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Source file src/net/parse.go

Documentation: net

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Simple file i/o and string manipulation, to avoid
     6  // depending on strconv and bufio and strings.
     7  
     8  package net
     9  
    10  import (
    11  	"internal/bytealg"
    12  	"io"
    13  	"os"
    14  	"time"
    15  )
    16  
    17  type file struct {
    18  	file  *os.File
    19  	data  []byte
    20  	atEOF bool
    21  }
    22  
    23  func (f *file) close() { f.file.Close() }
    24  
    25  func (f *file) getLineFromData() (s string, ok bool) {
    26  	data := f.data
    27  	i := 0
    28  	for i = 0; i < len(data); i++ {
    29  		if data[i] == '\n' {
    30  			s = string(data[0:i])
    31  			ok = true
    32  			// move data
    33  			i++
    34  			n := len(data) - i
    35  			copy(data[0:], data[i:])
    36  			f.data = data[0:n]
    37  			return
    38  		}
    39  	}
    40  	if f.atEOF && len(f.data) > 0 {
    41  		// EOF, return all we have
    42  		s = string(data)
    43  		f.data = f.data[0:0]
    44  		ok = true
    45  	}
    46  	return
    47  }
    48  
    49  func (f *file) readLine() (s string, ok bool) {
    50  	if s, ok = f.getLineFromData(); ok {
    51  		return
    52  	}
    53  	if len(f.data) < cap(f.data) {
    54  		ln := len(f.data)
    55  		n, err := io.ReadFull(f.file, f.data[ln:cap(f.data)])
    56  		if n >= 0 {
    57  			f.data = f.data[0 : ln+n]
    58  		}
    59  		if err == io.EOF || err == io.ErrUnexpectedEOF {
    60  			f.atEOF = true
    61  		}
    62  	}
    63  	s, ok = f.getLineFromData()
    64  	return
    65  }
    66  
    67  func open(name string) (*file, error) {
    68  	fd, err := os.Open(name)
    69  	if err != nil {
    70  		return nil, err
    71  	}
    72  	return &file{fd, make([]byte, 0, 64*1024), false}, nil
    73  }
    74  
    75  func stat(name string) (mtime time.Time, size int64, err error) {
    76  	st, err := os.Stat(name)
    77  	if err != nil {
    78  		return time.Time{}, 0, err
    79  	}
    80  	return st.ModTime(), st.Size(), nil
    81  }
    82  
    83  // Count occurrences in s of any bytes in t.
    84  func countAnyByte(s string, t string) int {
    85  	n := 0
    86  	for i := 0; i < len(s); i++ {
    87  		if bytealg.IndexByteString(t, s[i]) >= 0 {
    88  			n++
    89  		}
    90  	}
    91  	return n
    92  }
    93  
    94  // Split s at any bytes in t.
    95  func splitAtBytes(s string, t string) []string {
    96  	a := make([]string, 1+countAnyByte(s, t))
    97  	n := 0
    98  	last := 0
    99  	for i := 0; i < len(s); i++ {
   100  		if bytealg.IndexByteString(t, s[i]) >= 0 {
   101  			if last < i {
   102  				a[n] = s[last:i]
   103  				n++
   104  			}
   105  			last = i + 1
   106  		}
   107  	}
   108  	if last < len(s) {
   109  		a[n] = s[last:]
   110  		n++
   111  	}
   112  	return a[0:n]
   113  }
   114  
   115  func getFields(s string) []string { return splitAtBytes(s, " \r\t\n") }
   116  
   117  // Bigger than we need, not too big to worry about overflow
   118  const big = 0xFFFFFF
   119  
   120  // Decimal to integer.
   121  // Returns number, characters consumed, success.
   122  func dtoi(s string) (n int, i int, ok bool) {
   123  	n = 0
   124  	for i = 0; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
   125  		n = n*10 + int(s[i]-'0')
   126  		if n >= big {
   127  			return big, i, false
   128  		}
   129  	}
   130  	if i == 0 {
   131  		return 0, 0, false
   132  	}
   133  	return n, i, true
   134  }
   135  
   136  // Hexadecimal to integer.
   137  // Returns number, characters consumed, success.
