1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 1997-9, 2000, 2006, 2010, 2011, 2012, 2014 Free Software Foundation, Inc.
3
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
16
17 #include <config.h>
18
19 #include "private.h"
20
21 #include <ctype.h>
22 #include <float.h>
23 #include <limits.h>
24 #include <stdlib.h>
25
26 #include "data/case.h"
operator ()detail::less_by27 #include "data/dictionary.h"
28 #include "data/settings.h"
29 #include "data/variable.h"
30 #include "language/expressions/helpers.h"
31 #include "language/lexer/format-parser.h"
32 #include "language/lexer/lexer.h"
33 #include "language/lexer/variable-parser.h"
34 #include "libpspp/array.h"
35 #include "libpspp/assertion.h"
36 #include "libpspp/i18n.h"
37 #include "libpspp/message.h"
38 #include "libpspp/misc.h"
39 #include "libpspp/pool.h"
40 #include "libpspp/str.h"
41
42 #include "gl/c-strcase.h"
43 #include "gl/xalloc.h"
44
45 /* Declarations. */
46
47 /* Recursive descent parser in order of increasing precedence. */
48 typedef union any_node *parse_recursively_func (struct lexer *, struct expression *);
49 static parse_recursively_func parse_or, parse_and, parse_not;
50 static parse_recursively_func parse_rel, parse_add, parse_mul;
51 static parse_recursively_func parse_neg, parse_exp;
52 static parse_recursively_func parse_primary;
53 static parse_recursively_func parse_vector_element, parse_function;
54
55 /* Utility functions. */
56 static struct expression *expr_create (struct dataset *ds);
57 atom_type expr_node_returns (const union any_node *);
58
59 static const char *atom_type_name (atom_type);
60 static struct expression *finish_expression (union any_node *,
61 struct expression *);
62 static bool type_check (struct expression *, union any_node **,
63 enum expr_type expected_type);
64 static union any_node *allocate_unary_variable (struct expression *,
65 const struct variable *);
66
67 /* Public functions. */
68
69 /* Parses an expression of the given TYPE.
70 If DICT is nonnull then variables and vectors within it may be
71 referenced within the expression; otherwise, the expression
72 must not reference any variables or vectors.
73 Returns the new expression if successful or a null pointer
74 otherwise. */
75 struct expression *
76 expr_parse (struct lexer *lexer, struct dataset *ds, enum expr_type type)
77 {
78 union any_node *n;
79 struct expression *e;
80
81 assert (type == EXPR_NUMBER || type == EXPR_STRING || type == EXPR_BOOLEAN);
82
83 e = expr_create (ds);
84 n = parse_or (lexer, e);
85 if (n != NULL && type_check (e, &n, type))
86 return finish_expression (expr_optimize (n, e), e);
87 else
88 {
89 expr_free (e);
90 return NULL;
91 }
92 }
93
94 /* Parses and returns an expression of the given TYPE, as
95 expr_parse(), and sets up so that destroying POOL will free
96 the expression as well. */
97 struct expression *
98 expr_parse_pool (struct lexer *lexer,
99 struct pool *pool,
100 struct dataset *ds,
101 enum expr_type type)
102 {
103 struct expression *e = expr_parse (lexer, ds, type);
104 if (e != NULL)
105 pool_add_subpool (pool, e->expr_pool);
106 return e;
107 }
108
109 /* Free expression E. */
110 void
111 expr_free (struct expression *e)
112 {
113 if (e != NULL)
114 pool_destroy (e->expr_pool);
115 }
116
117 struct expression *
118 expr_parse_any (struct lexer *lexer, struct dataset *ds, bool optimize)
119 {
120 union any_node *n;
121 struct expression *e;
122
123 e = expr_create (ds);
124 n = parse_or (lexer, e);
125 if (n == NULL)
126 {
127 expr_free (e);
128 return NULL;
129 }
130
131 if (optimize)
132 n = expr_optimize (n, e);
133 return finish_expression (n, e);
134 }
135
136 /* Finishing up expression building. */
137
138 /* Height of an expression's stacks. */
139 struct stack_heights
140 {
141 int number_height; /* Height of number stack. */
142 int string_height; /* Height of string stack. */
143 };
144
145 /* Stack heights used by different kinds of arguments. */
146 static const struct stack_heights on_number_stack = {1, 0};
147 static const struct stack_heights on_string_stack = {0, 1};
148 static const struct stack_heights not_on_stack = {0, 0};
149
150 /* Returns the stack heights used by an atom of the given
151 TYPE. */
152 static const struct stack_heights *
153 atom_type_stack (atom_type type)
154 {
155 assert (is_atom (type));
156
157 switch (type)
158 {
159 case OP_number:
160 case OP_boolean:
161 return &on_number_stack;
162
163 case OP_string:
164 return &on_string_stack;
165
166 case OP_format:
167 case OP_ni_format:
168 case OP_no_format:
169 case OP_num_var:
170 case OP_str_var:
171 case OP_integer:
172 case OP_pos_int:
173 case OP_vector:
174 return ¬_on_stack;
175
176 default:
177 NOT_REACHED ();
178 }
179 }
180
181 /* Measures the stack height needed for node N, supposing that
182 the stack height is initially *HEIGHT and updating *HEIGHT to
183 the final stack height. Updates *MAX, if necessary, to
184 reflect the maximum intermediate or final height. */
185 static void
186 measure_stack (const union any_node *n,
187 struct stack_heights *height, struct stack_heights *max)
188 {
189 const struct stack_heights *return_height;
190
191 if (is_composite (n->type))
192 {
193 struct stack_heights args;
194 int i;
195
196 args = *height;
197 for (i = 0; i < n->composite.arg_cnt; i++)
198 measure_stack (n->composite.args[i], &args, max);
199
200 return_height = atom_type_stack (operations[n->type].returns);
201 }
202 else
203 return_height = atom_type_stack (n->type);
204
205 height->number_height += return_height->number_height;
206 height->string_height += return_height->string_height;
207
208 if (height->number_height > max->number_height)
209 max->number_height = height->number_height;
210 if (height->string_height > max->string_height)
211 max->string_height = height->string_height;
212 }
213
214 /* Allocates stacks within E sufficient for evaluating node N. */
215 static void
216 allocate_stacks (union any_node *n, struct expression *e)
217 {
218 struct stack_heights initial = {0, 0};
219 struct stack_heights max = {0, 0};
220
221 measure_stack (n, &initial, &max);
