atof_test.go

Documentation: strconv

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package strconv_test
     6  
     7  import (
     8  	"math"
     9  	"math/rand"
    10  	"reflect"
    11  	. "strconv"
    12  	"strings"
    13  	"sync"
    14  	"testing"
    15  	"time"
    16  )
    17  
    18  type atofTest struct {
    19  	in  string
    20  	out string
    21  	err error
    22  }
    23  
    24  var atoftests = []atofTest{
    25  	{"", "0", ErrSyntax},
    26  	{"1", "1", nil},
    27  	{"+1", "1", nil},
    28  	{"1x", "0", ErrSyntax},
    29  	{"1.1.", "0", ErrSyntax},
    30  	{"1e23", "1e+23", nil},
    31  	{"1E23", "1e+23", nil},
    32  	{"100000000000000000000000", "1e+23", nil},
    33  	{"1e-100", "1e-100", nil},
    34  	{"123456700", "1.234567e+08", nil},
    35  	{"99999999999999974834176", "9.999999999999997e+22", nil},
    36  	{"100000000000000000000001", "1.0000000000000001e+23", nil},
    37  	{"100000000000000008388608", "1.0000000000000001e+23", nil},
    38  	{"100000000000000016777215", "1.0000000000000001e+23", nil},
    39  	{"100000000000000016777216", "1.0000000000000003e+23", nil},
    40  	{"-1", "-1", nil},
    41  	{"-0.1", "-0.1", nil},
    42  	{"-0", "-0", nil},
    43  	{"1e-20", "1e-20", nil},
    44  	{"625e-3", "0.625", nil},
    45  
    46  	// zeros
    47  	{"0", "0", nil},
    48  	{"0e0", "0", nil},
    49  	{"-0e0", "-0", nil},
    50  	{"+0e0", "0", nil},
    51  	{"0e-0", "0", nil},
    52  	{"-0e-0", "-0", nil},
    53  	{"+0e-0", "0", nil},
    54  	{"0e+0", "0", nil},
    55  	{"-0e+0", "-0", nil},
    56  	{"+0e+0", "0", nil},
    57  	{"0e+01234567890123456789", "0", nil},
    58  	{"0.00e-01234567890123456789", "0", nil},
    59  	{"-0e+01234567890123456789", "-0", nil},
    60  	{"-0.00e-01234567890123456789", "-0", nil},
    61  	{"0e291", "0", nil}, // issue 15364
    62  	{"0e292", "0", nil}, // issue 15364
    63  	{"0e347", "0", nil}, // issue 15364
    64  	{"0e348", "0", nil}, // issue 15364
    65  	{"-0e291", "-0", nil},
    66  	{"-0e292", "-0", nil},
    67  	{"-0e347", "-0", nil},
    68  	{"-0e348", "-0", nil},
    69  
    70  	// NaNs
    71  	{"nan", "NaN", nil},
    72  	{"NaN", "NaN", nil},
    73  	{"NAN", "NaN", nil},
    74  
    75  	// Infs
    76  	{"inf", "+Inf", nil},
    77  	{"-Inf", "-Inf", nil},
    78  	{"+INF", "+Inf", nil},
    79  	{"-Infinity", "-Inf", nil},
    80  	{"+INFINITY", "+Inf", nil},
    81  	{"Infinity", "+Inf", nil},
    82  
    83  	// largest float64
    84  	{"1.7976931348623157e308", "1.7976931348623157e+308", nil},
    85  	{"-1.7976931348623157e308", "-1.7976931348623157e+308", nil},
    86  	// next float64 - too large
    87  	{"1.7976931348623159e308", "+Inf", ErrRange},
    88  	{"-1.7976931348623159e308", "-Inf", ErrRange},
    89  	// the border is ...158079
    90  	// borderline - okay
    91  	{"1.7976931348623158e308", "1.7976931348623157e+308", nil},
    92  	{"-1.7976931348623158e308", "-1.7976931348623157e+308", nil},
    93  	// borderline - too large
    94  	{"1.797693134862315808e308", "+Inf", ErrRange},
    95  	{"-1.797693134862315808e308", "-Inf", ErrRange},
