X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/0fb669f9d648dfdd7a39478a6b658511455ae966..e34e97bcd736ab3193bfd3abd4162db3b159836d:/src/LR0.c?ds=inline diff --git a/src/LR0.c b/src/LR0.c index 43030fc5..37bfe813 100644 --- a/src/LR0.c +++ b/src/LR0.c @@ -1,33 +1,31 @@ -/* Generate the nondeterministic finite state machine for Bison. +/* Generate the LR(0) parser states for Bison. - Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2004 Free + Copyright (C) 1984, 1986, 1989, 2000-2002, 2004-2007, 2009-2012 Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. - Bison is free software; you can redistribute it and/or modify + 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 2, or (at your option) - any later version. + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. - Bison is distributed in the hope that it will be useful, + 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 Bison; see the file COPYING. If not, write to - the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, - Boston, MA 02110-1301, USA. */ + 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" @@ -66,11 +64,6 @@ state_list_append (symbol_number sym, size_t core_size, item_number *core) fprintf (stderr, "state_list_append (state = %d, symbol = %d (%s))\n", nstates, sym, symbols[sym]->tag); - /* If this is the endtoken, and this is not the initial state, then - this is the final state. */ - if (sym == 0 && first_state) - final_state = s; - node->next = NULL; node->state = s; @@ -173,6 +166,10 @@ free_storage (void) | 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 @@ -187,8 +184,8 @@ new_itemsets (state *s) nshifts = 0; - for (i = 0; i < nritemset; ++i) - if (ritem[itemset[i]] >= 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]) @@ -213,20 +210,20 @@ new_itemsets (state *s) static state * get_state (symbol_number sym, size_t core_size, item_number *core) { - state *sp; + state *s; if (trace_flag & trace_automaton) fprintf (stderr, "Entering get_state, symbol = %d (%s)\n", sym, symbols[sym]->tag); - sp = state_hash_lookup (core_size, core); - if (!sp) - sp = state_list_append (sym, core_size, core); + 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", sp->number); + fprintf (stderr, "Exiting get_state => %d\n", s->number); - return sp; + return s; } /*---------------------------------------------------------------. @@ -276,11 +273,20 @@ save_reductions (state *s) size_t i; /* Find and count the active items that represent ends of rules. */ - for (i = 0; i < nritemset; ++i) + for (i = 0; i < nitemset; ++i) { - int item = ritem[itemset[i]]; - if (item < 0) - redset[count++] = &rules[item_number_as_rule_number (item)]; + 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. */ @@ -322,8 +328,8 @@ set_states (void) /*-------------------------------------------------------------------. -| Compute the nondeterministic finite state machine (see state.h for | -| details) from the grammar. | +| Compute the LR(0) parser states (see state.h for details) from the | +| grammar. | `-------------------------------------------------------------------*/ void @@ -338,19 +344,16 @@ generate_states (void) item of this initial rule. */ state_list_append (0, 1, &initial_core); - list = first_state; - - while (list) + /* 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 ruleset and itemset for the transitions out of this - state. ruleset gets a 1 bit for each rule that could reduce - now. itemset gets a vector of all the items that could be - accepted next. */ + /* 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); @@ -362,10 +365,6 @@ generate_states (void) /* 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); - - /* states are queued when they are created; process them all. - */ - list = list->next; } /* discard various storage */