libgo/go/strconv/atof_test.go

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