X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/0fb669f9d648dfdd7a39478a6b658511455ae966..0fe9720964da510a2b359af390a3053aace65f9f:/src/LR0.c diff --git a/src/LR0.c b/src/LR0.c index 43030fc5..a757f006 100644 --- a/src/LR0.c +++ b/src/LR0.c @@ -1,40 +1,37 @@ -/* 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 - Software Foundation, Inc. + Copyright (C) 1984, 1986, 1989, 2000-2002, 2004-2012 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" #include "complain.h" #include "getargs.h" #include "gram.h" -#include "gram.h" #include "lalr.h" #include "reader.h" #include "reduce.h" @@ -64,12 +61,7 @@ state_list_append (symbol_number sym, size_t core_size, item_number *core) if (trace_flag & trace_automaton) 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; + nstates, sym, symbols[sym]->tag); node->next = NULL; node->state = s; @@ -107,13 +99,13 @@ allocate_itemsets (void) symbols. */ size_t count = 0; size_t *symbol_count = xcalloc (nsyms + nuseless_nonterminals, - sizeof *symbol_count); + sizeof *symbol_count); for (r = 0; r < nrules; ++r) for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp) { - count++; - symbol_count[*rhsp]++; + count++; + symbol_count[*rhsp]++; } /* See comments before new_itemsets. All the vectors of items @@ -173,6 +165,10 @@ 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 @@ -187,18 +183,18 @@ 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]) - { - shift_symbol[nshifts] = sym; - nshifts++; - } - - kernel_base[sym][kernel_size[sym]] = itemset[i] + 1; - kernel_size[sym]++; + 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]++; } } @@ -213,25 +209,25 @@ 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); + 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; } /*---------------------------------------------------------------. | Use the information computed by new_itemsets to find the state | -| numbers reached by each shift transition from S. | +| numbers reached by each shift transition from S. | | | | SHIFTSET is set up as a vector of those states. | `---------------------------------------------------------------*/ @@ -251,7 +247,7 @@ append_states (state *s) 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] = shift_symbol[j - 1]; shift_symbol[j] = sym; } @@ -276,11 +272,20 @@ 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. */ @@ -302,14 +307,14 @@ set_states (void) 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. */ + 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); + state_transitions_set (s, 0, 0); if (!s->reductions) - state_reductions_set (s, 0, 0); + state_reductions_set (s, 0, 0); states[s->number] = s; @@ -322,8 +327,8 @@ 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 +343,16 @@ 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. */ + 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); @@ -360,12 +362,8 @@ generate_states (void) append_states (s); /* Create the shifts structures for the shifts to those states, - now that the state numbers transitioning to are known. */ + 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 */