Source file src/strconv/atof_test.go

Documentation: strconv

  // 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"
  	"sync"
  	"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 (
  	atofOnce               sync.Once
  	atofRandomTests        []atofSimpleTest
  	benchmarksRandomBits   [1024]string
  	benchmarksRandomNormal [1024]string
  )
  
  func initAtof() {
  	atofOnce.Do(initAtofOnce)
  }
  
  func initAtofOnce() {
  	// 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) {
  	initAtof()
  	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) {
  	initAtof()
  	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)
  	}
  }
  

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