github.com/dannin/go@v0.0.0-20161031215817-d35dfd405eaa/src/strconv/atof_test.go

// 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"
	"reflect"
	. "strconv"
	"strings"
	"testing"
	"time"
)

type atofTest struct {
	in  string
	out string
	err error
}

var atoftests = []atofTest{
	{"", "0", ErrSyntax},
	{"1", "1", nil},
	{"+1", "1", nil},
	{"1x", "0", ErrSyntax},
	{"1.1.", "0", ErrSyntax},
	{"1e23", "1e+23", nil},
	{"1E23", "1e+23", nil},
	{"100000000000000000000000", "1e+23", nil},
	{"1e-100", "1e-100", nil},
	{"123456700", "1.234567e+08", nil},
	{"99999999999999974834176", "9.999999999999997e+22", nil},
	{"100000000000000000000001", "1.0000000000000001e+23", nil},
	{"100000000000000008388608", "1.0000000000000001e+23", nil},
	{"100000000000000016777215", "1.0000000000000001e+23", nil},
	{"100000000000000016777216", "1.0000000000000003e+23", nil},
	{"-1", "-1", nil},
	{"-0.1", "-0.1", nil},
	{"-0", "-0", nil},
	{"1e-20", "1e-20", nil},
	{"625e-3", "0.625", nil},

	// zeros
	{"0", "0", nil},
	{"0e0", "0", nil},
	{"-0e0", "-0", nil},
	{"+0e0", "0", nil},
	{"0e-0", "0", nil},
	{"-0e-0", "-0", nil},
	{"+0e-0", "0", nil},
	{"0e+0", "0", nil},
	{"-0e+0", "-0", nil},
	{"+0e+0", "0", nil},
	{"0e+01234567890123456789", "0", nil},
	{"0.00e-01234567890123456789", "0", nil},
	{"-0e+01234567890123456789", "-0", nil},
	{"-0.00e-01234567890123456789", "-0", nil},
	{"0e291", "0", nil}, // issue 15364
	{"0e292", "0", nil}, // issue 15364
	{"0e347", "0", nil}, // issue 15364
	{"0e348", "0", nil}, // issue 15364
	{"-0e291", "-0", nil},
	{"-0e292", "-0", nil},
	{"-0e347", "-0", nil},
	{"-0e348", "-0", nil},

	// NaNs
	{"nan", "NaN", nil},
	{"NaN", "NaN", nil},
	{"NAN", "NaN", nil},

	// Infs
	{"inf", "+Inf", nil},
	{"-Inf", "-Inf", nil},
	{"+INF", "+Inf", nil},
	{"-Infinity", "-Inf", nil},
	{"+INFINITY", "+Inf", nil},
	{"Infinity", "+Inf", nil},

	// largest float64
	{"1.7976931348623157e308", "1.7976931348623157e+308", nil},
	{"-1.7976931348623157e308", "-1.7976931348623157e+308", nil},
	// next float64 - too large
	{"1.7976931348623159e308", "+Inf", ErrRange},
	{"-1.7976931348623159e308", "-Inf", ErrRange},
	// the border is ...158079
	// borderline - okay
	{"1.7976931348623158e308", "1.7976931348623157e+308", nil},
	{"-1.7976931348623158e308", "-1.7976931348623157e+308", nil},
	// borderline - too large
	{"1.797693134862315808e308", "+Inf", ErrRange},
	{"-1.797693134862315808e308", "-Inf", ErrRange},

	// a little too large
	{"1e308", "1e+308", nil},
	{"2e308", "+Inf", ErrRange},
	{"1e309", "+Inf", ErrRange},

	// way too large
	{"1e310", "+Inf", ErrRange},
	{"-1e310", "-Inf", ErrRange},
	{"1e400", "+Inf", ErrRange},
	{"-1e400", "-Inf", ErrRange},
	{"1e400000", "+Inf", ErrRange},
	{"-1e400000", "-Inf", ErrRange},

