444 lines
11 KiB
Go
444 lines
11 KiB
Go
// Copyright 2020 The Libc 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 libc // import "modernc.org/libc"
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import (
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"strings"
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"unsafe"
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)
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// The format string consists of a sequence of directives which describe how to
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// process the sequence of input characters. If processing of a directive
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// fails, no further input is read, and scanf() returns. A "failure" can
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// be either of the following: input failure, meaning that input characters
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// were unavailable, or matching failure, meaning that the input was
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// inappropriate.
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func scanf(r *strings.Reader, format, args uintptr) (nvalues int32) {
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// var src []byte //TODO-
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var ok bool
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out:
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for {
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c := *(*byte)(unsafe.Pointer(format))
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// src = append(src, c) //TODO-
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switch c {
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case '%':
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var n int
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var match bool
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format, n, match = scanfConversion(r, format, &args)
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if !match {
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break out
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}
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nvalues += int32(n)
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ok = true
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case 0:
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break out
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case ' ', '\t', '\n', '\r', '\v', '\f':
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format = skipWhiteSpace(format)
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ok = true
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next:
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for {
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c, err := r.ReadByte()
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if err != nil {
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break out
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}
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switch c {
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case ' ', '\t', '\n', '\r', '\v', '\f':
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// nop
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default:
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r.UnreadByte()
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break next
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}
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}
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default:
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c2, err := r.ReadByte()
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if err != nil {
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break out
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}
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if c2 != c {
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r.UnreadByte()
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break out
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}
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format++
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ok = true
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}
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}
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if ok {
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return nvalues
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}
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return -1 // stdio.EOF but not defined for windows
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}
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func scanfConversion(r *strings.Reader, format uintptr, args *uintptr) (_ uintptr, nvalues int, match bool) {
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format++ // '%'
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// Each conversion specification in format begins with either the character '%'
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// or the character sequence "%n$" (see below for the distinction) followed by:
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mod := 0
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width := -1
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flags:
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for {
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switch c := *(*byte)(unsafe.Pointer(format)); c {
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case '*':
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// An optional '*' assignment-suppression character: scanf() reads input as
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// directed by the conversion specification, but discards the input. No
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// corresponding pointer argument is re‐ quired, and this specification is not
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// included in the count of successful assignments returned by scanf().
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format++
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panic(todo(""))
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case '\'':
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// For decimal conversions, an optional quote character ('). This specifies
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// that the input number may include thousands' separators as defined by the
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// LC_NUMERIC category of the current locale. (See setlocale(3).) The quote
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// character may precede or follow the '*' assignment-suppression character.
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format++
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panic(todo(""))
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case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
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// An optional decimal integer which specifies the maximum field width.
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// Reading of characters stops either when this maximum is reached or when a
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// nonmatching character is found, whichever happens first. Most conversions
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// discard initial white space characters (the exceptions are noted below), and
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// these discarded characters don't count toward the maximum field width.
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// String input conversions store a terminating null byte ('\0') to mark the
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// end of the input; the maximum field width does not include this terminator.
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width = 0
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num:
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for {
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var digit int
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switch c := *(*byte)(unsafe.Pointer(format)); {
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default:
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break num
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case c >= '0' && c <= '9':
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format++
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digit = int(c) - '0'
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}
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width0 := width
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width = 10*width + digit
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if width < width0 {
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panic(todo(""))
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}
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}
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case 'h', 'j', 'l', 'L', 'q', 't', 'z':
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format, mod = parseLengthModifier(format)
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default:
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break flags
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}
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}
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// A conversion specifier that specifies the type of input conversion to be
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// performed.
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switch c := *(*byte)(unsafe.Pointer(format)); c {
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case '%':
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// Matches a literal '%'. That is, %% in the format string matches a single
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// input '%' character. No conversion is done (but initial white space
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// characters are discarded), and assign‐ ment does not occur.
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format++
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panic(todo(""))
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case 'd':
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// Matches an optionally signed decimal integer; the next pointer must be a
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// pointer to int.