222 e->number_stack = pool_alloc (e->expr_pool,
223 sizeof *e->number_stack * max.number_height);
224 e->string_stack = pool_alloc (e->expr_pool,
225 sizeof *e->string_stack * max.string_height);
226 }
227
228 /* Finalizes expression E for evaluating node N. */
229 static struct expression *
230 finish_expression (union any_node *n, struct expression *e)
231 {
232 /* Allocate stacks. */
233 allocate_stacks (n, e);
234
235 /* Output postfix representation. */
236 expr_flatten (n, e);
237
238 /* The eval_pool might have been used for allocating strings
239 during optimization. We need to keep those strings around
240 for all subsequent evaluations, so start a new eval_pool. */
241 e->eval_pool = pool_create_subpool (e->expr_pool);
242
243 return e;
244 }
245
246 /* Verifies that expression E, whose root node is *N, can be
247 converted to type EXPECTED_TYPE, inserting a conversion at *N
248 if necessary. Returns true if successful, false on failure. */
249 static bool
250 type_check (struct expression *e,
251 union any_node **n, enum expr_type expected_type)
252 {
253 atom_type actual_type = expr_node_returns (*n);
254
255 switch (expected_type)
256 {
257 case EXPR_BOOLEAN:
258 case EXPR_NUMBER:
259 if (actual_type != OP_number && actual_type != OP_boolean)
260 {
261 msg (SE, _("Type mismatch: expression has %s type, "
262 "but a numeric value is required here."),
263 atom_type_name (actual_type));
264 return false;
265 }
266 if (actual_type == OP_number && expected_type == EXPR_BOOLEAN)
267 *n = expr_allocate_binary (e, OP_NUM_TO_BOOLEAN, *n,
268 expr_allocate_string (e, ss_empty ()));
269 break;
270
271 case EXPR_STRING:
272 if (actual_type != OP_string)
273 {
274 msg (SE, _("Type mismatch: expression has %s type, "
275 "but a string value is required here."),
276 atom_type_name (actual_type));
277 return false;
278 }
279 break;
280
281 default:
282 NOT_REACHED ();
283 }
284
285 return true;
286 }
287
288 /* Recursive-descent expression parser. */
289
290 /* Considers whether *NODE may be coerced to type REQUIRED_TYPE.
291 Returns true if possible, false if disallowed.
292
293 If DO_COERCION is false, then *NODE is not modified and there
294 are no side effects.
295
296 If DO_COERCION is true, we perform the coercion if possible,
297 modifying *NODE if necessary. If the coercion is not possible
298 then we free *NODE and set *NODE to a null pointer.
299
300 This function's interface is somewhat awkward. Use one of the
301 wrapper functions type_coercion(), type_coercion_assert(), or
302 is_coercible() instead. */
303 static bool
304 type_coercion_core (struct expression *e,
305 atom_type required_type,
306 union any_node **node,
307 const char *operator_name,
308 bool do_coercion)
309 {
310 atom_type actual_type;
311
312 assert (!!do_coercion == (e != NULL));
313 if (*node == NULL)
314 {
315 /* Propagate error. Whatever caused the original error
316 already emitted an error message. */
317 return false;
318 }
319
320 actual_type = expr_node_returns (*node);
321 if (actual_type == required_type)
322 {
323 /* Type match. */
324 return true;
325 }
326
327 switch (required_type)
328 {
329 case OP_number:
330 if (actual_type == OP_boolean)
331 {
332 /* To enforce strict typing rules, insert Boolean to
333 numeric "conversion". This conversion is a no-op,
334 so it will be removed later. */
335 if (do_coercion)
336 *node = expr_allocate_unary (e, OP_BOOLEAN_TO_NUM, *node);
337 return true;
338 }
339 break;
340
341 case OP_string:
342 /* No coercion to string. */
343 break;
344
345 case OP_boolean:
346 if (actual_type == OP_number)
347 {
348 /* Convert numeric to boolean. */
349 if (do_coercion)
350 {
351 union any_node *op_name;
352
353 op_name = expr_allocate_string (e, ss_cstr (operator_name));
354 *node = expr_allocate_binary (e, OP_NUM_TO_BOOLEAN, *node,
355 op_name);
356 }
357 return true;
358 }
359 break;
360
361 case OP_format:
362 NOT_REACHED ();
363
364 case OP_ni_format:
365 msg_disable ();
366 if ((*node)->type == OP_format
367 && fmt_check_input (&(*node)->format.f)
368 && fmt_check_type_compat (&(*node)->format.f, VAL_NUMERIC))
369 {
370 msg_enable ();
371 if (do_coercion)
372 (*node)->type = OP_ni_format;
373 return true;
374 }
375 msg_enable ();
376 break;
377
378 case OP_no_format:
379 msg_disable ();
380 if ((*node)->type == OP_format
381 && fmt_check_output (&(*node)->format.f)
382 && fmt_check_type_compat (&(*node)->format.f, VAL_NUMERIC))
383 {
384 msg_enable ();
385 if (do_coercion)
386 (*node)->type = OP_no_format;
387 return true;
388 }
389 msg_enable ();
390 break;
391
392 case OP_num_var:
393 if ((*node)->type == OP_NUM_VAR)
394 {
395 if (do_coercion)
396 *node = (*node)->composite.args[0];
397 return true;
398 }
399 break;
400
401 case OP_str_var:
402 if ((*node)->type == OP_STR_VAR)
403 {
404 if (do_coercion)
405 *node = (*node)->composite.args[0];
406 return true;
407 }
408 break;
409
410 case OP_var:
411 if ((*node)->type == OP_NUM_VAR || (*node)->type == OP_STR_VAR)
412 {
413 if (do_coercion)
414 *node = (*node)->composite.args[0];
415 return true;
416 }
417 break;
418
419 case OP_pos_int:
420 if ((*node)->type == OP_number
421 && floor ((*node)->number.n) == (*node)->number.n
422 && (*node)->number.n > 0 && (*node)->number.n < INT_MAX)
423 {
424 if (do_coercion)
425 *node = expr_allocate_pos_int (e, (*node)->number.n);
426 return true;
427 }
428 break;
429
430 default:
431 NOT_REACHED ();
432 }
433
434 if (do_coercion)
435 {
436 msg (SE, _("Type mismatch while applying %s operator: "
437 "cannot convert %s to %s."),
438 operator_name,
439 atom_type_name (actual_type), atom_type_name (required_type));
440 *node = NULL;
441 }
442 return false;
443 }
444
445 /* Coerces *NODE to type REQUIRED_TYPE, and returns success. If
446 *NODE cannot be coerced to the desired type then we issue an
447 error message about operator OPERATOR_NAME and free *NODE. */
448 static bool
449 type_coercion (struct expression *e,
450 atom_type required_type, union any_node **node,
451 const char *operator_name)
452 {
453 return type_coercion_core (e, required_type, node, operator_name, true);
454 }
455
456 /* Coerces *NODE to type REQUIRED_TYPE.