    96  
    97  	// a little too large
    98  	{"1e308", "1e+308", nil},
    99  	{"2e308", "+Inf", ErrRange},
   100  	{"1e309", "+Inf", ErrRange},
   101  
   102  	// way too large
   103  	{"1e310", "+Inf", ErrRange},
   104  	{"-1e310", "-Inf", ErrRange},
   105  	{"1e400", "+Inf", ErrRange},
   106  	{"-1e400", "-Inf", ErrRange},
   107  	{"1e400000", "+Inf", ErrRange},
   108  	{"-1e400000", "-Inf", ErrRange},
   109  
   110  	// denormalized
   111  	{"1e-305", "1e-305", nil},
   112  	{"1e-306", "1e-306", nil},
   113  	{"1e-307", "1e-307", nil},
   114  	{"1e-308", "1e-308", nil},
   115  	{"1e-309", "1e-309", nil},
   116  	{"1e-310", "1e-310", nil},
   117  	{"1e-322", "1e-322", nil},
   118  	// smallest denormal
   119  	{"5e-324", "5e-324", nil},
   120  	{"4e-324", "5e-324", nil},
   121  	{"3e-324", "5e-324", nil},
   122  	// too small
   123  	{"2e-324", "0", nil},
   124  	// way too small
   125  	{"1e-350", "0", nil},
   126  	{"1e-400000", "0", nil},
   127  
   128  	// try to overflow exponent
   129  	{"1e-4294967296", "0", nil},
   130  	{"1e+4294967296", "+Inf", ErrRange},
   131  	{"1e-18446744073709551616", "0", nil},
   132  	{"1e+18446744073709551616", "+Inf", ErrRange},
   133  
   134  	// Parse errors
   135  	{"1e", "0", ErrSyntax},
   136  	{"1e-", "0", ErrSyntax},
   137  	{".e-1", "0", ErrSyntax},
   138  	{"1\x00.2", "0", ErrSyntax},
   139  
   140  	// https://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
   141  	{"2.2250738585072012e-308", "2.2250738585072014e-308", nil},
   142  	// https://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
   143  	{"2.2250738585072011e-308", "2.225073858507201e-308", nil},
   144  
   145  	// A very large number (initially wrongly parsed by the fast algorithm).
   146  	{"4.630813248087435e+307", "4.630813248087435e+307", nil},
   147  
   148  	// A different kind of very large number.
   149  	{"22.222222222222222", "22.22222222222222", nil},
   150  	{"2." + strings.Repeat("2", 4000) + "e+1", "22.22222222222222", nil},
   151  
   152  	// Exactly halfway between 1 and math.Nextafter(1, 2).
   153  	// Round to even (down).
   154  	{"1.00000000000000011102230246251565404236316680908203125", "1", nil},
   155  	// Slightly lower; still round down.
   156  	{"1.00000000000000011102230246251565404236316680908203124", "1", nil},
   157  	// Slightly higher; round up.
   158  	{"1.00000000000000011102230246251565404236316680908203126", "1.0000000000000002", nil},
   159  	// Slightly higher, but you have to read all the way to the end.
   160  	{"1.00000000000000011102230246251565404236316680908203125" + strings.Repeat("0", 10000) + "1", "1.0000000000000002", nil},
   161  }
   162  
   163  var atof32tests = []atofTest{
   164  	// Exactly halfway between 1 and the next float32.
   165  	// Round to even (down).
   166  	{"1.000000059604644775390625", "1", nil},
   167  	// Slightly lower.
   168  	{"1.000000059604644775390624", "1", nil},
   169  	// Slightly higher.
   170  	{"1.000000059604644775390626", "1.0000001", nil},
   171  	// Slightly higher, but you have to read all the way to the end.
