1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 2010, 2011, 2012 Free Software Foundation, Inc.
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.
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.
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/>. */
19 #include <gsl/gsl_cdf.h>
20 #include <gsl/gsl_matrix.h>
21 #include <gsl/gsl_combination.h>
24 #include "data/case.h"
25 #include "data/casegrouper.h"
26 #include "data/casereader.h"
27 #include "data/dataset.h"
28 #include "data/dictionary.h"
29 #include "data/format.h"
30 #include "data/value.h"
31 #include "language/command.h"
32 #include "language/dictionary/split-file.h"
33 #include "language/lexer/lexer.h"
34 #include "language/lexer/value-parser.h"
35 #include "language/lexer/variable-parser.h"
36 #include "libpspp/assertion.h"
37 #include "libpspp/ll.h"
38 #include "libpspp/message.h"
39 #include "libpspp/misc.h"
40 #include "libpspp/taint.h"
41 #include "linreg/sweep.h"
42 #include "math/categoricals.h"
43 #include "math/covariance.h"
44 #include "math/interaction.h"
45 #include "math/moments.h"
46 #include "output/tab.h"
49 #define _(msgid) gettext (msgid)
54 const struct variable **dep_vars;
57 const struct variable **factor_vars;
59 size_t n_interactions;
60 struct interaction **interactions;
62 enum mv_class exclude;
64 /* The weight variable */
65 const struct variable *wv;
67 const struct dictionary *dict;
80 struct moments *totals;
82 struct categoricals *cats;
85 Sums of squares due to different variables. Element 0 is the SSE
86 for the entire model. For i > 0, element i is the SS due to
93 /* Default design: all possible interactions */
95 design_full (struct glm_spec *glm)
99 glm->n_interactions = (1 << glm->n_factor_vars) - 1;
101 glm->interactions = xcalloc (glm->n_interactions, sizeof *glm->interactions);
103 /* All subsets, with exception of the empty set, of [0, glm->n_factor_vars) */
104 for (sz = 1; sz <= glm->n_factor_vars; ++sz)
106 gsl_combination *c = gsl_combination_calloc (glm->n_factor_vars, sz);
110 struct interaction *iact = interaction_create (NULL);
112 for (e = 0 ; e < gsl_combination_k (c); ++e)
113 interaction_add_variable (iact, glm->factor_vars [gsl_combination_get (c, e)]);
115 glm->interactions[i++] = iact;
117 while (gsl_combination_next (c) == GSL_SUCCESS);
119 gsl_combination_free (c);
123 static void output_glm (const struct glm_spec *,
124 const struct glm_workspace *ws);
125 static void run_glm (struct glm_spec *cmd, struct casereader *input,
126 const struct dataset *ds);
129 static bool parse_design_spec (struct lexer *lexer, struct glm_spec *glm);
133 cmd_glm (struct lexer *lexer, struct dataset *ds)
136 struct const_var_set *factors = NULL;
139 glm.dict = dataset_dict (ds);
141 glm.n_factor_vars = 0;
142 glm.n_interactions = 0;
143 glm.interactions = NULL;
145 glm.factor_vars = NULL;
146 glm.exclude = MV_ANY;
147 glm.intercept = true;
148 glm.wv = dict_get_weight (glm.dict);
150 glm.dump_coding = false;
153 if (!parse_variables_const (lexer, glm.dict,
154 &glm.dep_vars, &glm.n_dep_vars,
155 PV_NO_DUPLICATE | PV_NUMERIC))
158 if (! lex_force_match (lexer, T_BY))
161 if (!parse_variables_const (lexer, glm.dict,