457 Assert-fails if the coercion is disallowed. */
458 static void
459 type_coercion_assert (struct expression *e,
460 atom_type required_type, union any_node **node)
461 {
462 int success = type_coercion_core (e, required_type, node, NULL, true);
463 assert (success);
464 }
465
466 /* Returns true if *NODE may be coerced to type REQUIRED_TYPE,
467 false otherwise. */
468 static bool
469 is_coercible (atom_type required_type, union any_node *const *node)
470 {
471 return type_coercion_core (NULL, required_type,
472 (union any_node **) node, NULL, false);
473 }
474
475 /* Returns true if ACTUAL_TYPE is a kind of REQUIRED_TYPE, false
476 otherwise. */
477 static bool
478 is_compatible (atom_type required_type, atom_type actual_type)
479 {
480 return (required_type == actual_type
481 || (required_type == OP_var
482 && (actual_type == OP_num_var || actual_type == OP_str_var)));
483 }
484
485 /* How to parse an operator. */
486 struct operator
487 {
488 int token; /* Token representing operator. */
489 operation_type type; /* Operation type representing operation. */
490 const char *name; /* Name of operator. */
491 };
492
493 /* Attempts to match the current token against the tokens for the
494 OP_CNT operators in OPS[]. If successful, returns true
495 and, if OPERATOR is non-null, sets *OPERATOR to the operator.
496 On failure, returns false and, if OPERATOR is non-null, sets
497 *OPERATOR to a null pointer. */
498 static bool
499 match_operator (struct lexer *lexer, const struct operator ops[], size_t op_cnt,
500 const struct operator **operator)
501 {
502 const struct operator *op;
503
504 for (op = ops; op < ops + op_cnt; op++)
505 if (lex_token (lexer) == op->token)
506 {
507 if (op->token != T_NEG_NUM)
508 lex_get (lexer);
509 if (operator != NULL)
510 *operator = op;
511 return true;
512 }
513 if (operator != NULL)
514 *operator = NULL;
515 return false;
516 }
517
518 static bool
519 check_operator (const struct operator *op, int arg_cnt, atom_type arg_type)
520 {
521 const struct operation *o;
522 size_t i;
523
524 assert (op != NULL);
525 o = &operations[op->type];
526 assert (o->arg_cnt == arg_cnt);
527 assert ((o->flags & OPF_ARRAY_OPERAND) == 0);
528 for (i = 0; i < arg_cnt; i++)
529 assert (is_compatible (arg_type, o->args[i]));
530 return true;
531 }
532
533 static bool
534 check_binary_operators (const struct operator ops[], size_t op_cnt,
535 atom_type arg_type)
536 {
537 size_t i;
538
539 for (i = 0; i < op_cnt; i++)
540 check_operator (&ops[i], 2, arg_type);
541 return true;
542 }
543
544 static atom_type
545 get_operand_type (const struct operator *op)
546 {
547 return operations[op->type].args[0];
548 }
549
550 /* Parses a chain of left-associative operator/operand pairs.
551 There are OP_CNT operators, specified in OPS[]. The
552 operators' operands must all be the same type. The next
553 higher level is parsed by PARSE_NEXT_LEVEL. If CHAIN_WARNING
554 is non-null, then it will be issued as a warning if more than
555 one operator/operand pair is parsed. */
556 static union any_node *
557 parse_binary_operators (struct lexer *lexer, struct expression *e, union any_node *node,
558 const struct operator ops[], size_t op_cnt,
559 parse_recursively_func *parse_next_level,
560 const char *chain_warning)
561 {
562 atom_type operand_type = get_operand_type (&ops[0]);
563 int op_count;
564 const struct operator *operator;
565
566 assert (check_binary_operators (ops, op_cnt, operand_type));
567 if (node == NULL)
568 return node;
569
570 for (op_count = 0; match_operator (lexer, ops, op_cnt, &operator); op_count++)
571 {
572 union any_node *rhs;
573
574 /* Convert the left-hand side to type OPERAND_TYPE. */
575 if (!type_coercion (e, operand_type, &node, operator->name))
576 return NULL;
577
578 /* Parse the right-hand side and coerce to type
579 OPERAND_TYPE. */
580 rhs = parse_next_level (lexer, e);
581 if (!type_coercion (e, operand_type, &rhs, operator->name))
582 return NULL;
583 node = expr_allocate_binary (e, operator->type, node, rhs);
584 }
585
586 if (op_count > 1 && chain_warning != NULL)
587 msg (SW, "%s", chain_warning);
588
589 return node;
590 }
591
592 static union any_node *
593 parse_inverting_unary_operator (struct lexer *lexer, struct expression *e,
594 const struct operator *op,
595 parse_recursively_func *parse_next_level)
596 {
597 union any_node *node;
598 unsigned op_count;
599
600 check_operator (op, 1, get_operand_type (op));
601
602 op_count = 0;
603 while (match_operator (lexer, op, 1, NULL))
604 op_count++;
605
606 node = parse_next_level (lexer, e);
607 if (op_count > 0
608 && type_coercion (e, get_operand_type (op), &node, op->name)
609 && op_count % 2 != 0)
610 return expr_allocate_unary (e, op->type, node);
611 else
612 return node;
613 }
614
615 /* Parses the OR level. */
616 static union any_node *
617 parse_or (struct lexer *lexer, struct expression *e)
618 {
619 static const struct operator op =
620 { T_OR, OP_OR, "logical disjunction (`OR')" };
621
622 return parse_binary_operators (lexer, e, parse_and (lexer, e), &op, 1, parse_and, NULL);
623 }
624
625 /* Parses the AND level. */
626 static union any_node *
627 parse_and (struct lexer *lexer, struct expression *e)
628 {
629 static const struct operator op =
630 { T_AND, OP_AND, "logical conjunction (`AND')" };
631
632 return parse_binary_operators (lexer, e, parse_not (lexer, e),
633 &op, 1, parse_not, NULL);
634 }
635
636 /* Parses the NOT level. */
637 static union any_node *
638 parse_not (struct lexer *lexer, struct expression *e)
639 {
640 static const struct operator op
641 = { T_NOT, OP_NOT, "logical negation (`NOT')" };
