1// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT. 2 3package cases 4 5// This file contains definitions for interpreting the trie value of the case 6// trie generated by "go run gen*.go". It is shared by both the generator 7// program and the resultant package. Sharing is achieved by the generator 8// copying gen_trieval.go to trieval.go and changing what's above this comment. 9 10// info holds case information for a single rune. It is the value returned 11// by a trie lookup. Most mapping information can be stored in a single 16-bit 12// value. If not, for example when a rune is mapped to multiple runes, the value 13// stores some basic case data and an index into an array with additional data. 14// 15// The per-rune values have the following format: 16// 17// if (exception) { 18// 15..4 unsigned exception index 19// } else { 20// 15..8 XOR pattern or index to XOR pattern for case mapping 21// Only 13..8 are used for XOR patterns. 22// 7 inverseFold (fold to upper, not to lower) 23// 6 index: interpret the XOR pattern as an index 24// or isMid if case mode is cIgnorableUncased. 25// 5..4 CCC: zero (normal or break), above or other 26// } 27// 3 exception: interpret this value as an exception index 28// (TODO: is this bit necessary? Probably implied from case mode.) 29// 2..0 case mode 30// 31// For the non-exceptional cases, a rune must be either uncased, lowercase or 32// uppercase. If the rune is cased, the XOR pattern maps either a lowercase 33// rune to uppercase or an uppercase rune to lowercase (applied to the 10 34// least-significant bits of the rune). 35// 36// See the definitions below for a more detailed description of the various 37// bits. 38type info uint16 39 40const ( 41 casedMask = 0x0003 42 fullCasedMask = 0x0007 43 ignorableMask = 0x0006 44 ignorableValue = 0x0004 45 46 inverseFoldBit = 1 << 7 47 isMidBit = 1 << 6 48 49 exceptionBit = 1 << 3 50 exceptionShift = 4 51 numExceptionBits = 12 52 53 xorIndexBit = 1 << 6 54 xorShift = 8 55 56 // There is no mapping if all xor bits and the exception bit are zero. 57 hasMappingMask = 0xff80 | exceptionBit 58) 59 60// The case mode bits encodes the case type of a rune. This includes uncased, 61// title, upper and lower case and case ignorable. (For a definition of these 62// terms see Chapter 3 of The Unicode Standard Core Specification.) In some rare 63// cases, a rune can be both cased and case-ignorable. This is encoded by 64// cIgnorableCased. A rune of this type is always lower case. Some runes are 65// cased while not having a mapping. 66// 67// A common pattern for scripts in the Unicode standard is for upper and lower 68// case runes to alternate for increasing rune values (e.g. the accented Latin 69// ranges starting from U+0100 and U+1E00 among others and some Cyrillic 70// characters). We use this property by defining a cXORCase mode, where the case 71// mode (always upper or lower case) is derived from the rune value. As the XOR 72// pattern for case mappings is often identical for successive runes, using 73// cXORCase can result in large series of identical trie values. This, in turn, 74// allows us to better compress the trie blocks. 75const ( 76 cUncased info = iota // 000 77 cTitle // 001 78 cLower // 010 79 cUpper // 011 80 cIgnorableUncased // 100 81 cIgnorableCased // 101 // lower case if mappings exist 82 cXORCase // 11x // case is cLower | ((rune&1) ^ x) 83 84 maxCaseMode = cUpper 85) 86 87func (c info) isCased() bool { 88 return c&casedMask != 0 89} 90 91func (c info) isCaseIgnorable() bool { 92 return c&ignorableMask == ignorableValue 93} 94 95func (c info) isNotCasedAndNotCaseIgnorable() bool { 96 return c&fullCasedMask == 0 97} 98 99func (c info) isCaseIgnorableAndNotCased() bool { 100 return c&fullCasedMask == cIgnorableUncased 101} 102 103func (c info) isMid() bool { 104 return c&(fullCasedMask|isMidBit) == isMidBit|cIgnorableUncased 105} 106 107// The case mapping implementation will need to know about various Canonical 108// Combining Class (CCC) values. We encode two of these in the trie value: 109// cccZero (0) and cccAbove (230). If the value is cccOther, it means that 110// CCC(r) > 0, but not 230. A value of cccBreak means that CCC(r) == 0 and that 111// the rune also has the break category Break (see below). 112const ( 113 cccBreak info = iota << 4 114 cccZero 115 cccAbove 116 cccOther 117 118 cccMask = cccBreak | cccZero | cccAbove | cccOther 119) 120 121const ( 122 starter = 0 123 above = 230 124 iotaSubscript = 240 125) 126 127// The exceptions slice holds data that does not fit in a normal info entry. 128// The entry is pointed to by the exception index in an entry. It has the 129// following format: 130// 131// Header 132// byte 0: 133// 7..6 unused 134// 5..4 CCC type (same bits as entry) 135// 3 unused 136// 2..0 length of fold 137// 138// byte 1: 139// 7..6 unused 140// 5..3 length of 1st mapping of case type 141// 2..0 length of 2nd mapping of case type 142// 143// case 1st 2nd 144// lower -> upper, title 145// upper -> lower, title 146// title -> lower, upper 147// 148// Lengths with the value 0x7 indicate no value and implies no change. 149// A length of 0 indicates a mapping to zero-length string. 150// 151// Body bytes: 152// case folding bytes 153// lowercase mapping bytes 154// uppercase mapping bytes 155// titlecase mapping bytes 156// closure mapping bytes (for NFKC_Casefold). (TODO) 157// 158// Fallbacks: 159// missing fold -> lower 160// missing title -> upper 161// all missing -> original rune 162// 163// exceptions starts with a dummy byte to enforce that there is no zero index 164// value. 165const ( 166 lengthMask = 0x07 167 lengthBits = 3 168 noChange = 0 169) 170 171// References to generated trie. 172 173var trie = newCaseTrie(0) 174 175var sparse = sparseBlocks{ 176 values: sparseValues[:], 177 offsets: sparseOffsets[:], 178} 179 180// Sparse block lookup code. 181 182// valueRange is an entry in a sparse block. 183type valueRange struct { 184 value uint16 185 lo, hi byte 186} 187 188type sparseBlocks struct { 189 values []valueRange 190 offsets []uint16 191} 192 193// lookup returns the value from values block n for byte b using binary search. 194func (s *sparseBlocks) lookup(n uint32, b byte) uint16 { 195 lo := s.offsets[n] 196 hi := s.offsets[n+1] 197 for lo < hi { 198 m := lo + (hi-lo)/2 199 r := s.values[m] 200 if r.lo <= b && b <= r.hi { 201 return r.value 202 } 203 if b < r.lo { 204 hi = m 205 } else { 206 lo = m + 1 207 } 208 } 209 return 0 210} 211 212// lastRuneForTesting is the last rune used for testing. Everything after this 213// is boring. 214const lastRuneForTesting = rune(0x1FFFF) 215