162 &glm.factor_vars, &glm.n_factor_vars,
163 PV_NO_DUPLICATE | PV_NUMERIC))
166 if (glm.n_dep_vars > 1)
168 msg (ME, _("Multivariate analysis is not yet implemented"));
173 const_var_set_create_from_array (glm.factor_vars, glm.n_factor_vars);
175 while (lex_token (lexer) != T_ENDCMD)
177 lex_match (lexer, T_SLASH);
179 if (lex_match_id (lexer, "MISSING"))
181 lex_match (lexer, T_EQUALS);
182 while (lex_token (lexer) != T_ENDCMD
183 && lex_token (lexer) != T_SLASH)
185 if (lex_match_id (lexer, "INCLUDE"))
187 glm.exclude = MV_SYSTEM;
189 else if (lex_match_id (lexer, "EXCLUDE"))
191 glm.exclude = MV_ANY;
195 lex_error (lexer, NULL);
200 else if (lex_match_id (lexer, "INTERCEPT"))
202 lex_match (lexer, T_EQUALS);
203 while (lex_token (lexer) != T_ENDCMD
204 && lex_token (lexer) != T_SLASH)
206 if (lex_match_id (lexer, "INCLUDE"))
208 glm.intercept = true;
210 else if (lex_match_id (lexer, "EXCLUDE"))
212 glm.intercept = false;
216 lex_error (lexer, NULL);
221 else if (lex_match_id (lexer, "CRITERIA"))
223 lex_match (lexer, T_EQUALS);
224 if (lex_match_id (lexer, "ALPHA"))
226 if (lex_force_match (lexer, T_LPAREN))
228 if (! lex_force_num (lexer))
230 lex_error (lexer, NULL);
234 glm.alpha = lex_number (lexer);
236 if ( ! lex_force_match (lexer, T_RPAREN))
238 lex_error (lexer, NULL);
245 lex_error (lexer, NULL);
249 else if (lex_match_id (lexer, "METHOD"))
251 lex_match (lexer, T_EQUALS);
252 if ( !lex_force_match_id (lexer, "SSTYPE"))
254 lex_error (lexer, NULL);
258 if ( ! lex_force_match (lexer, T_LPAREN))
260 lex_error (lexer, NULL);
264 if ( ! lex_force_int (lexer))
266 lex_error (lexer, NULL);
270 glm.ss_type = lex_integer (lexer);
271 if (1 > glm.ss_type || 3 < glm.ss_type )
273 msg (ME, _("Only types 1, 2 & 3 sums of squares are currently implemented"));
279 if ( ! lex_force_match (lexer, T_RPAREN))
281 lex_error (lexer, NULL);
285 else if (lex_match_id (lexer, "DESIGN"))
287 lex_match (lexer, T_EQUALS);
289 if (! parse_design_spec (lexer, &glm))
292 if (glm.n_interactions > 0)
295 else if (lex_match_id (lexer, "SHOWCODES"))
296 /* Undocumented debug option */
298 lex_match (lexer, T_EQUALS);
300 glm.dump_coding = true;
304 lex_error (lexer, NULL);
315 struct casegrouper *grouper;
316 struct casereader *group;
319 grouper = casegrouper_create_splits (proc_open (ds), glm.dict);
320 while (casegrouper_get_next_group (grouper, &group))
321 run_glm (&glm, group, ds);
322 ok = casegrouper_destroy (grouper);
323 ok = proc_commit (ds) && ok;
326 const_var_set_destroy (factors);
327 free (glm.factor_vars);
328 for (i = 0 ; i < glm.n_interactions; ++i)
329 interaction_destroy (glm.interactions[i]);
331 free (glm.interactions);
339 const_var_set_destroy (factors);
340 free (glm.factor_vars);
341 for (i = 0 ; i < glm.n_interactions; ++i)
342 interaction_destroy (glm.interactions[i]);
344 free (glm.interactions);
351 not_dropped (size_t j, const bool *ff)
357 fill_submatrix (const gsl_matrix * cov, gsl_matrix * submatrix, bool *dropped_f)
364 for (i = 0; i < cov->size1; i++)
366 if (not_dropped (i, dropped_f))
369 for (j = 0; j < cov->size2; j++)
371 if (not_dropped (j, dropped_f))
373 gsl_matrix_set (submatrix, n, m,
374 gsl_matrix_get (cov, i, j));