   172  	{"1.000000059604644775390625" + strings.Repeat("0", 10000) + "1", "1.0000001", nil},
   173  
   174  	// largest float32: (1<<128) * (1 - 2^-24)
   175  	{"340282346638528859811704183484516925440", "3.4028235e+38", nil},
   176  	{"-340282346638528859811704183484516925440", "-3.4028235e+38", nil},
   177  	// next float32 - too large
   178  	{"3.4028236e38", "+Inf", ErrRange},
   179  	{"-3.4028236e38", "-Inf", ErrRange},
   180  	// the border is 3.40282356779...e+38
   181  	// borderline - okay
   182  	{"3.402823567e38", "3.4028235e+38", nil},
   183  	{"-3.402823567e38", "-3.4028235e+38", nil},
   184  	// borderline - too large
   185  	{"3.4028235678e38", "+Inf", ErrRange},
   186  	{"-3.4028235678e38", "-Inf", ErrRange},
   187  
   188  	// Denormals: less than 2^-126
   189  	{"1e-38", "1e-38", nil},
   190  	{"1e-39", "1e-39", nil},
   191  	{"1e-40", "1e-40", nil},
   192  	{"1e-41", "1e-41", nil},
   193  	{"1e-42", "1e-42", nil},
   194  	{"1e-43", "1e-43", nil},
   195  	{"1e-44", "1e-44", nil},
   196  	{"6e-45", "6e-45", nil}, // 4p-149 = 5.6e-45
   197  	{"5e-45", "6e-45", nil},
   198  	// Smallest denormal
   199  	{"1e-45", "1e-45", nil}, // 1p-149 = 1.4e-45
   200  	{"2e-45", "1e-45", nil},
   201  
   202  	// 2^92 = 8388608p+69 = 4951760157141521099596496896 (4.9517602e27)
   203  	// is an exact power of two that needs 8 decimal digits to be correctly
   204  	// parsed back.
   205  	// The float32 before is 16777215p+68 = 4.95175986e+27
   206  	// The halfway is 4.951760009. A bad algorithm that thinks the previous
   207  	// float32 is 8388607p+69 will shorten incorrectly to 4.95176e+27.
   208  	{"4951760157141521099596496896", "4.9517602e+27", nil},
   209  }
   210  
   211  type atofSimpleTest struct {
   212  	x float64
   213  	s string
   214  }
   215  
   216  var (
   217  	atofOnce               sync.Once
   218  	atofRandomTests        []atofSimpleTest
   219  	benchmarksRandomBits   [1024]string
   220  	benchmarksRandomNormal [1024]string
   221  )
   222  
   223  func initAtof() {
   224  	atofOnce.Do(initAtofOnce)
   225  }
   226  
   227  func initAtofOnce() {
   228  	// The atof routines return NumErrors wrapping
   229  	// the error and the string. Convert the table above.
   230  	for i := range atoftests {
   231  		test := &atoftests[i]
   232  		if test.err != nil {
   233  			test.err = &NumError{"ParseFloat", test.in, test.err}
   234  		}
   235  	}
   236  	for i := range atof32tests {
   237  		test := &atof32tests[i]
   238  		if test.err != nil {
   239  			test.err = &NumError{"ParseFloat", test.in, test.err}
   240  		}
   241  	}
   242  
   243  	// Generate random inputs for tests and benchmarks
   244  	rand.Seed(time.Now().UnixNano())
   245  	if testing.Short() {
   246  		atofRandomTests = make([]atofSimpleTest, 100)
   247  	} else {
   248  		atofRandomTests = make([]atofSimpleTest, 10000)
   249  	}
   250  	for i := range atofRandomTests {
   251  		n := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
   252  		x := math.Float64frombits(n)
   253  		s := FormatFloat(x, 'g', -1, 64)
   254  		atofRandomTests[i] = atofSimpleTest{x, s}
   255  	}
   256  
   257  	for i := range benchmarksRandomBits {
   258  		bits := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
   259  		x := math.Float64frombits(bits)
   260  		benchmarksRandomBits[i] = FormatFloat(x, 'g', -1, 64)
   261  	}
   262  
   263  	for i := range benchmarksRandomNormal {
   264  		x := rand.NormFloat64()
   265  		benchmarksRandomNormal[i] = FormatFloat(x, 'g', -1, 64)
   266  	}
   267  }
   268  
   269  func testAtof(t *testing.T, opt bool) {
   270  	initAtof()
   271  	oldopt := SetOptimize(opt)