642 return parse_inverting_unary_operator (lexer, e, &op, parse_rel);
643 }
644
645 /* Parse relational operators. */
646 static union any_node *
647 parse_rel (struct lexer *lexer, struct expression *e)
648 {
649 const char *chain_warning =
650 _("Chaining relational operators (e.g. `a < b < c') will "
651 "not produce the mathematically expected result. "
652 "Use the AND logical operator to fix the problem "
653 "(e.g. `a < b AND b < c'). "
654 "If chaining is really intended, parentheses will disable "
655 "this warning (e.g. `(a < b) < c'.)");
656
657 union any_node *node = parse_add (lexer, e);
658
659 if (node == NULL)
660 return NULL;
661
662 switch (expr_node_returns (node))
663 {
664 case OP_number:
665 case OP_boolean:
666 {
667 static const struct operator ops[] =
668 {
669 { T_EQUALS, OP_EQ, "numeric equality (`=')" },
670 { T_EQ, OP_EQ, "numeric equality (`EQ')" },
671 { T_GE, OP_GE, "numeric greater-than-or-equal-to (`>=')" },
672 { T_GT, OP_GT, "numeric greater than (`>')" },
673 { T_LE, OP_LE, "numeric less-than-or-equal-to (`<=')" },
674 { T_LT, OP_LT, "numeric less than (`<')" },
675 { T_NE, OP_NE, "numeric inequality (`<>')" },
676 };
677
678 return parse_binary_operators (lexer, e, node, ops,
679 sizeof ops / sizeof *ops,
680 parse_add, chain_warning);
681 }
682
683 case OP_string:
684 {
685 static const struct operator ops[] =
686 {
687 { T_EQUALS, OP_EQ_STRING, "string equality (`=')" },
688 { T_EQ, OP_EQ_STRING, "string equality (`EQ')" },
689 { T_GE, OP_GE_STRING, "string greater-than-or-equal-to (`>=')" },
690 { T_GT, OP_GT_STRING, "string greater than (`>')" },
691 { T_LE, OP_LE_STRING, "string less-than-or-equal-to (`<=')" },
692 { T_LT, OP_LT_STRING, "string less than (`<')" },
693 { T_NE, OP_NE_STRING, "string inequality (`<>')" },
694 };
695
696 return parse_binary_operators (lexer, e, node, ops,
697 sizeof ops / sizeof *ops,
698 parse_add, chain_warning);
699 }
700
701 default:
702 return node;
703 }
704 }
705
706 /* Parses the addition and subtraction level. */
707 static union any_node *
708 parse_add (struct lexer *lexer, struct expression *e)
709 {
710 static const struct operator ops[] =
711 {
712 { T_PLUS, OP_ADD, "addition (`+')" },
713 { T_DASH, OP_SUB, "subtraction (`-')" },
714 { T_NEG_NUM, OP_ADD, "subtraction (`-')" },
715 };
716
717 return parse_binary_operators (lexer, e, parse_mul (lexer, e),
718 ops, sizeof ops / sizeof *ops,
719 parse_mul, NULL);
720 }
721
722 /* Parses the multiplication and division level. */
723 static union any_node *
724 parse_mul (struct lexer *lexer, struct expression *e)
725 {
726 static const struct operator ops[] =
727 {
728 { T_ASTERISK, OP_MUL, "multiplication (`*')" },
729 { T_SLASH, OP_DIV, "division (`/')" },
730 };
731
732 return parse_binary_operators (lexer, e, parse_neg (lexer, e),
733 ops, sizeof ops / sizeof *ops,
734 parse_neg, NULL);
735 }
736
737 /* Parses the unary minus level. */
738 static union any_node *
739 parse_neg (struct lexer *lexer, struct expression *e)
740 {
741 static const struct operator op = { T_DASH, OP_NEG, "negation (`-')" };
742 return parse_inverting_unary_operator (lexer, e, &op, parse_exp);
743 }
744
745 static union any_node *
746 parse_exp (struct lexer *lexer, struct expression *e)
747 {
748 static const struct operator op =
749 { T_EXP, OP_POW, "exponentiation (`**')" };
750
751 const char *chain_warning =
752 _("The exponentiation operator (`**') is left-associative, "
753 "even though right-associative semantics are more useful. "
754 "That is, `a**b**c' equals `(a**b)**c', not as `a**(b**c)'. "
755 "To disable this warning, insert parentheses.");
756
757 union any_node *lhs, *node;
758 bool negative = false;
759
760 if (lex_token (lexer) == T_NEG_NUM)
761 {
762 lhs = expr_allocate_number (e, -lex_tokval (lexer));
763 negative = true;
764 lex_get (lexer);
765 }
766 else
767 lhs = parse_primary (lexer, e);
768
769 node = parse_binary_operators (lexer, e, lhs, &op, 1,
770 parse_primary, chain_warning);
771 return negative ? expr_allocate_unary (e, OP_NEG, node) : node;
772 }
773
774 /* Parses system variables. */
775 static union any_node *
776 parse_sysvar (struct lexer *lexer, struct expression *e)
777 {
778 if (lex_match_id (lexer, "$CASENUM"))
779 return expr_allocate_nullary (e, OP_CASENUM);
780 else if (lex_match_id (lexer, "$DATE"))
781 {
782 static const char *months[12] =
783 {
784 "JAN", "FEB", "MAR", "APR", "MAY", "JUN",
785 "JUL", "AUG", "SEP", "OCT", "NOV", "DEC",
786 };
787
788 time_t last_proc_time = time_of_last_procedure (e->ds);
789 struct tm *time;
790 char temp_buf[10];
791 struct substring s;
792
793 time = localtime (&last_proc_time);
794 sprintf (temp_buf, "%02d %s %02d", abs (time->tm_mday) % 100,
795 months[abs (time->tm_mon) % 12], abs (time->tm_year) % 100);
796
797 ss_alloc_substring (&s, ss_cstr (temp_buf));
798 return expr_allocate_string (e, s);
799 }
800 else if (lex_match_id (lexer, "$TRUE"))
801 return expr_allocate_boolean (e, 1.0);
802 else if (lex_match_id (lexer, "$FALSE"))
803 return expr_allocate_boolean (e, 0.0);
804 else if (lex_match_id (lexer, "$SYSMIS"))
805 return expr_allocate_number (e, SYSMIS);
806 else if (lex_match_id (lexer, "$JDATE"))
807 {
808 time_t time = time_of_last_procedure (e->ds);
809 struct tm *tm = localtime (&time);
810 return expr_allocate_number (e, expr_ymd_to_ofs (tm->tm_year + 1900,
811 tm->tm_mon + 1,
812 tm->tm_mday));
813 }
814 else if (lex_match_id (lexer, "$TIME"))
815 {
816 time_t time = time_of_last_procedure (e->ds);
817 struct tm *tm = localtime (&time);
818 return expr_allocate_number (e,
819 expr_ymd_to_date (tm->tm_year + 1900,
820 tm->tm_mon + 1,
821 tm->tm_mday)
822 + tm->tm_hour * 60 * 60.
