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// Copyright 2009 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 strconv_test
import (
"math"
"math/rand"
. "strconv"
"testing"
)
type ftoaTest struct {
f float64
fmt byte
prec int
s string
}
func fdiv(a, b float64) float64 { return a / b }
const (
below1e23 = 99999999999999974834176
above1e23 = 100000000000000008388608
)
var ftoatests = []ftoaTest{
{1, 'e', 5, "1.00000e+00"},
{1, 'f', 5, "1.00000"},
{1, 'g', 5, "1"},
{1, 'g', -1, "1"},
{1, 'x', -1, "0x1p+00"},
{1, 'x', 5, "0x1.00000p+00"},
{20, 'g', -1, "20"},
{20, 'x', -1, "0x1.4p+04"},
{1234567.8, 'g', -1, "1.2345678e+06"},
{1234567.8, 'x', -1, "0x1.2d687cccccccdp+20"},
{200000, 'g', -1, "200000"},
{200000, 'x', -1, "0x1.86ap+17"},
{200000, 'X', -1, "0X1.86AP+17"},
{2000000, 'g', -1, "2e+06"},
{1e10, 'g', -1, "1e+10"},
// g conversion and zero suppression
{400, 'g', 2, "4e+02"},
{40, 'g', 2, "40"},
{4, 'g', 2, "4"},
{.4, 'g', 2, "0.4"},
{.04, 'g', 2, "0.04"},
{.004, 'g', 2, "0.004"},
{.0004, 'g', 2, "0.0004"},
{.00004, 'g', 2, "4e-05"},
{.000004, 'g', 2, "4e-06"},
{0, 'e', 5, "0.00000e+00"},
{0, 'f', 5, "0.00000"},
{0, 'g', 5, "0"},
{0, 'g', -1, "0"},
{0, 'x', 5, "0x0.00000p+00"},
{-1, 'e', 5, "-1.00000e+00"},
{-1, 'f', 5, "-1.00000"},
{-1, 'g', 5, "-1"},
{-1, 'g', -1, "-1"},
{12, 'e', 5, "1.20000e+01"},
{12, 'f', 5, "12.00000"},
{12, 'g', 5, "12"},
{12, 'g', -1, "12"},
{123456700, 'e', 5, "1.23457e+08"},
{123456700, 'f', 5, "123456700.00000"},
{123456700, 'g', 5, "1.2346e+08"},
{123456700, 'g', -1, "1.234567e+08"},
{1.2345e6, 'e', 5, "1.23450e+06"},
{1.2345e6, 'f', 5, "1234500.00000"},
{1.2345e6, 'g', 5, "1.2345e+06"},
// Round to even
{1.2345e6, 'e', 3, "1.234e+06"},
{1.2355e6, 'e', 3, "1.236e+06"},
{1.2345, 'f', 3, "1.234"},
{1.2355, 'f', 3, "1.236"},
{1234567890123456.5, 'e', 15, "1.234567890123456e+15"},
{1234567890123457.5, 'e', 15, "1.234567890123458e+15"},
{108678236358137.625, 'g', -1, "1.0867823635813762e+14"},
{1e23, 'e', 17, "9.99999999999999916e+22"},
{1e23, 'f', 17, "99999999999999991611392.00000000000000000"},
{1e23, 'g', 17, "9.9999999999999992e+22"},
{1e23, 'e', -1, "1e+23"},
{1e23, 'f', -1, "100000000000000000000000"},
{1e23, 'g', -1, "1e+23"},
{below1e23, 'e', 17, "9.99999999999999748e+22"},
{below1e23, 'f', 17, "99999999999999974834176.00000000000000000"},
{below1e23, 'g', 17, "9.9999999999999975e+22"},
{below1e23, 'e', -1, "9.999999999999997e+22"},
{below1e23, 'f', -1, "99999999999999970000000"},
{below1e23, 'g', -1, "9.999999999999997e+22"},
{above1e23, 'e', 17, "1.00000000000000008e+23"},
{above1e23, 'f', 17, "100000000000000008388608.00000000000000000"},
{above1e23, 'g', 17, "1.0000000000000001e+23"},
{above1e23, 'e', -1, "1.0000000000000001e+23"},
{above1e23, 'f', -1, "100000000000000010000000"},
{above1e23, 'g', -1, "1.0000000000000001e+23"},
{fdiv(5e-304, 1e20), 'g', -1, "5e-324"}, // avoid constant arithmetic
{fdiv(-5e-304, 1e20), 'g', -1, "-5e-324"}, // avoid constant arithmetic