   138  func xtoi(s string) (n int, i int, ok bool) {
   139  	n = 0
   140  	for i = 0; i < len(s); i++ {
   141  		if '0' <= s[i] && s[i] <= '9' {
   142  			n *= 16
   143  			n += int(s[i] - '0')
   144  		} else if 'a' <= s[i] && s[i] <= 'f' {
   145  			n *= 16
   146  			n += int(s[i]-'a') + 10
   147  		} else if 'A' <= s[i] && s[i] <= 'F' {
   148  			n *= 16
   149  			n += int(s[i]-'A') + 10
   150  		} else {
   151  			break
   152  		}
   153  		if n >= big {
   154  			return 0, i, false
   155  		}
   156  	}
   157  	if i == 0 {
   158  		return 0, i, false
   159  	}
   160  	return n, i, true
   161  }
   162  
   163  // xtoi2 converts the next two hex digits of s into a byte.
   164  // If s is longer than 2 bytes then the third byte must be e.
   165  // If the first two bytes of s are not hex digits or the third byte
   166  // does not match e, false is returned.
   167  func xtoi2(s string, e byte) (byte, bool) {
   168  	if len(s) > 2 && s[2] != e {
   169  		return 0, false
   170  	}
   171  	n, ei, ok := xtoi(s[:2])
   172  	return byte(n), ok && ei == 2
   173  }
   174  
   175  // Convert integer to decimal string.
   176  func itoa(val int) string {
   177  	if val < 0 {
   178  		return "-" + uitoa(uint(-val))
   179  	}
   180  	return uitoa(uint(val))
   181  }
   182  
   183  // Convert unsigned integer to decimal string.
   184  func uitoa(val uint) string {
   185  	if val == 0 { // avoid string allocation
   186  		return "0"
   187  	}
   188  	var buf [20]byte // big enough for 64bit value base 10
   189  	i := len(buf) - 1
   190  	for val >= 10 {
   191  		q := val / 10
   192  		buf[i] = byte('0' + val - q*10)
   193  		i--
   194  		val = q
   195  	}
   196  	// val < 10
   197  	buf[i] = byte('0' + val)
   198  	return string(buf[i:])
   199  }
   200  
   201  // Convert i to a hexadecimal string. Leading zeros are not printed.
   202  func appendHex(dst []byte, i uint32) []byte {
   203  	if i == 0 {
   204  		return append(dst, '0')
   205  	}
   206  	for j := 7; j >= 0; j-- {
   207  		v := i >> uint(j*4)
   208  		if v > 0 {
   209  			dst = append(dst, hexDigit[v&0xf])
   210  		}
   211  	}
   212  	return dst
   213  }
   214  
   215  // Number of occurrences of b in s.
   216  func count(s string, b byte) int {
   217  	n := 0
   218  	for i := 0; i < len(s); i++ {
   219  		if s[i] == b {
   220  			n++
   221  		}
   222  	}
   223  	return n
   224  }
   225  
   226  // Index of rightmost occurrence of b in s.
   227  func last(s string, b byte) int {
   228  	i := len(s)
   229  	for i--; i >= 0; i-- {
   230  		if s[i] == b {
   231  			break
   232  		}
   233  	}
   234  	return i
   235  }
   236  
   237  // lowerASCIIBytes makes x ASCII lowercase in-place.
   238  func lowerASCIIBytes(x []byte) {
   239  	for i, b := range x {
   240  		if 'A' <= b && b <= 'Z' {
   241  			x[i] += 'a' - 'A'
   242  		}
   243  	}
   244  }
   245  
   246  // lowerASCII returns the ASCII lowercase version of b.
   247  func lowerASCII(b byte) byte {
   248  	if 'A' <= b && b <= 'Z' {
   249  		return b + ('a' - 'A')
   250  	}
   251  	return b
   252  }
   253  
   254  // trimSpace returns x without any leading or trailing ASCII whitespace.
   255  func trimSpace(x []byte) []byte {
   256  	for len(x) > 0 && isSpace(x[0]) {
   257  		x = x[1:]
   258  	}
   259  	for len(x) > 0 && isSpace(x[len(x)-1]) {
   260  		x = x[:len(x)-1]
   261  	}
   262  	return x
   263  }
   264  
   265  // isSpace reports whether b is an ASCII space character.
