X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/82841af7d05fd59204a55dd3c3669b7154a4d2b5..eb1b07409f0ccad9970c8a60ded9f2a56d205b9c:/src/LR0.c?ds=inline diff --git a/src/LR0.c b/src/LR0.c index 6a911f24..689bebcb 100644 --- a/src/LR0.c +++ b/src/LR0.c @@ -1,5 +1,7 @@ -/* Generate the nondeterministic finite state machine for bison, - Copyright 1984, 1986, 1989, 2000, 2001 Free Software Foundation, Inc. +/* 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. @@ -15,83 +17,109 @@ 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. */ + the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, + Boston, MA 02110-1301, USA. */ /* See comments in state.h for the data structures that represent it. The entry point is generate_states. */ +#include #include "system.h" -#include "symtab.h" + +#include +#include + +#include "LR0.h" +#include "closure.h" +#include "complain.h" #include "getargs.h" -#include "reader.h" #include "gram.h" -#include "state.h" -#include "complain.h" -#include "closure.h" -#include "LR0.h" +#include "gram.h" #include "lalr.h" +#include "reader.h" #include "reduce.h" +#include "state.h" +#include "symtab.h" -int nstates; -/* Initialize the final state to -1, otherwise, it might be set to 0 - by default, and since we don't compute the reductions of the final - state, we end up not computing the reductions of the initial state, - which is of course needed. +typedef struct state_list +{ + struct state_list *next; + state *state; +} state_list; - FINAL_STATE is properly set by new_state when it recognizes the - accessing symbol: EOF. */ -int final_state = -1; -static state_t *first_state = NULL; +static state_list *first_state = NULL; +static state_list *last_state = NULL; -static state_t *this_state = NULL; -static state_t *last_state = NULL; -static int nshifts; -static short *shift_symbol = 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); -static short *redset = NULL; -static short *shiftset = NULL; + if (trace_flag & trace_automaton) + fprintf (stderr, "state_list_append (state = %d, symbol = %d (%s))\n", + nstates, sym, symbols[sym]->tag); -static short **kernel_base = NULL; -static int *kernel_size = NULL; -static short *kernel_items = NULL; + node->next = NULL; + node->state = s; -/* hash table for states, to recognize equivalent ones. */ + if (!first_state) + first_state = node; + if (last_state) + last_state->next = node; + last_state = node; -#define STATE_HASH_SIZE 1009 -static state_t **state_hash = NULL; + 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) { - int i; + 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. */ - int count = 0; - short *symbol_count = XCALLOC (short, nsyms + nuseless_nonterminals); + size_t count = 0; + size_t *symbol_count = xcalloc (nsyms + nuseless_nonterminals, + sizeof *symbol_count); - for (i = 0; i < nritems; ++i) - if (ritem[i] >= 0) + for (r = 0; r < nrules; ++r) + for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp) { count++; - symbol_count[ritem[i]]++; + 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 cannot be more than the number of times that symbol - appears as an item, which is symbol_count[symbol]. + 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 = XCALLOC (short *, nsyms); - if (count) - kernel_items = XCALLOC (short, count); + kernel_base = xnmalloc (nsyms, sizeof *kernel_base); + kernel_items = xnmalloc (count, sizeof *kernel_items); count = 0; for (i = 0; i < nsyms; i++) @@ -101,7 +129,7 @@ allocate_itemsets (void) } free (symbol_count); - kernel_size = XCALLOC (int, nsyms); + kernel_size = xnmalloc (nsyms, sizeof *kernel_size); } @@ -110,10 +138,10 @@ allocate_storage (void) { allocate_itemsets (); - shiftset = XCALLOC (short, nsyms); - redset = XCALLOC (short, nrules + 1); - state_hash = XCALLOC (state_t *, STATE_HASH_SIZE); - shift_symbol = XCALLOC (short, nsyms); + shiftset = xnmalloc (nsyms, sizeof *shiftset); + redset = xnmalloc (nrules, sizeof *redset); + state_hash_new (); + shift_symbol = xnmalloc (nsyms, sizeof *shift_symbol); } @@ -125,211 +153,113 @@ free_storage (void) free (shiftset); free (kernel_base); free (kernel_size); - XFREE (kernel_items); - free (state_hash); + free (kernel_items); + state_hash_free (); } -/*----------------------------------------------------------------. -| Find which symbols can be shifted in the current state, 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. | -`----------------------------------------------------------------*/ +/*---------------------------------------------------------------. +| 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 (void) +new_itemsets (state *s) { - int i; + size_t i; - if (trace_flag) - fprintf (stderr, "Entering new_itemsets, state = %d\n", - this_state->number); + 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 < nitemset; ++i) - { - int symbol = ritem[itemset[i]]; - if (symbol >= 0) - { - if (!kernel_size[symbol]) - { - shift_symbol[nshifts] = symbol; - nshifts++; - } - - kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1; - kernel_size[symbol]++; - } - } + 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]++; + } } -/*-----------------------------------------------------------------. -| Subroutine of get_state. Create a new state for those items, if | -| necessary. | -`-----------------------------------------------------------------*/ - -static state_t * -new_state (int symbol) -{ - state_t *p; - - if (trace_flag) - fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n", - this_state->number, symbol, symbols[symbol]->tag); - - if (nstates >= MAXSHORT) - fatal (_("too many states (max %d)"), MAXSHORT); - - p = STATE_ALLOC (kernel_size[symbol]); - p->accessing_symbol = symbol; - p->number = nstates; - p->nitems = kernel_size[symbol]; - - shortcpy (p->items, kernel_base[symbol], kernel_size[symbol]); - - last_state->next = p; - last_state = p; - nstates++; - - /* If this is the eoftoken, then this is the final state. */ - if (symbol == 0) - final_state = p->number; - - return