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 // Sparse block handling code.
10 11 type valueRange struct {
12 value uint16 // header: value:stride
13 lo, hi byte // header: lo:n
14 }
15 16 type sparseBlocks struct {
17 values []valueRange
18 offset []uint16
19 }
20 21 var idnaSparse = sparseBlocks{
22 values: idnaSparseValues[:],
23 offset: idnaSparseOffset[:],
24 }
25 26 // Don't use newIdnaTrie to avoid unconditional linking in of the table.
27 var trie = &idnaTrie{}
28 29 // lookup determines the type of block n and looks up the value for b.
30 // For n < t.cutoff, the block is a simple lookup table. Otherwise, the block
31 // is a list of ranges with an accompanying value. Given a matching range r,
32 // the value for b is by r.value + (b - r.lo) * stride.
33 func (t *sparseBlocks) lookup(n uint32, b byte) uint16 {
34 offset := t.offset[n]
35 header := t.values[offset]
36 lo := offset + 1
37 hi := lo + uint16(header.lo)
38 for lo < hi {
39 m := lo + (hi-lo)/2
40 r := t.values[m]
41 if r.lo <= b && b <= r.hi {
42 return r.value + uint16(b-r.lo)*header.value
43 }
44 if b < r.lo {
45 hi = m
46 } else {
47 lo = m + 1
48 }
49 }
50 return 0
51 }
52