libgo/go/golang_org/x/net/idna/trieval.go

   1 // Code generated by running "go run gen.go -core" in golang.org/x/text. DO NOT EDIT.
   2
   3 // Code generated by running "go generate" in golang_org/x/text. DO NOT EDIT.
   4
   5 package idna
   6
   7 // This file contains definitions for interpreting the trie value of the idna
   8 // trie generated by "go run gen*.go". It is shared by both the generator
   9 // program and the resultant package. Sharing is achieved by the generator
  10 // copying gen_trieval.go to trieval.go and changing what's above this comment.
  11
  12 // info holds information from the IDNA mapping table for a single rune. It is
  13 // the value returned by a trie lookup. In most cases, all information fits in
  14 // a 16-bit value. For mappings, this value may contain an index into a slice
  15 // with the mapped string. Such mappings can consist of the actual mapped value
  16 // or an XOR pattern to be applied to the bytes of the UTF8 encoding of the
  17 // input rune. This technique is used by the cases packages and reduces the
  18 // table size significantly.
  19 //
  20 // The per-rune values have the following format:
  21 //
  22 //   if mapped {
  23 //     if inlinedXOR {
  24 //       15..13 inline XOR marker
  25 //       12..11 unused
  26 //       10..3  inline XOR mask
  27 //     } else {
  28 //       15..3  index into xor or mapping table
  29 //     }
  30 //   } else {
  31 //       15..13 unused
  32 //           12 modifier (including virama)
  33 //           11 virama modifier
  34 //       10..8  joining type
  35 //        7..3  category type
  36 //   }
  37 //      2  use xor pattern
  38 //   1..0  mapped category
  39 //
  40 // See the definitions below for a more detailed description of the various
  41 // bits.
  42 type info uint16
  43
  44 const (
  45         catSmallMask = 0x3
  46         catBigMask   = 0xF8
  47         indexShift   = 3
  48         xorBit       = 0x4    // interpret the index as an xor pattern
  49         inlineXOR    = 0xE000 // These bits are set if the XOR pattern is inlined.
  50
  51         joinShift = 8
  52         joinMask  = 0x07
  53
  54         viramaModifier = 0x0800
  55         modifier       = 0x1000
  56 )
  57
  58 // A category corresponds to a category defined in the IDNA mapping table.
  59 type category uint16
  60
  61 const (
  62         unknown              category = 0 // not defined currently in unicode.
  63         mapped               category = 1
  64         disallowedSTD3Mapped category = 2
  65         deviation            category = 3
  66 )
  67
  68 const (
  69         valid               category = 0x08
  70         validNV8            category = 0x18
  71         validXV8            category = 0x28
  72         disallowed          category = 0x40
  73         disallowedSTD3Valid category = 0x80
  74         ignored             category = 0xC0
  75 )
  76
  77 // join types and additional rune information
  78 const (
  79         joiningL = (iota + 1)
  80         joiningD
  81         joiningT
  82         joiningR
  83
  84         //the following types are derived during processing
  85         joinZWJ
  86         joinZWNJ
  87         joinVirama
  88         numJoinTypes
  89 )
  90
  91 func (c info) isMapped() bool {
  92         return c&0x3 != 0
  93 }
  94
  95 func (c info) category() category {
  96         small := c & catSmallMask
  97         if small != 0 {
  98                 return category(small)
  99         }
 100         return category(c & catBigMask)
 101 }
 102
 103 func (c info) joinType() info {
 104         if c.isMapped() {
 105                 return 0
 106         }
 107         return (c >> joinShift) & joinMask
 108 }
 109
 110 func (c info) isModifier() bool {
 111         return c&(modifier|catSmallMask) == modifier
 112 }
 113
 114 func (c info) isViramaModifier() bool {
 115         return c&(viramaModifier|catSmallMask) == viramaModifier
 116 }