xref: /original-bsd/usr.bin/pascal/pdx/sym/tree.c (revision 957a0273) 
1 /* Copyright (c) 1982 Regents of the University of California */
2 
3 static char sccsid[] = "@(#)tree.c 1.3 03/08/82";
4 
5 /*
6  * This module contains the interface between the SYM routines and
7  * the parse tree routines.  It would be nice if such a crude
8  * interface were not necessary, but some parts of tree building are
9  * language and hence SYM-representation dependent.  It's probably
10  * better to have tree-representation dependent code here than vice versa.
11  */
12 
13 #include "defs.h"
14 #include "tree.h"
15 #include "sym.h"
16 #include "btypes.h"
17 #include "classes.h"
18 #include "sym.rep"
19 #include "tree/tree.rep"
20 
21 typedef char *ARGLIST;
22 
23 #define nextarg(arglist, type)  ((type *) (arglist += sizeof(type)))[-1]
24 
25 LOCAL SYM *mkstring();
26 LOCAL SYM *namenode();
27 
28 /*
29  * Determine the type of a parse tree.  While we're at, check
30  * the parse tree out.
31  */
32 
33 SYM *treetype(p, ap)
34 register NODE *p;
35 register ARGLIST ap;
36 {
37     switch(p->op) {
38 	case O_NAME: {
39 	    SYM *s;
40 
41 	    s = nextarg(ap, SYM *);
42 	    s = which(s);
43 	    return namenode(p, s);
44 	    /* NOTREACHED */
45 	}
46 
47 	case O_WHICH:
48 	    p->nameval = nextarg(ap, SYM *);
49 	    p->nameval = which(p->nameval);
50 	    return NIL;
51 
52 	case O_LCON:
53 	    return t_int;
54 
55 	case O_FCON:
56 	    return t_real;
57 
58 	case O_SCON: {
59 	    char *cpy;
60 	    SYM *s;
61 
62 	    cpy = strdup(p->sconval);
63 	    p->sconval = cpy;
64 	    s = mkstring(p->sconval);
65 	    if (s == t_char) {
66 		p->op = O_LCON;
67 		p->lconval = p->sconval[0];
68 	    }
69 	    return s;
70 	}
71 
72 	case O_INDIR:
73 	    p->left = nextarg(ap, NODE *);
74 	    chkclass(p->left, PTR);
75 	    return rtype(p->left->nodetype)->type;
76 
77 	case O_RVAL: {
78 	    NODE *p1, *q;
79 
80 	    p1 = p->left;
81 	    p->nodetype = p1->nodetype;
82 	    if (p1->op == O_NAME) {
83 		if (p1->nodetype->class == FUNC) {
84 		    p->op = O_CALL;
85 		    p->right = NIL;
86 		} else if (p1->nameval->class == CONST) {
87 		    if (p1->nameval->type == t_real->type) {
88 			p->op = O_FCON;
89 			p->fconval = p1->nameval->symvalue.fconval;
90 			p->nodetype = t_real;
91 			dispose(p1);
92 		    } else {
93 			p->op = O_LCON;
94 			p->lconval = p1->nameval->symvalue.iconval;
95 			p->nodetype = p1->nameval->type;
96 			dispose(p1);
97 		    }
98 		}
99 	    }
100 	    return p->nodetype;
101 	    /* NOTREACHED */
102 	}
103 
104 	case O_CALL: {
105 	    SYM *s;
106 
107 	    p->left = nextarg(ap, NODE *);
108 	    p->right = nextarg(ap, NODE *);
109 	    s = p->left->nodetype;
110 	    if (isblock(s) && isbuiltin(s)) {
111 		p->op = (OP) s->symvalue.token.tokval;
112 		tfree(p->left);
113 		p->left = p->right;
114 		p->right = NIL;
115 	    }
116 	    return s->type;
117 	}
118 
119 	case O_ITOF:
120 	    return t_real;
121 
122 	case O_NEG: {
123 	    SYM *s;
124 
125 	    p->left = nextarg(ap, NODE *);
126 	    s = p->left->nodetype;
127 	    if (!compatible(s, t_int)) {
128 		if (!compatible(s, t_real)) {
129 		    trerror("%t is improper type", p->left);
130 		} else {
131 		    p->op = O_NEGF;
132 		}
133 	    }
134 	    return s;
135 	}
136 
137 	case O_ADD:
138 	case O_SUB:
139 	case O_MUL:
140 	case O_LT:
141 	case O_LE:
142 	case O_GT:
143 	case O_GE:
144 	case O_EQ:
145 	case O_NE:
146 	{
147 	    BOOLEAN t1real, t2real;
148 	    SYM *t1, *t2;
149 
150 	    p->left = nextarg(ap, NODE *);
151 	    p->right = nextarg(ap, NODE *);
152 	    t1 = rtype(p->left->nodetype);
153 	    t2 = rtype(p->right->nodetype);
154 	    t1real = (t1 == t_real);
155 	    t2real = (t2 == t_real);
156 	    if (t1real || t2real) {
157 		p->op++;
