, 1, 0)
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}
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func BenchmarkMinFloat(b *testing.B) {
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var m float64 = 0
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for i := 0; i < b.N; i++ {
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for _, f := range all {
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m = min(m, f)
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}
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}
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}
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func BenchmarkMaxFloat(b *testing.B) {
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var m float64 = 0
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for i := 0; i < b.N; i++ {
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for _, f := range all {
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m = max(m, f)
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}
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}
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}
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