vendor/golang.org/x/net/idna/trie.go

   1 // Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
   2
   3 // Copyright 2016 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 package idna
   8
   9 // appendMapping appends the mapping for the respective rune. isMapped must be
  10 // true. A mapping is a categorization of a rune as defined in UTS #46.
  11 func (c info) appendMapping(b []byte, s string) []byte {
  12         index := int(c >> indexShift)
  13         if c&xorBit == 0 {
  14                 s := mappings[index:]
  15                 return append(b, s[1:s[0]+1]...)
  16         }
  17         b = append(b, s...)
  18         if c&inlineXOR == inlineXOR {
  19                 // TODO: support and handle two-byte inline masks
  20                 b[len(b)-1] ^= byte(index)
  21         } else {
  22                 for p := len(b) - int(xorData[index]); p < len(b); p++ {
  23                         index++
  24                         b[p] ^= xorData[index]
  25                 }
  26         }
  27         return b
  28 }
  29
  30 // Sparse block handling code.
  31
  32 type valueRange struct {
  33         value  uint16 // header: value:stride
  34         lo, hi byte   // header: lo:n
  35 }
  36
  37 type sparseBlocks struct {
  38         values []valueRange
  39         offset []uint16
  40 }
  41
  42 var idnaSparse = sparseBlocks{
  43         values: idnaSparseValues[:],
  44         offset: idnaSparseOffset[:],
  45 }
  46
  47 // Don't use newIdnaTrie to avoid unconditional linking in of the table.
  48 var trie = &idnaTrie{}
  49
  50 // lookup determines the type of block n and looks up the value for b.
  51 // For n < t.cutoff, the block is a simple lookup table. Otherwise, the block
  52 // is a list of ranges with an accompanying value. Given a matching range r,
  53 // the value for b is by r.value + (b - r.lo) * stride.
  54 func (t *sparseBlocks) lookup(n uint32, b byte) uint16 {
  55         offset := t.offset[n]
  56         header := t.values[offset]
  57         lo := offset + 1
  58         hi := lo + uint16(header.lo)
  59         for lo < hi {
  60                 m := lo + (hi-lo)/2
  61                 r := t.values[m]
  62                 if r.lo <= b && b <= r.hi {
  63                         return r.value + uint16(b-r.lo)*header.value
  64                 }
  65                 if b < r.lo {
  66                         hi = m
  67                 } else {
  68                         lo = m + 1
  69                 }
  70         }
  71         return 0
  72 }