609 lines
9.8 KiB
C
609 lines
9.8 KiB
C
/* $Id: lr0.c,v 1.19 2016/06/07 00:21:53 tom Exp $ */
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#include "defs.h"
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static core *new_state(int symbol);
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static Value_t get_state(int symbol);
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static void allocate_itemsets(void);
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static void allocate_storage(void);
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static void append_states(void);
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static void free_storage(void);
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static void generate_states(void);
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static void initialize_states(void);
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static void new_itemsets(void);
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static void save_reductions(void);
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static void save_shifts(void);
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static void set_derives(void);
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static void set_nullable(void);
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int nstates;
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core *first_state;
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shifts *first_shift;
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reductions *first_reduction;
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static core **state_set;
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static core *this_state;
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static core *last_state;
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static shifts *last_shift;
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static reductions *last_reduction;
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static int nshifts;
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static Value_t *shift_symbol;
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static Value_t *rules;
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static Value_t *redset;
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static Value_t *shiftset;
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static Value_t **kernel_base;
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static Value_t **kernel_end;
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static Value_t *kernel_items;
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static void
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allocate_itemsets(void)
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{
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Value_t *itemp;
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Value_t *item_end;
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int symbol;
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int i;
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int count;
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int max;
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Value_t *symbol_count;
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count = 0;
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symbol_count = NEW2(nsyms, Value_t);
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item_end = ritem + nitems;
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for (itemp = ritem; itemp < item_end; itemp++)
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{
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symbol = *itemp;
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if (symbol >= 0)
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{
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count++;
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symbol_count[symbol]++;
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}
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}
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kernel_base = NEW2(nsyms, Value_t *);
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kernel_items = NEW2(count, Value_t);
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count = 0;
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max = 0;
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for (i = 0; i < nsyms; i++)
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{
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kernel_base[i] = kernel_items + count;
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count += symbol_count[i];
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if (max < symbol_count[i])
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max = symbol_count[i];
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}
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shift_symbol = symbol_count;
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kernel_end = NEW2(nsyms, Value_t *);
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}
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static void
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allocate_storage(void)
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{
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allocate_itemsets();
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shiftset = NEW2(nsyms, Value_t);
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redset = NEW2(nrules + 1, Value_t);
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state_set = NEW2(nitems, core *);
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}
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static void
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append_states(void)
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{
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int i;
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int j;
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Value_t symbol;
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#ifdef TRACE
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fprintf(stderr, "Entering append_states()\n");
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#endif
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for (i = 1; i < nshifts; i++)
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{
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symbol = shift_symbol[i];
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j = i;
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while (j > 0 && shift_symbol[j - 1] > symbol)
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{
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shift_symbol[j] = shift_symbol[j - 1];
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j--;
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}
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shift_symbol[j] = symbol;
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}
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for (i = 0; i < nshifts; i++)
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{
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symbol = shift_symbol[i];
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shiftset[i] = get_state(symbol);
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}
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}
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static void
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free_storage(void)
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{
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FREE(shift_symbol);
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FREE(redset);
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FREE(shiftset);
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FREE(kernel_base);
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FREE(kernel_end);
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FREE(kernel_items);
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FREE(state_set);
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}
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static void
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generate_states(void)
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{
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allocate_storage();
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itemset = NEW2(nitems, Value_t);
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ruleset = NEW2(WORDSIZE(nrules), unsigned);
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set_first_derives();
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initialize_states();
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while (this_state)
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{
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closure(this_state->items, this_state->nitems);
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save_reductions();
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new_itemsets();
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append_states();
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if (nshifts > 0)
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save_shifts();
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this_state = this_state->next;
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}
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free_storage();
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}
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static Value_t
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get_state(int symbol)
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{
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int key;
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Value_t *isp1;
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Value_t *isp2;
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Value_t *iend;
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core *sp;
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int found;
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int n;
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#ifdef TRACE
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fprintf(stderr, "Entering get_state(%d)\n", symbol);
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#endif
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isp1 = kernel_base[symbol];
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iend = kernel_end[symbol];
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n = (int)(iend - isp1);
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key = *isp1;
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assert(0 <= key && key < nitems);
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sp = state_set[key];
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if (sp)
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{
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found = 0;
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while (!found)
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{
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if (sp->nitems == n)
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{
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found = 1;
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isp1 = kernel_base[symbol];
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isp2 = sp->items;
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while (found && isp1 < iend)
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{
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if (*isp1++ != *isp2++)
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found = 0;
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}
