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467 lines
11 KiB
C
467 lines
11 KiB
C
/* Type definitions for the finite state machine for Bison.
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Copyright (C) 2001-2007, 2009-2013 Free Software Foundation, Inc.
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This file is part of Bison, the GNU Compiler Compiler.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <config.h>
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#include "system.h"
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#include <hash.h>
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#include "complain.h"
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#include "gram.h"
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#include "state.h"
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#include "print-xml.h"
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/*-------------------.
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| Shifts and Gotos. |
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`-------------------*/
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/*-----------------------------------------.
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| Create a new array of NUM shifts/gotos. |
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`-----------------------------------------*/
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static transitions *
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transitions_new (int num, state **the_states)
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{
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size_t states_size = num * sizeof *the_states;
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transitions *res = xmalloc (offsetof (transitions, states) + states_size);
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res->num = num;
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memcpy (res->states, the_states, states_size);
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return res;
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}
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/*-------------------------------------------------------.
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| Return the state such that SHIFTS contain a shift/goto |
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| to it on SYM. Abort if none found. |
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`-------------------------------------------------------*/
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state *
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transitions_to (transitions *shifts, symbol_number sym)
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{
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int j;
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for (j = 0; ; j++)
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{
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aver (j < shifts->num);
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if (TRANSITION_SYMBOL (shifts, j) == sym)
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return shifts->states[j];
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}
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}
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/*--------------------.
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| Error transitions. |
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`--------------------*/
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/*---------------------------------.
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| Create a new array of NUM errs. |
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`---------------------------------*/
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errs *
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errs_new (int num, symbol **tokens)
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{
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size_t symbols_size = num * sizeof *tokens;
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errs *res = xmalloc (offsetof (errs, symbols) + symbols_size);
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res->num = num;
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memcpy (res->symbols, tokens, symbols_size);
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return res;
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}
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/*-------------.
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| Reductions. |
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`-------------*/
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/*---------------------------------------.
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| Create a new array of NUM reductions. |
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`---------------------------------------*/
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static reductions *
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reductions_new (int num, rule **reds)
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{
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size_t rules_size = num * sizeof *reds;
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reductions *res = xmalloc (offsetof (reductions, rules) + rules_size);
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res->num = num;
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res->lookahead_tokens = NULL;
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memcpy (res->rules, reds, rules_size);
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return res;
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}
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/*---------.
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| States. |
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`---------*/
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state_number nstates = 0;
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/* FINAL_STATE is properly set by new_state when it recognizes its
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accessing symbol: $end. */
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state *final_state = NULL;
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/*------------------------------------------------------------------.
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| Create a new state with ACCESSING_SYMBOL, for those items. Store |
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| it in the state hash table. |
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`------------------------------------------------------------------*/
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state *
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state_new (symbol_number accessing_symbol,
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size_t nitems, item_number *core)
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{
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state *res;
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size_t items_size = nitems * sizeof *core;
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aver (nstates < STATE_NUMBER_MAXIMUM);
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res = xmalloc (offsetof (state, items) + items_size);
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res->number = nstates++;
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res->accessing_symbol = accessing_symbol;
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res->transitions = NULL;
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res->reductions = NULL;
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res->errs = NULL;
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res->state_list = NULL;
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res->consistent = 0;
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res->solved_conflicts = NULL;
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res->solved_conflicts_xml = NULL;
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res->nitems = nitems;
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memcpy (res->items, core, items_size);
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state_hash_insert (res);
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return res;
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}
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state *
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state_new_isocore (state const *s)
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{
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state *res;
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size_t items_size = s->nitems * sizeof *s->items;
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aver (nstates < STATE_NUMBER_MAXIMUM);
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res = xmalloc (offsetof (state, items) + items_size);
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res->number = nstates++;
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res->accessing_symbol = s->accessing_symbol;
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res->transitions =
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transitions_new (s->transitions->num, s->transitions->states);
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res->reductions = reductions_new (s->reductions->num, s->reductions->rules);
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res->errs = NULL;
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res->state_list = NULL;
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res->consistent = s->consistent;
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res->solved_conflicts = NULL;
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res->solved_conflicts_xml = NULL;
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res->nitems = s->nitems;
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memcpy (res->items, s->items, items_size);
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return res;
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}
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/*---------.
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| Free S. |
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`---------*/
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static void
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state_free (state *s)
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{
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free (s->transitions);
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free (s->reductions);
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free (s->errs);
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free (s);
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}
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/*---------------------------.
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| Set the transitions of S. |
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`---------------------------*/
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void
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state_transitions_set (state *s, int num, state **trans)
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{
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aver (!s->transitions);
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s->transitions = transitions_new (num, trans);
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}
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/*--------------------------.
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| Set the reductions of S. |
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`--------------------------*/
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void
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state_reductions_set (state *s, int num, rule **reds)
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{
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aver (!s->reductions);
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s->reductions = reductions_new (num, reds);
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}
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int
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state_reduction_find (state *s, rule *r)
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{
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int i;
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reductions *reds = s->reductions;
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for (i = 0; i < reds->num; ++i)
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if (reds->rules[i] == r)
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return i;
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return -1;
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}
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/*--------------------.
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| Set the errs of S. |
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`--------------------*/
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void
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state_errs_set (state *s, int num, symbol **tokens)
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{
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aver (!s->errs);
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s->errs = errs_new (num, tokens);
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}
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/*--------------------------------------------------.
