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  	"io"
    12  	"os"
    13  	"time"
    14  	_ "unsafe" // For go:linkname
    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  // byteIndex is strings.IndexByte. It returns the index of the
    84  // first instance of c in s, or -1 if c is not present in s.
    85  // strings.IndexByte is implemented in  runtime/asm_$GOARCH.s
    86  //go:linkname byteIndex strings.IndexByte
    87  func byteIndex(s string, c byte) int
    88  
    89  // Count occurrences in s of any bytes in t.
    90  func countAnyByte(s string, t string) int {
    91  	n := 0
    92  	for i := 0; i < len(s); i++ {
    93  		if byteIndex(t, s[i]) >= 0 {
    94  			n++
    95  		}
    96  	}
    97  	return n
    98  }
    99  
   100  // Split s at any bytes in t.
   101  func splitAtBytes(s string, t string) []string {
   102  	a := make([]string, 1+countAnyByte(s, t))
   103  	n := 0
   104  	last := 0
   105  	for i := 0; i < len(s); i++ {
   106  		if byteIndex(t, s[i]) >= 0 {
   107  			if last < i {
   108  				a[n] = s[last:i]
   109  				n++
   110  			}
   111  			last = i + 1
   112  		}
   113  	}
   114  	if last < len(s) {
   115  		a[n] = s[last:]
   116  		n++
   117  	}
   118  	return a[0:n]
   119  }
   120  
   121  func getFields(s string) []string { return splitAtBytes(s, " \r\t\n") }
   122  
   123  // Bigger than we need, not too big to worry about overflow
   124  const big = 0xFFFFFF
   125  
   126  // Decimal to integer.
   127  // Returns number, characters consumed, success.
   128  func dtoi(s string) (n int, i int, ok bool) {
   129  	n = 0
   130  	for i = 0; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
   131  		n = n*10 + int(s[i]-'0')
   132  		if n >= big {
   133  			return big, i, false
   134  		}
   135  	}
   136  	if i == 0 {
   137  		return 0, 0, false
   138  	}
   139  	return n, i, true
   140  }
   141  
   142  // Hexadecimal to integer.
   143  // Returns number, characters consumed, success.
   144  func xtoi(s string) (n int, i int, ok bool) {
   145  	n = 0
   146  	for i = 0; i < len(s); i++ {
   147  		if '0' <= s[i] && s[i] <= '9' {
   148  			n *= 16
   149  			n += int(s[i] - '0')
   150  		} else if 'a' <= s[i] && s[i] <= 'f' {
   151  			n *= 16
   152  			n += int(s[i]-'a') + 10
   153  		} else if 'A' <= s[i] && s[i] <= 'F' {
   154  			n *= 16
   155  			n += int(s[i]-'A') + 10
   156  		} else {
   157  			break
   158  		}
   159  		if n >= big {
   160  			return 0, i, false
   161  		}
   162  	}
   163  	if i == 0 {
   164  		return 0, i, false
   165  	}
   166  	return n, i, true
   167  }
   168  
   169  // xtoi2 converts the next two hex digits of s into a byte.
   170  // If s is longer than 2 bytes then the third byte must be e.
   171  // If the first two bytes of s are not hex digits or the third byte
   172  // does not match e, false is returned.
   173  func xtoi2(s string, e byte) (byte, bool) {
   174  	if len(s) > 2 && s[2] != e {
   175  		return 0, false
   176  	}
   177  	n, ei, ok := xtoi(s[:2])
   178  	return byte(n), ok && ei == 2
   179  }
   180  
   181  // Convert integer to decimal string.
   182  func itoa(val int) string {
   183  	if val < 0 {
   184  		return "-" + uitoa(uint(-val))
   185  	}
   186  	return uitoa(uint(val))
   187  }
   188  
   189  // Convert unsigned integer to decimal string.
   190  func uitoa(val uint) string {
   191  	if val == 0 { // avoid string allocation
   192  		return "0"
   193  	}
   194  	var buf [20]byte // big enough for 64bit value base 10
   195  	i := len(buf) - 1
   196  	for val >= 10 {
   197  		q := val / 10
   198  		buf[i] = byte('0' + val - q*10)
   199  		i--
   200  		val = q
   201  	}
   202  	// val < 10
   203  	buf[i] = byte('0' + val)
   204  	return string(buf[i:])
   205  }
   206  
   207  // Convert i to a hexadecimal string. Leading zeros are not printed.
   208  func appendHex(dst []byte, i uint32) []byte {
   209  	if i == 0 {
   210  		return append(dst, '0')
   211  	}
   212  	for j := 7; j >= 0; j-- {
   213  		v := i >> uint(j*4)
   214  		if v > 0 {
   215  			dst = append(dst, hexDigit[v&0xf])
   216  		}
   217  	}
   218  	return dst
   219  }
   220  
   221  // Number of occurrences of b in s.
   222  func count(s string, b byte) int {
   223  	n := 0
   224  	for i := 0; i < len(s); i++ {
   225  		if s[i] == b {
   226  			n++
   227  		}
   228  	}
   229  	return n
   230  }
   231  
   232  // Index of rightmost occurrence of b in s.
   233  func last(s string, b byte) int {
   234  	i := len(s)
   235  	for i--; i >= 0; i-- {
   236  		if s[i] == b {
   237  			break
   238  		}
   239  	}
   240  	return i
   241  }
   242  
   243  // lowerASCIIBytes makes x ASCII lowercase in-place.