   272  	for i := 0; i < len(atoftests); i++ {
   273  		test := &atoftests[i]
   274  		out, err := ParseFloat(test.in, 64)
   275  		outs := FormatFloat(out, 'g', -1, 64)
   276  		if outs != test.out || !reflect.DeepEqual(err, test.err) {
   277  			t.Errorf("ParseFloat(%v, 64) = %v, %v want %v, %v",
   278  				test.in, out, err, test.out, test.err)
   279  		}
   280  
   281  		if float64(float32(out)) == out {
   282  			out, err := ParseFloat(test.in, 32)
   283  			out32 := float32(out)
   284  			if float64(out32) != out {
   285  				t.Errorf("ParseFloat(%v, 32) = %v, not a float32 (closest is %v)", test.in, out, float64(out32))
   286  				continue
   287  			}
   288  			outs := FormatFloat(float64(out32), 'g', -1, 32)
   289  			if outs != test.out || !reflect.DeepEqual(err, test.err) {
   290  				t.Errorf("ParseFloat(%v, 32) = %v, %v want %v, %v  # %v",
   291  					test.in, out32, err, test.out, test.err, out)
   292  			}
   293  		}
   294  	}
   295  	for _, test := range atof32tests {
   296  		out, err := ParseFloat(test.in, 32)
   297  		out32 := float32(out)
   298  		if float64(out32) != out {
   299  			t.Errorf("ParseFloat(%v, 32) = %v, not a float32 (closest is %v)", test.in, out, float64(out32))
   300  			continue
   301  		}
   302  		outs := FormatFloat(float64(out32), 'g', -1, 32)
   303  		if outs != test.out || !reflect.DeepEqual(err, test.err) {
   304  			t.Errorf("ParseFloat(%v, 32) = %v, %v want %v, %v  # %v",
   305  				test.in, out32, err, test.out, test.err, out)
   306  		}
   307  	}
   308  	SetOptimize(oldopt)
   309  }
   310  
   311  func TestAtof(t *testing.T) { testAtof(t, true) }
   312  
   313  func TestAtofSlow(t *testing.T) { testAtof(t, false) }
   314  
   315  func TestAtofRandom(t *testing.T) {
   316  	initAtof()
   317  	for _, test := range atofRandomTests {
   318  		x, _ := ParseFloat(test.s, 64)
   319  		switch {
   320  		default:
   321  			t.Errorf("number %s badly parsed as %b (expected %b)", test.s, x, test.x)
   322  		case x == test.x:
   323  		case math.IsNaN(test.x) && math.IsNaN(x):
   324  		}
   325  	}
   326  	t.Logf("tested %d random numbers", len(atofRandomTests))
   327  }
   328  
   329  var roundTripCases = []struct {
   330  	f float64
   331  	s string
   332  }{
   333  	// Issue 2917.
   334  	// This test will break the optimized conversion if the
   335  	// FPU is using 80-bit registers instead of 64-bit registers,
   336  	// usually because the operating system initialized the
   337  	// thread with 80-bit precision and the Go runtime didn't
   338  	// fix the FP control word.
   339  	{8865794286000691 << 39, "4.87402195346389e+27"},
   340  	{8865794286000692 << 39, "4.8740219534638903e+27"},
   341  }
   342  
   343  func TestRoundTrip(t *testing.T) {
   344  	for _, tt := range roundTripCases {
   345  		old := SetOptimize(false)
   346  		s := FormatFloat(tt.f, 'g', -1, 64)
   347  		if s != tt.s {
   348  			t.Errorf("no-opt FormatFloat(%b) = %s, want %s", tt.f, s, tt.s)
   349  		}
   350  		f, err := ParseFloat(tt.s, 64)
   351  		if f != tt.f || err != nil {
   352  			t.Errorf("no-opt ParseFloat(%s) = %b, %v want %b, nil", tt.s, f, err, tt.f)
   353  		}
   354  		SetOptimize(true)
   355  		s = FormatFloat(tt.f, 'g', -1, 64)
   356  		if s != tt.s {
   357  			t.Errorf("opt FormatFloat(%b) = %s, want %s", tt.f, s, tt.s)
   358  		}
   359  		f, err = ParseFloat(tt.s, 64)
   360  		if f != tt.f || err != nil {
   361  			t.Errorf("opt ParseFloat(%s) = %b, %v want %b, nil", tt.s, f, err, tt.f)
   362  		}
   363  		SetOptimize(old)
   364  	}
   365  }
   366  
   367  // TestRoundTrip32 tries a fraction of all finite positive float32 values.