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format++
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skipReaderWhiteSpace(r)
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var digit, n uint64
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allowSign := true
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neg := false
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dec:
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for ; width != 0; width-- {
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c, err := r.ReadByte()
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if err != nil {
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if match {
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break dec
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}
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panic(todo("", err))
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}
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if allowSign {
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switch c {
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case '-':
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allowSign = false
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neg = true
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continue
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case '+':
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allowSign = false
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continue
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}
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}
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switch {
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case c >= '0' && c <= '9':
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digit = uint64(c) - '0'
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default:
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r.UnreadByte()
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break dec
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}
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match = true
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n0 := n
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n = n*10 + digit
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if n < n0 {
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panic(todo(""))
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}
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}
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if !match {
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break
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}
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arg := VaUintptr(args)
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v := int64(n)
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if neg {
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v = -v
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}
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switch mod {
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case modNone:
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*(*int32)(unsafe.Pointer(arg)) = int32(v)
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case modH:
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*(*int16)(unsafe.Pointer(arg)) = int16(v)
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case modHH:
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*(*int8)(unsafe.Pointer(arg)) = int8(v)
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case modL:
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*(*long)(unsafe.Pointer(arg)) = long(n)
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default:
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panic(todo(""))
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}
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nvalues = 1
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case 'D':
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// Equivalent to ld; this exists only for backward compatibility. (Note:
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// thus only in libc4. In libc5 and glibc the %D is silently ignored, causing
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// old programs to fail mysteriously.)
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format++
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panic(todo(""))
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case 'i':
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// Matches an optionally signed integer; the next pointer must be a pointer to
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// int. The integer is read in base 16 if it begins with 0x or 0X, in base 8
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// if it begins with 0, and in base 10 otherwise. Only characters that
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// correspond to the base are used.
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format++
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panic(todo(""))
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case 'o':
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// Matches an unsigned octal integer; the next pointer must be a pointer to
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// unsigned int.
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format++
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panic(todo(""))
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case 'u':
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// Matches an unsigned decimal integer; the next pointer must be a pointer to
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// unsigned int.
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format++
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panic(todo(""))
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case 'x', 'X':
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// Matches an unsigned hexadecimal integer; the next pointer must be a pointer
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// to unsigned int.
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format++
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skipReaderWhiteSpace(r)
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var digit, n uint64
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allowPrefix := true
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var b []byte
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hex:
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for ; width != 0; width-- {
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c, err := r.ReadByte()
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if err != nil {
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if match {
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break hex
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}
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panic(todo("", err))
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}
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if allowPrefix {
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if len(b) == 1 && b[0] == '0' && (c == 'x' || c == 'X') {
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allowPrefix = false
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match = false
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b = nil
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continue
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}
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b = append(b, c)
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}
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switch {
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case c >= '0' && c <= '9':
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digit = uint64(c) - '0'
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case c >= 'a' && c <= 'f':
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digit = uint64(c) - 'a' + 10
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case c >= 'A' && c <= 'F':
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digit = uint64(c) - 'A' + 10
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default:
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r.UnreadByte()
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break hex
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}
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match = true
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n0 := n
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n = n<<4 + digit
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if n < n0 {
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panic(todo(""))
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}
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}
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if !match {
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break
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}
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arg := VaUintptr(args)
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switch mod {
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case modNone:
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*(*uint32)(unsafe.Pointer(arg)) = uint32(n)
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case modH:
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*(*uint16)(unsafe.Pointer(arg)) = uint16(n)
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case modHH:
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*(*byte)(unsafe.Pointer(arg)) = byte(n)
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case modL:
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*(*ulong)(unsafe.Pointer(arg)) = ulong(n)
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default:
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panic(todo(""))
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}
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nvalues = 1
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case 'f', 'e', 'g', 'E', 'a':
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// Matches an optionally signed floating-point number; the next pointer must be
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// a pointer to float.
