1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524
|
// 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 fmt
import (
"math"
"strconv"
"unicode/utf8"
)
const (
// %b of an int64, plus a sign.
// Hex can add 0x and we handle it specially.
nByte = 65
ldigits = "0123456789abcdef"
udigits = "0123456789ABCDEF"
)
const (
signed = true
unsigned = false
)
var padZeroBytes = make([]byte, nByte)
var padSpaceBytes = make([]byte, nByte)
func init() {
for i := 0; i < nByte; i++ {
padZeroBytes[i] = '0'
padSpaceBytes[i] = ' '
}
}
// flags placed in a separate struct for easy clearing.
type fmtFlags struct {
widPresent bool
precPresent bool
minus bool
plus bool
sharp bool
space bool
unicode bool
uniQuote bool // Use 'x'= prefix for %U if printable.
zero bool
// For the formats %+v %#v, we set the plusV/sharpV flags
// and clear the plus/sharp flags since %+v and %#v are in effect
// different, flagless formats set at the top level.
plusV bool
sharpV bool
}
// A fmt is the raw formatter used by Printf etc.
// It prints into a buffer that must be set up separately.
type fmt struct {
intbuf [nByte]byte
buf *buffer
// width, precision
wid int
prec int
fmtFlags
}
func (f *fmt) clearflags() {
f.fmtFlags = fmtFlags{}
}
func (f *fmt) init(buf *buffer) {
f.buf = buf
f.clearflags()
}
// computePadding computes left and right padding widths (only one will be non-zero).
func (f *fmt) computePadding(width int) (padding []byte, leftWidth, rightWidth int) {
left := !f.minus
w := f.wid
if w < 0 {
left = false
w = -w
}
w -= width
if w > 0 {
if left && f.zero {
return padZeroBytes, w, 0
}
if left {
return padSpaceBytes, w, 0
} else {
// can't be zero padding on the right
return padSpaceBytes, 0, w
}
}
return
}
// writePadding generates n bytes of padding.
func (f *fmt) writePadding(n int, padding []byte) {
for n > 0 {
m := n
if m > nByte {
m = nByte
}
f.buf.Write(padding[0:m])
n -= m
}
}
// pad appends b to f.buf, padded on left (w > 0) or right (w < 0 or f.minus).
func (f *fmt) pad(b []byte) {
if !f.widPresent || f.wid == 0 {
f.buf.Write(b)
return
}
padding, left, right := f.computePadding(utf8.RuneCount(b))
if left > 0 {
f.writePadding(left, padding)
}
f.buf.Write(b)
if right > 0 {
f.writePadding(right, padding)
}
}
// padString appends s to buf, padded on left (w > 0) or right (w < 0 or f.minus).
func (f *fmt) padString(s string) {
if !f.widPresent || f.wid == 0 {
f.buf.WriteString(s)
return
}
padding, left, right := f.computePadding(utf8.RuneCountInString(s))
if left > 0 {
f.writePadding(left, padding)
}
f.buf.WriteString(s)
if right > 0 {
f.writePadding(right, padding)
}
}
var (
trueBytes = []byte("true")
falseBytes = []byte("false")
)
// fmt_boolean formats a boolean.
func (f *fmt) fmt_boolean(v bool) {
if v {
f.pad(trueBytes)
} else {
f.pad(falseBytes)
}
}
// integer; interprets prec but not wid. Once formatted, result is sent to pad()
// and then flags are cleared.
func (f *fmt) integer(a int64, base uint64, signedness bool, digits string) {
// precision of 0 and value of 0 means "print nothing"
if f.precPresent && f.prec == 0 && a == 0 {
return
}
var buf []byte = f.intbuf[0:]
if f.widPresent {
width := f.wid
if base == 16 && f.sharp {
// Also adds "0x".
width += 2
}
if width > nByte {
// We're going to need a bigger boat.
buf = make([]byte, width)
}
}
negative := signedness == signed && a < 0
if negative {
a = -a
}
// two ways to ask for extra leading zero digits: %.3d or %03d.
// apparently the first cancels the second.
prec := 0
if f.precPresent {
prec = f.prec
f.zero = false
} else if f.zero && f.widPresent && !f.minus && f.wid > 0 {
prec = f.wid
if negative || f.plus || f.space {
prec-- // leave room for sign
}
}
// format a into buf, ending at buf[i]. (printing is easier right-to-left.)
// a is made into unsigned ua. we could make things
// marginally faster by splitting the 32-bit case out into a separate
// block but it's not worth the duplication, so ua has 64 bits.
i := len(buf)
ua := uint64(a)
// use constants for the division and modulo for more efficient code.
