Index: source/i18n/collationfcd.h |
diff --git a/source/i18n/collationfcd.h b/source/i18n/collationfcd.h |
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+/* |
+******************************************************************************* |
+* Copyright (C) 2012-2014, International Business Machines |
+* Corporation and others. All Rights Reserved. |
+******************************************************************************* |
+* collationfcd.h |
+* |
+* created on: 2012aug18 |
+* created by: Markus W. Scherer |
+*/ |
+ |
+#ifndef __COLLATIONFCD_H__ |
+#define __COLLATIONFCD_H__ |
+ |
+#include "unicode/utypes.h" |
+ |
+#if !UCONFIG_NO_COLLATION |
+ |
+#include "unicode/utf16.h" |
+ |
+U_NAMESPACE_BEGIN |
+ |
+/** |
+ * Data and functions for the FCD check fast path. |
+ * |
+ * The fast path looks at a pair of 16-bit code units and checks |
+ * whether there is an FCD boundary between them; |
+ * there is if the first unit has a trailing ccc=0 (!hasTccc(first)) |
+ * or the second unit has a leading ccc=0 (!hasLccc(second)), |
+ * or both. |
+ * When the fast path finds a possible non-boundary, |
+ * then the FCD check slow path looks at the actual sequence of FCD values. |
+ * |
+ * This is a pure optimization. |
+ * The fast path must at least find all possible non-boundaries. |
+ * If the fast path is too pessimistic, it costs performance. |
+ * |
+ * For a pair of BMP characters, the fast path tests are precise (1 bit per character). |
+ * |
+ * For a supplementary code point, the two units are its lead and trail surrogates. |
+ * We set hasTccc(lead)=true if any of its 1024 associated supplementary code points |
+ * has lccc!=0 or tccc!=0. |
+ * We set hasLccc(trail)=true for all trail surrogates. |
+ * As a result, we leave the fast path if the lead surrogate might start a |
+ * supplementary code point that is not FCD-inert. |
+ * (So the fast path need not detect that there is a surrogate pair, |
+ * nor look ahead to the next full code point.) |
+ * |
+ * hasLccc(lead)=true if any of its 1024 associated supplementary code points |
+ * has lccc!=0, for fast boundary checking between BMP & supplementary. |
+ * |
+ * hasTccc(trail)=false: |
+ * It should only be tested for unpaired trail surrogates which are FCD-inert. |
+ */ |
+class U_I18N_API CollationFCD { |
+public: |
+ static inline UBool hasLccc(UChar32 c) { |
+ // assert c <= 0xffff |
+ // c can be negative, e.g., U_SENTINEL from UCharIterator; |
+ // that is handled in the first test. |
+ int32_t i; |
+ return |
+ // U+0300 is the first character with lccc!=0. |
+ c >= 0x300 && |
+ (i = lcccIndex[c >> 5]) != 0 && |
+ (lcccBits[i] & ((uint32_t)1 << (c & 0x1f))) != 0; |
+ } |
+ |
+ static inline UBool hasTccc(UChar32 c) { |
+ // assert c <= 0xffff |
+ // c can be negative, e.g., U_SENTINEL from UCharIterator; |
+ // that is handled in the first test. |
+ int32_t i; |
+ return |
+ // U+00C0 is the first character with tccc!=0. |
+ c >= 0xc0 && |
+ (i = tcccIndex[c >> 5]) != 0 && |
+ (tcccBits[i] & ((uint32_t)1 << (c & 0x1f))) != 0; |
+ } |
+ |
+ static inline UBool mayHaveLccc(UChar32 c) { |
+ // Handles all of Unicode 0..10FFFF. |
+ // c can be negative, e.g., U_SENTINEL. |
+ // U+0300 is the first character with lccc!=0. |
+ if(c < 0x300) { return FALSE; } |
+ if(c > 0xffff) { c = U16_LEAD(c); } |
+ int32_t i; |
+ return |
+ (i = lcccIndex[c >> 5]) != 0 && |
+ (lcccBits[i] & ((uint32_t)1 << (c & 0x1f))) != 0; |
+ } |
+ |
+ /** |
+ * Tibetan composite vowel signs (U+0F73, U+0F75, U+0F81) |
+ * must be decomposed before reaching the core collation code, |
+ * or else some sequences including them, even ones passing the FCD check, |
+ * do not yield canonically equivalent results. |
+ * |
+ * This is a fast and imprecise test. |
+ * |
+ * @param c a code point |
+ * @return TRUE if c is U+0F73, U+0F75 or U+0F81 or one of several other Tibetan characters |
+ */ |
+ static inline UBool maybeTibetanCompositeVowel(UChar32 c) { |
+ return (c & 0x1fff01) == 0xf01; |
+ } |
+ |
+ /** |
+ * Tibetan composite vowel signs (U+0F73, U+0F75, U+0F81) |
+ * must be decomposed before reaching the core collation code, |
+ * or else some sequences including them, even ones passing the FCD check, |
+ * do not yield canonically equivalent results. |
+ * |
+ * They have distinct lccc/tccc combinations: 129/130 or 129/132. |
+ * |
+ * @param fcd16 the FCD value (lccc/tccc combination) of a code point |
+ * @return TRUE if fcd16 is from U+0F73, U+0F75 or U+0F81 |
+ */ |
+ static inline UBool isFCD16OfTibetanCompositeVowel(uint16_t fcd16) { |
+ return fcd16 == 0x8182 || fcd16 == 0x8184; |
+ } |
+ |
+private: |
+ CollationFCD(); // No instantiation. |
+ |
+ static const uint8_t lcccIndex[2048]; |
+ static const uint8_t tcccIndex[2048]; |
+ static const uint32_t lcccBits[]; |
+ static const uint32_t tcccBits[]; |
+}; |
+ |
+U_NAMESPACE_END |
+ |
+#endif // !UCONFIG_NO_COLLATION |
+#endif // __COLLATIONFCD_H__ |