af146490bb
It is not needed due to the removal of the ctx field.
Reviewed-on: https://go-review.googlesource.com/16525
From-SVN: r229616
536 lines
12 KiB
Go
536 lines
12 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package fmt
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import (
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"math"
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"strconv"
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"unicode/utf8"
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)
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const (
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// %b of an int64, plus a sign.
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// Hex can add 0x and we handle it specially.
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nByte = 65
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ldigits = "0123456789abcdef"
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udigits = "0123456789ABCDEF"
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)
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const (
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signed = true
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unsigned = false
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)
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var padZeroBytes = make([]byte, nByte)
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var padSpaceBytes = make([]byte, nByte)
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func init() {
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for i := 0; i < nByte; i++ {
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padZeroBytes[i] = '0'
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padSpaceBytes[i] = ' '
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}
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}
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// flags placed in a separate struct for easy clearing.
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type fmtFlags struct {
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widPresent bool
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precPresent bool
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minus bool
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plus bool
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sharp bool
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space bool
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unicode bool
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uniQuote bool // Use 'x'= prefix for %U if printable.
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zero bool
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// For the formats %+v %#v, we set the plusV/sharpV flags
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// and clear the plus/sharp flags since %+v and %#v are in effect
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// different, flagless formats set at the top level.
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plusV bool
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sharpV bool
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}
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// A fmt is the raw formatter used by Printf etc.
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// It prints into a buffer that must be set up separately.
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type fmt struct {
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intbuf [nByte]byte
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buf *buffer
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// width, precision
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wid int
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prec int
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fmtFlags
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}
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func (f *fmt) clearflags() {
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f.fmtFlags = fmtFlags{}
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}
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func (f *fmt) init(buf *buffer) {
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f.buf = buf
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f.clearflags()
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}
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// computePadding computes left and right padding widths (only one will be non-zero).
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func (f *fmt) computePadding(width int) (padding []byte, leftWidth, rightWidth int) {
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left := !f.minus
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w := f.wid
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if w < 0 {
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left = false
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w = -w
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}
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w -= width
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if w > 0 {
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if left && f.zero {
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return padZeroBytes, w, 0
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}
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if left {
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return padSpaceBytes, w, 0
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} else {
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// can't be zero padding on the right
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return padSpaceBytes, 0, w
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}
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}
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return
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}
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// writePadding generates n bytes of padding.
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func (f *fmt) writePadding(n int, padding []byte) {
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for n > 0 {
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m := n
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if m > nByte {
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m = nByte
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}
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f.buf.Write(padding[0:m])
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n -= m
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}
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}
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// pad appends b to f.buf, padded on left (w > 0) or right (w < 0 or f.minus).
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func (f *fmt) pad(b []byte) {
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if !f.widPresent || f.wid == 0 {
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f.buf.Write(b)
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return
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}
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padding, left, right := f.computePadding(utf8.RuneCount(b))
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if left > 0 {
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f.writePadding(left, padding)
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}
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f.buf.Write(b)
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if right > 0 {
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f.writePadding(right, padding)
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}
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}
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// padString appends s to buf, padded on left (w > 0) or right (w < 0 or f.minus).
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func (f *fmt) padString(s string) {
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if !f.widPresent || f.wid == 0 {
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f.buf.WriteString(s)
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return
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}
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padding, left, right := f.computePadding(utf8.RuneCountInString(s))
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if left > 0 {
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f.writePadding(left, padding)
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}
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f.buf.WriteString(s)
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if right > 0 {
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f.writePadding(right, padding)
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}
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}
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var (
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trueBytes = []byte("true")
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falseBytes = []byte("false")
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)
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// fmt_boolean formats a boolean.
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func (f *fmt) fmt_boolean(v bool) {
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if v {
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f.pad(trueBytes)
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} else {
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f.pad(falseBytes)
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}
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}
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// integer; interprets prec but not wid. Once formatted, result is sent to pad()
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// and then flags are cleared.