	// denormalized
	{"1e-305", "1e-305", nil},
	{"1e-306", "1e-306", nil},
	{"1e-307", "1e-307", nil},
	{"1e-308", "1e-308", nil},
	{"1e-309", "1e-309", nil},
	{"1e-310", "1e-310", nil},
	{"1e-322", "1e-322", nil},
	// smallest denormal
	{"5e-324", "5e-324", nil},
	{"4e-324", "5e-324", nil},
	{"3e-324", "5e-324", nil},
	// too small
	{"2e-324", "0", nil},
	// way too small
	{"1e-350", "0", nil},
	{"1e-400000", "0", nil},

	// try to overflow exponent
	{"1e-4294967296", "0", nil},
	{"1e+4294967296", "+Inf", ErrRange},
	{"1e-18446744073709551616", "0", nil},
	{"1e+18446744073709551616", "+Inf", ErrRange},

	// Parse errors
	{"1e", "0", ErrSyntax},
	{"1e-", "0", ErrSyntax},
	{".e-1", "0", ErrSyntax},
	{"1\x00.2", "0", ErrSyntax},

	// http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
	{"2.2250738585072012e-308", "2.2250738585072014e-308", nil},
	// http://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
	{"2.2250738585072011e-308", "2.225073858507201e-308", nil},

	// A very large number (initially wrongly parsed by the fast algorithm).
	{"4.630813248087435e+307", "4.630813248087435e+307", nil},

	// A different kind of very large number.
	{"22.222222222222222", "22.22222222222222", nil},
	{"2." + strings.Repeat("2", 4000) + "e+1", "22.22222222222222", nil},

	// Exactly halfway between 1 and math.Nextafter(1, 2).
	// Round to even (down).
	{"1.00000000000000011102230246251565404236316680908203125", "1", nil},
	// Slightly lower; still round down.
	{"1.00000000000000011102230246251565404236316680908203124", "1", nil},
	// Slightly higher; round up.
	{"1.00000000000000011102230246251565404236316680908203126", "1.0000000000000002", nil},
	// Slightly higher, but you have to read all the way to the end.
	{"1.00000000000000011102230246251565404236316680908203125" + strings.Repeat("0", 10000) + "1", "1.0000000000000002", nil},
}

var atof32tests = []atofTest{
	// Exactly halfway between 1 and the next float32.
	// Round to even (down).
	{"1.000000059604644775390625", "1", nil},
	// Slightly lower.
	{"1.000000059604644775390624", "1", nil},
	// Slightly higher.
	{"1.000000059604644775390626", "1.0000001", nil},
	// Slightly higher, but you have to read all the way to the end.
	{"1.000000059604644775390625" + strings.Repeat("0", 10000) + "1", "1.0000001", nil},

	// largest float32: (1<<128) * (1 - 2^-24)
	{"340282346638528859811704183484516925440", "3.4028235e+38", nil},
	{"-340282346638528859811704183484516925440", "-3.4028235e+38", nil},
	// next float32 - too large
	{"3.4028236e38", "+Inf", ErrRange},
	{"-3.4028236e38", "-Inf", ErrRange},
	// the border is 3.40282356779...e+38
	// borderline - okay
	{"3.402823567e38", "3.4028235e+38", nil},
	{"-3.402823567e38", "-3.4028235e+38", nil},
	// borderline - too large
	{"3.4028235678e38", "+Inf", ErrRange},
	{"-3.4028235678e38", "-Inf", ErrRange},

	// Denormals: less than 2^-126
	{"1e-38", "1e-38", nil},
	{"1e-39", "1e-39", nil},
	{"1e-40", "1e-40", nil},
	{"1e-41", "1e-41", nil},
	{"1e-42", "1e-42", nil},
	{"1e-43", "1e-43", nil},
	{"1e-44", "1e-44", nil},
	{"6e-45", "6e-45", nil}, // 4p-149 = 5.6e-45
	{"5e-45", "6e-45", nil},
	// Smallest denormal
	{"1e-45", "1e-45", nil}, // 1p-149 = 1.4e-45
	{"2e-45", "1e-45", nil},