   266  func isSpace(b byte) bool {
   267  	return b == ' ' || b == '\t' || b == '\n' || b == '\r'
   268  }
   269  
   270  // removeComment returns line, removing any '#' byte and any following
   271  // bytes.
   272  func removeComment(line []byte) []byte {
   273  	if i := bytealg.IndexByte(line, '#'); i != -1 {
   274  		return line[:i]
   275  	}
   276  	return line
   277  }
   278  
   279  // foreachLine runs fn on each line of x.
   280  // Each line (except for possibly the last) ends in '\n'.
   281  // It returns the first non-nil error returned by fn.
   282  func foreachLine(x []byte, fn func(line []byte) error) error {
   283  	for len(x) > 0 {
   284  		nl := bytealg.IndexByte(x, '\n')
   285  		if nl == -1 {
   286  			return fn(x)
   287  		}
   288  		line := x[:nl+1]
   289  		x = x[nl+1:]
   290  		if err := fn(line); err != nil {
   291  			return err
   292  		}
   293  	}
   294  	return nil
   295  }
   296  
   297  // foreachField runs fn on each non-empty run of non-space bytes in x.
   298  // It returns the first non-nil error returned by fn.
   299  func foreachField(x []byte, fn func(field []byte) error) error {
   300  	x = trimSpace(x)
   301  	for len(x) > 0 {
   302  		sp := bytealg.IndexByte(x, ' ')
   303  		if sp == -1 {
   304  			return fn(x)
   305  		}
   306  		if field := trimSpace(x[:sp]); len(field) > 0 {
   307  			if err := fn(field); err != nil {
   308  				return err
   309  			}
   310  		}
   311  		x = trimSpace(x[sp+1:])
   312  	}
   313  	return nil
   314  }
   315  
   316  // stringsHasSuffix is strings.HasSuffix. It reports whether s ends in
   317  // suffix.
   318  func stringsHasSuffix(s, suffix string) bool {
   319  	return len(s) >= len(suffix) && s[len(s)-len(suffix):] == suffix
   320  }
   321  
   322  // stringsHasSuffixFold reports whether s ends in suffix,
   323  // ASCII-case-insensitively.
   324  func stringsHasSuffixFold(s, suffix string) bool {
   325  	return len(s) >= len(suffix) && stringsEqualFold(s[len(s)-len(suffix):], suffix)
   326  }
   327  
   328  // stringsHasPrefix is strings.HasPrefix. It reports whether s begins with prefix.
   329  func stringsHasPrefix(s, prefix string) bool {
   330  	return len(s) >= len(prefix) && s[:len(prefix)] == prefix
   331  }
   332  
   333  // stringsEqualFold is strings.EqualFold, ASCII only. It reports whether s and t
   334  // are equal, ASCII-case-insensitively.
   335  func stringsEqualFold(s, t string) bool {
   336  	if len(s) != len(t) {
   337  		return false
   338  	}
   339  	for i := 0; i < len(s); i++ {
   340  		if lowerASCII(s[i]) != lowerASCII(t[i]) {
   341  			return false
   342  		}
   343  	}
   344  	return true
   345  }
   346  
   347  func readFull(r io.Reader) (all []byte, err error) {
   348  	buf := make([]byte, 1024)
   349  	for {
   350  		n, err := r.Read(buf)
   351  		all = append(all, buf[:n]...)
   352  		if err == io.EOF {
   353  			return all, nil
   354  		}
   355  		if err != nil {
   356  			return nil, err
   357  		}
   358  	}
   359  }
   360  
   361  // goDebugString returns the value of the named GODEBUG key.
   362  // GODEBUG is of the form "key=val,key2=val2"
   363  func goDebugString(key string) string {
   364  	s := os.Getenv("GODEBUG")
   365  	for i := 0; i < len(s)-len(key)-1; i++ {
   366  		if i > 0 && s[i-1] != ',' {
   367  			continue
   368  		}
   369  		afterKey := s[i+len(key):]
   370  		if afterKey[0] != '=' || s[i:i+len(key)] != key {
   371  			continue
   372  		}
   373  		val := afterKey[1:]
   374  		for i, b := range val {
   375  			if b == ',' {
   376  				return val[:i]
   377  			}
   378  		}
   379  		return val
   380  	}
   381  	return ""
   382  }
   383  

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