Source file src/strconv/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  	// Hexadecimal floating-point.
		47  	{"0x1p0", "1", nil},
		48  	{"0x1p1", "2", nil},
		49  	{"0x1p-1", "0.5", nil},
		50  	{"0x1ep-1", "15", nil},
		51  	{"-0x1ep-1", "-15", nil},
		52  	{"-0x1_ep-1", "-15", nil},
		53  	{"0x1p-200", "6.223015277861142e-61", nil},
		54  	{"0x1p200", "1.6069380442589903e+60", nil},
		55  	{"0x1fFe2.p0", "131042", nil},
		56  	{"0x1fFe2.P0", "131042", nil},
		57  	{"-0x2p3", "-16", nil},
		58  	{"0x0.fp4", "15", nil},
		59  	{"0x0.fp0", "0.9375", nil},
		60  	{"0x1e2", "0", ErrSyntax},
		61  	{"1p2", "0", ErrSyntax},
		62  
		63  	// zeros
		64  	{"0", "0", nil},
		65  	{"0e0", "0", nil},
		66  	{"-0e0", "-0", nil},
		67  	{"+0e0", "0", nil},
		68  	{"0e-0", "0", nil},
		69  	{"-0e-0", "-0", nil},
		70  	{"+0e-0", "0", nil},
		71  	{"0e+0", "0", nil},
		72  	{"-0e+0", "-0", nil},
		73  	{"+0e+0", "0", nil},
		74  	{"0e+01234567890123456789", "0", nil},
		75  	{"0.00e-01234567890123456789", "0", nil},
		76  	{"-0e+01234567890123456789", "-0", nil},
		77  	{"-0.00e-01234567890123456789", "-0", nil},
		78  	{"0x0p+01234567890123456789", "0", nil},
		79  	{"0x0.00p-01234567890123456789", "0", nil},
		80  	{"-0x0p+01234567890123456789", "-0", nil},
		81  	{"-0x0.00p-01234567890123456789", "-0", nil},
		82  
		83  	{"0e291", "0", nil}, // issue 15364
		84  	{"0e292", "0", nil}, // issue 15364
		85  	{"0e347", "0", nil}, // issue 15364
		86  	{"0e348", "0", nil}, // issue 15364
		87  	{"-0e291", "-0", nil},
		88  	{"-0e292", "-0", nil},
		89  	{"-0e347", "-0", nil},
		90  	{"-0e348", "-0", nil},
		91  	{"0x0p126", "0", nil},
		92  	{"0x0p127", "0", nil},
		93  	{"0x0p128", "0", nil},
		94  	{"0x0p129", "0", nil},
		95  	{"0x0p130", "0", nil},
		96  	{"0x0p1022", "0", nil},
		97  	{"0x0p1023", "0", nil},
		98  	{"0x0p1024", "0", nil},
		99  	{"0x0p1025", "0", nil},
	 100  	{"0x0p1026", "0", nil},
	 101  	{"-0x0p126", "-0", nil},
	 102  	{"-0x0p127", "-0", nil},
	 103  	{"-0x0p128", "-0", nil},
	 104  	{"-0x0p129", "-0", nil},
	 105  	{"-0x0p130", "-0", nil},
	 106  	{"-0x0p1022", "-0", nil},
	 107  	{"-0x0p1023", "-0", nil},
	 108  	{"-0x0p1024", "-0", nil},
	 109  	{"-0x0p1025", "-0", nil},
	 110  	{"-0x0p1026", "-0", nil},
	 111  
	 112  	// NaNs
	 113  	{"nan", "NaN", nil},
	 114  	{"NaN", "NaN", nil},
	 115  	{"NAN", "NaN", nil},
	 116  
	 117  	// Infs
	 118  	{"inf", "+Inf", nil},
	 119  	{"-Inf", "-Inf", nil},
	 120  	{"+INF", "+Inf", nil},
	 121  	{"-Infinity", "-Inf", nil},
	 122  	{"+INFINITY", "+Inf", nil},
	 123  	{"Infinity", "+Inf", nil},
	 124  
	 125  	// largest float64
	 126  	{"1.7976931348623157e308", "1.7976931348623157e+308", nil},
	 127  	{"-1.7976931348623157e308", "-1.7976931348623157e+308", nil},
	 128  	{"0x1.fffffffffffffp1023", "1.7976931348623157e+308", nil},
	 129  	{"-0x1.fffffffffffffp1023", "-1.7976931348623157e+308", nil},