// switch cases ordered by popularity.
switch base {
case 10:
for ua >= 10 {
i--
next := ua / 10
buf[i] = byte('0' + ua - next*10)
ua = next
}
case 16:
for ua >= 16 {
i--
buf[i] = digits[ua&0xF]
ua >>= 4
}
case 8:
for ua >= 8 {
i--
buf[i] = byte('0' + ua&7)
ua >>= 3
}
case 2:
for ua >= 2 {
i--
buf[i] = byte('0' + ua&1)
ua >>= 1
}
default:
panic("fmt: unknown base; can't happen")
}
i--
buf[i] = digits[ua]
for i > 0 && prec > len(buf)-i {
i--
buf[i] = '0'
}
// Various prefixes: 0x, -, etc.
if f.sharp {
switch base {
case 8:
if buf[i] != '0' {
i--
buf[i] = '0'
}
case 16:
i--
buf[i] = 'x' + digits[10] - 'a'
i--
buf[i] = '0'
}
}
if f.unicode {
i--
buf[i] = '+'
i--
buf[i] = 'U'
}
if negative {
i--
buf[i] = '-'
} else if f.plus {
i--
buf[i] = '+'
} else if f.space {
i--
buf[i] = ' '
}
// If we want a quoted char for %#U, move the data up to make room.
if f.unicode && f.uniQuote && a >= 0 && a <= utf8.MaxRune && strconv.IsPrint(rune(a)) {
runeWidth := utf8.RuneLen(rune(a))
width := 1 + 1 + runeWidth + 1 // space, quote, rune, quote
copy(buf[i-width:], buf[i:]) // guaranteed to have enough room.
i -= width
// Now put " 'x'" at the end.
j := len(buf) - width
buf[j] = ' '
j++
buf[j] = '\''
j++
utf8.EncodeRune(buf[j:], rune(a))
j += runeWidth
buf[j] = '\''
}
f.pad(buf[i:])
}
// truncate truncates the string to the specified precision, if present.
func (f *fmt) truncate(s string) string {
if f.precPresent && f.prec < utf8.RuneCountInString(s) {
n := f.prec
for i := range s {
if n == 0 {
s = s[:i]
break
}
n--
}
}
return s
}
// fmt_s formats a string.
func (f *fmt) fmt_s(s string) {
s = f.truncate(s)
f.padString(s)
}
// fmt_sbx formats a string or byte slice as a hexadecimal encoding of its bytes.
func (f *fmt) fmt_sbx(s string, b []byte, digits string) {
n := len(b)
if b == nil {
n = len(s)
}
x := digits[10] - 'a' + 'x'
// TODO: Avoid buffer by pre-padding.
var buf []byte
for i := 0; i < n; i++ {
if i > 0 && f.space {
buf = append(buf, ' ')
}
if f.sharp && (f.space || i == 0) {
buf = append(buf, '0', x)
}
var c byte
if b == nil {
c = s[i]
} else {
c = b[i]
}
buf = append(buf, digits[c>>4], digits[c&0xF])
}
f.pad(buf)
}
// fmt_sx formats a string as a hexadecimal encoding of its bytes.
func (f *fmt) fmt_sx(s, digits string) {
if f.precPresent && f.prec < len(s) {
s = s[:f.prec]
}
f.fmt_sbx(s, nil, digits)
}
// fmt_bx formats a byte slice as a hexadecimal encoding of its bytes.
func (f *fmt) fmt_bx(b []byte, digits string) {
if f.precPresent && f.prec < len(b) {
b = b[:f.prec]
}
f.fmt_sbx("", b, digits)
}
// fmt_q formats a string as a double-quoted, escaped Go string constant.
func (f *fmt) fmt_q(s string) {
s = f.truncate(s)
var quoted string
if f.sharp && strconv.CanBackquote(s) {
quoted = "`" + s + "`"
} else {
if f.plus {
quoted = strconv.QuoteToASCII(s)
} else {
quoted = strconv.Quote(s)
}
}
f.padString(quoted)
}
// fmt_qc formats the integer as a single-quoted, escaped Go character constant.
// If the character is not valid Unicode, it will print '\ufffd'.
func (f *fmt) fmt_qc(c int64) {
var quoted []byte
if f.plus {
quoted = strconv.AppendQuoteRuneToASCII(f.intbuf[0:0], rune(c))
} else {
quoted = strconv.AppendQuoteRune(f.intbuf[0:0], rune(c))
}
f.pad(quoted)
}
// floating-point
func doPrec(f *fmt, def int) int {
if f.precPresent {
return f.prec
}
return def
}
// formatFloat formats a float64; it is an efficient equivalent to f.pad(strconv.FormatFloat()...).
func (f *fmt) formatFloat(v float64, verb byte, prec, n int) {
// Format number, reserving space for leading + sign if needed.
num := strconv.AppendFloat(f.intbuf[0:1], v, verb, prec, n)
if num[1] == '-' || num[1] == '+' {
num = num[1:]
} else {
num[0] = '+'
}
// Special handling for infinity, which doesn't look like a number so shouldn't be padded with zeros.
if math.IsInf(v, 0) {
if f.zero {
defer func() { f.zero = true }()
f.zero = false
}
}
// num is now a signed version of the number.
