source: code/trunk/vendor/golang.org/x/net/idna/trie.go@ 145

// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.

// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package idna

// appendMapping appends the mapping for the respective rune. isMapped must be
// true. A mapping is a categorization of a rune as defined in UTS #46.
func (c info) appendMapping(b []byte, s string) []byte {
        index := int(c >> indexShift)
        if c&xorBit == 0 {
                s := mappings[index:]
                return append(b, s[1:s[0]+1]...)
        }
        b = append(b, s...)
        if c&inlineXOR == inlineXOR {
                // TODO: support and handle two-byte inline masks
                b[len(b)-1] ^= byte(index)
        } else {
                for p := len(b) - int(xorData[index]); p < len(b); p++ {
                        index++
                        b[p] ^= xorData[index]
                }
        }
        return b
}

// Sparse block handling code.

type valueRange struct {
        value  uint16 // header: value:stride
        lo, hi byte   // header: lo:n
}

type sparseBlocks struct {
        values []valueRange
        offset []uint16
}

var idnaSparse = sparseBlocks{
        values: idnaSparseValues[:],
        offset: idnaSparseOffset[:],
}

// Don't use newIdnaTrie to avoid unconditional linking in of the table.
var trie = &idnaTrie{}

// lookup determines the type of block n and looks up the value for b.
// For n < t.cutoff, the block is a simple lookup table. Otherwise, the block
// is a list of ranges with an accompanying value. Given a matching range r,
// the value for b is by r.value + (b - r.lo) * stride.
func (t *sparseBlocks) lookup(n uint32, b byte) uint16 {
        offset := t.offset[n]
        header := t.values[offset]
        lo := offset + 1
        hi := lo + uint16(header.lo)
        for lo < hi {
                m := lo + (hi-lo)/2
                r := t.values[m]
                if r.lo <= b && b <= r.hi {
                        return r.value + uint16(b-r.lo)*header.value
                }
                if b < r.lo {
                        hi = m
                } else {
                        lo = m + 1
                }
        }
        return 0
}