	 130  	{"0x1fffffffffffffp+971", "1.7976931348623157e+308", nil},
	 131  	{"-0x1fffffffffffffp+971", "-1.7976931348623157e+308", nil},
	 132  	{"0x.1fffffffffffffp1027", "1.7976931348623157e+308", nil},
	 133  	{"-0x.1fffffffffffffp1027", "-1.7976931348623157e+308", nil},
	 134  
	 135  	// next float64 - too large
	 136  	{"1.7976931348623159e308", "+Inf", ErrRange},
	 137  	{"-1.7976931348623159e308", "-Inf", ErrRange},
	 138  	{"0x1p1024", "+Inf", ErrRange},
	 139  	{"-0x1p1024", "-Inf", ErrRange},
	 140  	{"0x2p1023", "+Inf", ErrRange},
	 141  	{"-0x2p1023", "-Inf", ErrRange},
	 142  	{"0x.1p1028", "+Inf", ErrRange},
	 143  	{"-0x.1p1028", "-Inf", ErrRange},
	 144  	{"0x.2p1027", "+Inf", ErrRange},
	 145  	{"-0x.2p1027", "-Inf", ErrRange},
	 146  
	 147  	// the border is ...158079
	 148  	// borderline - okay
	 149  	{"1.7976931348623158e308", "1.7976931348623157e+308", nil},
	 150  	{"-1.7976931348623158e308", "-1.7976931348623157e+308", nil},
	 151  	{"0x1.fffffffffffff7fffp1023", "1.7976931348623157e+308", nil},
	 152  	{"-0x1.fffffffffffff7fffp1023", "-1.7976931348623157e+308", nil},
	 153  	// borderline - too large
	 154  	{"1.797693134862315808e308", "+Inf", ErrRange},
	 155  	{"-1.797693134862315808e308", "-Inf", ErrRange},
	 156  	{"0x1.fffffffffffff8p1023", "+Inf", ErrRange},
	 157  	{"-0x1.fffffffffffff8p1023", "-Inf", ErrRange},
	 158  	{"0x1fffffffffffff.8p+971", "+Inf", ErrRange},
	 159  	{"-0x1fffffffffffff8p+967", "-Inf", ErrRange},
	 160  	{"0x.1fffffffffffff8p1027", "+Inf", ErrRange},
	 161  	{"-0x.1fffffffffffff9p1027", "-Inf", ErrRange},
	 162  
	 163  	// a little too large
	 164  	{"1e308", "1e+308", nil},
	 165  	{"2e308", "+Inf", ErrRange},
	 166  	{"1e309", "+Inf", ErrRange},
	 167  	{"0x1p1025", "+Inf", ErrRange},
	 168  
	 169  	// way too large
	 170  	{"1e310", "+Inf", ErrRange},
	 171  	{"-1e310", "-Inf", ErrRange},
	 172  	{"1e400", "+Inf", ErrRange},
	 173  	{"-1e400", "-Inf", ErrRange},
	 174  	{"1e400000", "+Inf", ErrRange},
	 175  	{"-1e400000", "-Inf", ErrRange},
	 176  	{"0x1p1030", "+Inf", ErrRange},
	 177  	{"0x1p2000", "+Inf", ErrRange},
	 178  	{"0x1p2000000000", "+Inf", ErrRange},
	 179  	{"-0x1p1030", "-Inf", ErrRange},
	 180  	{"-0x1p2000", "-Inf", ErrRange},
	 181  	{"-0x1p2000000000", "-Inf", ErrRange},
	 182  
	 183  	// denormalized
	 184  	{"1e-305", "1e-305", nil},
	 185  	{"1e-306", "1e-306", nil},
	 186  	{"1e-307", "1e-307", nil},
	 187  	{"1e-308", "1e-308", nil},
	 188  	{"1e-309", "1e-309", nil},
	 189  	{"1e-310", "1e-310", nil},
	 190  	{"1e-322", "1e-322", nil},
	 191  	// smallest denormal
	 192  	{"5e-324", "5e-324", nil},
	 193  	{"4e-324", "5e-324", nil},
	 194  	{"3e-324", "5e-324", nil},
	 195  	// too small
	 196  	{"2e-324", "0", nil},
	 197  	// way too small
	 198  	{"1e-350", "0", nil},
	 199  	{"1e-400000", "0", nil},
	 200  
	 201  	// Near denormals and denormals.