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}
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if (!found)
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{
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if (sp->link)
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{
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sp = sp->link;
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}
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else
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{
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sp = sp->link = new_state(symbol);
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found = 1;
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}
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}
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}
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}
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else
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{
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state_set[key] = sp = new_state(symbol);
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}
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return (sp->number);
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}
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static void
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initialize_states(void)
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{
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unsigned i;
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Value_t *start_derives;
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core *p;
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start_derives = derives[start_symbol];
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for (i = 0; start_derives[i] >= 0; ++i)
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continue;
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p = (core *)MALLOC(sizeof(core) + i * sizeof(Value_t));
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NO_SPACE(p);
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p->next = 0;
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p->link = 0;
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p->number = 0;
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p->accessing_symbol = 0;
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p->nitems = (Value_t)i;
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for (i = 0; start_derives[i] >= 0; ++i)
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p->items[i] = rrhs[start_derives[i]];
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first_state = last_state = this_state = p;
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nstates = 1;
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}
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static void
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new_itemsets(void)
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{
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Value_t i;
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int shiftcount;
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Value_t *isp;
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Value_t *ksp;
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Value_t symbol;
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for (i = 0; i < nsyms; i++)
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kernel_end[i] = 0;
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shiftcount = 0;
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isp = itemset;
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while (isp < itemsetend)
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{
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i = *isp++;
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symbol = ritem[i];
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if (symbol > 0)
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{
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ksp = kernel_end[symbol];
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if (!ksp)
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{
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shift_symbol[shiftcount++] = symbol;
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ksp = kernel_base[symbol];
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}
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*ksp++ = (Value_t)(i + 1);
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kernel_end[symbol] = ksp;
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}
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}
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nshifts = shiftcount;
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}
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static core *
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new_state(int symbol)
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{
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unsigned n;
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core *p;
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Value_t *isp1;
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Value_t *isp2;
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Value_t *iend;
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#ifdef TRACE
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fprintf(stderr, "Entering new_state(%d)\n", symbol);
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#endif
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if (nstates >= MAXYYINT)
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fatal("too many states");
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isp1 = kernel_base[symbol];
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iend = kernel_end[symbol];
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n = (unsigned)(iend - isp1);
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p = (core *)allocate((sizeof(core) + (n - 1) * sizeof(Value_t)));
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p->accessing_symbol = (Value_t)symbol;
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p->number = (Value_t)nstates;
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p->nitems = (Value_t)n;
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isp2 = p->items;
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while (isp1 < iend)
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*isp2++ = *isp1++;
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last_state->next = p;
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last_state = p;
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nstates++;
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return (p);
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}
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/* show_cores is used for debugging */
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#ifdef DEBUG
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void
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show_cores(void)
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{
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core *p;
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int i, j, k, n;
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int itemno;
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k = 0;
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for (p = first_state; p; ++k, p = p->next)
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{
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if (k)
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printf("\n");
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printf("state %d, number = %d, accessing symbol = %s\n",
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k, p->number, symbol_name[p->accessing_symbol]);
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n = p->nitems;
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for (i = 0; i < n; ++i)
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{
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itemno = p->items[i];
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printf("%4d ", itemno);
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j = itemno;
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while (ritem[j] >= 0)
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++j;
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printf("%s :", symbol_name[rlhs[-ritem[j]]]);
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j = rrhs[-ritem[j]];
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while (j < itemno)
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printf(" %s", symbol_name[ritem[j++]]);
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printf(" .");
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while (ritem[j] >= 0)
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printf(" %s", symbol_name[ritem[j++]]);
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printf("\n");
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fflush(stdout);
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}
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}
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}
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/* show_ritems is used for debugging */
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void
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show_ritems(void)
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{
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int i;
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for (i = 0; i < nitems; ++i)
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printf("ritem[%d] = %d\n", i, ritem[i]);
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}
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/* show_rrhs is used for debugging */
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void
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show_rrhs(void)
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{
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int i;
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for (i = 0; i < nrules; ++i)
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printf("rrhs[%d] = %d\n", i, rrhs[i]);
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}
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/* show_shifts is used for debugging */
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void
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show_shifts(void)
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{
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shifts *p;
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int i, j, k;
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k = 0;
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for (p = first_shift; p; ++k, p = p->next)
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{
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if (k)
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printf("\n");
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printf("shift %d, number = %d, nshifts = %d\n", k, p->number,
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p->nshifts);
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j = p->nshifts;
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for (i = 0; i < j; ++i)
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printf("\t%d\n", p->shift[i]);
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}
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}
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#endif
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static void
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save_shifts(void)