385 Type 1 sums of squares.
386 Populate SSQ with the Type 1 sums of squares according to COV
389 ssq_type1 (struct covariance *cov, gsl_vector *ssq, const struct glm_spec *cmd)
391 const gsl_matrix *cm = covariance_calculate_unnormalized (cov);
394 bool *model_dropped = xcalloc (covariance_dim (cov), sizeof (*model_dropped));
395 bool *submodel_dropped = xcalloc (covariance_dim (cov), sizeof (*submodel_dropped));
396 const struct categoricals *cats = covariance_get_categoricals (cov);
398 size_t n_dropped_model = 0;
399 size_t n_dropped_submodel = 0;
401 for (i = cmd->n_dep_vars; i < covariance_dim (cov); i++)
404 n_dropped_submodel++;
405 model_dropped[i] = true;
406 submodel_dropped[i] = true;
409 for (k = 0; k < cmd->n_interactions; k++)
411 gsl_matrix *model_cov = NULL;
412 gsl_matrix *submodel_cov = NULL;
414 n_dropped_submodel = n_dropped_model;
415 for (i = cmd->n_dep_vars; i < covariance_dim (cov); i++)
417 submodel_dropped[i] = model_dropped[i];
420 for (i = cmd->n_dep_vars; i < covariance_dim (cov); i++)
422 const struct interaction * x =
423 categoricals_get_interaction_by_subscript (cats, i - cmd->n_dep_vars);
425 if ( x == cmd->interactions [k])
427 model_dropped[i] = false;
432 model_cov = gsl_matrix_alloc (cm->size1 - n_dropped_model, cm->size2 - n_dropped_model);
433 submodel_cov = gsl_matrix_alloc (cm->size1 - n_dropped_submodel, cm->size2 - n_dropped_submodel);
435 fill_submatrix (cm, model_cov, model_dropped);
436 fill_submatrix (cm, submodel_cov, submodel_dropped);
438 reg_sweep (model_cov, 0);
439 reg_sweep (submodel_cov, 0);
441 gsl_vector_set (ssq, k + 1,
442 gsl_matrix_get (submodel_cov, 0, 0) - gsl_matrix_get (model_cov, 0, 0)
445 gsl_matrix_free (model_cov);
446 gsl_matrix_free (submodel_cov);
449 free (model_dropped);
450 free (submodel_dropped);
454 Type 2 sums of squares.
455 Populate SSQ with the Type 2 sums of squares according to COV
458 ssq_type2 (struct covariance *cov, gsl_vector *ssq, const struct glm_spec *cmd)
460 const gsl_matrix *cm = covariance_calculate_unnormalized (cov);
463 bool *model_dropped = xcalloc (covariance_dim (cov), sizeof (*model_dropped));
464 bool *submodel_dropped = xcalloc (covariance_dim (cov), sizeof (*submodel_dropped));
465 const struct categoricals *cats = covariance_get_categoricals (cov);
467 for (k = 0; k < cmd->n_interactions; k++)
469 gsl_matrix *model_cov = NULL;
470 gsl_matrix *submodel_cov = NULL;
471 size_t n_dropped_model = 0;
472 size_t n_dropped_submodel = 0;
473 for (i = cmd->n_dep_vars; i < covariance_dim (cov); i++)
475 const struct interaction * x =
476 categoricals_get_interaction_by_subscript (cats, i - cmd->n_dep_vars);
478 model_dropped[i] = false;
479 submodel_dropped[i] = false;
480 if (interaction_is_subset (cmd->interactions [k], x))
482 assert (n_dropped_submodel < covariance_dim (cov));
483 n_dropped_submodel++;
484 submodel_dropped[i] = true;
486 if ( cmd->interactions [k]->n_vars < x->n_vars)
488 assert (n_dropped_model < covariance_dim (cov));
490 model_dropped[i] = true;
495 model_cov = gsl_matrix_alloc (cm->size1 - n_dropped_model, cm->size2 - n_dropped_model);
496 submodel_cov = gsl_matrix_alloc (cm->size1 - n_dropped_submodel, cm->size2 - n_dropped_submodel);
498 fill_submatrix (cm, model_cov, model_dropped);
499 fill_submatrix (cm, submodel_cov, submodel_dropped);
501 reg_sweep (model_cov, 0);
502 reg_sweep (submodel_cov, 0);
504 gsl_vector_set (ssq, k + 1,
505 gsl_matrix_get (submodel_cov, 0, 0) - gsl_matrix_get (model_cov, 0, 0)
508 gsl_matrix_free (model_cov);
509 gsl_matrix_free (submodel_cov);
512 free (model_dropped);
513 free (submodel_dropped);