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func (f *fmt) integer(a int64, base uint64, signedness bool, digits string) {
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// precision of 0 and value of 0 means "print nothing"
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if f.precPresent && f.prec == 0 && a == 0 {
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return
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}
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negative := signedness == signed && a < 0
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if negative {
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a = -a
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}
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var buf []byte = f.intbuf[0:]
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if f.widPresent || f.precPresent || f.plus || f.space {
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width := f.wid + f.prec // Only one will be set, both are positive; this provides the maximum.
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if base == 16 && f.sharp {
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// Also adds "0x".
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width += 2
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}
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if f.unicode {
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// Also adds "U+".
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width += 2
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if f.uniQuote {
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// Also adds " 'x'".
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width += 1 + 1 + utf8.UTFMax + 1
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}
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}
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if negative || f.plus || f.space {
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width++
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}
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if width > nByte {
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// We're going to need a bigger boat.
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buf = make([]byte, width)
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}
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}
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// two ways to ask for extra leading zero digits: %.3d or %03d.
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// apparently the first cancels the second.
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prec := 0
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if f.precPresent {
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prec = f.prec
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f.zero = false
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} else if f.zero && f.widPresent && !f.minus && f.wid > 0 {
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prec = f.wid
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if negative || f.plus || f.space {
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prec-- // leave room for sign
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}
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}
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// format a into buf, ending at buf[i]. (printing is easier right-to-left.)
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// a is made into unsigned ua. we could make things
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// marginally faster by splitting the 32-bit case out into a separate
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// block but it's not worth the duplication, so ua has 64 bits.
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i := len(buf)
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ua := uint64(a)
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// use constants for the division and modulo for more efficient code.
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// switch cases ordered by popularity.
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switch base {
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case 10:
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for ua >= 10 {
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i--
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next := ua / 10
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buf[i] = byte('0' + ua - next*10)
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ua = next
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}
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case 16:
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for ua >= 16 {
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i--
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buf[i] = digits[ua&0xF]
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ua >>= 4
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}
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case 8:
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for ua >= 8 {
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i--
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buf[i] = byte('0' + ua&7)
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ua >>= 3
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}
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case 2:
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for ua >= 2 {
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i--
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buf[i] = byte('0' + ua&1)
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ua >>= 1
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}
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default:
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panic("fmt: unknown base; can't happen")
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}
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i--
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buf[i] = digits[ua]
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for i > 0 && prec > len(buf)-i {
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i--
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buf[i] = '0'
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}
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// Various prefixes: 0x, -, etc.
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if f.sharp {
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switch base {
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case 8:
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if buf[i] != '0' {
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i--
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buf[i] = '0'
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}
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case 16:
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i--
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buf[i] = 'x' + digits[10] - 'a'
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i--
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buf[i] = '0'
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}
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}
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if f.unicode {
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i--
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buf[i] = '+'
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i--
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buf[i] = 'U'
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}
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if negative {
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i--
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buf[i] = '-'
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} else if f.plus {
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i--
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buf[i] = '+'
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} else if f.space {
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i--
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buf[i] = ' '
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}
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// If we want a quoted char for %#U, move the data up to make room.
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if f.unicode && f.uniQuote && a >= 0 && a <= utf8.MaxRune && strconv.IsPrint(rune(a)) {
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runeWidth := utf8.RuneLen(rune(a))
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width := 1 + 1 + runeWidth + 1 // space, quote, rune, quote
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copy(buf[i-width:], buf[i:]) // guaranteed to have enough room.
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i -= width
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// Now put " 'x'" at the end.
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j := len(buf) - width
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buf[j] = ' '
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j++
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buf[j] = '\''
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j++
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utf8.EncodeRune(buf[j:], rune(a))
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j += runeWidth
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buf[j] = '\''
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}
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f.pad(buf[i:])
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}
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// truncate truncates the string to the specified precision, if present.
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func (f *fmt) truncate(s string) string {
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if f.precPresent && f.prec < utf8.RuneCountInString(s) {
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n := f.prec
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for i := range s {
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if n == 0 {
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s = s[:i]
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break
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}
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n--
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}
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}
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return s
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}
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// fmt_s formats a string.