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{
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shifts *p;
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Value_t *sp1;
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Value_t *sp2;
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Value_t *send;
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p = (shifts *)allocate((sizeof(shifts) +
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(unsigned)(nshifts - 1) * sizeof(Value_t)));
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p->number = this_state->number;
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p->nshifts = (Value_t)nshifts;
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sp1 = shiftset;
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sp2 = p->shift;
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send = shiftset + nshifts;
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while (sp1 < send)
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*sp2++ = *sp1++;
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if (last_shift)
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{
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last_shift->next = p;
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last_shift = p;
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}
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else
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{
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first_shift = p;
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last_shift = p;
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}
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}
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static void
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save_reductions(void)
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{
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Value_t *isp;
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Value_t *rp1;
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Value_t *rp2;
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int item;
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Value_t count;
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reductions *p;
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Value_t *rend;
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count = 0;
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for (isp = itemset; isp < itemsetend; isp++)
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{
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item = ritem[*isp];
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if (item < 0)
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{
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redset[count++] = (Value_t)-item;
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}
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}
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if (count)
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{
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p = (reductions *)allocate((sizeof(reductions) +
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(unsigned)(count - 1) *
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sizeof(Value_t)));
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p->number = this_state->number;
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p->nreds = count;
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rp1 = redset;
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rp2 = p->rules;
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rend = rp1 + count;
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while (rp1 < rend)
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*rp2++ = *rp1++;
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if (last_reduction)
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{
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last_reduction->next = p;
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last_reduction = p;
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}
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else
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{
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first_reduction = p;
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last_reduction = p;
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}
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}
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}
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static void
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set_derives(void)
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{
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Value_t i, k;
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int lhs;
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derives = NEW2(nsyms, Value_t *);
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rules = NEW2(nvars + nrules, Value_t);
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k = 0;
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for (lhs = start_symbol; lhs < nsyms; lhs++)
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{
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derives[lhs] = rules + k;
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for (i = 0; i < nrules; i++)
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{
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if (rlhs[i] == lhs)
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{
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rules[k] = i;
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k++;
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}
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}
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rules[k] = -1;
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k++;
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}
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#ifdef DEBUG
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print_derives();
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#endif
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}
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#ifdef DEBUG
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void
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print_derives(void)
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{
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int i;
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Value_t *sp;
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printf("\nDERIVES\n\n");
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for (i = start_symbol; i < nsyms; i++)
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{
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printf("%s derives ", symbol_name[i]);
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for (sp = derives[i]; *sp >= 0; sp++)
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{
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printf(" %d", *sp);
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}
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putchar('\n');
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}
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putchar('\n');
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}
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#endif
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static void
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set_nullable(void)
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{
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int i, j;
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int empty;
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int done_flag;
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nullable = TMALLOC(char, nsyms);
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NO_SPACE(nullable);
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for (i = 0; i < nsyms; ++i)
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nullable[i] = 0;
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done_flag = 0;
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while (!done_flag)
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{
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done_flag = 1;
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for (i = 1; i < nitems; i++)
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{
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empty = 1;
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while ((j = ritem[i]) >= 0)
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{
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if (!nullable[j])
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empty = 0;
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++i;
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}
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if (empty)
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{
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j = rlhs[-j];
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if (!nullable[j])
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{
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nullable[j] = 1;
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done_flag = 0;
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}
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}
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}
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}
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#ifdef DEBUG
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for (i = 0; i < nsyms; i++)
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{
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if (nullable[i])
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printf("%s is nullable\n", symbol_name[i]);
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else
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printf("%s is not nullable\n", symbol_name[i]);
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}
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#endif
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}
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void
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lr0(void)
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{
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set_derives();
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set_nullable();
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generate_states();
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}
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#ifdef NO_LEAKS
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void
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lr0_leaks(void)
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{
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if (derives)
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{
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if (derives[start_symbol] != rules)
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{
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DO_FREE(derives[start_symbol]);
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}
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DO_FREE(derives);
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DO_FREE(rules);
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}
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DO_FREE(nullable);
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}
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#endif
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