823 + tm->tm_min * 60.
824 + tm->tm_sec);
825 }
826 else if (lex_match_id (lexer, "$LENGTH"))
827 return expr_allocate_number (e, settings_get_viewlength ());
828 else if (lex_match_id (lexer, "$WIDTH"))
829 return expr_allocate_number (e, settings_get_viewwidth ());
830 else
831 {
832 msg (SE, _("Unknown system variable %s."), lex_tokcstr (lexer));
833 return NULL;
834 }
835 }
836
837 /* Parses numbers, varnames, etc. */
838 static union any_node *
839 parse_primary (struct lexer *lexer, struct expression *e)
840 {
841 switch (lex_token (lexer))
842 {
843 case T_ID:
844 if (lex_next_token (lexer, 1) == T_LPAREN)
845 {
846 /* An identifier followed by a left parenthesis may be
847 a vector element reference. If not, it's a function
848 call. */
849 if (e->ds != NULL && dict_lookup_vector (dataset_dict (e->ds), lex_tokcstr (lexer)) != NULL)
850 return parse_vector_element (lexer, e);
851 else
852 return parse_function (lexer, e);
853 }
854 else if (lex_tokcstr (lexer)[0] == '$')
855 {
856 /* $ at the beginning indicates a system variable. */
857 return parse_sysvar (lexer, e);
858 }
859 else if (e->ds != NULL && dict_lookup_var (dataset_dict (e->ds), lex_tokcstr (lexer)))
860 {
861 /* It looks like a user variable.
862 (It could be a format specifier, but we'll assume
863 it's a variable unless proven otherwise. */
864 return allocate_unary_variable (e, parse_variable (lexer, dataset_dict (e->ds)));
865 }
866 else
867 {
868 /* Try to parse it as a format specifier. */
869 struct fmt_spec fmt;
870 bool ok;
871
872 msg_disable ();
873 ok = parse_format_specifier (lexer, &fmt);
874 msg_enable ();
875
876 if (ok)
877 return expr_allocate_format (e, &fmt);
878
879 /* All attempts failed. */
880 msg (SE, _("Unknown identifier %s."), lex_tokcstr (lexer));
881 return NULL;
882 }
883 break;
884
885 case T_POS_NUM:
886 case T_NEG_NUM:
887 {
888 union any_node *node = expr_allocate_number (e, lex_tokval (lexer));
889 lex_get (lexer);
890 return node;
891 }
892
893 case T_STRING:
894 {
895 const char *dict_encoding;
896 union any_node *node;
897 char *s;
898
899 dict_encoding = (e->ds != NULL
900 ? dict_get_encoding (dataset_dict (e->ds))
901 : "UTF-8");
902 s = recode_string_pool (dict_encoding, "UTF-8", lex_tokcstr (lexer),
903 ss_length (lex_tokss (lexer)), e->expr_pool);
904 node = expr_allocate_string (e, ss_cstr (s));
905
906 lex_get (lexer);
907 return node;
908 }
909
910 case T_LPAREN:
911 {
912 union any_node *node;
913 lex_get (lexer);
914 node = parse_or (lexer, e);
915 if (node != NULL && !lex_force_match (lexer, T_RPAREN))
916 return NULL;
917 return node;
918 }
919
920 default:
921 lex_error (lexer, NULL);
922 return NULL;
923 }
924 }
925
926 static union any_node *
927 parse_vector_element (struct lexer *lexer, struct expression *e)
928 {
929 const struct vector *vector;
930 union any_node *element;
931
932 /* Find vector, skip token.
933 The caller must already have verified that the current token
934 is the name of a vector. */
935 vector = dict_lookup_vector (dataset_dict (e->ds), lex_tokcstr (lexer));
936 assert (vector != NULL);
937 lex_get (lexer);
938
939 /* Skip left parenthesis token.
940 The caller must have verified that the lookahead is a left
941 parenthesis. */
942 assert (lex_token (lexer) == T_LPAREN);
943 lex_get (lexer);
944
945 element = parse_or (lexer, e);
946 if (!type_coercion (e, OP_number, &element, "vector indexing")
947 || !lex_match (lexer, T_RPAREN))
948 return NULL;
949
950 return expr_allocate_binary (e, (vector_get_type (vector) == VAL_NUMERIC
951 ? OP_VEC_ELEM_NUM : OP_VEC_ELEM_STR),
952 element, expr_allocate_vector (e, vector));
953 }
954
955 /* Individual function parsing. */
956
957 const struct operation operations[OP_first + OP_cnt] = {
958 #include "parse.inc"
959 };
960
961 static bool
962 word_matches (const char **test, const char **name)
963 {
964 size_t test_len = strcspn (*test, ".");
965 size_t name_len = strcspn (*name, ".");
966 if (test_len == name_len)
967 {
968 if (buf_compare_case (*test, *name, test_len))
969 return false;
970 }
971 else if (test_len < 3 || test_len > name_len)
972 return false;
973 else
974 {
975 if (buf_compare_case (*test, *name, test_len))
976 return false;
977 }
978
979 *test += test_len;
980 *name += name_len;
981 if (**test != **name)
982 return false;
983
984 if (**test == '.')
