trie.go (1288B)
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 }