icuSources/i18n/collationweights.h

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