| Index: bison/src/bison/2.4.1/bison-2.4.1-src/src/LR0.c
|
| ===================================================================
|
| --- bison/src/bison/2.4.1/bison-2.4.1-src/src/LR0.c (revision 0)
|
| +++ bison/src/bison/2.4.1/bison-2.4.1-src/src/LR0.c (revision 0)
|
| @@ -0,0 +1,377 @@
|
| +/* Generate the nondeterministic finite state machine for Bison.
|
| +
|
| + Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2004, 2005, 2006, 2007
|
| + Free Software Foundation, Inc.
|
| +
|
| + This file is part of Bison, the GNU Compiler Compiler.
|
| +
|
| + This program is free software: you can redistribute it and/or modify
|
| + it under the terms of the GNU General Public License as published by
|
| + the Free Software Foundation, either version 3 of the License, or
|
| + (at your option) any later version.
|
| +
|
| + This program is distributed in the hope that it will be useful,
|
| + but WITHOUT ANY WARRANTY; without even the implied warranty of
|
| + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
| + GNU General Public License for more details.
|
| +
|
| + You should have received a copy of the GNU General Public License
|
| + along with this program. If not, see <http://www.gnu.org/licenses/>. */
|
| +
|
| +
|
| +/* See comments in state.h for the data structures that represent it.
|
| + The entry point is generate_states. */
|
| +
|
| +#include <config.h>
|
| +#include "system.h"
|
| +
|
| +#include <bitset.h>
|
| +#include <quotearg.h>
|
| +
|
| +#include "LR0.h"
|
| +#include "closure.h"
|
| +#include "complain.h"
|
| +#include "getargs.h"
|
| +#include "gram.h"
|
| +#include "gram.h"
|
| +#include "lalr.h"
|
| +#include "reader.h"
|
| +#include "reduce.h"
|
| +#include "state.h"
|
| +#include "symtab.h"
|
| +
|
| +typedef struct state_list
|
| +{
|
| + struct state_list *next;
|
| + state *state;
|
| +} state_list;
|
| +
|
| +static state_list *first_state = NULL;
|
| +static state_list *last_state = NULL;
|
| +
|
| +
|
| +/*------------------------------------------------------------------.
|
| +| A state was just discovered from another state. Queue it for |
|
| +| later examination, in order to find its transitions. Return it. |
|
| +`------------------------------------------------------------------*/
|
| +
|
| +static state *
|
| +state_list_append (symbol_number sym, size_t core_size, item_number *core)
|
| +{
|
| + state_list *node = xmalloc (sizeof *node);
|
| + state *s = state_new (sym, core_size, core);
|
| +
|
| + if (trace_flag & trace_automaton)
|
| + fprintf (stderr, "state_list_append (state = %d, symbol = %d (%s))\n",
|
| + nstates, sym, symbols[sym]->tag);
|
| +
|
| + node->next = NULL;
|
| + node->state = s;
|
| +
|
| + if (!first_state)
|
| + first_state = node;
|
| + if (last_state)
|
| + last_state->next = node;
|
| + last_state = node;
|
| +
|
| + return s;
|
| +}
|
| +
|
| +static int nshifts;
|
| +static symbol_number *shift_symbol;
|
| +
|
| +static rule **redset;
|
| +static state **shiftset;
|
| +
|
| +static item_number **kernel_base;
|
| +static int *kernel_size;
|
| +static item_number *kernel_items;
|
| +
|
| +
|
| +static void
|
| +allocate_itemsets (void)
|
| +{
|
| + symbol_number i;
|
| + rule_number r;
|
| + item_number *rhsp;
|
| +
|
| + /* Count the number of occurrences of all the symbols in RITEMS.
|
| + Note that useless productions (hence useless nonterminals) are
|
| + browsed too, hence we need to allocate room for _all_ the
|
| + symbols. */
|
| + size_t count = 0;
|
| + size_t *symbol_count = xcalloc (nsyms + nuseless_nonterminals,
|
| + sizeof *symbol_count);
|
| +
|
| + for (r = 0; r < nrules; ++r)
|
| + for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
|
| + {
|
| + count++;
|
| + symbol_count[*rhsp]++;
|
| + }
|
| +
|
| + /* See comments before new_itemsets. All the vectors of items
|
| + live inside KERNEL_ITEMS. The number of active items after
|
| + some symbol S cannot be more than the number of times that S
|
| + appears as an item, which is SYMBOL_COUNT[S].
