-
Notifications
You must be signed in to change notification settings - Fork 1
/
rules.c
167 lines (156 loc) · 4.63 KB
/
rules.c
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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
/************************************************************
*
* Routines to manage rules
*
************************************************************/
#include "def.h"
int label_count; /* number of label names in a rule */
/*****************************************************************
*
* Compare two pattern expressions to determine which is "more specific".
* In general, a pattern is more specific if it matches a subset of
* the expressions matched by another pattern. We require, however,
* that two expressions are equally specific ONLY if they are the same
* expression, so we need to set up a total ordering out of this partial
* ordering.
*
* returns:
* 1 if A is more specific than B
* -1 if B is more specific than A
* 0 if they are equally specific
*
*
* An untyped parameter (which matches anything) is less specific
* than anything else.
* An operator or type is more specific than a supertype.
* A term is more specific than a parameter.
* compare the precedence of operator A to the precedence of operator B
* compare the address of operator A to the address of operator B
*
* If the two operators the same, then compare their arguments.
*
*****************************************************************/
static int
more_specific(A, B)
NODE *A, *B;
{
extern OP *untyped_prim; /* from primitive.c */
extern OP *undeclared_prim; /* from primitive.c */
extern OP *positive_type, *nonzero_type; /* from primitive.c */
register OP *opa = A->op;
register OP *opb = B->op;
register OP *sop;
if (opa != opb) {
if (opb == untyped_prim) return 1;
if (opa == untyped_prim) return -1;
for (sop = opa->super; sop; sop = sop->super) if (sop == opb) return 1;
for (sop = opb->super; sop; sop = sop->super) if (sop == opa) return -1;
if (opb->arity == OP_NAME && opa->arity != OP_NAME) return 1;
if (opa->arity == OP_NAME && opb->arity != OP_NAME) return -1;
if (opa->precedence > opb->precedence) return 1;
if (opa->precedence < opb->precedence) return -1;
if (opa > opb) return 1;
if (opa < opb) return -1;
}
/* same operator */
if (opa->arity == NULLARY) return 0;
if ((opa->arity & BINARY) || (opa->arity & UNARY)) {
if ((opa->arity & BINARY) || (opa->arity == POSTFIX))
return more_specific(((TERM_NODE *)A)->left, ((TERM_NODE *)B)->left);
if (opa->arity != POSTFIX)
return more_specific(((TERM_NODE *)A)->right, ((TERM_NODE *)B)->right);
}
return 0;
}
/************************************************************
*
* Build a rule, and insert it as the hash value of the
* root operator of the head expression.
* Return a pointer to the rule, in case someone wants to
* print it, or something.
*
* TO DO: shouldn't use malloc direcly.
*
************************************************************/
RULE *
rule_build(head, body, tag, names)
NODE *head, *body;
OP *tag;
NAME_NODE *names; /* local name space */
{
void *malloc();
void rule_print(); /* forward reference */
register RULE *rr;
RULE *cr, *pr = NULL; /* used to insert rule into list */
int cmp;
static int rule_verbose = -1;
if (!(head->op->arity & OP_TERM)) {
error("head of rule must be an expression");
}
rr = (RULE *) malloc(sizeof(RULE));
rr->head = head;
rr->body = body;
rr->tag = tag;
rr->space = names;
rr->size = label_count; /* number of label names */
if (rule_verbose == -1) rule_verbose = verbose;
if (rule_verbose) {
rr->verbose = 1;
rule_print(rr);
}
else rr->verbose = 0;
rule_verbose = verbose;
cr = head->op->hash;
if (cr == NULL) { /* no rules for this op */
rr->next = NULL;
head->op->hash = rr;
return rr;
}
while (cr) {
if (1 == more_specific(rr->head, cr->head)) { /* insert here */
rr->next = cr;
if (pr) pr->next = rr;
else head->op->hash = rr;
return rr;
}
pr = cr;
cr = cr->next;
}
pr->next = rr;
rr->next = NULL;
return rr;
}
/************************************************************
*
* Free a rule.
*
************************************************************/
void rule_free(rr)
RULE *rr;
{
void expr_free(); /* from expr.c */
expr_free(rr->head);
expr_free(rr->body);
name_free(rr->space);
free((char *)rr);
}
/************************************************************
*
* Print out a rule.
*
************************************************************/
void rule_print(rp)
RULE *rp;
{
void expr_print(); /* from expr.c */
void name_space_print(); /* from names.c */
fprintf(stderr, " RULE: ");
expr_print(rp->head);
fprintf(stderr, " { ");
expr_print(rp->body);
fprintf(stderr, " }");
if (rp->tag) fprintf(stderr, " '%s", rp->tag->pname);
fprintf(stderr, " NAMESPACE: ");
name_space_print(rp->space);
fprintf(stderr, "\n");
}