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// 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 (
"bytes"
"strconv"
"unicode"
"utf8"
)
const (
nByte = 64
ldigits = "0123456789abcdef"
udigits = "0123456789ABCDEF"
)
const (
signed = true
unsigned = false
)
var padZeroBytes = make([]byte, nByte)
var padSpaceBytes = make([]byte, nByte)
var newline = []byte{'\n'}
func init() {
for i := 0; i < nByte; i++ {
padZeroBytes[i] = '0'
padSpaceBytes[i] = ' '
}
}
// A fmt is the raw formatter used by Printf etc.
// It prints into a bytes.Buffer that must be set up externally.
type fmt struct {
intbuf [nByte]byte
buf *bytes.Buffer
// width, precision
wid int
prec int
// flags
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
}
func (f *fmt) clearflags() {
f.wid = 0
f.widPresent = false
f.prec = 0
f.precPresent = false
f.minus = false
f.plus = false
f.sharp = false
f.space = false
f.unicode = false
f.uniQuote = false
f.zero = false
}
func (f *fmt) init(buf *bytes.Buffer) {
f.buf = buf
f.clearflags()
}
// Compute 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
}
// Generate 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
}
}
// Append b to f.buf, padded on left (w > 0) or right (w < 0 or f.minus)
// clear flags afterwards.
func (f *fmt) pad(b []byte) {
var padding []byte
var left, right int
if f.widPresent && f.wid != 0 {
padding, left, right = f.computePadding(len(b))
}
if left > 0 {
f.writePadding(left, padding)
}
f.buf.Write(b)
if right > 0 {
f.writePadding(right, padding)
}
}
// append s to buf, padded on left (w > 0) or right (w < 0 or f.minus).
// clear flags afterwards.
func (f *fmt) padString(s string) {
var padding []byte
var left, right int
if f.widPresent && f.wid != 0 {
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)
}
}
func putint(buf []byte, base, val uint64, digits string) int {
i := len(buf) - 1
for val >= base {
buf[i] = digits[val%base]
i--
val /= base
}
buf[i] = digits[val]
return i - 1
}
// fmt_boolean formats a boolean.
func (f *fmt) fmt_boolean(v bool) {
if v {
f.padString("true")
} else {
f.padString("false")
}
}
// 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:]
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(f.intbuf)
ua := uint64(a)
for ua >= base {
i--
buf[i] = digits[ua%base]
ua /= base
}
i--
buf[i] = digits[ua]
for i > 0 && prec > nByte-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 <= unicode.MaxRune && unicode.IsPrint(int(a)) {
runeWidth := utf8.RuneLen(int(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:], int(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_sx formats a string as a hexadecimal encoding of its bytes.
func (f *fmt) fmt_sx(s string) {
t := ""
for i := 0; i < len(s); i++ {
if i > 0 && f.space {
t += " "
}
v := s[i]
t += string(ldigits[v>>4])
t += string(ldigits[v&0xF])
}
f.padString(t)
}
// fmt_sX formats a string as an uppercase hexadecimal encoding of its bytes.
func (f *fmt) fmt_sX(s string) {
t := ""
for i := 0; i < len(s); i++ {
if i > 0 && f.space {
t += " "
}
v := s[i]
t += string(udigits[v>>4])
t += string(udigits[v&0xF])
}
f.padString(t)
}
// 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 string
if f.plus {
quoted = strconv.QuoteRuneToASCII(int(c))
} else {
quoted = strconv.QuoteRune(int(c))
}
f.padString(quoted)
}
// floating-point
func doPrec(f *fmt, def int) int {
if f.precPresent {
return f.prec
}
return def
}
// Add a plus sign or space to the floating-point string representation if missing and required.
func (f *fmt) plusSpace(s string) {
if s[0] != '-' {
if f.plus {
s = "+" + s
} else if f.space {
s = " " + s
}
}
f.padString(s)
}
// fmt_e64 formats a float64 in the form -1.23e+12.
func (f *fmt) fmt_e64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'e', doPrec(f, 6))) }
// fmt_E64 formats a float64 in the form -1.23E+12.
func (f *fmt) fmt_E64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'E', doPrec(f, 6))) }
// fmt_f64 formats a float64 in the form -1.23.
func (f *fmt) fmt_f64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'f', doPrec(f, 6))) }
// fmt_g64 formats a float64 in the 'f' or 'e' form according to size.
func (f *fmt) fmt_g64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'g', doPrec(f, -1))) }
// fmt_g64 formats a float64 in the 'f' or 'E' form according to size.
func (f *fmt) fmt_G64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'G', doPrec(f, -1))) }
// fmt_fb64 formats a float64 in the form -123p3 (exponent is power of 2).
func (f *fmt) fmt_fb64(v float64) { f.plusSpace(strconv.Ftoa64(v, 'b', 0)) }
// 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.plusSpace(strconv.Ftoa32(v, 'e', doPrec(f, 6))) }
// fmt_E32 formats a float32 in the form -1.23E+12.
func (f *fmt) fmt_E32(v float32) { f.plusSpace(strconv.Ftoa32(v, 'E', doPrec(f, 6))) }
// fmt_f32 formats a float32 in the form -1.23.
func (f *fmt) fmt_f32(v float32) { f.plusSpace(strconv.Ftoa32(v, 'f', doPrec(f, 6))) }
// fmt_g32 formats a float32 in the 'f' or 'e' form according to size.
func (f *fmt) fmt_g32(v float32) { f.plusSpace(strconv.Ftoa32(v, 'g', doPrec(f, -1))) }
// fmt_G32 formats a float32 in the 'f' or 'E' form according to size.
func (f *fmt) fmt_G32(v float32) { f.plusSpace(strconv.Ftoa32(v, 'G', doPrec(f, -1))) }
// fmt_fb32 formats a float32 in the form -123p3 (exponent is power of 2).
func (f *fmt) fmt_fb32(v float32) { f.padString(strconv.Ftoa32(v, 'b', 0)) }
// fmt_c64 formats a complex64 according to the verb.
func (f *fmt) fmt_c64(v complex64, verb int) {
f.buf.WriteByte('(')
r := real(v)
for i := 0; ; i++ {
switch verb {
case 'e':
f.fmt_e32(r)
case 'E':
f.fmt_E32(r)
case 'f':
f.fmt_f32(r)
case 'g':
f.fmt_g32(r)
case 'G':
f.fmt_G32(r)
}
if i != 0 {
break
}
f.plus = true
r = imag(v)
}
f.buf.Write(irparenBytes)
}
// fmt_c128 formats a complex128 according to the verb.
func (f *fmt) fmt_c128(v complex128, verb int) {
f.buf.WriteByte('(')
r := real(v)
for i := 0; ; i++ {
switch verb {
case 'e':
f.fmt_e64(r)
case 'E':
f.fmt_E64(r)
case 'f':
f.fmt_f64(r)
case 'g':
f.fmt_g64(r)
case 'G':
f.fmt_G64(r)
}
if i != 0 {
break
}
f.plus = true
r = imag(v)
}
f.buf.Write(irparenBytes)
}