517 Type 3 sums of squares.
518 Populate SSQ with the Type 2 sums of squares according to COV
521 ssq_type3 (struct covariance *cov, gsl_vector *ssq, const struct glm_spec *cmd)
523 const gsl_matrix *cm = covariance_calculate_unnormalized (cov);
526 bool *model_dropped = xcalloc (covariance_dim (cov), sizeof (*model_dropped));
527 bool *submodel_dropped = xcalloc (covariance_dim (cov), sizeof (*submodel_dropped));
528 const struct categoricals *cats = covariance_get_categoricals (cov);
531 gsl_matrix *submodel_cov = gsl_matrix_alloc (cm->size1, cm->size2);
532 fill_submatrix (cm, submodel_cov, submodel_dropped);
533 reg_sweep (submodel_cov, 0);
534 ss0 = gsl_matrix_get (submodel_cov, 0, 0);
535 gsl_matrix_free (submodel_cov);
536 free (submodel_dropped);
538 for (k = 0; k < cmd->n_interactions; k++)
540 gsl_matrix *model_cov = NULL;
541 size_t n_dropped_model = 0;
543 for (i = cmd->n_dep_vars; i < covariance_dim (cov); i++)
545 const struct interaction * x =
546 categoricals_get_interaction_by_subscript (cats, i - cmd->n_dep_vars);
548 model_dropped[i] = false;
550 if ( cmd->interactions [k] == x)
552 assert (n_dropped_model < covariance_dim (cov));
554 model_dropped[i] = true;
558 model_cov = gsl_matrix_alloc (cm->size1 - n_dropped_model, cm->size2 - n_dropped_model);
560 fill_submatrix (cm, model_cov, model_dropped);
562 reg_sweep (model_cov, 0);
564 gsl_vector_set (ssq, k + 1,
565 gsl_matrix_get (model_cov, 0, 0) - ss0);
567 gsl_matrix_free (model_cov);
569 free (model_dropped);
574 //static void dump_matrix (const gsl_matrix *m);
577 run_glm (struct glm_spec *cmd, struct casereader *input,
578 const struct dataset *ds)
580 bool warn_bad_weight = true;
583 struct dictionary *dict = dataset_dict (ds);
584 struct casereader *reader;
587 struct glm_workspace ws;
588 struct covariance *cov;
590 input = casereader_create_filter_missing (input,
591 cmd->dep_vars, cmd->n_dep_vars,
595 input = casereader_create_filter_missing (input,
596 cmd->factor_vars, cmd->n_factor_vars,
600 ws.cats = categoricals_create (cmd->interactions, cmd->n_interactions,
601 cmd->wv, cmd->exclude, MV_ANY);
603 cov = covariance_2pass_create (cmd->n_dep_vars, cmd->dep_vars,
604 ws.cats, cmd->wv, cmd->exclude);
607 c = casereader_peek (input, 0);
610 casereader_destroy (input);
613 output_split_file_values (ds, c);
616 taint = taint_clone (casereader_get_taint (input));
618 ws.totals = moments_create (MOMENT_VARIANCE);
620 for (reader = casereader_clone (input);
621 (c = casereader_read (reader)) != NULL; case_unref (c))
623 double weight = dict_get_case_weight (dict, c, &warn_bad_weight);
625 for (v = 0; v < cmd->n_dep_vars; ++v)
626 moments_pass_one (ws.totals, case_data (c, cmd->dep_vars[v])->f,
629 covariance_accumulate_pass1 (cov, c);
631 casereader_destroy (reader);
633 if (cmd->dump_coding)
634 reader = casereader_clone (input);
639 (c = casereader_read (reader)) != NULL; case_unref (c))
641 double weight = dict_get_case_weight (dict, c, &warn_bad_weight);
643 for (v = 0; v < cmd->n_dep_vars; ++v)
644 moments_pass_two (ws.totals, case_data (c, cmd->dep_vars[v])->f,
647 covariance_accumulate_pass2 (cov, c);
649 casereader_destroy (reader);
652 if (cmd->dump_coding)
654 struct tab_table *t =
655 covariance_dump_enc_header (cov,
656 1 + casereader_count_cases (input));
658 (c = casereader_read (reader)) != NULL; case_unref (c))
660 covariance_dump_enc (cov, c, t);
662 casereader_destroy (reader);
667 const gsl_matrix *ucm = covariance_calculate_unnormalized (cov);
668 gsl_matrix *cm = gsl_matrix_alloc (ucm->size1, ucm->size2);
669 gsl_matrix_memcpy (cm, ucm);
673 ws.total_ssq = gsl_matrix_get (cm, 0, 0);