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func (f *fmt) fmt_s(s string) {
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s = f.truncate(s)
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f.padString(s)
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}
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// fmt_sbx formats a string or byte slice as a hexadecimal encoding of its bytes.
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func (f *fmt) fmt_sbx(s string, b []byte, digits string) {
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n := len(b)
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if b == nil {
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n = len(s)
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}
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x := digits[10] - 'a' + 'x'
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// TODO: Avoid buffer by pre-padding.
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var buf []byte
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for i := 0; i < n; i++ {
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if i > 0 && f.space {
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buf = append(buf, ' ')
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}
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if f.sharp && (f.space || i == 0) {
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buf = append(buf, '0', x)
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}
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var c byte
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if b == nil {
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c = s[i]
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} else {
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c = b[i]
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}
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buf = append(buf, digits[c>>4], digits[c&0xF])
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}
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f.pad(buf)
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}
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// fmt_sx formats a string as a hexadecimal encoding of its bytes.
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func (f *fmt) fmt_sx(s, digits string) {
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if f.precPresent && f.prec < len(s) {
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s = s[:f.prec]
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}
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f.fmt_sbx(s, nil, digits)
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}
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// fmt_bx formats a byte slice as a hexadecimal encoding of its bytes.
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func (f *fmt) fmt_bx(b []byte, digits string) {
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if f.precPresent && f.prec < len(b) {
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b = b[:f.prec]
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}
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f.fmt_sbx("", b, digits)
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}
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// fmt_q formats a string as a double-quoted, escaped Go string constant.
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func (f *fmt) fmt_q(s string) {
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s = f.truncate(s)
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var quoted string
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if f.sharp && strconv.CanBackquote(s) {
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quoted = "`" + s + "`"
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} else {
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if f.plus {
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quoted = strconv.QuoteToASCII(s)
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} else {
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quoted = strconv.Quote(s)
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}
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}
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f.padString(quoted)
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}
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// fmt_qc formats the integer as a single-quoted, escaped Go character constant.
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// If the character is not valid Unicode, it will print '\ufffd'.
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func (f *fmt) fmt_qc(c int64) {
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var quoted []byte
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if f.plus {
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quoted = strconv.AppendQuoteRuneToASCII(f.intbuf[0:0], rune(c))
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} else {
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quoted = strconv.AppendQuoteRune(f.intbuf[0:0], rune(c))
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}
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f.pad(quoted)
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}
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// floating-point
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func doPrec(f *fmt, def int) int {
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if f.precPresent {
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return f.prec
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}
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return def
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}
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// formatFloat formats a float64; it is an efficient equivalent to f.pad(strconv.FormatFloat()...).
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func (f *fmt) formatFloat(v float64, verb byte, prec, n int) {
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// Format number, reserving space for leading + sign if needed.
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num := strconv.AppendFloat(f.intbuf[0:1], v, verb, prec, n)
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if num[1] == '-' || num[1] == '+' {
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num = num[1:]
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} else {
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num[0] = '+'
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}
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// Special handling for infinity, which doesn't look like a number so shouldn't be padded with zeros.
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if math.IsInf(v, 0) {
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if f.zero {
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defer func() { f.zero = true }()
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f.zero = false
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}
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}
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// num is now a signed version of the number.
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// If we're zero padding, want the sign before the leading zeros.
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// Achieve this by writing the sign out and then padding the unsigned number.
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if f.zero && f.widPresent && f.wid > len(num) {
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if f.space && v >= 0 {
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f.buf.WriteByte(' ') // This is what C does: even with zero, f.space means space.
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f.wid--
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} else if f.plus || v < 0 {
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f.buf.WriteByte(num[0])
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f.wid--
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}
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f.pad(num[1:])
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return
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}
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// f.space says to replace a leading + with a space.
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if f.space && num[0] == '+' {
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num[0] = ' '
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f.pad(num)
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return
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}
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// Now we know the sign is attached directly to the number, if present at all.