   368  func TestRoundTrip32(t *testing.T) {
   369  	step := uint32(997)
   370  	if testing.Short() {
   371  		step = 99991
   372  	}
   373  	count := 0
   374  	for i := uint32(0); i < 0xff<<23; i += step {
   375  		f := math.Float32frombits(i)
   376  		if i&1 == 1 {
   377  			f = -f // negative
   378  		}
   379  		s := FormatFloat(float64(f), 'g', -1, 32)
   380  
   381  		parsed, err := ParseFloat(s, 32)
   382  		parsed32 := float32(parsed)
   383  		switch {
   384  		case err != nil:
   385  			t.Errorf("ParseFloat(%q, 32) gave error %s", s, err)
   386  		case float64(parsed32) != parsed:
   387  			t.Errorf("ParseFloat(%q, 32) = %v, not a float32 (nearest is %v)", s, parsed, parsed32)
   388  		case parsed32 != f:
   389  			t.Errorf("ParseFloat(%q, 32) = %b (expected %b)", s, parsed32, f)
   390  		}
   391  		count++
   392  	}
   393  	t.Logf("tested %d float32's", count)
   394  }
   395  
   396  func BenchmarkAtof64Decimal(b *testing.B) {
   397  	for i := 0; i < b.N; i++ {
   398  		ParseFloat("33909", 64)
   399  	}
   400  }
   401  
   402  func BenchmarkAtof64Float(b *testing.B) {
   403  	for i := 0; i < b.N; i++ {
   404  		ParseFloat("339.7784", 64)
   405  	}
   406  }
   407  
   408  func BenchmarkAtof64FloatExp(b *testing.B) {
   409  	for i := 0; i < b.N; i++ {
   410  		ParseFloat("-5.09e75", 64)
   411  	}
   412  }
   413  
   414  func BenchmarkAtof64Big(b *testing.B) {
   415  	for i := 0; i < b.N; i++ {
   416  		ParseFloat("123456789123456789123456789", 64)
   417  	}
   418  }
   419  
   420  func BenchmarkAtof64RandomBits(b *testing.B) {
   421  	for i := 0; i < b.N; i++ {
   422  		ParseFloat(benchmarksRandomBits[i%1024], 64)
   423  	}
   424  }
   425  
   426  func BenchmarkAtof64RandomFloats(b *testing.B) {
   427  	for i := 0; i < b.N; i++ {
   428  		ParseFloat(benchmarksRandomNormal[i%1024], 64)
   429  	}
   430  }
   431  
   432  func BenchmarkAtof32Decimal(b *testing.B) {
   433  	for i := 0; i < b.N; i++ {
   434  		ParseFloat("33909", 32)
   435  	}
   436  }
   437  
   438  func BenchmarkAtof32Float(b *testing.B) {
   439  	for i := 0; i < b.N; i++ {
   440  		ParseFloat("339.778", 32)
   441  	}
   442  }
   443  
   444  func BenchmarkAtof32FloatExp(b *testing.B) {
   445  	for i := 0; i < b.N; i++ {
   446  		ParseFloat("12.3456e32", 32)
   447  	}
   448  }
   449  
   450  var float32strings [4096]string
   451  
   452  func BenchmarkAtof32Random(b *testing.B) {
   453  	n := uint32(997)
   454  	for i := range float32strings {
   455  		n = (99991*n + 42) % (0xff << 23)
   456  		float32strings[i] = FormatFloat(float64(math.Float32frombits(n)), 'g', -1, 32)
   457  	}
   458  	b.ResetTimer()
   459  	for i := 0; i < b.N; i++ {
   460  		ParseFloat(float32strings[i%4096], 32)
   461  	}
   462  }
   463
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