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-rw-r--r--src/fmt/format.go524
1 files changed, 524 insertions, 0 deletions
diff --git a/src/fmt/format.go b/src/fmt/format.go
new file mode 100644
index 000000000..4d97d1443
--- /dev/null
+++ b/src/fmt/format.go
@@ -0,0 +1,524 @@
+// 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)
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-05-01 23:40:02 +0000