| // Copyright 2008 The RE2 Authors. All Rights Reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| #ifndef RE2_UNICODE_CASEFOLD_H_ |
| #define RE2_UNICODE_CASEFOLD_H_ |
| |
| // Unicode case folding tables. |
| |
| // The Unicode case folding tables encode the mapping from one Unicode point |
| // to the next largest Unicode point with equivalent folding. The largest |
| // point wraps back to the first. For example, the tables map: |
| // |
| // 'A' -> 'a' |
| // 'a' -> 'A' |
| // |
| // 'K' -> 'k' |
| // 'k' -> 'K' (Kelvin symbol) |
| // 'K' -> 'K' |
| // |
| // Like everything Unicode, these tables are big. If we represent the table |
| // as a sorted list of uint32_t pairs, it has 2049 entries and is 16 kB. |
| // Most table entries look like the ones around them: |
| // 'A' maps to 'A'+32, 'B' maps to 'B'+32, etc. |
| // Instead of listing all the pairs explicitly, we make a list of ranges |
| // and deltas, so that the table entries for 'A' through 'Z' can be represented |
| // as a single entry { 'A', 'Z', +32 }. |
| // |
| // In addition to blocks that map to each other (A-Z mapping to a-z) |
| // there are blocks of pairs that individually map to each other |
| // (for example, 0100<->0101, 0102<->0103, 0104<->0105, ...). |
| // For those, the special delta value EvenOdd marks even/odd pairs |
| // (if even, add 1; if odd, subtract 1), and OddEven marks odd/even pairs. |
| // |
| // In this form, the table has 274 entries, about 3kB. If we were to split |
| // the table into one for 16-bit codes and an overflow table for larger ones, |
| // we could get it down to about 1.5kB, but that's not worth the complexity. |
| // |
| // The grouped form also allows for efficient fold range calculations |
| // rather than looping one character at a time. |
| |
| #include <stdint.h> |
| |
| #include "util/util.h" |
| #include "util/utf.h" |
| |
| namespace re2 { |
| |
| enum { |
| EvenOdd = 1, |
| OddEven = -1, |
| EvenOddSkip = 1<<30, |
| OddEvenSkip, |
| }; |
| |
| struct CaseFold { |
| Rune lo; |
| Rune hi; |
| int32_t delta; |
| }; |
| |
| extern const CaseFold unicode_casefold[]; |
| extern const int num_unicode_casefold; |
| |
| extern const CaseFold unicode_tolower[]; |
| extern const int num_unicode_tolower; |
| |
| // Returns the CaseFold* in the tables that contains rune. |
| // If rune is not in the tables, returns the first CaseFold* after rune. |
| // If rune is larger than any value in the tables, returns NULL. |
| extern const CaseFold* LookupCaseFold(const CaseFold*, int, Rune rune); |
| |
| // Returns the result of applying the fold f to the rune r. |
| extern Rune ApplyFold(const CaseFold *f, Rune r); |
| |
| } // namespace re2 |
| |
| #endif // RE2_UNICODE_CASEFOLD_H_ |