	 202  	{"0x2.00000000000000p-1010", "1.8227805048890994e-304", nil}, // 0x00e0000000000000
	 203  	{"0x1.fffffffffffff0p-1010", "1.8227805048890992e-304", nil}, // 0x00dfffffffffffff
	 204  	{"0x1.fffffffffffff7p-1010", "1.8227805048890992e-304", nil}, // rounded down
	 205  	{"0x1.fffffffffffff8p-1010", "1.8227805048890994e-304", nil}, // rounded up
	 206  	{"0x1.fffffffffffff9p-1010", "1.8227805048890994e-304", nil}, // rounded up
	 207  
	 208  	{"0x2.00000000000000p-1022", "4.450147717014403e-308", nil},	// 0x0020000000000000
	 209  	{"0x1.fffffffffffff0p-1022", "4.4501477170144023e-308", nil}, // 0x001fffffffffffff
	 210  	{"0x1.fffffffffffff7p-1022", "4.4501477170144023e-308", nil}, // rounded down
	 211  	{"0x1.fffffffffffff8p-1022", "4.450147717014403e-308", nil},	// rounded up
	 212  	{"0x1.fffffffffffff9p-1022", "4.450147717014403e-308", nil},	// rounded up
	 213  
	 214  	{"0x1.00000000000000p-1022", "2.2250738585072014e-308", nil}, // 0x0010000000000000
	 215  	{"0x0.fffffffffffff0p-1022", "2.225073858507201e-308", nil},	// 0x000fffffffffffff
	 216  	{"0x0.ffffffffffffe0p-1022", "2.2250738585072004e-308", nil}, // 0x000ffffffffffffe
	 217  	{"0x0.ffffffffffffe7p-1022", "2.2250738585072004e-308", nil}, // rounded down
	 218  	{"0x1.ffffffffffffe8p-1023", "2.225073858507201e-308", nil},	// rounded up
	 219  	{"0x1.ffffffffffffe9p-1023", "2.225073858507201e-308", nil},	// rounded up
	 220  
	 221  	{"0x0.00000003fffff0p-1022", "2.072261e-317", nil},	// 0x00000000003fffff
	 222  	{"0x0.00000003456780p-1022", "1.694649e-317", nil},	// 0x0000000000345678
	 223  	{"0x0.00000003456787p-1022", "1.694649e-317", nil},	// rounded down
	 224  	{"0x0.00000003456788p-1022", "1.694649e-317", nil},	// rounded down (half to even)
	 225  	{"0x0.00000003456790p-1022", "1.6946496e-317", nil}, // 0x0000000000345679
	 226  	{"0x0.00000003456789p-1022", "1.6946496e-317", nil}, // rounded up
	 227  
	 228  	{"0x0.0000000345678800000000000000000000000001p-1022", "1.6946496e-317", nil}, // rounded up
	 229  
	 230  	{"0x0.000000000000f0p-1022", "7.4e-323", nil}, // 0x000000000000000f
	 231  	{"0x0.00000000000060p-1022", "3e-323", nil},	 // 0x0000000000000006
	 232  	{"0x0.00000000000058p-1022", "3e-323", nil},	 // rounded up
	 233  	{"0x0.00000000000057p-1022", "2.5e-323", nil}, // rounded down
	 234  	{"0x0.00000000000050p-1022", "2.5e-323", nil}, // 0x0000000000000005
	 235  
	 236  	{"0x0.00000000000010p-1022", "5e-324", nil},	// 0x0000000000000001
	 237  	{"0x0.000000000000081p-1022", "5e-324", nil}, // rounded up
	 238  	{"0x0.00000000000008p-1022", "0", nil},			 // rounded down
	 239  	{"0x0.00000000000007fp-1022", "0", nil},			// rounded down
	 240  
	 241  	// try to overflow exponent
	 242  	{"1e-4294967296", "0", nil},
	 243  	{"1e+4294967296", "+Inf", ErrRange},
	 244  	{"1e-18446744073709551616", "0", nil},
	 245  	{"1e+18446744073709551616", "+Inf", ErrRange},
	 246  	{"0x1p-4294967296", "0", nil},
	 247  	{"0x1p+4294967296", "+Inf", ErrRange},
	 248  	{"0x1p-18446744073709551616", "0", nil},
	 249  	{"0x1p+18446744073709551616", "+Inf", ErrRange},
	 250  
	 251  	// Parse errors
	 252  	{"1e", "0", ErrSyntax},
	 253  	{"1e-", "0", ErrSyntax},
	 254  	{".e-1", "0", ErrSyntax},
	 255  	{"1\x00.2", "0", ErrSyntax},
	 256  	{"0x", "0", ErrSyntax},
	 257  	{"0x.", "0", ErrSyntax},
	 258  	{"0x1", "0", ErrSyntax},
	 259  	{"0x.1", "0", ErrSyntax},
	 260  	{"0x1p", "0", ErrSyntax},
	 261  	{"0x.1p", "0", ErrSyntax},
	 262  	{"0x1p+", "0", ErrSyntax},
	 263  	{"0x.1p+", "0", ErrSyntax},
	 264  	{"0x1p-", "0", ErrSyntax},
	 265  	{"0x.1p-", "0", ErrSyntax},
	 266  	{"0x1p+2", "4", nil},
	 267  	{"0x.1p+2", "0.25", nil},
	 268  	{"0x1p-2", "0.25", nil},
	 269  	{"0x.1p-2", "0.015625", nil},
	 270  
	 271  	// https://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
	 272  	{"2.2250738585072012e-308", "2.2250738585072014e-308", nil},
	 273  	// https://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
	 274  	{"2.2250738585072011e-308", "2.225073858507201e-308", nil},
	 275  
	 276  	// A very large number (initially wrongly parsed by the fast algorithm).
	 277  	{"4.630813248087435e+307", "4.630813248087435e+307", nil},
	 278  
	 279  	// A different kind of very large number.