p; -} - - /*--------------------------------------------------------------. -| Find the state number for the state we would get to (from the | -| current state) by shifting symbol. Create a new state if no | -| equivalent one exists already. Used by append_states. | +| 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 int -get_state (int symbol) +static state * +get_state (symbol_number sym, size_t core_size, item_number *core) { - int key; - int i; - state_t *sp; + state *s; - if (trace_flag) - fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n", - this_state->number, symbol, symbols[symbol]->tag); + if (trace_flag & trace_automaton) + fprintf (stderr, "Entering get_state, symbol = %d (%s)\n", + sym, symbols[sym]->tag); - /* Add up the target state's active item numbers to get a hash key. - */ - key = 0; - for (i = 0; i < kernel_size[symbol]; ++i) - key += kernel_base[symbol][i]; - key = key % STATE_HASH_SIZE; - sp = state_hash[key]; + s = state_hash_lookup (core_size, core); + if (!s) + s = state_list_append (sym, core_size, core); - if (sp) - { - int found = 0; - while (!found) - { - if (sp->nitems == kernel_size[symbol]) - { - found = 1; - for (i = 0; i < kernel_size[symbol]; ++i) - if (kernel_base[symbol][i] != sp->items[i]) - found = 0; - } + if (trace_flag & trace_automaton) + fprintf (stderr, "Exiting get_state => %d\n", s->number); - if (!found) - { - if (sp->link) - { - sp = sp->link; - } - else /* bucket exhausted and no match */ - { - sp = sp->link = new_state (symbol); - found = 1; - } - } - } - } - else /* bucket is empty */ - { - state_hash[key] = sp = new_state (symbol); - } - - if (trace_flag) - fprintf (stderr, "Exiting get_state => %d\n", sp->number); - - return sp->number; + return s; } -/*------------------------------------------------------------------. -| Use the information computed by new_itemsets to find the state | -| numbers reached by each shift transition from the current state. | -| | -| shiftset is set up as a vector of state numbers of those states. | -`------------------------------------------------------------------*/ +/*---------------------------------------------------------------. +| 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 (void) +append_states (state *s) { int i; - int j; - int symbol; - if (trace_flag) - fprintf (stderr, "Entering append_states, state = %d\n", - this_state->number); + if (trace_flag & trace_automaton) + fprintf (stderr, "Entering append_states, state = %d\n", s->number); - /* first sort shift_symbol into increasing order */ + /* First sort shift_symbol into increasing order. */ for (i = 1; i < nshifts; i++) { - symbol = shift_symbol[i]; - j = i; - while (j > 0 && shift_symbol[j - 1] > symbol) - { - shift_symbol[j] = shift_symbol[j - 1]; - j--; - } - shift_symbol[j] = symbol; + 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++) - shiftset[i] = get_state (shift_symbol[i]); -} - - -static void -new_states (void) -{ - first_state = last_state = this_state = STATE_ALLOC (0); - nstates = 1; -} - - -/*------------------------------------------------------------. -| Save the NSHIFTS of SHIFTSET into the current linked list. | -`------------------------------------------------------------*/ - -static void -save_shifts (void) -{ - shifts *p = shifts_new (nshifts); - shortcpy (p->shifts, shiftset, nshifts); - this_state->shifts = p; + { + symbol_number sym = shift_symbol[i]; + shiftset[i] = get_state (sym, kernel_size[sym], kernel_base[sym]); + } } @@ -340,27 +270,30 @@ save_shifts (void) `----------------------------------------------------------------*/ static void -save_reductions (void) +save_reductions (state *s) { int count = 0; - int i; - - /* If this is the final state, we want it to have no reductions at - all, although it has one for `START_SYMBOL EOF .'. */ - if (this_state->number == final_state) - return; + size_t i; /* Find and count the active items that represent ends of rules. */ for (i = 0; i < nitemset; ++i) { - int item = ritem[itemset[i]]; - if (item < 0) - redset[count++] = -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. */ - this_state->reductions = reductions_new (count); - shortcpy (this_state->reductions->rules, redset, count); + state_reductions_set (s, count, redset); } @@ -371,25 +304,32 @@ save_reductions (void) static void set_states (void) { - state_t *sp; - states = XCALLOC (state_t *, nstates); + states = xcalloc (nstates, sizeof *states); - for (sp = first_state; sp; sp = sp->next) + while (first_state) { + state_list *this = first_state; + /* Pessimization, but simplification of the code: make sure all - the states have a shifts, errs, and reductions, even if - reduced to 0. */ - if (!sp->shifts) - sp->shifts = shifts_new (0); - if (!sp->errs) - sp->errs = errs_new (0); - if (!sp->reductions) - sp->reductions = reductions_new (0); - - states[sp->number] = sp; + 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. | @@ -398,34 +338,36 @@ set_states (void) void generate_states (void) { + item_number initial_core = 0; + state_list *list = NULL; allocate_storage (); new_closure (nritems); - new_states (); - while (this_state) + /* 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) { - if (trace_flag) + state *s = list->state; + if (trace_flag & trace_automaton) fprintf (stderr, "Processing state %d (reached by %s)\n", - this_state->number, - symbols[this_state->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. */ - closure (this_state->items, this_state->nitems); - /* record the reductions allowed out of this state */ - save_reductions (); - /* find the itemsets of the states that shifts can reach */ - new_itemsets (); - /* find or create the core structures for those states */ - append_states (); - - /* create the shifts structures for the shifts to those states, - now that the state numbers transitioning to are known */ - save_shifts (); - - /* states are queued when they are created; process them all */ - this_state = this_state->next; + 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 */