X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/afbb696d1936dd21929ce156868b7c5ebd88b544..ccdc1577ef7fb32a5e30cb655337e7cd42b98987:/src/LR0.c diff --git a/src/LR0.c b/src/LR0.c index c2a491e8..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., 59 Temple Place - Suite 330, - Boston, MA 02111-1307, USA. */ + along with this program. If not, see . */ /* See comments in state.h for the data structures that represent it. The entry point is generate_states. */ +#include #include "system.h" #include -#include #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" @@ -59,17 +56,12 @@ static state_list *last_state = NULL; static state * state_list_append (symbol_number sym, size_t core_size, item_number *core) { - state_list *node = MALLOC (node, 1); + 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); - - /* 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; @@ -84,14 +76,14 @@ state_list_append (symbol_number sym, size_t core_size, item_number *core) } static int nshifts; -static symbol_number *shift_symbol = NULL; +static symbol_number *shift_symbol; -static rule **redset = NULL; -static state **shiftset = NULL; +static rule **redset; +static state **shiftset; -static item_number **kernel_base = NULL; -static int *kernel_size = NULL; -static item_number *kernel_items = NULL; +static item_number **kernel_base; +static int *kernel_size; +static item_number *kernel_items; static void @@ -105,15 +97,15 @@ allocate_itemsets (void) Note that useless productions (hence useless nonterminals) are browsed too, hence we need to allocate room for _all_ the symbols. */ - int count = 0; - short int *symbol_count = CALLOC (symbol_count, - nsyms + nuseless_nonterminals); + 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]++; + count++; + symbol_count[*rhsp]++; } /* See comments before new_itemsets. All the vectors of items @@ -122,9 +114,8 @@ allocate_itemsets (void) appears as an item, which is SYMBOL_COUNT[S]. We allocate that much space for each symbol. */ - CALLOC (kernel_base, nsyms); - if (count) - CALLOC (kernel_items, count); + kernel_base = xnmalloc (nsyms, sizeof *kernel_base); + kernel_items = xnmalloc (count, sizeof *kernel_items); count = 0; for (i = 0; i < nsyms; i++) @@ -134,7 +125,7 @@ allocate_itemsets (void) } free (symbol_count); - CALLOC (kernel_size, nsyms); + kernel_size = xnmalloc (nsyms, sizeof *kernel_size); } @@ -143,10 +134,10 @@ allocate_storage (void) { allocate_itemsets (); - CALLOC (shiftset, nsyms); - CALLOC (redset, nrules); + shiftset = xnmalloc (nsyms, sizeof *shiftset); + redset = xnmalloc (nrules, sizeof *redset); state_hash_new (); - CALLOC (shift_symbol, nsyms); + shift_symbol = xnmalloc (nsyms, sizeof *shift_symbol); } @@ -174,33 +165,36 @@ 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 new_itemsets (state *s) { - int i; + size_t i; if (trace_flag & trace_automaton) fprintf (stderr, "Entering new_itemsets, state = %d\n", s->number); - for (i = 0; i < nsyms; i++) - kernel_size[i] = 0; + memset (kernel_size, 0, nsyms * sizeof *kernel_size); 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]++; } } @@ -215,25 +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. | `---------------------------------------------------------------*/ @@ -252,8 +246,8 @@ 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]; + for (j = i; 0 < j && sym < shift_symbol[j - 1]; j--) + shift_symbol[j] = shift_symbol[j - 1]; shift_symbol[j] = sym; } @@ -275,14 +269,23 @@ static void save_reductions (state *s) { int count = 0; - int i; + 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. */ @@ -297,21 +300,21 @@ save_reductions (state *s) static void set_states (void) { - CALLOC (states, nstates); + 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. */ + 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; @@ -324,36 +327,32 @@ 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 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. */ - kernel_base[0][0] = 0; - kernel_size[0] = 1; - state_list_append (0, kernel_size[0], kernel_base[0]); + 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); @@ -363,12 +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 */