icuSources/i18n/collationweights.h

   1 // © 2016 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html
   3 /*
   4 *******************************************************************************
   5 *
   6 *   Copyright (C) 1999-2014, International Business Machines
   7 *   Corporation and others.  All Rights Reserved.
   8 *
   9 *******************************************************************************
  10 *   file name:  collationweights.h
  11 *   encoding:   UTF-8
  12 *   tab size:   8 (not used)
  13 *   indentation:4
  14 *
  15 *   created on: 2001mar08 as ucol_wgt.h
  16 *   created by: Markus W. Scherer
  17 */
  18
  19 #ifndef __COLLATIONWEIGHTS_H__
  20 #define __COLLATIONWEIGHTS_H__
  21
  22 #include "unicode/utypes.h"
  23
  24 #if !UCONFIG_NO_COLLATION
  25
  26 #include "unicode/uobject.h"
  27
  28 U_NAMESPACE_BEGIN
  29
  30 /**
  31  * Allocates n collation element weights between two exclusive limits.
  32  * Used only internally by the collation tailoring builder.
  33  */
  34 class U_I18N_API CollationWeights : public UMemory {
  35 public:
  36     CollationWeights();
  37
  38     static inline int32_t lengthOfWeight(uint32_t weight) {
  39         if((weight&0xffffff)==0) {
  40             return 1;
  41         } else if((weight&0xffff)==0) {
  42             return 2;
  43         } else if((weight&0xff)==0) {
  44             return 3;
  45         } else {
  46             return 4;
  47         }
  48     }
  49
  50     void initForPrimary(UBool compressible);
  51     void initForSecondary();
  52     void initForTertiary();
  53
  54     /**
  55      * Determine heuristically
  56      * what ranges to use for a given number of weights between (excluding)
  57      * two limits.
  58      *
  59      * @param lowerLimit A collation element weight; the ranges will be filled to cover
  60      *                   weights greater than this one.
  61      * @param upperLimit A collation element weight; the ranges will be filled to cover
  62      *                   weights less than this one.
  63      * @param n          The number of collation element weights w necessary such that
  64      *                   lowerLimit<w<upperLimit in lexical order.
  65      * @return TRUE if it is possible to fit n elements between the limits
  66      */
  67     UBool allocWeights(uint32_t lowerLimit, uint32_t upperLimit, int32_t n);
  68
  69     /**
  70      * Given a set of ranges calculated by allocWeights(),
  71      * iterate through the weights.
  72      * The ranges are modified to keep the current iteration state.
  73      *
  74      * @return The next weight in the ranges, or 0xffffffff if there is none left.
  75      */
  76     uint32_t nextWeight();
  77
  78     /** @internal */
  79     struct WeightRange {
  80         uint32_t start, end;
  81         int32_t length, count;
  82     };
  83
  84 private:
  85     /** @return number of usable byte values for byte idx */
  86     inline int32_t countBytes(int32_t idx) const {
  87         return (int32_t)(maxBytes[idx] - minBytes[idx] + 1);
  88     }
  89
  90     uint32_t incWeight(uint32_t weight, int32_t length) const;
  91     uint32_t incWeightByOffset(uint32_t weight, int32_t length, int32_t offset) const;
  92     void lengthenRange(WeightRange &range) const;
  93     /**
  94      * Takes two CE weights and calculates the
  95      * possible ranges of weights between the two limits, excluding them.
  96      * For weights with up to 4 bytes there are up to 2*4-1=7 ranges.
  97      */
  98     UBool getWeightRanges(uint32_t lowerLimit, uint32_t upperLimit);
  99     UBool allocWeightsInShortRanges(int32_t n, int32_t minLength);
 100     UBool allocWeightsInMinLengthRanges(int32_t n, int32_t minLength);
 101
 102     int32_t middleLength;
 103     uint32_t minBytes[5];  // for byte 1, 2, 3, 4
 104     uint32_t maxBytes[5];
 105     WeightRange ranges[7];
 106     int32_t rangeIndex;
 107     int32_t rangeCount;
 108 };
 109
 110 U_NAMESPACE_END
 111
 112 #endif  // !UCONFIG_NO_COLLATION
 113 #endif  // __COLLATIONWEIGHTS_H__