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d3e5ef98 PK |
1 | /* Copyright (c) 1979 Regents of the University of California */ |
2 | ||
31cef89c | 3 | static char sccsid[] = "@(#)tree.c 1.1 8/27/80"; |
d3e5ef98 PK |
4 | |
5 | #include "whoami.h" | |
6 | #include "0.h" | |
7 | ||
8 | /* | |
9 | * TREE SPACE DECLARATIONS | |
10 | */ | |
11 | struct tr { | |
12 | int *tr_low; | |
13 | int *tr_high; | |
14 | } ttab[MAXTREE], *tract; | |
15 | ||
16 | /* | |
17 | * The variable space is the | |
18 | * absolute base of the tree segments. | |
19 | * (exactly the same as ttab[0].tr_low) | |
20 | * Spacep is maintained to point at the | |
21 | * beginning of the next tree slot to | |
22 | * be allocated for use by the grammar. | |
23 | * Spacep is used "extern" by the semantic | |
24 | * actions in pas.y. | |
25 | * The variable tract is maintained to point | |
26 | * at the tree segment out of which we are | |
27 | * allocating (the active segment). | |
28 | */ | |
29 | int *space, *spacep; | |
30 | ||
31 | /* | |
32 | * TREENMAX is the maximum width | |
33 | * in words that any tree node | |
34 | * due to the way in which the parser uses | |
35 | * the pointer spacep. | |
36 | */ | |
37 | #define TREENMAX 6 | |
38 | ||
39 | int trspace[ITREE]; | |
40 | int *space = trspace; | |
41 | int *spacep = trspace; | |
42 | struct tr *tract = ttab; | |
43 | ||
44 | /* | |
45 | * Inittree allocates the first tree slot | |
46 | * and sets up the first segment descriptor. | |
47 | * A lot of this work is actually done statically | |
48 | * above. | |
49 | */ | |
50 | inittree() | |
51 | { | |
52 | ||
53 | ttab[0].tr_low = space; | |
54 | ttab[0].tr_high = &space[ITREE]; | |
55 | } | |
56 | ||
57 | /* | |
58 | * Tree builds the nodes in the | |
59 | * parse tree. It is rarely called | |
60 | * directly, rather calls are made | |
61 | * to tree[12345] which supplies the | |
62 | * first argument to save space in | |
63 | * the code. Tree also guarantees | |
64 | * that spacep points to the beginning | |
65 | * of the next slot it will return, | |
66 | * a property required by the parser | |
67 | * which was always true before we | |
68 | * segmented the tree space. | |
69 | */ | |
70 | int *tree(cnt, a) | |
71 | int cnt; | |
72 | { | |
73 | register int *p, *q; | |
74 | register int i; | |
75 | ||
76 | i = cnt; | |
77 | p = spacep; | |
78 | q = &a; | |
79 | do | |
80 | *p++ = *q++; | |
81 | while (--i); | |
82 | q = spacep; | |
83 | spacep = p; | |
84 | if (p+TREENMAX >= tract->tr_high) | |
85 | /* | |
86 | * this peek-ahead should | |
87 | * save a great number of calls | |
88 | * to tralloc. | |
89 | */ | |
90 | tralloc(TREENMAX); | |
91 | return (q); | |
92 | } | |
93 | ||
94 | /* | |
95 | * Tralloc preallocates enough | |
96 | * space in the tree to allow | |
97 | * the grammar to use the variable | |
98 | * spacep, as it did before the | |
99 | * tree was segmented. | |
100 | */ | |
101 | tralloc(howmuch) | |
102 | { | |
103 | register char *cp; | |
104 | register i; | |
105 | ||
106 | if (spacep + howmuch >= tract->tr_high) { | |
107 | i = TRINC; | |
108 | cp = malloc(i * sizeof ( int )); | |
109 | if (cp == -1) { | |
110 | yerror("Ran out of memory (tralloc)"); | |
111 | pexit(DIED); | |
112 | } | |
113 | spacep = cp; | |
114 | tract++; | |
115 | if (tract >= &ttab[MAXTREE]) { | |
116 | yerror("Ran out of tree tables"); | |
117 | pexit(DIED); | |
118 | } | |
119 | tract->tr_low = cp; | |
120 | tract->tr_high = tract->tr_low+i; | |
121 | } | |
122 | } | |
123 | ||
124 | extern int yylacnt; | |
125 | extern bottled; | |
126 | #ifdef PXP | |
127 | #endif | |
128 | /* | |
129 | * Free up the tree segments | |
130 | * at the end of a block. | |
131 | * If there is scanner lookahead, | |
132 | * i.e. if yylacnt != 0 or there is bottled output, then we | |
133 | * cannot free the tree space. | |
134 | * This happens only when errors | |
135 | * occur and the forward move extends | |
136 | * across "units". | |
137 | */ | |
138 | trfree() | |
139 | { | |
140 | ||
141 | if (yylacnt != 0 || bottled != NIL) | |
142 | return; | |
143 | #ifdef PXP | |
144 | if (needtree()) | |
145 | return; | |
146 | #endif | |
147 | spacep = space; | |
148 | while (tract->tr_low > spacep || tract->tr_high <= spacep) { | |
149 | free(tract->tr_low); | |
150 | tract->tr_low = NIL; | |
151 | tract->tr_high = NIL; | |
152 | tract--; | |
153 | if (tract < ttab) | |
154 | panic("ttab"); | |
155 | } | |
156 | #ifdef PXP | |
157 | packtree(); | |
158 | #endif | |
159 | } | |
160 | ||
161 | /* | |
162 | * Copystr copies a token from | |
163 | * the "token" buffer into the | |
164 | * tree space. | |
165 | */ | |
166 | copystr(token) | |
167 | register char *token; | |
168 | { | |
169 | register char *cp; | |
170 | register int i; | |
171 | ||
172 | i = (strlen(token) + sizeof ( int )) & ~( ( sizeof ( int ) ) - 1 ); | |
173 | tralloc(i / sizeof ( int )); | |
174 | strcpy(spacep, token); | |
175 | cp = spacep; | |
176 | spacep = cp + i; | |
177 | tralloc(TREENMAX); | |
178 | return (cp); | |
179 | } |