/
Goal.h
146 lines (130 loc) · 5.11 KB
/
Goal.h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/*
Goal.h
Author: Richard Dale
Date: Feb 1993
Copyright (c) 1993-2009 Richard Dale.
*/
/*
MIT License
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
#import <Foundation/NSArray.h>
#import <Foundation/NSDictionary.h>
#import "NSOutputStream_Printf.h"
enum ProofState {
START_PROOF,
CALL_SYSTEM_PREDICATE,
TRY_CLAUSE,
PROVE_HEAD,
PROVE_BODY,
ALWAYS_FAIL,
};
typedef enum ProofState ProofState;
@class Clause;
@class ListIterator;
@class NestedStructureIterator;
@class Prolog;
@class ProofTree;
@interface Goal : NSObject
/*----------------------------------------------------------
* Goal Instance Variables
*
* - goalSequence
* - each goal is given a unique sequence number. It is used to check if
* a goal is more recent than another, and consequently whether or not
* a binding instantiation should be trailed.
* - proofTree
* This object contains global state infomation about the proof tree. It is
* used to return the next goal sequence number.
* - parentGoal
* - the goal immediately above in the proof tree
* - parentTermIterator
* - contains the goal whose variables are to be bound against,
* and the term containing the variables.
* - systemPredicate, argIterator
* - a builtin predicate to call and a list iterator for convenient
* access to the arguments
* - proofState
* - START_PROOF
* - retrieve the clauses for a relation from the database
* - CALL_SYSTEM_PREDICATE
* - call a built-in predicate
* - TRY_CLAUSE
* - get the next clause for the relation.
* - PROVE_HEAD
* - unify the head of the current clause with the current term in the
* parent goal.
* - PROVE_BODY
* - try prove the subgoals in a clause, return all solutions until the
* clause fails.
* - ALWAYS_FAIL
* - used for goals which can only succeed once. They succeed and then set the
* proofState to ALWAYS_FAIL.
* - relation
* - the list of alternative clauses in the database to match against.
* - currentClause, clause
* - the index within the list of alternatives for the current clause,
* and the clause itself
* - currentTerm, termIterator
* - the index of the current term within the body of the clause, and
* an iterator to access it.
* - subGoals
* - a list of sub-goals tried.
* - variableTable
* - a hash table of variable names against current variable bindings.
* - localStorage
* - storage allocated by the built in predicates
* - trail
* - a hash table of variable names against former variable bindings.
*----------------------------------------------------------*/
{
int goalSequence;
ProofTree * proofTree;
Goal * parentGoal;
NestedStructureIterator * parentTermIterator;
SEL systemPredicate;
ListIterator * argIterator;
ProofState proofState;
NSMutableArray * relation;
int currentClause;
Clause * clause;
int currentTerm;
NestedStructureIterator * termIterator;
NSMutableArray * subGoals;
NSMutableDictionary * variableTable;
NSMutableArray * localStorage;
NSMutableArray * trail;
int currentDepth;
}
- initGoal: aRelation proofTree: aProofTree parent: aGoal goalDepth: (int) depth;
- (void) reset;
- (void) fail;
- store: localObject;
- (void) dealloc;
- (BOOL) prove: anIterator lastGoal: (BOOL) isLastGoal;
- (void) continue;
- (int) printResults;
- indent: (NSOutputStream *) stream;
- (void) printForDebugger: (NSOutputStream *) stream;
- (NSString *) proofStateToString;
- setProofState: (ProofState) aState;
- (ProofState) proofState;
- (int) goalSequence;
- dereference;
- parentGoal;
- parentTermIterator;
@end