	 280  	{"22.222222222222222", "22.22222222222222", nil},
	 281  	{"2." + strings.Repeat("2", 4000) + "e+1", "22.22222222222222", nil},
	 282  	{"0x1.1111111111111p222", "7.18931911124017e+66", nil},
	 283  	{"0x2.2222222222222p221", "7.18931911124017e+66", nil},
	 284  	{"0x2." + strings.Repeat("2", 4000) + "p221", "7.18931911124017e+66", nil},
	 285  
	 286  	// Exactly halfway between 1 and math.Nextafter(1, 2).
	 287  	// Round to even (down).
	 288  	{"1.00000000000000011102230246251565404236316680908203125", "1", nil},
	 289  	{"0x1.00000000000008p0", "1", nil},
	 290  	// Slightly lower; still round down.
	 291  	{"1.00000000000000011102230246251565404236316680908203124", "1", nil},
	 292  	{"0x1.00000000000007Fp0", "1", nil},
	 293  	// Slightly higher; round up.
	 294  	{"1.00000000000000011102230246251565404236316680908203126", "1.0000000000000002", nil},
	 295  	{"0x1.000000000000081p0", "1.0000000000000002", nil},
	 296  	{"0x1.00000000000009p0", "1.0000000000000002", nil},
	 297  	// Slightly higher, but you have to read all the way to the end.
	 298  	{"1.00000000000000011102230246251565404236316680908203125" + strings.Repeat("0", 10000) + "1", "1.0000000000000002", nil},
	 299  	{"0x1.00000000000008" + strings.Repeat("0", 10000) + "1p0", "1.0000000000000002", nil},
	 300  
	 301  	// Halfway between x := math.Nextafter(1, 2) and math.Nextafter(x, 2)
	 302  	// Round to even (up).
	 303  	{"1.00000000000000033306690738754696212708950042724609375", "1.0000000000000004", nil},
	 304  	{"0x1.00000000000018p0", "1.0000000000000004", nil},
	 305  
	 306  	// Halfway between 1090544144181609278303144771584 and 1090544144181609419040633126912
	 307  	// (15497564393479157p+46, should round to even 15497564393479156p+46, issue 36657)
	 308  	{"1090544144181609348671888949248", "1.0905441441816093e+30", nil},
	 309  	// slightly above, rounds up
	 310  	{"1090544144181609348835077142190", "1.0905441441816094e+30", nil},
	 311  
	 312  	// Underscores.
	 313  	{"1_23.50_0_0e+1_2", "1.235e+14", nil},
	 314  	{"-_123.5e+12", "0", ErrSyntax},
	 315  	{"+_123.5e+12", "0", ErrSyntax},
	 316  	{"_123.5e+12", "0", ErrSyntax},
	 317  	{"1__23.5e+12", "0", ErrSyntax},
	 318  	{"123_.5e+12", "0", ErrSyntax},
	 319  	{"123._5e+12", "0", ErrSyntax},
	 320  	{"123.5_e+12", "0", ErrSyntax},
	 321  	{"123.5__0e+12", "0", ErrSyntax},
	 322  	{"123.5e_+12", "0", ErrSyntax},
	 323  	{"123.5e+_12", "0", ErrSyntax},
	 324  	{"123.5e_-12", "0", ErrSyntax},
	 325  	{"123.5e-_12", "0", ErrSyntax},
	 326  	{"123.5e+1__2", "0", ErrSyntax},
	 327  	{"123.5e+12_", "0", ErrSyntax},
	 328  
	 329  	{"0x_1_2.3_4_5p+1_2", "74565", nil},
	 330  	{"-_0x12.345p+12", "0", ErrSyntax},
	 331  	{"+_0x12.345p+12", "0", ErrSyntax},
	 332  	{"_0x12.345p+12", "0", ErrSyntax},
	 333  	{"0x__12.345p+12", "0", ErrSyntax},
	 334  	{"0x1__2.345p+12", "0", ErrSyntax},
	 335  	{"0x12_.345p+12", "0", ErrSyntax},
	 336  	{"0x12._345p+12", "0", ErrSyntax},
	 337  	{"0x12.3__45p+12", "0", ErrSyntax},
	 338  	{"0x12.345_p+12", "0", ErrSyntax},
	 339  	{"0x12.345p_+12", "0", ErrSyntax},
	 340  	{"0x12.345p+_12", "0", ErrSyntax},
	 341  	{"0x12.345p_-12", "0", ErrSyntax},
	 342  	{"0x12.345p-_12", "0", ErrSyntax},
	 343  	{"0x12.345p+1__2", "0", ErrSyntax},
	 344  	{"0x12.345p+12_", "0", ErrSyntax},
	 345  
	 346  	{"1e100x", "0", ErrSyntax},
	 347  	{"1e1000x", "0", ErrSyntax},
	 348  }
	 349  
	 350  var atof32tests = []atofTest{
	 351  	// Hex
	 352  	{"0x1p-100", "7.888609e-31", nil},
	 353  	{"0x1p100", "1.2676506e+30", nil},
	 354  
	 355  	// Exactly halfway between 1 and the next float32.