   244  func lowerASCIIBytes(x []byte) {
   245  	for i, b := range x {
   246  		if 'A' <= b && b <= 'Z' {
   247  			x[i] += 'a' - 'A'
   248  		}
   249  	}
   250  }
   251  
   252  // lowerASCII returns the ASCII lowercase version of b.
   253  func lowerASCII(b byte) byte {
   254  	if 'A' <= b && b <= 'Z' {
   255  		return b + ('a' - 'A')
   256  	}
   257  	return b
   258  }
   259  
   260  // trimSpace returns x without any leading or trailing ASCII whitespace.
   261  func trimSpace(x []byte) []byte {
   262  	for len(x) > 0 && isSpace(x[0]) {
   263  		x = x[1:]
   264  	}
   265  	for len(x) > 0 && isSpace(x[len(x)-1]) {
   266  		x = x[:len(x)-1]
   267  	}
   268  	return x
   269  }
   270  
   271  // isSpace reports whether b is an ASCII space character.
   272  func isSpace(b byte) bool {
   273  	return b == ' ' || b == '\t' || b == '\n' || b == '\r'
   274  }
   275  
   276  // removeComment returns line, removing any '#' byte and any following
   277  // bytes.
   278  func removeComment(line []byte) []byte {
   279  	if i := bytesIndexByte(line, '#'); i != -1 {
   280  		return line[:i]
   281  	}
   282  	return line
   283  }
   284  
   285  // foreachLine runs fn on each line of x.
   286  // Each line (except for possibly the last) ends in '\n'.
   287  // It returns the first non-nil error returned by fn.
   288  func foreachLine(x []byte, fn func(line []byte) error) error {
   289  	for len(x) > 0 {
   290  		nl := bytesIndexByte(x, '\n')
   291  		if nl == -1 {
   292  			return fn(x)
   293  		}
   294  		line := x[:nl+1]
   295  		x = x[nl+1:]
   296  		if err := fn(line); err != nil {
   297  			return err
   298  		}
   299  	}
   300  	return nil
   301  }
   302  
   303  // foreachField runs fn on each non-empty run of non-space bytes in x.
   304  // It returns the first non-nil error returned by fn.
   305  func foreachField(x []byte, fn func(field []byte) error) error {
   306  	x = trimSpace(x)
   307  	for len(x) > 0 {
   308  		sp := bytesIndexByte(x, ' ')
   309  		if sp == -1 {
   310  			return fn(x)
   311  		}
   312  		if field := trimSpace(x[:sp]); len(field) > 0 {
   313  			if err := fn(field); err != nil {
   314  				return err
   315  			}
   316  		}
   317  		x = trimSpace(x[sp+1:])
   318  	}
   319  	return nil
   320  }
   321  
   322  // bytesIndexByte is bytes.IndexByte. It returns the index of the
   323  // first instance of c in s, or -1 if c is not present in s.
   324  // bytes.IndexByte is implemented in  runtime/asm_$GOARCH.s
   325  //go:linkname bytesIndexByte bytes.IndexByte
   326  func bytesIndexByte(s []byte, c byte) int
   327  
   328  // stringsHasSuffix is strings.HasSuffix. It reports whether s ends in
   329  // suffix.
   330  func stringsHasSuffix(s, suffix string) bool {
   331  	return len(s) >= len(suffix) && s[len(s)-len(suffix):] == suffix
   332  }
   333  
   334  // stringsHasSuffixFold reports whether s ends in suffix,
   335  // ASCII-case-insensitively.
   336  func stringsHasSuffixFold(s, suffix string) bool {
   337  	return len(s) >= len(suffix) && stringsEqualFold(s[len(s)-len(suffix):], suffix)
   338  }
   339  
   340  // stringsHasPrefix is strings.HasPrefix. It reports whether s begins with prefix.
   341  func stringsHasPrefix(s, prefix string) bool {
   342  	return len(s) >= len(prefix) && s[:len(prefix)] == prefix
   343  }
   344  
   345  // stringsEqualFold is strings.EqualFold, ASCII only. It reports whether s and t
   346  // are equal, ASCII-case-insensitively.
   347  func stringsEqualFold(s, t string) bool {
   348  	if len(s) != len(t) {
   349  		return false
   350  	}
   351  	for i := 0; i < len(s); i++ {
   352  		if lowerASCII(s[i]) != lowerASCII(t[i]) {
   353  			return false
   354  		}
   355  	}
   356  	return true
   357  }
   358  
   359  func readFull(r io.Reader) (all []byte, err error) {
   360  	buf := make([]byte, 1024)
   361  	for {
   362  		n, err := r.Read(buf)
   363  		all = append(all, buf[:n]...)
   364  		if err == io.EOF {
   365  			return all, nil
   366  		}
   367  		if err != nil {
   368  			return nil, err
   369  		}
   370  	}
   371  }
   372  
   373  // goDebugString returns the value of the named GODEBUG key.
   374  // GODEBUG is of the form "key=val,key2=val2"
   375  func goDebugString(key string) string {
   376  	s := os.Getenv("GODEBUG")
   377  	for i := 0; i < len(s)-len(key)-1; i++ {
   378  		if i > 0 && s[i-1] != ',' {
   379  			continue
   380  		}
   381  		afterKey := s[i+len(key):]
   382  		if afterKey[0] != '=' || s[i:i+len(key)] != key {
   383  			continue
   384  		}
   385  		val := afterKey[1:]
   386  		for i, b := range val {
   387  			if b == ',' {
   388  				return val[:i]
   389  			}
   390  		}
   391  		return val
   392  	}
   393  	return ""
   394  }
   395
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