{32, 'g', -1, "32"},
{32, 'g', 0, "3e+01"},
{100, 'x', -1, "0x1.9p+06"},
{100, 'y', -1, "%y"},
{math.NaN(), 'g', -1, "NaN"},
{-math.NaN(), 'g', -1, "NaN"},
{math.Inf(0), 'g', -1, "+Inf"},
{math.Inf(-1), 'g', -1, "-Inf"},
{-math.Inf(0), 'g', -1, "-Inf"},
{-1, 'b', -1, "-4503599627370496p-52"},
// fixed bugs
{0.9, 'f', 1, "0.9"},
{0.09, 'f', 1, "0.1"},
{0.0999, 'f', 1, "0.1"},
{0.05, 'f', 1, "0.1"},
{0.05, 'f', 0, "0"},
{0.5, 'f', 1, "0.5"},
{0.5, 'f', 0, "0"},
{1.5, 'f', 0, "2"},
// https://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
{2.2250738585072012e-308, 'g', -1, "2.2250738585072014e-308"},
// https://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
{2.2250738585072011e-308, 'g', -1, "2.225073858507201e-308"},
// Issue 2625.
{383260575764816448, 'f', 0, "383260575764816448"},
{383260575764816448, 'g', -1, "3.8326057576481645e+17"},
// Issue 29491.
{498484681984085570, 'f', -1, "498484681984085570"},
{-5.8339553793802237e+23, 'g', -1, "-5.8339553793802237e+23"},
// rounding
{2.275555555555555, 'x', -1, "0x1.23456789abcdep+01"},
{2.275555555555555, 'x', 0, "0x1p+01"},
{2.275555555555555, 'x', 2, "0x1.23p+01"},
{2.275555555555555, 'x', 16, "0x1.23456789abcde000p+01"},
{2.275555555555555, 'x', 21, "0x1.23456789abcde00000000p+01"},
{2.2755555510520935, 'x', -1, "0x1.2345678p+01"},
{2.2755555510520935, 'x', 6, "0x1.234568p+01"},
{2.275555431842804, 'x', -1, "0x1.2345668p+01"},
{2.275555431842804, 'x', 6, "0x1.234566p+01"},
{3.999969482421875, 'x', -1, "0x1.ffffp+01"},
{3.999969482421875, 'x', 4, "0x1.ffffp+01"},
{3.999969482421875, 'x', 3, "0x1.000p+02"},
{3.999969482421875, 'x', 2, "0x1.00p+02"},
{3.999969482421875, 'x', 1, "0x1.0p+02"},
{3.999969482421875, 'x', 0, "0x1p+02"},
}
func TestFtoa(t *testing.T) {
for i := 0; i < len(ftoatests); i++ {
test := &ftoatests[i]
s := FormatFloat(test.f, test.fmt, test.prec, 64)
if s != test.s {
t.Error("testN=64", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
}
x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 64)
if string(x) != "abc"+test.s {
t.Error("AppendFloat testN=64", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
}
if float64(float32(test.f)) == test.f && test.fmt != 'b' {
s := FormatFloat(test.f, test.fmt, test.prec, 32)
if s != test.s {
t.Error("testN=32", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
}
x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 32)
if string(x) != "abc"+test.s {
t.Error("AppendFloat testN=32", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
}
}
}
}
func TestFtoaPowersOfTwo(t *testing.T) {
for exp := -2048; exp <= 2048; exp++ {
f := math.Ldexp(1, exp)
if !math.IsInf(f, 0) {
s := FormatFloat(f, 'e', -1, 64)
if x, _ := ParseFloat(s, 64); x != f {
t.Errorf("failed roundtrip %v => %s => %v", f, s, x)
}
}
f32 := float32(f)
if !math.IsInf(float64(f32), 0) {
s := FormatFloat(float64(f32), 'e', -1, 32)
if x, _ := ParseFloat(s, 32); float32(x) != f32 {