	 356  	// Round to even (down).
	 357  	{"1.000000059604644775390625", "1", nil},
	 358  	{"0x1.000001p0", "1", nil},
	 359  	// Slightly lower.
	 360  	{"1.000000059604644775390624", "1", nil},
	 361  	{"0x1.0000008p0", "1", nil},
	 362  	{"0x1.000000fp0", "1", nil},
	 363  	// Slightly higher.
	 364  	{"1.000000059604644775390626", "1.0000001", nil},
	 365  	{"0x1.000002p0", "1.0000001", nil},
	 366  	{"0x1.0000018p0", "1.0000001", nil},
	 367  	{"0x1.0000011p0", "1.0000001", nil},
	 368  	// Slightly higher, but you have to read all the way to the end.
	 369  	{"1.000000059604644775390625" + strings.Repeat("0", 10000) + "1", "1.0000001", nil},
	 370  	{"0x1.000001" + strings.Repeat("0", 10000) + "1p0", "1.0000001", nil},
	 371  
	 372  	// largest float32: (1<<128) * (1 - 2^-24)
	 373  	{"340282346638528859811704183484516925440", "3.4028235e+38", nil},
	 374  	{"-340282346638528859811704183484516925440", "-3.4028235e+38", nil},
	 375  	{"0x.ffffffp128", "3.4028235e+38", nil},
	 376  	{"-340282346638528859811704183484516925440", "-3.4028235e+38", nil},
	 377  	{"-0x.ffffffp128", "-3.4028235e+38", nil},
	 378  	// next float32 - too large
	 379  	{"3.4028236e38", "+Inf", ErrRange},
	 380  	{"-3.4028236e38", "-Inf", ErrRange},
	 381  	{"0x1.0p128", "+Inf", ErrRange},
	 382  	{"-0x1.0p128", "-Inf", ErrRange},
	 383  	// the border is 3.40282356779...e+38
	 384  	// borderline - okay
	 385  	{"3.402823567e38", "3.4028235e+38", nil},
	 386  	{"-3.402823567e38", "-3.4028235e+38", nil},
	 387  	{"0x.ffffff7fp128", "3.4028235e+38", nil},
	 388  	{"-0x.ffffff7fp128", "-3.4028235e+38", nil},
	 389  	// borderline - too large
	 390  	{"3.4028235678e38", "+Inf", ErrRange},
	 391  	{"-3.4028235678e38", "-Inf", ErrRange},
	 392  	{"0x.ffffff8p128", "+Inf", ErrRange},
	 393  	{"-0x.ffffff8p128", "-Inf", ErrRange},
	 394  
	 395  	// Denormals: less than 2^-126
	 396  	{"1e-38", "1e-38", nil},
	 397  	{"1e-39", "1e-39", nil},
	 398  	{"1e-40", "1e-40", nil},
	 399  	{"1e-41", "1e-41", nil},
	 400  	{"1e-42", "1e-42", nil},
	 401  	{"1e-43", "1e-43", nil},
	 402  	{"1e-44", "1e-44", nil},
	 403  	{"6e-45", "6e-45", nil}, // 4p-149 = 5.6e-45
	 404  	{"5e-45", "6e-45", nil},
	 405  
	 406  	// Smallest denormal
	 407  	{"1e-45", "1e-45", nil}, // 1p-149 = 1.4e-45
	 408  	{"2e-45", "1e-45", nil},
	 409  	{"3e-45", "3e-45", nil},
	 410  
	 411  	// Near denormals and denormals.
	 412  	{"0x0.89aBcDp-125", "1.2643093e-38", nil},	// 0x0089abcd
	 413  	{"0x0.8000000p-125", "1.1754944e-38", nil}, // 0x00800000
	 414  	{"0x0.1234560p-125", "1.671814e-39", nil},	// 0x00123456
	 415  	{"0x0.1234567p-125", "1.671814e-39", nil},	// rounded down
	 416  	{"0x0.1234568p-125", "1.671814e-39", nil},	// rounded down
	 417  	{"0x0.1234569p-125", "1.671815e-39", nil},	// rounded up
	 418  	{"0x0.1234570p-125", "1.671815e-39", nil},	// 0x00123457
	 419  	{"0x0.0000010p-125", "1e-45", nil},				 // 0x00000001
	 420  	{"0x0.00000081p-125", "1e-45", nil},				// rounded up
	 421  	{"0x0.0000008p-125", "0", nil},						 // rounded down
	 422  	{"0x0.0000007p-125", "0", nil},						 // rounded down
	 423  
	 424  	// 2^92 = 8388608p+69 = 4951760157141521099596496896 (4.9517602e27)
	 425  	// is an exact power of two that needs 8 decimal digits to be correctly
	 426  	// parsed back.