|
| + We allocate that much space for each symbol. */
|
| +
|
| + kernel_base = xnmalloc (nsyms, sizeof *kernel_base);
|
| + kernel_items = xnmalloc (count, sizeof *kernel_items);
|
| +
|
| + count = 0;
|
| + for (i = 0; i < nsyms; i++)
|
| + {
|
| + kernel_base[i] = kernel_items + count;
|
| + count += symbol_count[i];
|
| + }
|
| +
|
| + free (symbol_count);
|
| + kernel_size = xnmalloc (nsyms, sizeof *kernel_size);
|
| +}
|
| +
|
| +
|
| +static void
|
| +allocate_storage (void)
|
| +{
|
| + allocate_itemsets ();
|
| +
|
| + shiftset = xnmalloc (nsyms, sizeof *shiftset);
|
| + redset = xnmalloc (nrules, sizeof *redset);
|
| + state_hash_new ();
|
| + shift_symbol = xnmalloc (nsyms, sizeof *shift_symbol);
|
| +}
|
| +
|
| +
|
| +static void
|
| +free_storage (void)
|
| +{
|
| + free (shift_symbol);
|
| + free (redset);
|
| + free (shiftset);
|
| + free (kernel_base);
|
| + free (kernel_size);
|
| + free (kernel_items);
|
| + state_hash_free ();
|
| +}
|
| +
|
| +
|
| +
|
| +
|
| +/*---------------------------------------------------------------.
|
| +| Find which symbols can be shifted in S, and for each one |
|
| +| record which items would be active after that shift. Uses the |
|
| +| contents of itemset. |
|
| +| |
|
| +| shift_symbol is set to a vector of the symbols that can be |
|
| +| shifted. For each symbol in the grammar, kernel_base[symbol] |
|
| +| points to a vector of item numbers activated if that symbol is |
|
| +| shifted, and kernel_size[symbol] is their numbers. |
|
| +| |
|
| +| itemset is sorted on item index in ritem, which is sorted on |
|
| +| rule number. Compute each kernel_base[symbol] with the same |
|
| +| sort. |
|
| +`---------------------------------------------------------------*/
|
| +
|
| +static void
|
| +new_itemsets (state *s)
|
| +{
|
| + size_t i;
|
| +
|
| + if (trace_flag & trace_automaton)
|
| + fprintf (stderr, "Entering new_itemsets, state = %d\n", s->number);
|
| +
|
| + memset (kernel_size, 0, nsyms * sizeof *kernel_size);
|
| +
|
| + nshifts = 0;
|
| +
|
| + for (i = 0; i < nitemset; ++i)
|
| + if (item_number_is_symbol_number (ritem[itemset[i]]))
|
| + {
|
| + symbol_number sym = item_number_as_symbol_number (ritem[itemset[i]]);
|
| + if (!kernel_size[sym])
|
| + {
|
| + shift_symbol[nshifts] = sym;
|
| + nshifts++;
|
| + }
|
| +
|
| + kernel_base[sym][kernel_size[sym]] = itemset[i] + 1;
|
| + kernel_size[sym]++;
|
| + }
|
| +}
|
| +
|
| +
|
| +
|
| +/*--------------------------------------------------------------.
|
| +| Find the state we would get to (from the current state) by |
|
| +| shifting SYM. Create a new state if no equivalent one exists |
|
| +| already. Used by append_states. |
|
| +`--------------------------------------------------------------*/
|
| +
|
| +static state *
|
| +get_state (symbol_number sym, size_t core_size, item_number *core)
|
| +{
|
| + state *s;
|
| +
|
| + if (trace_flag & trace_automaton)
|
| + fprintf (stderr, "Entering get_state, symbol = %d (%s)\n",
|
| + sym, symbols[sym]->tag);
|
| +
|
| + s = state_hash_lookup (core_size, core);
|
| + if (!s)
|
| + s = state_list_append (sym, core_size, core);
|
| +
|
| + if (trace_flag & trace_automaton)
|
| + fprintf (stderr, "Exiting get_state => %d\n", s->number);
|
| +
|
| + return s;
|
| +}
|
| +
|
| +/*---------------------------------------------------------------.
|
| +| Use the information computed by new_itemsets to find the state |
|
| +| numbers reached by each shift transition from S. |
|
| +| |
|
| +| SHIFTSET is set up as a vector of those states. |
|
| +`---------------------------------------------------------------*/
|
| +
|
| +static void
|
| +append_states (state *s)
|
| +{
|
| + int i;
|
| +
|
| + if (trace_flag & trace_automaton)
|
| + fprintf (stderr, "Entering append_states, state = %d\n", s->number);
|
| +
|
| + /* First sort shift_symbol into increasing order. */
|
| +
|
| + for (i = 1; i < nshifts; i++)
|
| + {
|
| + symbol_number sym = shift_symbol[i];
|
| + int j;
|
| + for (j = i; 0 < j && sym < shift_symbol[j - 1]; j--)
|
| + shift_symbol[j] = shift_symbol[j - 1];
|
| + shift_symbol[j] = sym;
|
| + }
|
| +
|
| + for (i = 0; i < nshifts; i++)
|
| + {
|
| + symbol_number sym = shift_symbol[i];
|
| + shiftset[i] = get_state (sym, kernel_size[sym], kernel_base[sym]);
|
| + }
|
| +}
|
| +
|
| +
|
| +/*----------------------------------------------------------------.