// If we're zero padding, want the sign before the leading zeros.
// Achieve this by writing the sign out and then padding the unsigned number.
if f.zero && f.widPresent && f.wid > len(num) {
if f.space && v >= 0 {
f.buf.WriteByte(' ') // This is what C does: even with zero, f.space means space.
f.wid--
} else if f.plus || v < 0 {
f.buf.WriteByte(num[0])
f.wid--
}
f.pad(num[1:])
return
}
// f.space says to replace a leading + with a space.
if f.space && num[0] == '+' {
num[0] = ' '
f.pad(num)
return
}
// Now we know the sign is attached directly to the number, if present at all.
// We want a sign if asked for, if it's negative, or if it's infinity (+Inf vs. -Inf).
if f.plus || num[0] == '-' || math.IsInf(v, 0) {
f.pad(num)
return
}
// No sign to show and the number is positive; just print the unsigned number.
f.pad(num[1:])
}
// fmt_e64 formats a float64 in the form -1.23e+12.
func (f *fmt) fmt_e64(v float64) { f.formatFloat(v, 'e', doPrec(f, 6), 64) }
// fmt_E64 formats a float64 in the form -1.23E+12.
func (f *fmt) fmt_E64(v float64) { f.formatFloat(v, 'E', doPrec(f, 6), 64) }
// fmt_f64 formats a float64 in the form -1.23.
func (f *fmt) fmt_f64(v float64) { f.formatFloat(v, 'f', doPrec(f, 6), 64) }
// fmt_g64 formats a float64 in the 'f' or 'e' form according to size.
func (f *fmt) fmt_g64(v float64) { f.formatFloat(v, 'g', doPrec(f, -1), 64) }
// fmt_G64 formats a float64 in the 'f' or 'E' form according to size.
func (f *fmt) fmt_G64(v float64) { f.formatFloat(v, 'G', doPrec(f, -1), 64) }
// fmt_fb64 formats a float64 in the form -123p3 (exponent is power of 2).
func (f *fmt) fmt_fb64(v float64) { f.formatFloat(v, 'b', 0, 64) }
// float32
// cannot defer to float64 versions
// because it will get rounding wrong in corner cases.
// fmt_e32 formats a float32 in the form -1.23e+12.
func (f *fmt) fmt_e32(v float32) { f.formatFloat(float64(v), 'e', doPrec(f, 6), 32) }
// fmt_E32 formats a float32 in the form -1.23E+12.
func (f *fmt) fmt_E32(v float32) { f.formatFloat(float64(v), 'E', doPrec(f, 6), 32) }
// fmt_f32 formats a float32 in the form -1.23.
func (f *fmt) fmt_f32(v float32) { f.formatFloat(float64(v), 'f', doPrec(f, 6), 32) }
// fmt_g32 formats a float32 in the 'f' or 'e' form according to size.
func (f *fmt) fmt_g32(v float32) { f.formatFloat(float64(v), 'g', doPrec(f, -1), 32) }
// fmt_G32 formats a float32 in the 'f' or 'E' form according to size.
func (f *fmt) fmt_G32(v float32) { f.formatFloat(float64(v), 'G', doPrec(f, -1), 32) }
// fmt_fb32 formats a float32 in the form -123p3 (exponent is power of 2).
func (f *fmt) fmt_fb32(v float32) { f.formatFloat(float64(v), 'b', 0, 32) }
// fmt_c64 formats a complex64 according to the verb.
func (f *fmt) fmt_c64(v complex64, verb rune) {
f.fmt_complex(float64(real(v)), float64(imag(v)), 32, verb)
}
// fmt_c128 formats a complex128 according to the verb.
func (f *fmt) fmt_c128(v complex128, verb rune) {
f.fmt_complex(real(v), imag(v), 64, verb)
}
// fmt_complex formats a complex number as (r+ji).
func (f *fmt) fmt_complex(r, j float64, size int, verb rune) {
f.buf.WriteByte('(')
oldPlus := f.plus
oldSpace := f.space
oldWid := f.wid
for i := 0; ; i++ {
switch verb {
case 'b':
f.formatFloat(r, 'b', 0, size)
case 'e':
f.formatFloat(r, 'e', doPrec(f, 6), size)
case 'E':
f.formatFloat(r, 'E', doPrec(f, 6), size)
case 'f', 'F':
f.formatFloat(r, 'f', doPrec(f, 6), size)
case 'g':
f.formatFloat(r, 'g', doPrec(f, -1), size)
case 'G':
f.formatFloat(r, 'G', doPrec(f, -1), size)
}
if i != 0 {
break
}
// Imaginary part always has a sign.
f.plus = true
f.space = false
f.wid = oldWid
r = j
}
f.space = oldSpace
f.plus = oldPlus
f.wid = oldWid
f.buf.Write(irparenBytes)
}
|