t.Errorf("failed roundtrip %v => %s => %v", f32, s, float32(x))
}
}
}
}
func TestFtoaRandom(t *testing.T) {
N := int(1e4)
if testing.Short() {
N = 100
}
t.Logf("testing %d random numbers with fast and slow FormatFloat", N)
for i := 0; i < N; i++ {
bits := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
x := math.Float64frombits(bits)
shortFast := FormatFloat(x, 'g', -1, 64)
SetOptimize(false)
shortSlow := FormatFloat(x, 'g', -1, 64)
SetOptimize(true)
if shortSlow != shortFast {
t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
}
prec := rand.Intn(12) + 5
shortFast = FormatFloat(x, 'e', prec, 64)
SetOptimize(false)
shortSlow = FormatFloat(x, 'e', prec, 64)
SetOptimize(true)
if shortSlow != shortFast {
t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
}
}
}
func TestFormatFloatInvalidBitSize(t *testing.T) {
defer func() {
if r := recover(); r == nil {
t.Fatalf("expected panic due to invalid bitSize")
}
}()
_ = FormatFloat(3.14, 'g', -1, 100)
}
var ftoaBenches = []struct {
name string
float float64
fmt byte
prec int
bitSize int
}{
{"Decimal", 33909, 'g', -1, 64},
{"Float", 339.7784, 'g', -1, 64},
{"Exp", -5.09e75, 'g', -1, 64},
{"NegExp", -5.11e-95, 'g', -1, 64},
{"LongExp", 1.234567890123456e-78, 'g', -1, 64},
{"Big", 123456789123456789123456789, 'g', -1, 64},
{"BinaryExp", -1, 'b', -1, 64},
{"32Integer", 33909, 'g', -1, 32},
{"32ExactFraction", 3.375, 'g', -1, 32},
{"32Point", 339.7784, 'g', -1, 32},
{"32Exp", -5.09e25, 'g', -1, 32},
{"32NegExp", -5.11e-25, 'g', -1, 32},
{"32Shortest", 1.234567e-8, 'g', -1, 32},
{"32Fixed8Hard", math.Ldexp(15961084, -125), 'e', 8, 32},
{"32Fixed9Hard", math.Ldexp(14855922, -83), 'e', 9, 32},
{"64Fixed1", 123456, 'e', 3, 64},
{"64Fixed2", 123.456, 'e', 3, 64},
{"64Fixed3", 1.23456e+78, 'e', 3, 64},
{"64Fixed4", 1.23456e-78, 'e', 3, 64},
{"64Fixed12", 1.23456e-78, 'e', 12, 64},
{"64Fixed16", 1.23456e-78, 'e', 16, 64},
// From testdata/testfp.txt
{"64Fixed12Hard", math.Ldexp(6965949469487146, -249), 'e', 12, 64},
{"64Fixed17Hard", math.Ldexp(8887055249355788, 665), 'e', 17, 64},
{"64Fixed18Hard", math.Ldexp(6994187472632449, 690), 'e', 18, 64},
// Trigger slow path (see issue #15672).
// The shortest is: 8.034137530808823e+43
{"Slowpath64", 8.03413753080882349e+43, 'e', -1, 64},
// This denormal is pathological because the lower/upper
// halfways to neighboring floats are:
// 622666234635.321003e-320 ~= 622666234635.321e-320
// 622666234635.321497e-320 ~= 622666234635.3215e-320
// making it hard to find the 3rd digit
{"SlowpathDenormal64", 622666234635.3213e-320, 'e', -1, 64},
}
func BenchmarkFormatFloat(b *testing.B) {
for _, c := range ftoaBenches {
b.Run(c.name, func(b *testing.B) {
for i := 0; i < b.N; i++ {
FormatFloat(c.float, c.fmt, c.prec, c.bitSize)
}
})
}
}
func BenchmarkAppendFloat(b *testing.B) {
dst := make([]byte, 30)
for _, c := range ftoaBenches {
b.Run(c.name, func(b *testing.B) {
for i := 0; i < b.N; i++ {
AppendFloat(dst[:0], c.float, c.fmt, c.prec, c.bitSize)
}
})
}
}
|