	 427  	// The float32 before is 16777215p+68 = 4.95175986e+27
	 428  	// The halfway is 4.951760009. A bad algorithm that thinks the previous
	 429  	// float32 is 8388607p+69 will shorten incorrectly to 4.95176e+27.
	 430  	{"4951760157141521099596496896", "4.9517602e+27", nil},
	 431  }
	 432  
	 433  type atofSimpleTest struct {
	 434  	x float64
	 435  	s string
	 436  }
	 437  
	 438  var (
	 439  	atofOnce							 sync.Once
	 440  	atofRandomTests				[]atofSimpleTest
	 441  	benchmarksRandomBits	 [1024]string
	 442  	benchmarksRandomNormal [1024]string
	 443  )
	 444  
	 445  func initAtof() {
	 446  	atofOnce.Do(initAtofOnce)
	 447  }
	 448  
	 449  func initAtofOnce() {
	 450  	// The atof routines return NumErrors wrapping
	 451  	// the error and the string. Convert the table above.
	 452  	for i := range atoftests {
	 453  		test := &atoftests[i]
	 454  		if test.err != nil {
	 455  			test.err = &NumError{"ParseFloat", test.in, test.err}
	 456  		}
	 457  	}
	 458  	for i := range atof32tests {
	 459  		test := &atof32tests[i]
	 460  		if test.err != nil {
	 461  			test.err = &NumError{"ParseFloat", test.in, test.err}
	 462  		}
	 463  	}
	 464  
	 465  	// Generate random inputs for tests and benchmarks
	 466  	rand.Seed(time.Now().UnixNano())
	 467  	if testing.Short() {
	 468  		atofRandomTests = make([]atofSimpleTest, 100)
	 469  	} else {
	 470  		atofRandomTests = make([]atofSimpleTest, 10000)
	 471  	}
	 472  	for i := range atofRandomTests {
	 473  		n := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
	 474  		x := math.Float64frombits(n)
	 475  		s := FormatFloat(x, 'g', -1, 64)
	 476  		atofRandomTests[i] = atofSimpleTest{x, s}
	 477  	}
	 478  
	 479  	for i := range benchmarksRandomBits {
	 480  		bits := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
	 481  		x := math.Float64frombits(bits)
	 482  		benchmarksRandomBits[i] = FormatFloat(x, 'g', -1, 64)
	 483  	}
	 484  
	 485  	for i := range benchmarksRandomNormal {
	 486  		x := rand.NormFloat64()
	 487  		benchmarksRandomNormal[i] = FormatFloat(x, 'g', -1, 64)
	 488  	}
	 489  }
	 490  
	 491  func TestParseFloatPrefix(t *testing.T) {
	 492  	for i := range atoftests {
	 493  		test := &atoftests[i]
	 494  		if test.err != nil {
	 495  			continue
	 496  		}
	 497  		// Adding characters that do not extend a number should not invalidate it.
	 498  		// Test a few. The "i" and "init" cases test that we accept "infi", "infinit"
	 499  		// correctly as "inf" with suffix.
	 500  		for _, suffix := range []string{" ", "q", "+", "-", "<", "=", ">", "(", ")", "i", "init"} {
	 501  			in := test.in + suffix
	 502  			_, n, err := ParseFloatPrefix(in, 64)
	 503  			if err != nil {
	 504  				t.Errorf("ParseFloatPrefix(%q, 64): err = %v; want no error", in, err)
	 505  			}
	 506  			if n != len(test.in) {
	 507  				t.Errorf("ParseFloatPrefix(%q, 64): n = %d; want %d", in, n, len(test.in))
	 508  			}
	 509  		}
	 510  	}
	 511  }
	 512  
	 513  func testAtof(t *testing.T, opt bool) {
	 514  	initAtof()
	 515  	oldopt := SetOptimize(opt)
	 516  	for i := 0; i < len(atoftests); i++ {
	 517  		test := &atoftests[i]
	 518  		out, err := ParseFloat(test.in, 64)
	 519  		outs := FormatFloat(out, 'g', -1, 64)
	 520  		if outs != test.out || !reflect.DeepEqual(err, test.err) {
	 521  			t.Errorf("ParseFloat(%v, 64) = %v, %v want %v, %v",
	 522  				test.in, out, err, test.out, test.err)
	 523  		}
	 524  
	 525  		if float64(float32(out)) == out {
	 526  			out, err := ParseFloat(test.in, 32)
	 527  			out32 := float32(out)
	 528  			if float64(out32) != out {
	 529  				t.Errorf("ParseFloat(%v, 32) = %v, not a float32 (closest is %v)", test.in, out, float64(out32))
	 530  				continue
	 531  			}
	 532  			outs := FormatFloat(float64(out32), 'g', -1, 32)
	 533  			if outs != test.out || !reflect.DeepEqual(err, test.err) {