985 {
986 (*test)++;
987 (*name)++;
988 }
989 return true;
990 }
991
992 static int
993 compare_names (const char *test, const char *name, bool abbrev_ok)
994 {
995 if (!abbrev_ok)
996 return true;
997
998 for (;;)
999 {
1000 if (!word_matches (&test, &name))
1001 return true;
1002 if (*name == '\0' && *test == '\0')
1003 return false;
1004 }
1005 }
1006
1007 static int
1008 compare_strings (const char *test, const char *name, bool abbrev_ok UNUSED)
1009 {
1010 return c_strcasecmp (test, name);
1011 }
1012
1013 static bool
1014 lookup_function_helper (const char *name,
1015 int (*compare) (const char *test, const char *name,
1016 bool abbrev_ok),
1017 const struct operation **first,
1018 const struct operation **last)
1019 {
1020 const struct operation *f;
1021
1022 for (f = operations + OP_function_first;
1023 f <= operations + OP_function_last; f++)
1024 if (!compare (name, f->name, !(f->flags & OPF_NO_ABBREV)))
1025 {
1026 *first = f;
1027
1028 while (f <= operations + OP_function_last
1029 && !compare (name, f->name, !(f->flags & OPF_NO_ABBREV)))
1030 f++;
1031 *last = f;
1032
1033 return true;
1034 }
1035
1036 return false;
1037 }
1038
1039 static bool
1040 lookup_function (const char *name,
1041 const struct operation **first,
1042 const struct operation **last)
1043 {
1044 *first = *last = NULL;
1045 return (lookup_function_helper (name, compare_strings, first, last)
1046 || lookup_function_helper (name, compare_names, first, last));
1047 }
1048
1049 static int
1050 extract_min_valid (const char *s)
1051 {
1052 char *p = strrchr (s, '.');
1053 if (p == NULL
1054 || p[1] < '0' || p[1] > '9'
1055 || strspn (p + 1, "0123456789") != strlen (p + 1))
1056 return -1;
1057 *p = '\0';
1058 return atoi (p + 1);
1059 }
1060
1061 static atom_type
1062 function_arg_type (const struct operation *f, size_t arg_idx)
1063 {
1064 assert (arg_idx < f->arg_cnt || (f->flags & OPF_ARRAY_OPERAND));
1065
1066 return f->args[arg_idx < f->arg_cnt ? arg_idx : f->arg_cnt - 1];
1067 }
1068
1069 static bool
1070 match_function (union any_node **args, int arg_cnt, const struct operation *f)
1071 {
1072 size_t i;
1073
1074 if (arg_cnt < f->arg_cnt
1075 || (arg_cnt > f->arg_cnt && (f->flags & OPF_ARRAY_OPERAND) == 0)
1076 || arg_cnt - (f->arg_cnt - 1) < f->array_min_elems)
1077 return false;
1078
1079 for (i = 0; i < arg_cnt; i++)
1080 if (!is_coercible (function_arg_type (f, i), &args[i]))
1081 return false;
1082
1083 return true;
1084 }
1085
1086 static void
1087 coerce_function_args (struct expression *e, const struct operation *f,
1088 union any_node **args, size_t arg_cnt)
1089 {
1090 int i;
1091
1092 for (i = 0; i < arg_cnt; i++)
1093 type_coercion_assert (e, function_arg_type (f, i), &args[i]);
1094 }
1095
1096 static bool
1097 validate_function_args (const struct operation *f, int arg_cnt, int min_valid)
1098 {
1099 int array_arg_cnt = arg_cnt - (f->arg_cnt - 1);
1100 if (array_arg_cnt < f->array_min_elems)
1101 {
1102 msg (SE, _("%s must have at least %d arguments in list."),
1103 f->prototype, f->array_min_elems);
1104 return false;
1105 }
1106
1107 if ((f->flags & OPF_ARRAY_OPERAND)
1108 && array_arg_cnt % f->array_granularity != 0)
1109 {
1110 if (f->array_granularity == 2)
1111 msg (SE, _("%s must have an even number of arguments in list."),
1112 f->prototype);
1113 else
1114 msg (SE, _("%s must have multiple of %d arguments in list."),
1115 f->prototype, f->array_granularity);
1116 return false;
1117 }
1118
1119 if (min_valid != -1)
1120 {
1121 if (f->array_min_elems == 0)
1122 {
1123 assert ((f->flags & OPF_MIN_VALID) == 0);
1124 msg (SE, _("%s function does not accept a minimum valid "
1125 "argument count."), f->prototype);
1126 return false;
1127 }
1128 else
1129 {
1130 assert (f->flags & OPF_MIN_VALID);
1131 if (array_arg_cnt < f->array_min_elems)
1132 {
1133 msg (SE, _("%s requires at least %d valid arguments in list."),
1134 f->prototype, f->array_min_elems);
1135 return false;
1136 }
1137 else if (min_valid > array_arg_cnt)
1138 {
1139 msg (SE, _("With %s, "
1140 "using minimum valid argument count of %d "
1141 "does not make sense when passing only %d "
1142 "arguments in list."),
1143 f->prototype, min_valid, array_arg_cnt);
1144 return false;
1145 }
1146 }
1147 }
1148
1149 return true;
1150 }
1151
1152 static void
1153 add_arg (union any_node ***args, int *arg_cnt, int *arg_cap,
1154 union any_node *arg)
1155 {
1156 if (*arg_cnt >= *arg_cap)
1157 {
1158 *arg_cap += 8;
1159 *args = xrealloc (*args, sizeof **args * *arg_cap);
1160 }
1161
1162 (*args)[(*arg_cnt)++] = arg;
1163 }
1164
1165 static void
1166 put_invocation (struct string *s,
1167 const char *func_name, union any_node **args, size_t arg_cnt)
1168 {
1169 size_t i;
1170
1171 ds_put_format (s, "%s(", func_name);
1172 for (i = 0; i < arg_cnt; i++)
1173 {
1174 if (i > 0)
1175 ds_put_cstr (s, ", ");
1176 ds_put_cstr (s, operations[expr_node_returns (args[i])].prototype);
1177 }
1178 ds_put_byte (s, ')');
1179 }
1180
1181 static void
1182 no_match (const char *func_name,
1183 union any_node **args, size_t arg_cnt,
1184 const struct operation *first, const struct operation *last)