|
| +| Find which rules can be used for reduction transitions from the |
|
| +| current state and make a reductions structure for the state to |
|
| +| record their rule numbers. |
|
| +`----------------------------------------------------------------*/
|
| +
|
| +static void
|
| +save_reductions (state *s)
|
| +{
|
| + int count = 0;
|
| + size_t i;
|
| +
|
| + /* Find and count the active items that represent ends of rules. */
|
| + for (i = 0; i < nitemset; ++i)
|
| + {
|
| + item_number item = ritem[itemset[i]];
|
| + if (item_number_is_rule_number (item))
|
| + {
|
| + rule_number r = item_number_as_rule_number (item);
|
| + redset[count++] = &rules[r];
|
| + if (r == 0)
|
| + {
|
| + /* This is "reduce 0", i.e., accept. */
|
| + aver (!final_state);
|
| + final_state = s;
|
| + }
|
| + }
|
| + }
|
| +
|
| + /* Make a reductions structure and copy the data into it. */
|
| + state_reductions_set (s, count, redset);
|
| +}
|
| +
|
| +
|
| +/*---------------.
|
| +| Build STATES. |
|
| +`---------------*/
|
| +
|
| +static void
|
| +set_states (void)
|
| +{
|
| + states = xcalloc (nstates, sizeof *states);
|
| +
|
| + while (first_state)
|
| + {
|
| + state_list *this = first_state;
|
| +
|
| + /* Pessimization, but simplification of the code: make sure all
|
| + the states have valid transitions and reductions members,
|
| + even if reduced to 0. It is too soon for errs, which are
|
| + computed later, but set_conflicts. */
|
| + state *s = this->state;
|
| + if (!s->transitions)
|
| + state_transitions_set (s, 0, 0);
|
| + if (!s->reductions)
|
| + state_reductions_set (s, 0, 0);
|
| +
|
| + states[s->number] = s;
|
| +
|
| + first_state = this->next;
|
| + free (this);
|
| + }
|
| + first_state = NULL;
|
| + last_state = NULL;
|
| +}
|
| +
|
| +
|
| +/*-------------------------------------------------------------------.
|
| +| Compute the nondeterministic finite state machine (see state.h for |
|
| +| details) from the grammar. |
|
| +`-------------------------------------------------------------------*/
|
| +
|
| +void
|
| +generate_states (void)
|
| +{
|
| + item_number initial_core = 0;
|
| + state_list *list = NULL;
|
| + allocate_storage ();
|
| + new_closure (nritems);
|
| +
|
| + /* Create the initial state. The 0 at the lhs is the index of the
|
| + item of this initial rule. */
|
| + state_list_append (0, 1, &initial_core);
|
| +
|
| + /* States are queued when they are created; process them all. */
|
| + for (list = first_state; list; list = list->next)
|
| + {
|
| + state *s = list->state;
|
| + if (trace_flag & trace_automaton)
|
| + fprintf (stderr, "Processing state %d (reached by %s)\n",
|
| + s->number,
|
| + symbols[s->accessing_symbol]->tag);
|
| + /* Set up itemset for the transitions out of this state. itemset gets a
|
| + vector of all the items that could be accepted next. */
|
| + closure (s->items, s->nitems);
|
| + /* Record the reductions allowed out of this state. */
|
| + save_reductions (s);
|
| + /* Find the itemsets of the states that shifts can reach. */
|
| + new_itemsets (s);
|
| + /* Find or create the core structures for those states. */
|
| + append_states (s);
|
| +
|
| + /* Create the shifts structures for the shifts to those states,
|
| + now that the state numbers transitioning to are known. */
|
| + state_transitions_set (s, nshifts, shiftset);
|
| + }
|
| +
|
| + /* discard various storage */
|
| + free_closure ();
|
| + free_storage ();
|
| +
|
| + /* Set up STATES. */
|
| + set_states ();
|
| +}
|
|
|
| Property changes on: bison\src\bison\2.4.1\bison-2.4.1-src\src\LR0.c
|
| ___________________________________________________________________
|
| Added: svn:eol-style
|
| + LF
|
|
|
|
|