	 534  				t.Errorf("ParseFloat(%v, 32) = %v, %v want %v, %v	# %v",
	 535  					test.in, out32, err, test.out, test.err, out)
	 536  			}
	 537  		}
	 538  	}
	 539  	for _, test := range atof32tests {
	 540  		out, err := ParseFloat(test.in, 32)
	 541  		out32 := float32(out)
	 542  		if float64(out32) != out {
	 543  			t.Errorf("ParseFloat(%v, 32) = %v, not a float32 (closest is %v)", test.in, out, float64(out32))
	 544  			continue
	 545  		}
	 546  		outs := FormatFloat(float64(out32), 'g', -1, 32)
	 547  		if outs != test.out || !reflect.DeepEqual(err, test.err) {
	 548  			t.Errorf("ParseFloat(%v, 32) = %v, %v want %v, %v	# %v",
	 549  				test.in, out32, err, test.out, test.err, out)
	 550  		}
	 551  	}
	 552  	SetOptimize(oldopt)
	 553  }
	 554  
	 555  func TestAtof(t *testing.T) { testAtof(t, true) }
	 556  
	 557  func TestAtofSlow(t *testing.T) { testAtof(t, false) }
	 558  
	 559  func TestAtofRandom(t *testing.T) {
	 560  	initAtof()
	 561  	for _, test := range atofRandomTests {
	 562  		x, _ := ParseFloat(test.s, 64)
	 563  		switch {
	 564  		default:
	 565  			t.Errorf("number %s badly parsed as %b (expected %b)", test.s, x, test.x)
	 566  		case x == test.x:
	 567  		case math.IsNaN(test.x) && math.IsNaN(x):
	 568  		}
	 569  	}
	 570  	t.Logf("tested %d random numbers", len(atofRandomTests))
	 571  }
	 572  
	 573  var roundTripCases = []struct {
	 574  	f float64
	 575  	s string
	 576  }{
	 577  	// Issue 2917.
	 578  	// This test will break the optimized conversion if the
	 579  	// FPU is using 80-bit registers instead of 64-bit registers,
	 580  	// usually because the operating system initialized the
	 581  	// thread with 80-bit precision and the Go runtime didn't
	 582  	// fix the FP control word.
	 583  	{8865794286000691 << 39, "4.87402195346389e+27"},
	 584  	{8865794286000692 << 39, "4.8740219534638903e+27"},
	 585  }
	 586  
	 587  func TestRoundTrip(t *testing.T) {
	 588  	for _, tt := range roundTripCases {
	 589  		old := SetOptimize(false)
	 590  		s := FormatFloat(tt.f, 'g', -1, 64)
	 591  		if s != tt.s {
	 592  			t.Errorf("no-opt FormatFloat(%b) = %s, want %s", tt.f, s, tt.s)
	 593  		}
	 594  		f, err := ParseFloat(tt.s, 64)
	 595  		if f != tt.f || err != nil {
	 596  			t.Errorf("no-opt ParseFloat(%s) = %b, %v want %b, nil", tt.s, f, err, tt.f)
	 597  		}
	 598  		SetOptimize(true)
	 599  		s = FormatFloat(tt.f, 'g', -1, 64)
	 600  		if s != tt.s {
	 601  			t.Errorf("opt FormatFloat(%b) = %s, want %s", tt.f, s, tt.s)
	 602  		}
	 603  		f, err = ParseFloat(tt.s, 64)
	 604  		if f != tt.f || err != nil {
	 605  			t.Errorf("opt ParseFloat(%s) = %b, %v want %b, nil", tt.s, f, err, tt.f)
	 606  		}
	 607  		SetOptimize(old)
	 608  	}
	 609  }
	 610  
	 611  // TestRoundTrip32 tries a fraction of all finite positive float32 values.
	 612  func TestRoundTrip32(t *testing.T) {
	 613  	step := uint32(997)
	 614  	if testing.Short() {
	 615  		step = 99991
	 616  	}
	 617  	count := 0
	 618  	for i := uint32(0); i < 0xff<<23; i += step {
	 619  		f := math.Float32frombits(i)
	 620  		if i&1 == 1 {
	 621  			f = -f // negative
	 622  		}
	 623  		s := FormatFloat(float64(f), 'g', -1, 32)
	 624  
	 625  		parsed, err := ParseFloat(s, 32)
	 626  		parsed32 := float32(parsed)
	 627  		switch {
	 628  		case err != nil:
	 629  			t.Errorf("ParseFloat(%q, 32) gave error %s", s, err)
	 630  		case float64(parsed32) != parsed:
	 631  			t.Errorf("ParseFloat(%q, 32) = %v, not a float32 (nearest is %v)", s, parsed, parsed32)
	 632  		case parsed32 != f:
	 633  			t.Errorf("ParseFloat(%q, 32) = %b (expected %b)", s, parsed32, f)
	 634  		}
	 635  		count++
	 636  	}
	 637  	t.Logf("tested %d float32's", count)
	 638  }
	 639  
	 640  // Issue 42297: a lot of code in the wild accidentally calls ParseFloat(s, 10)
	 641  // or ParseFloat(s, 0), so allow bitSize values other than 32 and 64.