158 		if (!t1real) {
159 		    p->left = build(O_ITOF, p->left);
160 		} else if (!t2real) {
161 		    p->right = build(O_ITOF, p->right);
162 		}
163 	    } else {
164 		if (t1real) {
165 		    convert(&p->left, t_int, O_NOP);
166 		}
167 		if (t2real) {
168 		    convert(&p->right, t_int, O_NOP);
169 		}
170 	    }
171 	    if (p->op >= O_LT) {
172 		return t_boolean;
173 	    } else {
174 		if (t1real || t2real) {
175 		    return t_real;
176 		} else {
177 		    return t_int;
178 		}
179 	    }
180 	    /* NOTREACHED */
181 	}
182 
183 	case O_DIVF:
184 	    p->left = nextarg(ap, NODE *);
185 	    p->right = nextarg(ap, NODE *);
186 	    convert(&p->left, t_real, O_ITOF);
187 	    convert(&p->right, t_real, O_ITOF);
188 	    return t_real;
189 
190 	case O_DIV:
191 	case O_MOD:
192 	    p->left = nextarg(ap, NODE *);
193 	    p->right = nextarg(ap, NODE *);
194 	    convert(&p->left, t_int, O_NOP);
195 	    convert(&p->right, t_int, O_NOP);
196 	    return t_int;
197 
198 	case O_AND:
199 	case O_OR:
200 	    p->left = nextarg(ap, NODE *);
201 	    p->right = nextarg(ap, NODE *);
202 	    chkboolean(p->left);
203 	    chkboolean(p->right);
204 	    return t_boolean;
205 
206 	default:
207 	    return NIL;
208     }
209 }
210 
211 /*
212  * Create a node for a name.  The symbol for the name has already
213  * been chosen, either implicitly with "which" or explicitly from
214  * the dot routine.
215  */
216 
217 LOCAL SYM *namenode(p, s)
218 NODE *p;
219 SYM *s;
220 {
221     NODE *np;
222 
223     p->nameval = s;
224     if (s->class == REF) {
225 	np = alloc(1, NODE);
226 	*np = *p;
227 	p->op = O_INDIR;
228 	p->left = np;
229 	np->nodetype = s;
230     }
231     if (s->class == CONST || s->class == VAR || s->class == FVAR) {
232 	return s->type;
233     } else {
234 	return s;
235     }
236 }
237 
238 /*
239  * Convert a tree to a type via a conversion operator;
240  * if this isn't possible generate an error.
241  *
242  * Note the tree is call by address, hence the #define below.
243  */
244 
245 LOCAL convert(tp, typeto, op)
246 NODE **tp;
247 SYM *typeto;
248 OP op;
249 {
250 #define tree    (*tp)
251 
252     SYM *s;
253 
254     s = rtype(tree->nodetype);
255     typeto = rtype(typeto);
256     if (typeto == t_real && compatible(s, t_int)) {
257 	tree = build(op, tree);
258     } else if (!compatible(s, typeto)) {
259 	trerror("%t is improper type");
260     } else if (op != O_NOP && s != typeto) {
261 	tree = build(op, tree);
262     }
263 
264 #undef tree
265 }
266 
267 /*
268  * Construct a node for the Pascal dot operator.
269  *
270  * If the left operand is not a record, but rather a procedure
271  * or function, then we interpret the "." as referencing an
272  * "invisible" variable; i.e. a variable within a dynamically
273  * active block but not within the static scope of the current procedure.
274  */
275 
276 NODE *dot(record, field)
277 NODE *record;
278 SYM *field;
279 {
280     register NODE *p;
281     register SYM *s;
282 
283     if (isblock(record->nodetype)) {
284 	s = findsym(field, record->nodetype);
285 	if (s == NIL) {
286 	    error("\"%s\" is not defined in \"%s\"",
287 		field->symbol, record->nodetype->symbol);
288 	}
289 	p = alloc(1, NODE);
290 	p->op = O_NAME;
291 	p->nodetype = namenode(p, s);
292     } else {
293 	s = findclass(field, FIELD);
294 	if (s == NIL) {
295 	    error("\"%s\" is not a field", field->symbol);
296 	}
297 	field = s;
298 	chkfield(record, field);
299 	p = alloc(1, NODE);
300 	p->op = O_ADD;
301 	p->nodetype = field->type;
302 	p->left = record;
303 	p->left->nodetype = t_int;
304 	p->right = build(O_LCON, (long) field->symvalue.offset);
305     }
306     return p;
307 }
308 
309 /*
310  * Return a tree corresponding to an array reference and do the
311  * error checking.