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| Print on OUT all the lookahead tokens such that S |
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| wants to reduce R. |
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`--------------------------------------------------*/
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void
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state_rule_lookahead_tokens_print (state *s, rule *r, FILE *out)
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{
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/* Find the reduction we are handling. */
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reductions *reds = s->reductions;
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int red = state_reduction_find (s, r);
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/* Print them if there are. */
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if (reds->lookahead_tokens && red != -1)
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{
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bitset_iterator biter;
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int k;
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char const *sep = "";
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fprintf (out, " [");
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BITSET_FOR_EACH (biter, reds->lookahead_tokens[red], k, 0)
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{
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fprintf (out, "%s%s", sep, symbols[k]->tag);
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sep = ", ";
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}
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fprintf (out, "]");
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}
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}
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void
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state_rule_lookahead_tokens_print_xml (state *s, rule *r,
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FILE *out, int level)
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{
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/* Find the reduction we are handling. */
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reductions *reds = s->reductions;
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int red = state_reduction_find (s, r);
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/* Print them if there are. */
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if (reds->lookahead_tokens && red != -1)
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{
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bitset_iterator biter;
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int k;
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xml_puts (out, level, "<lookaheads>");
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BITSET_FOR_EACH (biter, reds->lookahead_tokens[red], k, 0)
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{
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xml_printf (out, level + 1, "<symbol>%s</symbol>",
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xml_escape (symbols[k]->tag));
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}
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xml_puts (out, level, "</lookaheads>");
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}
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}
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/*---------------------.
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| A state hash table. |
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`---------------------*/
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/* Initial capacity of states hash table. */
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#define HT_INITIAL_CAPACITY 257
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static struct hash_table *state_table = NULL;
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/* Two states are equal if they have the same core items. */
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static inline bool
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state_compare (state const *s1, state const *s2)
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{
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size_t i;
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if (s1->nitems != s2->nitems)
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return false;
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for (i = 0; i < s1->nitems; ++i)
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if (s1->items[i] != s2->items[i])
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return false;
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return true;
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}
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static bool
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state_comparator (void const *s1, void const *s2)
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{
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return state_compare (s1, s2);
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}
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static inline size_t
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state_hash (state const *s, size_t tablesize)
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{
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/* Add up the state's item numbers to get a hash key. */
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size_t key = 0;
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size_t i;
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for (i = 0; i < s->nitems; ++i)
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key += s->items[i];
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return key % tablesize;
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}
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static size_t
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state_hasher (void const *s, size_t tablesize)
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{
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return state_hash (s, tablesize);
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}
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/*-------------------------------.
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| Create the states hash table. |
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`-------------------------------*/
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void
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state_hash_new (void)
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{
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state_table = hash_initialize (HT_INITIAL_CAPACITY,
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NULL,
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state_hasher,
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state_comparator,
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NULL);
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}
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/*---------------------------------------------.
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| Free the states hash table, not the states. |
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`---------------------------------------------*/
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void
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state_hash_free (void)
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{
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hash_free (state_table);
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}
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/*-----------------------------------.
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| Insert S in the state hash table. |
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`-----------------------------------*/
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void
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state_hash_insert (state *s)
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{
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if (!hash_insert (state_table, s))
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xalloc_die ();
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}
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/*------------------------------------------------------------------.
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| Find the state associated to the CORE, and return it. If it does |
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| not exist yet, return NULL. |
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`------------------------------------------------------------------*/
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state *
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state_hash_lookup (size_t nitems, item_number *core)
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{
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size_t items_size = nitems * sizeof *core;
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state *probe = xmalloc (offsetof (state, items) + items_size);
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state *entry;
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probe->nitems = nitems;
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memcpy (probe->items, core, items_size);
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entry = hash_lookup (state_table, probe);
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free (probe);
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return entry;
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}
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/*--------------------------------------------------------.
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| Record S and all states reachable from S in REACHABLE. |
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`--------------------------------------------------------*/
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static void
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state_record_reachable_states (state *s, bitset reachable)
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{
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if (bitset_test (reachable, s->number))
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return;
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bitset_set (reachable, s->number);
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{
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int i;
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for (i = 0; i < s->transitions->num; ++i)
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if (!TRANSITION_IS_DISABLED (s->transitions, i))
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state_record_reachable_states (s->transitions->states[i], reachable);
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}
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}
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void
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state_remove_unreachable_states (state_number old_to_new[])
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{
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state_number nstates_reachable = 0;
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bitset reachable = bitset_create (nstates, BITSET_FIXED);
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state_record_reachable_states (states[0], reachable);
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{
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state_number i;
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for (i = 0; i < nstates; ++i)
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{
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if (bitset_test (reachable, states[i]->number))
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{
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states[nstates_reachable] = states[i];
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states[nstates_reachable]->number = nstates_reachable;
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old_to_new[i] = nstates_reachable++;
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}
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else
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{
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state_free (states[i]);
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old_to_new[i] = nstates;
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}
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}
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}
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nstates = nstates_reachable;
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bitset_free (reachable);
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}
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/* All the decorated states, indexed by the state number. */
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state **states = NULL;
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/*----------------------.
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| Free all the states. |
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`----------------------*/
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void
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states_free (void)
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{
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state_number i;
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for (i = 0; i < nstates; ++i)
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state_free (states[i]);
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free (states);
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}
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