	 642  func TestParseFloatIncorrectBitSize(t *testing.T) {
	 643  	const s = "1.5e308"
	 644  	const want = 1.5e308
	 645  
	 646  	for _, bitSize := range []int{0, 10, 100, 128} {
	 647  		f, err := ParseFloat(s, bitSize)
	 648  		if err != nil {
	 649  			t.Fatalf("ParseFloat(%q, %d) gave error %s", s, bitSize, err)
	 650  		}
	 651  		if f != want {
	 652  			t.Fatalf("ParseFloat(%q, %d) = %g (expected %g)", s, bitSize, f, want)
	 653  		}
	 654  	}
	 655  }
	 656  
	 657  func BenchmarkAtof64Decimal(b *testing.B) {
	 658  	for i := 0; i < b.N; i++ {
	 659  		ParseFloat("33909", 64)
	 660  	}
	 661  }
	 662  
	 663  func BenchmarkAtof64Float(b *testing.B) {
	 664  	for i := 0; i < b.N; i++ {
	 665  		ParseFloat("339.7784", 64)
	 666  	}
	 667  }
	 668  
	 669  func BenchmarkAtof64FloatExp(b *testing.B) {
	 670  	for i := 0; i < b.N; i++ {
	 671  		ParseFloat("-5.09e75", 64)
	 672  	}
	 673  }
	 674  
	 675  func BenchmarkAtof64Big(b *testing.B) {
	 676  	for i := 0; i < b.N; i++ {
	 677  		ParseFloat("123456789123456789123456789", 64)
	 678  	}
	 679  }
	 680  
	 681  func BenchmarkAtof64RandomBits(b *testing.B) {
	 682  	initAtof()
	 683  	b.ResetTimer()
	 684  	for i := 0; i < b.N; i++ {
	 685  		ParseFloat(benchmarksRandomBits[i%1024], 64)
	 686  	}
	 687  }
	 688  
	 689  func BenchmarkAtof64RandomFloats(b *testing.B) {
	 690  	initAtof()
	 691  	b.ResetTimer()
	 692  	for i := 0; i < b.N; i++ {
	 693  		ParseFloat(benchmarksRandomNormal[i%1024], 64)
	 694  	}
	 695  }
	 696  
	 697  func BenchmarkAtof64RandomLongFloats(b *testing.B) {
	 698  	initAtof()
	 699  	samples := make([]string, len(atofRandomTests))
	 700  	for i, t := range atofRandomTests {
	 701  		samples[i] = FormatFloat(t.x, 'g', 20, 64)
	 702  	}
	 703  	b.ResetTimer()
	 704  	idx := 0
	 705  	for i := 0; i < b.N; i++ {
	 706  		ParseFloat(samples[idx], 64)
	 707  		idx++
	 708  		if idx == len(samples) {
	 709  			idx = 0
	 710  		}
	 711  	}
	 712  }
	 713  
	 714  func BenchmarkAtof32Decimal(b *testing.B) {
	 715  	for i := 0; i < b.N; i++ {
	 716  		ParseFloat("33909", 32)
	 717  	}
	 718  }
	 719  
	 720  func BenchmarkAtof32Float(b *testing.B) {
	 721  	for i := 0; i < b.N; i++ {
	 722  		ParseFloat("339.778", 32)
	 723  	}
	 724  }
	 725  
	 726  func BenchmarkAtof32FloatExp(b *testing.B) {
	 727  	for i := 0; i < b.N; i++ {
	 728  		ParseFloat("12.3456e32", 32)
	 729  	}
	 730  }
	 731  
	 732  func BenchmarkAtof32Random(b *testing.B) {
	 733  	n := uint32(997)
	 734  	var float32strings [4096]string
	 735  	for i := range float32strings {
	 736  		n = (99991*n + 42) % (0xff << 23)
	 737  		float32strings[i] = FormatFloat(float64(math.Float32frombits(n)), 'g', -1, 32)
	 738  	}
	 739  	b.ResetTimer()
	 740  	for i := 0; i < b.N; i++ {
	 741  		ParseFloat(float32strings[i%4096], 32)
	 742  	}
	 743  }
	 744  
	 745  func BenchmarkAtof32RandomLong(b *testing.B) {
	 746  	n := uint32(997)
	 747  	var float32strings [4096]string
	 748  	for i := range float32strings {
	 749  		n = (99991*n + 42) % (0xff << 23)
	 750  		float32strings[i] = FormatFloat(float64(math.Float32frombits(n)), 'g', 20, 32)
	 751  	}
	 752  	b.ResetTimer()
	 753  	for i := 0; i < b.N; i++ {
	 754  		ParseFloat(float32strings[i%4096], 32)
	 755  	}
	 756  }
	 757  

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