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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 
lengthOfWeight(uint32_t weight)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 */
countBytes(int32_t 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__
114