312  */
313 
314 NODE *subscript(a, slist)
315 NODE *a, *slist;
316 {
317     register SYM *t;
318     register NODE *p;
319     SYM *etype, *atype, *eltype;
320     NODE *esub, *olda;
321 
322     olda = a;
323     t = rtype(a->nodetype);
324     if (t->class != ARRAY) {
325 	trerror("%t is not an array");
326     }
327     eltype = t->type;
328     p = slist;
329     t = t->chain;
330     for (; p != NIL && t != NIL; p = p->right, t = t->chain) {
331 	esub = p->left;
332 	etype = rtype(esub->nodetype);
333 	atype = rtype(t);
334 	if (!compatible(atype, etype)) {
335 	    trerror("subscript %t is the wrong type", esub);
336 	}
337 	a = build(O_INDEX, a, esub);
338 	a->nodetype = eltype;
339     }
340     if (p != NIL) {
341 	trerror("too many subscripts for %t", olda);
342     } else if (t != NIL) {
343 	trerror("not enough subscripts for %t", olda);
344     }
345     return(a);
346 }
347 
348 /*
349  * Evaluate a subscript index.
350  */
351 
352 evalindex(arraytype, index)
353 SYM *arraytype;
354 long index;
355 {
356     long lb, ub;
357     SYM *indextype;
358 
359     indextype = arraytype->chain;
360     lb = indextype->symvalue.rangev.lower;
361     ub = indextype->symvalue.rangev.upper;
362     if (index < lb || index > ub) {
363 	error("subscript out of range");
364     }
365     return(index - lb);
366 }
367 
368 /*
369  * Check that a record.field usage is proper.
370  */
371 
372 LOCAL chkfield(r, f)
373 NODE *r;
374 SYM *f;
375 {
376     register SYM *s;
377 
378     chkclass(r, RECORD);
379 
380     /*
381      * Don't do this for compiled code.
382      */
383 #   if (!isvax)
384 	for (s = r->nodetype->chain; s != NIL; s = s->chain) {
385 	    if (s == f) {
386 		break;
387 	    }
388 	}
389 	if (s == NIL) {
390 	    error("\"%s\" is not a field in specified record", f->symbol);
391 	}
392 #   endif
393 }
394 
395 /*
396  * Check to see if a tree is boolean-valued, if not it's an error.
397  */
398 
399 chkboolean(p)
400 register NODE *p;
401 {
402     if (p->nodetype != t_boolean) {
403 	trerror("found %t, expected boolean expression");
404     }
405 }
406 
407 /*
408  * Check to make sure the given tree has a type of the given class.
409  */
410 
411 LOCAL chkclass(p, class)
412 NODE *p;
413 int class;
414 {
415     SYM tmpsym;
416 
417     tmpsym.class = class;
418     if (p->nodetype->class != class) {
419 	trerror("%t is not a %s", p, classname(&tmpsym));
420     }
421 }
422 
423 /*
424  * Construct a node for the type of a string.  While we're at it,
425  * scan the string for '' that collapse to ', and chop off the ends.
426  */
427 
428 LOCAL SYM *mkstring(str)
429 char *str;
430 {
431     register char *p, *q;
432     SYM *s, *t;
433     static SYM zerosym;
434 
435     p = str;
436     q = str + 1;
437     while (*q != '\0') {
438 	if (q[0] != '\'' || q[1] != '\'') {
439 	    *p = *q;
440 	    p++;
441 	}
442 	q++;
443     }
444     *--p = '\0';
445     if (p == str + 1) {
446 	return t_char;
447     }
448     s = alloc(1, SYM);
449     *s = zerosym;
450     s->class = ARRAY;
451     s->type = t_char;
452     s->chain = alloc(1, SYM);
453     t = s->chain;
454     *t = zerosym;
455     t->class = RANGE;
456     t->type = t_int;
457     t->symvalue.rangev.lower = 1;
458     t->symvalue.rangev.upper = p - str + 1;
459     return s;
460 }
461 
462 /*
463  * Free up the space allocated for a string type.
464  */
465 
466 unmkstring(s)
467 SYM *s;
468 {
469     dispose(s->chain);
470 }
471