	// 2^92 = 8388608p+69 = 4951760157141521099596496896 (4.9517602e27)
	// is an exact power of two that needs 8 decimal digits to be correctly
	// parsed back.
	// The float32 before is 16777215p+68 = 4.95175986e+27
	// The halfway is 4.951760009. A bad algorithm that thinks the previous
	// float32 is 8388607p+69 will shorten incorrectly to 4.95176e+27.
	{"4951760157141521099596496896", "4.9517602e+27", nil},
}

type atofSimpleTest struct {
	x float64
	s string
}

var (
	atofRandomTests        []atofSimpleTest
	benchmarksRandomBits   [1024]string
	benchmarksRandomNormal [1024]string
)

func init() {
	// The atof routines return NumErrors wrapping
	// the error and the string. Convert the table above.
	for i := range atoftests {
		test := &atoftests[i]
		if test.err != nil {
			test.err = &NumError{"ParseFloat", test.in, test.err}
		}
	}
	for i := range atof32tests {
		test := &atof32tests[i]
		if test.err != nil {
			test.err = &NumError{"ParseFloat", test.in, test.err}
		}
	}

	// Generate random inputs for tests and benchmarks
	rand.Seed(time.Now().UnixNano())
	if testing.Short() {
		atofRandomTests = make([]atofSimpleTest, 100)
	} else {
		atofRandomTests = make([]atofSimpleTest, 10000)
	}
	for i := range atofRandomTests {
		n := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
		x := math.Float64frombits(n)
		s := FormatFloat(x, 'g', -1, 64)
		atofRandomTests[i] = atofSimpleTest{x, s}
	}

	for i := range benchmarksRandomBits {
		bits := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
		x := math.Float64frombits(bits)
		benchmarksRandomBits[i] = FormatFloat(x, 'g', -1, 64)
	}

	for i := range benchmarksRandomNormal {
		x := rand.NormFloat64()
		benchmarksRandomNormal[i] = FormatFloat(x, 'g', -1, 64)
	}
}

func testAtof(t *testing.T, opt bool) {
	oldopt := SetOptimize(opt)
	for i := 0; i < len(atoftests); i++ {
		test := &atoftests[i]
		out, err := ParseFloat(test.in, 64)
		outs := FormatFloat(out, 'g', -1, 64)
		if outs != test.out || !reflect.DeepEqual(err, test.err) {
			t.Errorf("ParseFloat(%v, 64) = %v, %v want %v, %v",
				test.in, out, err, test.out, test.err)
		}

		if float64(float32(out)) == out {
			out, err := ParseFloat(test.in, 32)
			out32 := float32(out)
			if float64(out32) != out {
				t.Errorf("ParseFloat(%v, 32) = %v, not a float32 (closest is %v)", test.in, out, float64(out32))
				continue
			}
			outs := FormatFloat(float64(out32), 'g', -1, 32)
			if outs != test.out || !reflect.DeepEqual(err, test.err) {
				t.Errorf("ParseFloat(%v, 32) = %v, %v want %v, %v  # %v",
					test.in, out32, err, test.out, test.err, out)
			}
		}
	}
	for _, test := range atof32tests {
		out, err := ParseFloat(test.in, 32)
		out32 := float32(out)
		if float64(out32) != out {
			t.Errorf("ParseFloat(%v, 32) = %v, not a float32 (closest is %v)", test.in, out, float64(out32))
			continue
		}
		outs := FormatFloat(float64(out32), 'g', -1, 32)
		if outs != test.out || !reflect.DeepEqual(err, test.err) {
			t.Errorf("ParseFloat(%v, 32) = %v, %v want %v, %v  # %v",
				test.in, out32, err, test.out, test.err, out)
		}
	}
	SetOptimize(oldopt)
}

func TestAtof(t *testing.T) { testAtof(t, true) }

func TestAtofSlow(t *testing.T) { testAtof(t, false) }

func TestAtofRandom(t *testing.T) {
	for _, test := range atofRandomTests {
		x, _ := ParseFloat(test.s, 64)
		switch {
		default:
			t.Errorf("number %s badly parsed as %b (expected %b)", test.s, x, test.x)
		case x == test.x:
		case math.IsNaN(test.x) && math.IsNaN(x):
		}
	}
	t.Logf("tested %d random numbers", len(atofRandomTests))
}