678 Store the overall SSE.
680 ws.ssq = gsl_vector_alloc (cm->size1);
681 gsl_vector_set (ws.ssq, 0, gsl_matrix_get (cm, 0, 0));
682 switch (cmd->ss_type)
685 ssq_type1 (cov, ws.ssq, cmd);
688 ssq_type2 (cov, ws.ssq, cmd);
691 ssq_type3 (cov, ws.ssq, cmd);
698 gsl_matrix_free (cm);
701 if (!taint_has_tainted_successor (taint))
702 output_glm (cmd, &ws);
704 gsl_vector_free (ws.ssq);
706 covariance_destroy (cov);
707 moments_destroy (ws.totals);
709 taint_destroy (taint);
712 static const char *roman[] =
714 "", /* The Romans had no concept of zero */
722 output_glm (const struct glm_spec *cmd, const struct glm_workspace *ws)
724 const struct fmt_spec *wfmt =
725 cmd->wv ? var_get_print_format (cmd->wv) : &F_8_0;
727 double intercept_ssq;
729 double n_total, mean;
730 double df_corr = 1.0;
735 const int heading_columns = 1;
736 const int heading_rows = 1;
740 int nr = heading_rows + 3 + cmd->n_interactions;
744 t = tab_create (nc, nr);
745 tab_set_format (t, RC_WEIGHT, wfmt);
746 tab_title (t, _("Tests of Between-Subjects Effects"));
748 tab_headers (t, heading_columns, 0, heading_rows, 0);
750 tab_box (t, TAL_2, TAL_2, -1, TAL_1, 0, 0, nc - 1, nr - 1);
752 tab_hline (t, TAL_2, 0, nc - 1, heading_rows);
753 tab_vline (t, TAL_2, heading_columns, 0, nr - 1);
755 tab_text (t, 0, 0, TAB_CENTER | TAT_TITLE, _("Source"));
757 /* TRANSLATORS: The parameter is a roman numeral */
758 tab_text_format (t, 1, 0, TAB_CENTER | TAT_TITLE,
759 _("Type %s Sum of Squares"),
760 roman[cmd->ss_type]);
761 tab_text (t, 2, 0, TAB_CENTER | TAT_TITLE, _("df"));
762 tab_text (t, 3, 0, TAB_CENTER | TAT_TITLE, _("Mean Square"));
763 tab_text (t, 4, 0, TAB_CENTER | TAT_TITLE, _("F"));
764 tab_text (t, 5, 0, TAB_CENTER | TAT_TITLE, _("Sig."));
766 moments_calculate (ws->totals, &n_total, &mean, NULL, NULL, NULL);
768 df_corr += categoricals_df_total (ws->cats);
772 tab_text (t, 0, r, TAB_LEFT | TAT_TITLE, _("Corrected Model"));
774 tab_text (t, 0, r, TAB_LEFT | TAT_TITLE, _("Model"));
778 mse = gsl_vector_get (ws->ssq, 0) / (n_total - df_corr);
780 intercept_ssq = pow2 (mean * n_total) / n_total;
785 const double df = 1.0;
786 const double F = intercept_ssq / df / mse;
787 tab_text (t, 0, r, TAB_LEFT | TAT_TITLE, _("Intercept"));
788 /* The intercept for unbalanced models is of limited use and
789 nobody knows how to calculate it properly */
790 if (categoricals_isbalanced (ws->cats))
792 tab_double (t, 1, r, 0, intercept_ssq, NULL, RC_OTHER);
793 tab_double (t, 2, r, 0, 1.00, NULL, RC_WEIGHT);
794 tab_double (t, 3, r, 0, intercept_ssq / df, NULL, RC_OTHER);
795 tab_double (t, 4, r, 0, F, NULL, RC_OTHER);
796 tab_double (t, 5, r, 0, gsl_cdf_fdist_Q (F, df, n_total - df_corr),
802 for (f = 0; f < cmd->n_interactions; ++f)
804 struct string str = DS_EMPTY_INITIALIZER;
805 double df = categoricals_df (ws->cats, f);
807 double ssq = gsl_vector_get (ws->ssq, f + 1);
812 if (! cmd->intercept)
815 ssq += intercept_ssq;
819 interaction_to_string (cmd->interactions[f], &str);