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format++
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panic(todo(""))
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case 's':
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// Matches a sequence of non-white-space characters; the next pointer must be
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// a pointer to the initial element of a character array that is long enough to
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// hold the input sequence and the terminating null byte ('\0'), which is added
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// automatically. The input string stops at white space or at the maximum
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// field width, whichever occurs first.
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format++
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panic(todo(""))
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case 'c':
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// Matches a sequence of characters whose length is specified by the maximum
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// field width (default 1); the next pointer must be a pointer to char, and
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// there must be enough room for all the characters (no terminating null byte
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// is added). The usual skip of leading white space is suppressed. To skip
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// white space first, use an explicit space in the format.
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format++
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panic(todo(""))
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case '[':
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// Matches a nonempty sequence of characters from the specified set of
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// accepted characters; the next pointer must be a pointer to char, and there
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// must be enough room for all the char‐ acters in the string, plus a
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// terminating null byte. The usual skip of leading white space is suppressed.
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// The string is to be made up of characters in (or not in) a particular set;
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// the set is defined by the characters between the open bracket [ character
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// and a close bracket ] character. The set excludes those characters if the
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// first character after the open bracket is a circumflex (^). To include a
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// close bracket in the set, make it the first character after the open bracket
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// or the circumflex; any other position will end the set. The hyphen
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// character - is also special; when placed between two other characters, it
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// adds all intervening characters to the set. To include a hyphen, make it
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// the last character before the final close bracket. For instance, [^]0-9-]
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// means the set "everything except close bracket, zero through nine, and
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// hyphen". The string ends with the appearance of a character not in the
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// (or, with a circumflex, in) set or when the field width runs out.
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format++
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panic(todo(""))
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case 'p':
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// Matches a pointer value (as printed by %p in printf(3); the next pointer
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// must be a pointer to a pointer to void.
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format++
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skipReaderWhiteSpace(r)
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c, err := r.ReadByte()
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if err != nil {
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panic(todo(""))
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}
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if c != '0' {
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r.UnreadByte()
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panic(todo(""))
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}
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if c, err = r.ReadByte(); err != nil {
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panic(todo(""))
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}
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if c != 'x' && c != 'X' {
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r.UnreadByte()
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panic(todo(""))
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}
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var digit, n uint64
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ptr:
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for ; width != 0; width-- {
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c, err := r.ReadByte()
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if err != nil {
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if match {
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break ptr
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}
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panic(todo(""))
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}
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switch {
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case c >= '0' && c <= '9':
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digit = uint64(c) - '0'
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case c >= 'a' && c <= 'f':
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digit = uint64(c) - 'a' + 10
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case c >= 'A' && c <= 'F':
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digit = uint64(c) - 'A' + 10
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default:
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r.UnreadByte()
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break ptr
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}
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match = true
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n0 := n
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n = n<<4 + digit
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if n < n0 {
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panic(todo(""))
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}
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}
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if !match {
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break
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}
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arg := VaUintptr(args)
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*(*uintptr)(unsafe.Pointer(arg)) = uintptr(n)
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nvalues = 1
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case 'n':
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// Nothing is expected; instead, the number of characters consumed thus far
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// from the input is stored through the next pointer, which must be a pointer
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// to int. This is not a conversion and does not increase the count returned
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// by the function. The assignment can be suppressed with the *
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// assignment-suppression character, but the effect on the return value is
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// undefined. Therefore %*n conversions should not be used.
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format++
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panic(todo(""))
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default:
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panic(todo("%#U", c))
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}
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return format, nvalues, match
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}
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func skipReaderWhiteSpace(r *strings.Reader) error {
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for {
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c, err := r.ReadByte()
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if err != nil {
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return err
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}
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switch c {
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case ' ', '\t', '\n', '\r', '\v', '\f':
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// ok
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default:
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r.UnreadByte()
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return nil
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}
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}
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}
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func skipWhiteSpace(s uintptr) uintptr {
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for {
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switch c := *(*byte)(unsafe.Pointer(s)); c {
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case ' ', '\t', '\n', '\r', '\v', '\f':
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s++
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default:
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return s
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}
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}
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}
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