1185 {
1186 struct string s;
1187 const struct operation *f;
1188
1189 ds_init_empty (&s);
1190
1191 if (last - first == 1)
1192 {
1193 ds_put_format (&s, _("Type mismatch invoking %s as "), first->prototype);
1194 put_invocation (&s, func_name, args, arg_cnt);
1195 }
1196 else
1197 {
1198 ds_put_cstr (&s, _("Function invocation "));
1199 put_invocation (&s, func_name, args, arg_cnt);
1200 ds_put_cstr (&s, _(" does not match any known function. Candidates are:"));
1201
1202 for (f = first; f < last; f++)
1203 ds_put_format (&s, "\n%s", f->prototype);
1204 }
1205 ds_put_byte (&s, '.');
1206
1207 msg (SE, "%s", ds_cstr (&s));
1208
1209 ds_destroy (&s);
1210 }
1211
1212 static union any_node *
1213 parse_function (struct lexer *lexer, struct expression *e)
1214 {
1215 int min_valid;
1216 const struct operation *f, *first, *last;
1217
1218 union any_node **args = NULL;
1219 int arg_cnt = 0;
1220 int arg_cap = 0;
1221
1222 struct string func_name;
1223
1224 union any_node *n;
1225
1226 ds_init_substring (&func_name, lex_tokss (lexer));
1227 min_valid = extract_min_valid (lex_tokcstr (lexer));
1228 if (!lookup_function (lex_tokcstr (lexer), &first, &last))
1229 {
1230 msg (SE, _("No function or vector named %s."), lex_tokcstr (lexer));
1231 ds_destroy (&func_name);
1232 return NULL;
1233 }
1234
1235 lex_get (lexer);
1236 if (!lex_force_match (lexer, T_LPAREN))
1237 {
1238 ds_destroy (&func_name);
1239 return NULL;
1240 }
1241
1242 args = NULL;
1243 arg_cnt = arg_cap = 0;
1244 if (lex_token (lexer) != T_RPAREN)
1245 for (;;)
1246 {
1247 if (lex_token (lexer) == T_ID
1248 && lex_next_token (lexer, 1) == T_TO)
1249 {
1250 const struct variable **vars;
1251 size_t var_cnt;
1252 size_t i;
1253
1254 if (!parse_variables_const (lexer, dataset_dict (e->ds), &vars, &var_cnt, PV_SINGLE))
1255 goto fail;
1256 for (i = 0; i < var_cnt; i++)
1257 add_arg (&args, &arg_cnt, &arg_cap,
1258 allocate_unary_variable (e, vars[i]));
1259 free (vars);
1260 }
1261 else
1262 {
1263 union any_node *arg = parse_or (lexer, e);
1264 if (arg == NULL)
1265 goto fail;
1266
1267 add_arg (&args, &arg_cnt, &arg_cap, arg);
1268 }
1269 if (lex_match (lexer, T_RPAREN))
1270 break;
1271 else if (!lex_match (lexer, T_COMMA))
1272 {
1273 lex_error_expecting (lexer, "`,'", "`)'");
1274 goto fail;
1275 }
1276 }
1277
1278 for (f = first; f < last; f++)
1279 if (match_function (args, arg_cnt, f))
1280 break;
1281 if (f >= last)
1282 {
1283 no_match (ds_cstr (&func_name), args, arg_cnt, first, last);
1284 goto fail;
1285 }
1286
1287 coerce_function_args (e, f, args, arg_cnt);
1288 if (!validate_function_args (f, arg_cnt, min_valid))
1289 goto fail;
1290
1291 if ((f->flags & OPF_EXTENSION) && settings_get_syntax () == COMPATIBLE)
1292 msg (SW, _("%s is a PSPP extension."), f->prototype);
1293 if (f->flags & OPF_UNIMPLEMENTED)
1294 {
1295 msg (SE, _("%s is not available in this version of PSPP."),
1296 f->prototype);
1297 goto fail;
1298 }
1299 if ((f->flags & OPF_PERM_ONLY) &&
1300 proc_in_temporary_transformations (e->ds))
1301 {
1302 msg (SE, _("%s may not appear after %s."), f->prototype, "TEMPORARY");
1303 goto fail;
1304 }
1305
1306 n = expr_allocate_composite (e, f - operations, args, arg_cnt);
1307 n->composite.min_valid = min_valid != -1 ? min_valid : f->array_min_elems;
1308
1309 if (n->type == OP_LAG_Vn || n->type == OP_LAG_Vs)
1310 dataset_need_lag (e->ds, 1);
1311 else if (n->type == OP_LAG_Vnn || n->type == OP_LAG_Vsn)
1312 {
1313 int n_before;
1314 assert (n->composite.arg_cnt == 2);
1315 assert (n->composite.args[1]->type == OP_pos_int);
1316 n_before = n->composite.args[1]->integer.i;
1317 dataset_need_lag (e->ds, n_before);
1318 }
1319
1320 free (args);
1321 ds_destroy (&func_name);
1322 return n;
1323
1324 fail:
1325 free (args);
1326 ds_destroy (&func_name);
1327 return NULL;
1328 }
1329
1330 /* Utility functions. */
1331
1332 static struct expression *
1333 expr_create (struct dataset *ds)
1334 {
1335 struct pool *pool = pool_create ();
1336 struct expression *e = pool_alloc (pool, sizeof *e);
1337 e->expr_pool = pool;
1338 e->ds = ds;
1339 e->eval_pool = pool_create_subpool (e->expr_pool);
1340 e->ops = NULL;
1341 e->op_types = NULL;
1342 e->op_cnt = e->op_cap = 0;
1343 return e;
1344 }
1345
1346 atom_type
1347 expr_node_returns (const union any_node *n)
1348 {
1349 assert (n != NULL);
1350 assert (is_operation (n->type));
1351 if (is_atom (n->type))
1352 return n->type;
1353 else if (is_composite (n->type))
1354 return operations[n->type].returns;
1355 else
1356 NOT_REACHED ();
1357 }
1358
1359 static const char *
1360 atom_type_name (atom_type type)
1361 {
1362 assert (is_atom (type));
1363 return operations[type].name;
1364 }
1365
1366 union any_node *
1367 expr_allocate_nullary (struct expression *e, operation_type op)
1368 {
1369 return expr_allocate_composite (e, op, NULL, 0);
1370 }
1371
1372 union any_node *
1373 expr_allocate_unary (struct expression *e, operation_type op,
1374 union any_node *arg0)
1375 {
1376 return expr_allocate_composite (e, op, &arg0, 1);
1377 }
1378
1379 union any_node *
1380 expr_allocate_binary (struct expression *e, operation_type op,
