| [2] | 1 |
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| 2 | /* Computation of FIRST stets */
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| 3 |
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| 4 | #include "pgenheaders.h"
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| 5 | #include "grammar.h"
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| 6 | #include "token.h"
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| 7 |
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| 8 | extern int Py_DebugFlag;
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| 9 |
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| 10 | /* Forward */
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| 11 | static void calcfirstset(grammar *, dfa *);
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| 12 |
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| 13 | void
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| 14 | addfirstsets(grammar *g)
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| 15 | {
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| [391] | 16 | int i;
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| 17 | dfa *d;
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| [2] | 18 |
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| [391] | 19 | if (Py_DebugFlag)
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| 20 | printf("Adding FIRST sets ...\n");
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| 21 | for (i = 0; i < g->g_ndfas; i++) {
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| 22 | d = &g->g_dfa[i];
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| 23 | if (d->d_first == NULL)
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| 24 | calcfirstset(g, d);
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| 25 | }
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| [2] | 26 | }
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| 27 |
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| 28 | static void
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| 29 | calcfirstset(grammar *g, dfa *d)
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| 30 | {
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| [391] | 31 | int i, j;
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| 32 | state *s;
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| 33 | arc *a;
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| 34 | int nsyms;
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| 35 | int *sym;
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| 36 | int nbits;
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| 37 | static bitset dummy;
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| 38 | bitset result;
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| 39 | int type;
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| 40 | dfa *d1;
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| 41 | label *l0;
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| [2] | 42 |
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| [391] | 43 | if (Py_DebugFlag)
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| 44 | printf("Calculate FIRST set for '%s'\n", d->d_name);
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| 45 |
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| 46 | if (dummy == NULL)
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| 47 | dummy = newbitset(1);
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| 48 | if (d->d_first == dummy) {
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| 49 | fprintf(stderr, "Left-recursion for '%s'\n", d->d_name);
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| 50 | return;
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| 51 | }
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| 52 | if (d->d_first != NULL) {
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| 53 | fprintf(stderr, "Re-calculating FIRST set for '%s' ???\n",
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| 54 | d->d_name);
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| 55 | }
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| 56 | d->d_first = dummy;
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| 57 |
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| 58 | l0 = g->g_ll.ll_label;
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| 59 | nbits = g->g_ll.ll_nlabels;
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| 60 | result = newbitset(nbits);
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| 61 |
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| 62 | sym = (int *)PyObject_MALLOC(sizeof(int));
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| 63 | if (sym == NULL)
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| 64 | Py_FatalError("no mem for new sym in calcfirstset");
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| 65 | nsyms = 1;
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| 66 | sym[0] = findlabel(&g->g_ll, d->d_type, (char *)NULL);
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| 67 |
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| 68 | s = &d->d_state[d->d_initial];
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| 69 | for (i = 0; i < s->s_narcs; i++) {
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| 70 | a = &s->s_arc[i];
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| 71 | for (j = 0; j < nsyms; j++) {
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| 72 | if (sym[j] == a->a_lbl)
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| 73 | break;
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| 74 | }
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| 75 | if (j >= nsyms) { /* New label */
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| 76 | sym = (int *)PyObject_REALLOC(sym,
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| 77 | sizeof(int) * (nsyms + 1));
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| 78 | if (sym == NULL)
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| 79 | Py_FatalError(
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| 80 | "no mem to resize sym in calcfirstset");
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| 81 | sym[nsyms++] = a->a_lbl;
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| 82 | type = l0[a->a_lbl].lb_type;
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| 83 | if (ISNONTERMINAL(type)) {
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| 84 | d1 = PyGrammar_FindDFA(g, type);
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| 85 | if (d1->d_first == dummy) {
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| 86 | fprintf(stderr,
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| 87 | "Left-recursion below '%s'\n",
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| 88 | d->d_name);
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| 89 | }
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| 90 | else {
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| 91 | if (d1->d_first == NULL)
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| 92 | calcfirstset(g, d1);
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| 93 | mergebitset(result,
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| 94 | d1->d_first, nbits);
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| 95 | }
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| 96 | }
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| 97 | else if (ISTERMINAL(type)) {
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| 98 | addbit(result, a->a_lbl);
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| 99 | }
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| 100 | }
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| 101 | }
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| 102 | d->d_first = result;
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| 103 | if (Py_DebugFlag) {
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| 104 | printf("FIRST set for '%s': {", d->d_name);
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| 105 | for (i = 0; i < nbits; i++) {
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| 106 | if (testbit(result, i))
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| 107 | printf(" %s", PyGrammar_LabelRepr(&l0[i]));
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| 108 | }
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| 109 | printf(" }\n");
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| 110 | }
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| 111 |
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| 112 | PyObject_FREE(sym);
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| [2] | 113 | }
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