Line data    Source code

       1             : /*
       2             : Copyright 2013 The Perkeep Authors
       3             : 
       4             : Licensed under the Apache License, Version 2.0 (the "License");
       5             : you may not use this file except in compliance with the License.
       6             : You may obtain a copy of the License at
       7             : 
       8             :      http://www.apache.org/licenses/LICENSE-2.0
       9             : 
      10             : Unless required by applicable law or agreed to in writing, software
      11             : distributed under the License is distributed on an "AS IS" BASIS,
      12             : WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      13             : See the License for the specific language governing permissions and
      14             : limitations under the License.
      15             : */
      16             : 
      17             : package testkeys
      18             : 
      19             : import (
      20             :         "strconv"
      21             : 
      22             :         "github.com/cockroachdb/errors"
      23             : )
      24             : 
      25             : // parseUintBytes is like strconv.ParseUint, but using a []byte. Use of this
      26             : // function avoids an allocation when parsing an integer out of a []byte.
      27             : //
      28             : // This function is copied from go4.org/strconv.
      29           2 : func parseUintBytes(s []byte, base int, bitSize int) (n uint64, err error) {
      30           2 :         var cutoff, maxVal uint64
      31           2 : 
      32           2 :         if bitSize == 0 {
      33           0 :                 bitSize = int(strconv.IntSize)
      34           0 :         }
      35             : 
      36           2 :         s0 := s
      37           2 :         switch {
      38           0 :         case len(s) < 1:
      39           0 :                 err = strconv.ErrSyntax
      40           0 :                 goto Error
      41             : 
      42           2 :         case 2 <= base && base <= 36:
      43             :                 // valid base; nothing to do
      44             : 
      45           0 :         case base == 0:
      46           0 :                 // Look for octal, hex prefix.
      47           0 :                 switch {
      48           0 :                 case s[0] == '0' && len(s) > 1 && (s[1] == 'x' || s[1] == 'X'):
      49           0 :                         base = 16
      50           0 :                         s = s[2:]
      51           0 :                         if len(s) < 1 {
      52           0 :                                 err = strconv.ErrSyntax
      53           0 :                                 goto Error
      54             :                         }
      55           0 :                 case s[0] == '0':
      56           0 :                         base = 8
      57           0 :                 default:
      58           0 :                         base = 10
      59             :                 }
      60             : 
      61           0 :         default:
      62           0 :                 err = errors.New("invalid base " + strconv.Itoa(base))
      63           0 :                 goto Error
      64             :         }
      65             : 
      66           2 :         n = 0
      67           2 :         cutoff = cutoff64(base)
      68           2 :         maxVal = 1<<uint(bitSize) - 1
      69           2 : 
      70           2 :         for i := 0; i < len(s); i++ {
      71           2 :                 var v byte
      72           2 :                 d := s[i]
      73           2 :                 switch {
      74           2 :                 case '0' <= d && d <= '9':
      75           2 :                         v = d - '0'
      76           0 :                 case 'a' <= d && d <= 'z':
      77           0 :                         v = d - 'a' + 10
      78           0 :                 case 'A' <= d && d <= 'Z':
      79           0 :                         v = d - 'A' + 10
      80           0 :                 default:
      81           0 :                         n = 0
      82           0 :                         err = strconv.ErrSyntax
      83           0 :                         goto Error
      84             :                 }
      85           2 :                 if int(v) >= base {
      86           0 :                         n = 0
      87           0 :                         err = strconv.ErrSyntax
      88           0 :                         goto Error
      89             :                 }
      90             : 
      91           2 :                 if n >= cutoff {
      92           0 :                         // n*base overflows
      93           0 :                         n = 1<<64 - 1
      94           0 :                         err = strconv.ErrRange
      95           0 :                         goto Error
      96             :                 }
      97           2 :                 n *= uint64(base)
      98           2 : 
      99           2 :                 n1 := n + uint64(v)
     100           2 :                 if n1 < n || n1 > maxVal {
     101           0 :                         // n+v overflows
     102           0 :                         n = 1<<64 - 1
     103           0 :                         err = strconv.ErrRange
     104           0 :                         goto Error
     105             :                 }
     106           2 :                 n = n1
     107             :         }
     108             : 
     109           2 :         return n, nil
     110           2 : 
     111           2 : Error:
     112           0 :         return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err}
     113             : }
     114             : 
     115             : // Return the first number n such that n*base >= 1<<64.
     116           2 : func cutoff64(base int) uint64 {
     117           2 :         if base < 2 {
     118           0 :                 return 0
     119           0 :         }
     120           2 :         return (1<<64-1)/uint64(base) + 1
     121             : }