var roundTripCases = []struct {
	f float64
	s string
}{
	// Issue 2917.
	// This test will break the optimized conversion if the
	// FPU is using 80-bit registers instead of 64-bit registers,
	// usually because the operating system initialized the
	// thread with 80-bit precision and the Go runtime didn't
	// fix the FP control word.
	{8865794286000691 << 39, "4.87402195346389e+27"},
	{8865794286000692 << 39, "4.8740219534638903e+27"},
}

func TestRoundTrip(t *testing.T) {
	for _, tt := range roundTripCases {
		old := SetOptimize(false)
		s := FormatFloat(tt.f, 'g', -1, 64)
		if s != tt.s {
			t.Errorf("no-opt FormatFloat(%b) = %s, want %s", tt.f, s, tt.s)
		}
		f, err := ParseFloat(tt.s, 64)
		if f != tt.f || err != nil {
			t.Errorf("no-opt ParseFloat(%s) = %b, %v want %b, nil", tt.s, f, err, tt.f)
		}
		SetOptimize(true)
		s = FormatFloat(tt.f, 'g', -1, 64)
		if s != tt.s {
			t.Errorf("opt FormatFloat(%b) = %s, want %s", tt.f, s, tt.s)
		}
		f, err = ParseFloat(tt.s, 64)
		if f != tt.f || err != nil {
			t.Errorf("opt ParseFloat(%s) = %b, %v want %b, nil", tt.s, f, err, tt.f)
		}
		SetOptimize(old)
	}
}

// TestRoundTrip32 tries a fraction of all finite positive float32 values.
func TestRoundTrip32(t *testing.T) {
	step := uint32(997)
	if testing.Short() {
		step = 99991
	}
	count := 0
	for i := uint32(0); i < 0xff<<23; i += step {
		f := math.Float32frombits(i)
		if i&1 == 1 {
			f = -f // negative
		}
		s := FormatFloat(float64(f), 'g', -1, 32)

		parsed, err := ParseFloat(s, 32)
		parsed32 := float32(parsed)
		switch {
		case err != nil:
			t.Errorf("ParseFloat(%q, 32) gave error %s", s, err)
		case float64(parsed32) != parsed:
			t.Errorf("ParseFloat(%q, 32) = %v, not a float32 (nearest is %v)", s, parsed, parsed32)
		case parsed32 != f:
			t.Errorf("ParseFloat(%q, 32) = %b (expected %b)", s, parsed32, f)
		}
		count++
	}
	t.Logf("tested %d float32's", count)
}

func BenchmarkAtof64Decimal(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ParseFloat("33909", 64)
	}
}

func BenchmarkAtof64Float(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ParseFloat("339.7784", 64)
	}
}

func BenchmarkAtof64FloatExp(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ParseFloat("-5.09e75", 64)
	}
}

func BenchmarkAtof64Big(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ParseFloat("123456789123456789123456789", 64)
	}
}

func BenchmarkAtof64RandomBits(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ParseFloat(benchmarksRandomBits[i%1024], 64)
	}
}

func BenchmarkAtof64RandomFloats(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ParseFloat(benchmarksRandomNormal[i%1024], 64)
	}
}

func BenchmarkAtof32Decimal(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ParseFloat("33909", 32)
	}
}

func BenchmarkAtof32Float(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ParseFloat("339.778", 32)
	}
}

func BenchmarkAtof32FloatExp(b *testing.B) {
	for i := 0; i < b.N; i++ {
		ParseFloat("12.3456e32", 32)
	}
}

var float32strings [4096]string

func BenchmarkAtof32Random(b *testing.B) {
	n := uint32(997)
	for i := range float32strings {
		n = (99991*n + 42) % (0xff << 23)
		float32strings[i] = FormatFloat(float64(math.Float32frombits(n)), 'g', -1, 32)
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		ParseFloat(float32strings[i%4096], 32)
	}
}