libgo/go/net/parse.go

   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 )
  14
  15 type file struct {
  16         file  *os.File
  17         data  []byte
  18         atEOF bool
  19 }
  20
  21 func (f *file) close() { f.file.Close() }
  22
  23 func (f *file) getLineFromData() (s string, ok bool) {
  24         data := f.data
  25         i := 0
  26         for i = 0; i < len(data); i++ {
  27                 if data[i] == '\n' {
  28                         s = string(data[0:i])
  29                         ok = true
  30                         // move data
  31                         i++
  32                         n := len(data) - i
  33                         copy(data[0:], data[i:])
  34                         f.data = data[0:n]
  35                         return
  36                 }
  37         }
  38         if f.atEOF && len(f.data) > 0 {
  39                 // EOF, return all we have
  40                 s = string(data)
  41                 f.data = f.data[0:0]
  42                 ok = true
  43         }
  44         return
  45 }
  46
  47 func (f *file) readLine() (s string, ok bool) {
  48         if s, ok = f.getLineFromData(); ok {
  49                 return
  50         }
  51         if len(f.data) < cap(f.data) {
  52                 ln := len(f.data)
  53                 n, err := io.ReadFull(f.file, f.data[ln:cap(f.data)])
  54                 if n >= 0 {
  55                         f.data = f.data[0 : ln+n]
  56                 }
  57                 if err == io.EOF {
  58                         f.atEOF = true
  59                 }
  60         }
  61         s, ok = f.getLineFromData()
  62         return
  63 }
  64
  65 func open(name string) (*file, error) {
  66         fd, err := os.Open(name)
  67         if err != nil {
  68                 return nil, err
  69         }
  70         return &file{fd, make([]byte, os.Getpagesize())[0:0], false}, nil
  71 }
  72
  73 func byteIndex(s string, c byte) int {
  74         for i := 0; i < len(s); i++ {
  75                 if s[i] == c {
  76                         return i
  77                 }
  78         }
  79         return -1
  80 }
  81
  82 // Count occurrences in s of any bytes in t.
  83 func countAnyByte(s string, t string) int {
  84         n := 0
  85         for i := 0; i < len(s); i++ {
  86                 if byteIndex(t, s[i]) >= 0 {
  87                         n++
  88                 }
  89         }
  90         return n
  91 }
  92
  93 // Split s at any bytes in t.
  94 func splitAtBytes(s string, t string) []string {
  95         a := make([]string, 1+countAnyByte(s, t))
  96         n := 0
  97         last := 0
  98         for i := 0; i < len(s); i++ {
  99                 if byteIndex(t, s[i]) >= 0 {
 100                         if last < i {
 101                                 a[n] = string(s[last:i])
 102                                 n++
 103                         }
 104                         last = i + 1
 105                 }
 106         }
 107         if last < len(s) {
 108                 a[n] = string(s[last:])
 109                 n++
 110         }
 111         return a[0:n]
 112 }
 113
 114 func getFields(s string) []string { return splitAtBytes(s, " \r\t\n") }
 115
 116 // Bigger than we need, not too big to worry about overflow
 117 const big = 0xFFFFFF
 118
 119 // Decimal to integer starting at &s[i0].
 120 // Returns number, new offset, success.
 121 func dtoi(s string, i0 int) (n int, i int, ok bool) {
 122         n = 0
 123         for i = i0; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
 124                 n = n*10 + int(s[i]-'0')
 125                 if n >= big {
 126                         return 0, i, false
 127                 }
 128         }
 129         if i == i0 {
 130                 return 0, i, false
 131         }
 132         return n, i, true
 133 }
 134
 135 // Hexadecimal to integer starting at &s[i0].
 136 // Returns number, new offset, success.
 137 func xtoi(s string, i0 int) (n int, i int, ok bool) {
 138         n = 0
 139         for i = i0; i < len(s); i++ {
 140                 if '0' <= s[i] && s[i] <= '9' {
 141                         n *= 16
 142                         n += int(s[i] - '0')
 143                 } else if 'a' <= s[i] && s[i] <= 'f' {
 144                         n *= 16
 145                         n += int(s[i]-'a') + 10
 146                 } else if 'A' <= s[i] && s[i] <= 'F' {
 147                         n *= 16
 148                         n += int(s[i]-'A') + 10
 149                 } else {
 150                         break
 151                 }
 152                 if n >= big {
 153                         return 0, i, false
 154                 }
 155         }
 156         if i == i0 {
 157                 return 0, i, false
 158         }
 159         return n, i, true
 160 }
 161
 162 // xtoi2 converts the next two hex digits of s into a byte.
 163 // If s is longer than 2 bytes then the third byte must be e.
 164 // If the first two bytes of s are not hex digits or the third byte
 165 // does not match e, false is returned.
 166 func xtoi2(s string, e byte) (byte, bool) {
 167         if len(s) > 2 && s[2] != e {
 168                 return 0, false
 169         }
 170         n, ei, ok := xtoi(s[:2], 0)
 171         return byte(n), ok && ei == 2
 172 }
 173
 174 // Integer to decimal.
 175 func itoa(i int) string {
 176         var buf [30]byte
 177         n := len(buf)
 178         neg := false
 179         if i < 0 {
 180                 i = -i
 181                 neg = true
 182         }
 183         ui := uint(i)
 184         for ui > 0 || n == len(buf) {
 185                 n--
 186                 buf[n] = byte('0' + ui%10)
 187                 ui /= 10
 188         }
 189         if neg {
 190                 n--
 191                 buf[n] = '-'
 192         }
 193         return string(buf[n:])
 194 }
 195
 196 // Convert i to decimal string.
 197 func itod(i uint) string {
 198         if i == 0 {
 199                 return "0"
 200         }
 201
 202         // Assemble decimal in reverse order.
 203         var b [32]byte
 204         bp := len(b)
 205         for ; i > 0; i /= 10 {
 206                 bp--
 207                 b[bp] = byte(i%10) + '0'
 208         }
 209
 210         return string(b[bp:])
 211 }
 212
 213 // Convert i to hexadecimal string.
 214 func itox(i uint, min int) string {
 215         // Assemble hexadecimal in reverse order.
 216         var b [32]byte
 217         bp := len(b)
 218         for ; i > 0 || min > 0; i /= 16 {
 219                 bp--
 220                 b[bp] = "0123456789abcdef"[byte(i%16)]
 221                 min--
 222         }
 223
 224         return string(b[bp:])
 225 }
 226
 227 // Number of occurrences of b in s.
 228 func count(s string, b byte) int {
 229         n := 0
 230         for i := 0; i < len(s); i++ {
 231                 if s[i] == b {
 232                         n++
 233                 }
 234         }
 235         return n
 236 }
 237
 238 // Index of rightmost occurrence of b in s.
 239 func last(s string, b byte) int {
 240         i := len(s)
 241         for i--; i >= 0; i-- {
 242                 if s[i] == b {
 243                         break
 244                 }
 245         }
 246         return i
 247 }