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      1 // Code generated by running "go generate" 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..14 unused
     32 //       13     mayNeedNorm
     33 //       12..11 attributes
     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 	// Attributes
     55 	attributesMask = 0x1800
     56 	viramaModifier = 0x1800
     57 	modifier       = 0x1000
     58 	rtl            = 0x0800
     59 
     60 	mayNeedNorm = 0x2000
     61 )
     62 
     63 // A category corresponds to a category defined in the IDNA mapping table.
     64 type category uint16
     65 
     66 const (
     67 	unknown              category = 0 // not currently defined in unicode.
     68 	mapped               category = 1
     69 	disallowedSTD3Mapped category = 2
     70 	deviation            category = 3
     71 )
     72 
     73 const (
     74 	valid               category = 0x08
     75 	validNV8            category = 0x18
     76 	validXV8            category = 0x28
     77 	disallowed          category = 0x40
     78 	disallowedSTD3Valid category = 0x80
     79 	ignored             category = 0xC0
     80 )
     81 
     82 // join types and additional rune information
     83 const (
     84 	joiningL = (iota + 1)
     85 	joiningD
     86 	joiningT
     87 	joiningR
     88 
     89 	//the following types are derived during processing
     90 	joinZWJ
     91 	joinZWNJ
     92 	joinVirama
     93 	numJoinTypes
     94 )
     95 
     96 func (c info) isMapped() bool {
     97 	return c&0x3 != 0
     98 }
     99 
    100 func (c info) category() category {
    101 	small := c & catSmallMask
    102 	if small != 0 {
    103 		return category(small)
    104 	}
    105 	return category(c & catBigMask)
    106 }
    107 
    108 func (c info) joinType() info {
    109 	if c.isMapped() {
    110 		return 0
    111 	}
    112 	return (c >> joinShift) & joinMask
    113 }
    114 
    115 func (c info) isModifier() bool {
    116 	return c&(modifier|catSmallMask) == modifier
    117 }
    118 
    119 func (c info) isViramaModifier() bool {
    120 	return c&(attributesMask|catSmallMask) == viramaModifier
    121 }
    122