1381 union any_node *arg0, union any_node *arg1)
1382 {
1383 union any_node *args[2];
1384 args[0] = arg0;
1385 args[1] = arg1;
1386 return expr_allocate_composite (e, op, args, 2);
1387 }
1388
1389 static bool
1390 is_valid_node (union any_node *n)
1391 {
1392 const struct operation *op;
1393 size_t i;
1394
1395 assert (n != NULL);
1396 assert (is_operation (n->type));
1397 op = &operations[n->type];
1398
1399 if (!is_atom (n->type))
1400 {
1401 struct composite_node *c = &n->composite;
1402
1403 assert (is_composite (n->type));
1404 assert (c->arg_cnt >= op->arg_cnt);
1405 for (i = 0; i < op->arg_cnt; i++)
1406 assert (is_compatible (op->args[i], expr_node_returns (c->args[i])));
1407 if (c->arg_cnt > op->arg_cnt && !is_operator (n->type))
1408 {
1409 assert (op->flags & OPF_ARRAY_OPERAND);
1410 for (i = 0; i < c->arg_cnt; i++)
1411 assert (is_compatible (op->args[op->arg_cnt - 1],
1412 expr_node_returns (c->args[i])));
1413 }
1414 }
1415
1416 return true;
1417 }
1418
1419 union any_node *
1420 expr_allocate_composite (struct expression *e, operation_type op,
1421 union any_node **args, size_t arg_cnt)
1422 {
1423 union any_node *n;
1424 size_t i;
1425
1426 n = pool_alloc (e->expr_pool, sizeof n->composite);
1427 n->type = op;
1428 n->composite.arg_cnt = arg_cnt;
1429 n->composite.args = pool_alloc (e->expr_pool,
1430 sizeof *n->composite.args * arg_cnt);
1431 for (i = 0; i < arg_cnt; i++)
1432 {
1433 if (args[i] == NULL)
1434 return NULL;
1435 n->composite.args[i] = args[i];
1436 }
1437 memcpy (n->composite.args, args, sizeof *n->composite.args * arg_cnt);
1438 n->composite.min_valid = 0;
1439 assert (is_valid_node (n));
1440 return n;
1441 }
1442
1443 union any_node *
1444 expr_allocate_number (struct expression *e, double d)
1445 {
1446 union any_node *n = pool_alloc (e->expr_pool, sizeof n->number);
1447 n->type = OP_number;
1448 n->number.n = d;
1449 return n;
1450 }
1451
1452 union any_node *
1453 expr_allocate_boolean (struct expression *e, double b)
1454 {
1455 union any_node *n = pool_alloc (e->expr_pool, sizeof n->number);
1456 assert (b == 0.0 || b == 1.0 || b == SYSMIS);
1457 n->type = OP_boolean;
1458 n->number.n = b;
1459 return n;
1460 }
1461
1462 union any_node *
1463 expr_allocate_integer (struct expression *e, int i)
1464 {
1465 union any_node *n = pool_alloc (e->expr_pool, sizeof n->integer);
1466 n->type = OP_integer;
1467 n->integer.i = i;
1468 return n;
1469 }
1470
1471 union any_node *
1472 expr_allocate_pos_int (struct expression *e, int i)
1473 {
1474 union any_node *n = pool_alloc (e->expr_pool, sizeof n->integer);
1475 assert (i > 0);
1476 n->type = OP_pos_int;
1477 n->integer.i = i;
1478 return n;
1479 }
1480
1481 union any_node *
1482 expr_allocate_vector (struct expression *e, const struct vector *vector)
1483 {
1484 union any_node *n = pool_alloc (e->expr_pool, sizeof n->vector);
1485 n->type = OP_vector;
1486 n->vector.v = vector;
1487 return n;
1488 }
1489
1490 union any_node *
1491 expr_allocate_string (struct expression *e, struct substring s)
1492 {
1493 union any_node *n = pool_alloc (e->expr_pool, sizeof n->string);
1494 n->type = OP_string;
1495 n->string.s = s;
1496 return n;
1497 }
1498
1499 union any_node *
1500 expr_allocate_variable (struct expression *e, const struct variable *v)
1501 {
1502 union any_node *n = pool_alloc (e->expr_pool, sizeof n->variable);
1503 n->type = var_is_numeric (v) ? OP_num_var : OP_str_var;
1504 n->variable.v = v;
1505 return n;
1506 }
1507
1508 union any_node *
1509 expr_allocate_format (struct expression *e, const struct fmt_spec *format)
1510 {
1511 union any_node *n = pool_alloc (e->expr_pool, sizeof n->format);
1512 n->type = OP_format;
1513 n->format.f = *format;
1514 return n;
1515 }
1516
1517 /* Allocates a unary composite node that represents the value of
1518 variable V in expression E. */
1519 static union any_node *
1520 allocate_unary_variable (struct expression *e, const struct variable *v)
1521 {
1522 assert (v != NULL);
1523 return expr_allocate_unary (e, var_is_numeric (v) ? OP_NUM_VAR : OP_STR_VAR,
1524 expr_allocate_variable (e, v));
1525 }
1526
1527 /* Export function details to other modules. */
1528
1529 /* Returns the operation structure for the function with the
1530 given IDX. */
1531 const struct operation *
1532 expr_get_function (size_t idx)
1533 {
1534 assert (idx < OP_function_cnt);
1535 return &operations[OP_function_first + idx];
1536 }
1537
1538 /* Returns the number of expression functions. */
1539 size_t
1540 expr_get_function_cnt (void)
1541 {
1542 return OP_function_cnt;
1543 }
1544
1545 /* Returns the name of operation OP. */
1546 const char *
1547 expr_operation_get_name (const struct operation *op)
1548 {
1549 return op->name;
1550 }
1551
1552 /* Returns the human-readable prototype for operation OP. */
1553 const char *
1554 expr_operation_get_prototype (const struct operation *op)
1555 {
1556 return op->prototype;
1557 }
1558
1559 /* Returns the number of arguments for operation OP. */
1560 int
1561 expr_operation_get_arg_cnt (const struct operation *op)
1562 {
1563 return op->arg_cnt;
1564 }
1565