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// We want a sign if asked for, if it's negative, or if it's infinity (+Inf vs. -Inf).
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if f.plus || num[0] == '-' || math.IsInf(v, 0) {
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f.pad(num)
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return
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}
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// No sign to show and the number is positive; just print the unsigned number.
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f.pad(num[1:])
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}
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// fmt_e64 formats a float64 in the form -1.23e+12.
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func (f *fmt) fmt_e64(v float64) { f.formatFloat(v, 'e', doPrec(f, 6), 64) }
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// fmt_E64 formats a float64 in the form -1.23E+12.
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func (f *fmt) fmt_E64(v float64) { f.formatFloat(v, 'E', doPrec(f, 6), 64) }
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// fmt_f64 formats a float64 in the form -1.23.
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func (f *fmt) fmt_f64(v float64) { f.formatFloat(v, 'f', doPrec(f, 6), 64) }
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// fmt_g64 formats a float64 in the 'f' or 'e' form according to size.
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func (f *fmt) fmt_g64(v float64) { f.formatFloat(v, 'g', doPrec(f, -1), 64) }
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// fmt_G64 formats a float64 in the 'f' or 'E' form according to size.
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func (f *fmt) fmt_G64(v float64) { f.formatFloat(v, 'G', doPrec(f, -1), 64) }
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// fmt_fb64 formats a float64 in the form -123p3 (exponent is power of 2).
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func (f *fmt) fmt_fb64(v float64) { f.formatFloat(v, 'b', 0, 64) }
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// float32
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// cannot defer to float64 versions
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// because it will get rounding wrong in corner cases.
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// fmt_e32 formats a float32 in the form -1.23e+12.
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func (f *fmt) fmt_e32(v float32) { f.formatFloat(float64(v), 'e', doPrec(f, 6), 32) }
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// fmt_E32 formats a float32 in the form -1.23E+12.
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func (f *fmt) fmt_E32(v float32) { f.formatFloat(float64(v), 'E', doPrec(f, 6), 32) }
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// fmt_f32 formats a float32 in the form -1.23.
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func (f *fmt) fmt_f32(v float32) { f.formatFloat(float64(v), 'f', doPrec(f, 6), 32) }
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// fmt_g32 formats a float32 in the 'f' or 'e' form according to size.
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func (f *fmt) fmt_g32(v float32) { f.formatFloat(float64(v), 'g', doPrec(f, -1), 32) }
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// fmt_G32 formats a float32 in the 'f' or 'E' form according to size.
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func (f *fmt) fmt_G32(v float32) { f.formatFloat(float64(v), 'G', doPrec(f, -1), 32) }
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// fmt_fb32 formats a float32 in the form -123p3 (exponent is power of 2).
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func (f *fmt) fmt_fb32(v float32) { f.formatFloat(float64(v), 'b', 0, 32) }
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// fmt_c64 formats a complex64 according to the verb.
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func (f *fmt) fmt_c64(v complex64, verb rune) {
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f.fmt_complex(float64(real(v)), float64(imag(v)), 32, verb)
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}
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// fmt_c128 formats a complex128 according to the verb.
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func (f *fmt) fmt_c128(v complex128, verb rune) {
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f.fmt_complex(real(v), imag(v), 64, verb)
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}
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// fmt_complex formats a complex number as (r+ji).
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func (f *fmt) fmt_complex(r, j float64, size int, verb rune) {
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f.buf.WriteByte('(')
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oldPlus := f.plus
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oldSpace := f.space
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oldWid := f.wid
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for i := 0; ; i++ {
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switch verb {
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case 'b':
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f.formatFloat(r, 'b', 0, size)
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case 'e':
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f.formatFloat(r, 'e', doPrec(f, 6), size)
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case 'E':
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f.formatFloat(r, 'E', doPrec(f, 6), size)
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case 'f', 'F':
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f.formatFloat(r, 'f', doPrec(f, 6), size)
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case 'g':
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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)
|
|
}
|