820 tab_text (t, 0, r, TAB_LEFT | TAT_TITLE, ds_cstr (&str));
823 tab_double (t, 1, r, 0, ssq, NULL, RC_OTHER);
824 tab_double (t, 2, r, 0, df, NULL, RC_WEIGHT);
825 tab_double (t, 3, r, 0, ssq / df, NULL, RC_OTHER);
826 tab_double (t, 4, r, 0, F, NULL, RC_OTHER);
828 tab_double (t, 5, r, 0, gsl_cdf_fdist_Q (F, df, n_total - df_corr),
834 /* Model / Corrected Model */
836 double ssq = ws->total_ssq - gsl_vector_get (ws->ssq, 0);
839 if ( cmd->intercept )
842 ssq += intercept_ssq;
845 tab_double (t, 1, heading_rows, 0, ssq, NULL, RC_OTHER);
846 tab_double (t, 2, heading_rows, 0, df, NULL, RC_WEIGHT);
847 tab_double (t, 3, heading_rows, 0, ssq / df, NULL, RC_OTHER);
848 tab_double (t, 4, heading_rows, 0, F, NULL, RC_OTHER);
850 tab_double (t, 5, heading_rows, 0,
851 gsl_cdf_fdist_Q (F, df, n_total - df_corr), NULL, RC_PVALUE);
855 const double df = n_total - df_corr;
856 const double ssq = gsl_vector_get (ws->ssq, 0);
857 const double mse = ssq / df;
858 tab_text (t, 0, r, TAB_LEFT | TAT_TITLE, _("Error"));
859 tab_double (t, 1, r, 0, ssq, NULL, RC_OTHER);
860 tab_double (t, 2, r, 0, df, NULL, RC_WEIGHT);
861 tab_double (t, 3, r++, 0, mse, NULL, RC_OTHER);
865 tab_text (t, 0, r, TAB_LEFT | TAT_TITLE, _("Total"));
866 tab_double (t, 1, r, 0, ws->total_ssq + intercept_ssq, NULL, RC_OTHER);
867 tab_double (t, 2, r, 0, n_total, NULL, RC_WEIGHT);
874 tab_text (t, 0, r, TAB_LEFT | TAT_TITLE, _("Corrected Total"));
875 tab_double (t, 1, r, 0, ws->total_ssq, NULL, RC_OTHER);
876 tab_double (t, 2, r, 0, n_total - 1.0, NULL, RC_WEIGHT);
884 dump_matrix (const gsl_matrix * m)
887 for (i = 0; i < m->size1; ++i)
889 for (j = 0; j < m->size2; ++j)
891 double x = gsl_matrix_get (m, i, j);
903 parse_nested_variable (struct lexer *lexer, struct glm_spec *glm)
905 const struct variable *v = NULL;
906 if ( ! lex_match_variable (lexer, glm->dict, &v))
909 if (lex_match (lexer, T_LPAREN))
911 if ( ! parse_nested_variable (lexer, glm))
914 if ( ! lex_force_match (lexer, T_RPAREN))
918 lex_error (lexer, "Nested variables are not yet implemented"); return false;
922 /* A design term is an interaction OR a nested variable */
924 parse_design_term (struct lexer *lexer, struct glm_spec *glm)
926 struct interaction *iact = NULL;
927 if (parse_design_interaction (lexer, glm->dict, &iact))
929 /* Interaction parsing successful. Add to list of interactions */
930 glm->interactions = xrealloc (glm->interactions, sizeof *glm->interactions * ++glm->n_interactions);
931 glm->interactions[glm->n_interactions - 1] = iact;
935 if ( parse_nested_variable (lexer, glm))
943 /* Parse a complete DESIGN specification.
944 A design spec is a design term, optionally followed by a comma,
945 and another design spec.
948 parse_design_spec (struct lexer *lexer, struct glm_spec *glm)
950 if (lex_token (lexer) == T_ENDCMD || lex_token (lexer) == T_SLASH)
953 if ( ! parse_design_term (lexer, glm))
956 lex_match (lexer, T_COMMA);
958 return parse_design_spec (lexer, glm);