| 1 | /* List implementation of a partition of consecutive integers.
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| 2 | Copyright (C) 2000, 2001 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 GNU CC.
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| 6 |
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| 7 | GNU CC 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 | GNU CC 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 GNU CC; see the file COPYING. If not, write to
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| 19 | the Free Software Foundation, 59 Temple Place - Suite 330,
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| 20 | Boston, MA 02111-1307, 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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| 48 | /* The canonical element that represents the class containing this
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| 49 | element. */
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| 50 | int class_element;
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| 51 | /* The next element in this class. Elements in each class form a
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| 52 | circular list. */
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| 53 | struct partition_elem* next;
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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 PARAMS((int));
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| 68 | extern void partition_delete PARAMS((partition));
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| 69 | extern int partition_union PARAMS((partition,
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| 70 | int,
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| 71 | int));
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| 72 | extern void partition_print PARAMS((partition,
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| 73 | FILE*));
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| 74 |
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| 75 | /* Returns the canonical element corresponding to the class containing
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| 76 | ELEMENT__ in PARTITION__. */
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| 77 |
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| 78 | #define partition_find(partition__, element__) \
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| 79 | ((partition__)->elements[(element__)].class_element)
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| 80 |
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| 81 | #endif /* _PARTITION_H */
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