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1 /* List implementation of a partition of consecutive integers.
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145
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2 Copyright (C) 2000-2020 Free Software Foundation, Inc.
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3 Contributed by CodeSourcery, LLC.
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4
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5 This file is part of GCC.
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6
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7 GCC is free software; you can redistribute it and/or modify
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8 it under the terms of the GNU General Public License as published by
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9 the Free Software Foundation; either version 2, or (at your option)
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10 any later version.
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11
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12 GCC is distributed in the hope that it will be useful,
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13 but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 GNU General Public License for more details.
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16
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17 You should have received a copy of the GNU General Public License
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18 along with GCC; see the file COPYING. If not, write to
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19 the Free Software Foundation, 51 Franklin Street - Fifth Floor,
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20 Boston, MA 02110-1301, USA. */
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21
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22 /* This package implements a partition of consecutive integers. The
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23 elements are partitioned into classes. Each class is represented
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24 by one of its elements, the canonical element, which is chosen
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25 arbitrarily from elements in the class. The principal operations
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26 on a partition are FIND, which takes an element, determines its
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27 class, and returns the canonical element for that class, and UNION,
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28 which unites the two classes that contain two given elements into a
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29 single class.
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30
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31 The list implementation used here provides constant-time finds. By
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32 storing the size of each class with the class's canonical element,
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33 it is able to perform unions over all the classes in the partition
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34 in O (N log N) time. */
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35
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36 #ifndef _PARTITION_H
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37 #define _PARTITION_H
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38
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39 #ifdef __cplusplus
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40 extern "C" {
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41 #endif /* __cplusplus */
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42
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43 #include "ansidecl.h"
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44 #include <stdio.h>
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45
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46 struct partition_elem
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47 {
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111
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48 /* The next element in this class. Elements in each class form a
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49 circular list. */
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50 struct partition_elem* next;
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51 /* The canonical element that represents the class containing this
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52 element. */
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53 int class_element;
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54 /* The number of elements in this class. Valid only if this is the
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55 canonical element for its class. */
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56 unsigned class_count;
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57 };
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58
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59 typedef struct partition_def
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60 {
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61 /* The number of elements in this partition. */
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62 int num_elements;
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63 /* The elements in the partition. */
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64 struct partition_elem elements[1];
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65 } *partition;
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66
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67 extern partition partition_new (int);
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68 extern void partition_delete (partition);
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69 extern int partition_union (partition, int, int);
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70 extern void partition_print (partition, FILE*);
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71
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72 /* Returns the canonical element corresponding to the class containing
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73 ELEMENT__ in PARTITION__. */
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74
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75 #define partition_find(partition__, element__) \
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76 ((partition__)->elements[(element__)].class_element)
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77
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78 #ifdef __cplusplus
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79 }
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80 #endif /* __cplusplus */
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81
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82 #endif /* _PARTITION_H */
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