X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/3628146521aa93cdd499fa5058d21c7be33014bf..c826013fb38c98861ef0fc5d4dc3fb3fb4f555be:/src/LR0.c?ds=inline diff --git a/src/LR0.c b/src/LR0.c index 8bdcd75f..31eab0da 100644 --- a/src/LR0.c +++ b/src/LR0.c @@ -1,119 +1,122 @@ -/* Generate the nondeterministic finite state machine for bison, - Copyright (C) 1984, 1986, 1989 Free Software Foundation, Inc. +/* Generate the LR(0) parser states for Bison. -This file is part of Bison, the GNU Compiler Compiler. + Copyright (C) 1984, 1986, 1989, 2000-2002, 2004-2010 Free Software + Foundation, Inc. -Bison 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. + This file is part of Bison, the GNU Compiler Compiler. -Bison 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. + 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 3 of the License, or + (at your option) any later version. -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. */ + 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 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 #include "system.h" -#include "machine.h" -#include "alloc.h" + +#include +#include + +#include "LR0.h" +#include "closure.h" +#include "complain.h" +#include "getargs.h" #include "gram.h" +#include "lalr.h" +#include "reader.h" +#include "reduce.h" #include "state.h" -#include "complain.h" +#include "symtab.h" +typedef struct state_list +{ + struct state_list *next; + state *state; +} state_list; -extern char *nullable; -extern short *itemset; -extern short *itemsetend; - - -int nstates; -int final_state; -core *first_state; -shifts *first_shift; -reductions *first_reduction; - -int get_state PARAMS((int)); -core *new_state PARAMS((int)); - -void allocate_itemsets PARAMS((void)); -void allocate_storage PARAMS((void)); -void free_storage PARAMS((void)); -void generate_states PARAMS((void)); -void new_itemsets PARAMS((void)); -void append_states PARAMS((void)); -void initialize_states PARAMS((void)); -void save_shifts PARAMS((void)); -void save_reductions PARAMS((void)); -void augment_automaton PARAMS((void)); -void insert_start_shift PARAMS((void)); -extern void initialize_closure PARAMS((int)); -extern void closure PARAMS((short *, int)); -extern void finalize_closure PARAMS((void)); - -static core *this_state; -static core *last_state; -static shifts *last_shift; -static reductions *last_reduction; +static state_list *first_state = NULL; +static state_list *last_state = NULL; -static int nshifts; -static short *shift_symbol; -static short *redset; -static short *shiftset; +/*------------------------------------------------------------------. +| A state was just discovered from another state. Queue it for | +| later examination, in order to find its transitions. Return it. | +`------------------------------------------------------------------*/ -static short **kernel_base; -static short **kernel_end; -static short *kernel_items; +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); -/* hash table for states, to recognize equivalent ones. */ + if (trace_flag & trace_automaton) + fprintf (stderr, "state_list_append (state = %d, symbol = %d (%s))\n", + nstates, sym, symbols[sym]->tag); -#define STATE_TABLE_SIZE 1009 -static core **state_table; + node->next = NULL; + node->state = s; + if (!first_state) + first_state = node; + if (last_state) + last_state->next = node; + last_state = node; + return s; +} -void -allocate_itemsets (void) -{ - register short *itemp; - register int symbol; - register int i; - register int count; - register short *symbol_count; +static int nshifts; +static symbol_number *shift_symbol; - count = 0; - symbol_count = NEW2(nsyms, short); +static rule **redset; +static state **shiftset; - itemp = ritem; - symbol = *itemp++; - while (symbol) - { - if (symbol > 0) - { - count++; - symbol_count[symbol]++; - } - symbol = *itemp++; - } +static item_number **kernel_base; +static int *kernel_size; +static item_number *kernel_items; - /* 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]. + +static void +allocate_itemsets (void) +{ + 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. */ + 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]++; + } + + /* See comments before new_itemsets. All the vectors of items + live inside KERNEL_ITEMS. The number of active items after + 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 = NEW2(nsyms, short *); - kernel_items = NEW2(count, short); + kernel_base = xnmalloc (nsyms, sizeof *kernel_base); + kernel_items = xnmalloc (count, sizeof *kernel_items); count = 0; for (i = 0; i < nsyms; i++) @@ -122,586 +125,252 @@ allocate_itemsets (void) count += symbol_count[i]; } - shift_symbol = symbol_count; - kernel_end = NEW2(nsyms, short *); + free (symbol_count); + kernel_size = xnmalloc (nsyms, sizeof *kernel_size); } -void +static void allocate_storage (void) { - allocate_itemsets(); + allocate_itemsets (); - shiftset = NEW2(nsyms, short); - redset = NEW2(nrules + 1, short); - state_table = NEW2(STATE_TABLE_SIZE, core *); + shiftset = xnmalloc (nsyms, sizeof *shiftset); + redset = xnmalloc (nrules, sizeof *redset); + state_hash_new (); + shift_symbol = xnmalloc (nsyms, sizeof *shift_symbol); } -void +static void free_storage (void) { - FREE(shift_symbol); - FREE(redset); - FREE(shiftset); - FREE(kernel_base); - FREE(kernel_end); - FREE(kernel_items); - FREE(state_table); + free (shift_symbol); + free (redset); + free (shiftset); + free (kernel_base); + free (kernel_size); + free (kernel_items); + state_hash_free (); } -/* compute the nondeterministic finite state machine (see state.h for details) -from the grammar. */ -void -generate_states (void) -{ - allocate_storage(); - initialize_closure(nitems); - initialize_states(); - while (this_state) - { - /* 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 */ - if (nshifts > 0) - save_shifts(); - - /* states are queued when they are created; process them all */ - this_state = this_state->next; - } - - /* discard various storage */ - finalize_closure(); - free_storage(); +/*---------------------------------------------------------------. +| 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. | +`---------------------------------------------------------------*/ - /* set up initial and final states as parser wants them */ - augment_automaton(); -} +static void +new_itemsets (state *s) +{ + size_t i; + if (trace_flag & trace_automaton) + fprintf (stderr, "Entering new_itemsets, state = %d\n", s->number); + memset (kernel_size, 0, nsyms * sizeof *kernel_size); -/* 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_end[symbol] points after the end of that vector. */ -void -new_itemsets (void) -{ - register int i; - register int shiftcount; - register short *isp; - register short *ksp; - register int symbol; + nshifts = 0; -#ifdef TRACE - fprintf(stderr, "Entering new_itemsets\n"); -#endif + 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++; + } - for (i = 0; i < nsyms; i++) - kernel_end[i] = NULL; + kernel_base[sym][kernel_size[sym]] = itemset[i] + 1; + kernel_size[sym]++; + } +} - shiftcount = 0; - isp = itemset; - while (isp < itemsetend) - { - i = *isp++; - symbol = ritem[i]; - if (symbol > 0) - { - ksp = kernel_end[symbol]; +/*--------------------------------------------------------------. +| 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. | +`--------------------------------------------------------------*/ - if (!ksp) - { - shift_symbol[shiftcount++] = symbol; - ksp = kernel_base[symbol]; - } +static state * +get_state (symbol_number sym, size_t core_size, item_number *core) +{ + state *s; - *ksp++ = i + 1; - kernel_end[symbol] = ksp; - } - } + if (trace_flag & trace_automaton) + fprintf (stderr, "Entering get_state, symbol = %d (%s)\n", + sym, symbols[sym]->tag); - nshifts = shiftcount; -} + 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", s->number); + return s; +} -/* Use the information computed by new_itemsets to find the state numbers - reached by each shift transition from the current state. +/*---------------------------------------------------------------. +| 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. | +`---------------------------------------------------------------*/ - shiftset is set up as a vector of state numbers of those states. */ -void -append_states (void) +static void +append_states (state *s) { - register int i; - register int j; - register int symbol; + int i; -#ifdef TRACE - fprintf(stderr, "Entering append_states\n"); -#endif + 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++) { - symbol = shift_symbol[i]; - shiftset[i] = get_state(symbol); + symbol_number sym = shift_symbol[i]; + shiftset[i] = get_state (sym, kernel_size[sym], kernel_base[sym]); } } +/*----------------------------------------------------------------. +| Find which rules can be used for reduction transitions from the | +| current state and make a reductions structure for the state to | +| record their rule numbers. | +`----------------------------------------------------------------*/ -/* 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 */ - -int -get_state (int symbol) +static void +save_reductions (state *s) { - register int key; - register short *isp1; - register short *isp2; - register short *iend; - register core *sp; - register int found; - - int n; - -#ifdef TRACE - fprintf(stderr, "Entering get_state, symbol = %d\n", symbol); -#endif - - isp1 = kernel_base[symbol]; - iend = kernel_end[symbol]; - n = iend - isp1; + int count = 0; + size_t i; - /* add up the target state's active item numbers to get a hash key */ - key = 0; - while (isp1 < iend) - key += *isp1++; - - key = key % STATE_TABLE_SIZE; - - sp = state_table[key]; - - if (sp) + /* Find and count the active items that represent ends of rules. */ + for (i = 0; i < nitemset; ++i) { - found = 0; - while (!found) + item_number item = ritem[itemset[i]]; + if (item_number_is_rule_number (item)) { - if (sp->nitems == n) + rule_number r = item_number_as_rule_number (item); + redset[count++] = &rules[r]; + if (r == 0) { - found = 1; - isp1 = kernel_base[symbol]; - isp2 = sp->items; - - while (found && isp1 < iend) - { - if (*isp1++ != *isp2++) - found = 0; - } - } - - if (!found) - { - if (sp->link) - { - sp = sp->link; - } - else /* bucket exhausted and no match */ - { - sp = sp->link = new_state(symbol); - found = 1; - } + /* This is "reduce 0", i.e., accept. */ + aver (!final_state); + final_state = s; } } } - else /* bucket is empty */ - { - state_table[key] = sp = new_state(symbol); - } - - return sp->number; -} - - - -/* subroutine of get_state. create a new state for those items, if necessary. */ - -core * -new_state (int symbol) -{ - register int n; - register core *p; - register short *isp1; - register short *isp2; - register short *iend; - -#ifdef TRACE - fprintf(stderr, "Entering new_state, symbol = %d\n", symbol); -#endif - - if (nstates >= MAXSHORT) - fatal (_("too many states (max %d)"), MAXSHORT); - isp1 = kernel_base[symbol]; - iend = kernel_end[symbol]; - n = iend - isp1; - - p = (core *) xmalloc((unsigned) (sizeof(core) + (n - 1) * sizeof(short))); - p->accessing_symbol = symbol; - p->number = nstates; - p->nitems = n; - - isp2 = p->items; - while (isp1 < iend) - *isp2++ = *isp1++; - - last_state->next = p; - last_state = p; - - nstates++; - - return p; -} - - -void -initialize_states (void) -{ - register core *p; -/* register unsigned *rp1; JF unused */ -/* register unsigned *rp2; JF unused */ -/* register unsigned *rend; JF unused */ - - p = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short))); - first_state = last_state = this_state = p; - nstates = 1; -} - - -void -save_shifts (void) -{ - register shifts *p; - register short *sp1; - register short *sp2; - register short *send; - - p = (shifts *) xmalloc((unsigned) (sizeof(shifts) + - (nshifts - 1) * sizeof(short))); - - p->number = this_state->number; - p->nshifts = nshifts; - - sp1 = shiftset; - sp2 = p->shifts; - send = shiftset + nshifts; - - while (sp1 < send) - *sp2++ = *sp1++; - - if (last_shift) - { - last_shift->next = p; - last_shift = p; - } - else - { - first_shift = p; - last_shift = p; - } + /* Make a reductions structure and copy the data into it. */ + state_reductions_set (s, count, redset); } + +/*---------------. +| Build STATES. | +`---------------*/ - -/* find which rules can be used for reduction transitions from the current state - and make a reductions structure for the state to record their rule numbers. */ -void -save_reductions (void) +static void +set_states (void) { - register short *isp; - register short *rp1; - register short *rp2; - register int item; - register int count; - register reductions *p; - - short *rend; - - /* find and count the active items that represent ends of rules */ - - count = 0; - for (isp = itemset; isp < itemsetend; isp++) - { - item = ritem[*isp]; - if (item < 0) - { - redset[count++] = -item; - } - } + states = xcalloc (nstates, sizeof *states); - /* make a reductions structure and copy the data into it. */ - - if (count) + while (first_state) { - p = (reductions *) xmalloc((unsigned) (sizeof(reductions) + - (count - 1) * sizeof(short))); - - p->number = this_state->number; - p->nreds = count; - - rp1 = redset; - rp2 = p->rules; - rend = rp1 + count; - - while (rp1 < rend) - *rp2++ = *rp1++; - - if (last_reduction) - { - last_reduction->next = p; - last_reduction = p; - } - else - { - first_reduction = p; - last_reduction = p; - } + 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. */ + 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 LR(0) parser states (see state.h for details) from the | +| grammar. | +`-------------------------------------------------------------------*/ -/* Make sure that the initial state has a shift that accepts the -grammar's start symbol and goes to the next-to-final state, -which has a shift going to the final state, which has a shift -to the termination state. -Create such states and shifts if they don't happen to exist already. */ void -augment_automaton (void) +generate_states (void) { - register int i; - register int k; -/* register int found; JF unused */ - register core *statep; - register shifts *sp; - register shifts *sp2; - register shifts *sp1 = NULL; - - sp = first_shift; - - if (sp) - { - if (sp->number == 0) - { - k = sp->nshifts; - statep = first_state->next; + item_number initial_core = 0; + state_list *list = NULL; + allocate_storage (); + new_closure (nritems); - /* The states reached by shifts from first_state are numbered 1...K. - Look for one reached by start_symbol. */ - while (statep->accessing_symbol < start_symbol - && statep->number < k) - statep = statep->next; + /* 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); - if (statep->accessing_symbol == start_symbol) - { - /* We already have a next-to-final state. - Make sure it has a shift to what will be the final state. */ - k = statep->number; - - while (sp && sp->number < k) - { - sp1 = sp; - sp = sp->next; - } - - if (sp && sp->number == k) - { - sp2 = (shifts *) xmalloc((unsigned) (sizeof(shifts) - + sp->nshifts * sizeof(short))); - sp2->number = k; - sp2->nshifts = sp->nshifts + 1; - sp2->shifts[0] = nstates; - for (i = sp->nshifts; i > 0; i--) - sp2->shifts[i] = sp->shifts[i - 1]; - - /* Patch sp2 into the chain of shifts in place of sp, - following sp1. */ - sp2->next = sp->next; - sp1->next = sp2; - if (sp == last_shift) - last_shift = sp2; - FREE(sp); - } - else - { - sp2 = NEW(shifts); - sp2->number = k; - sp2->nshifts = 1; - sp2->shifts[0] = nstates; - - /* Patch sp2 into the chain of shifts between sp1 and sp. */ - sp2->next = sp; - sp1->next = sp2; - if (sp == 0) - last_shift = sp2; - } - } - else - { - /* There is no next-to-final state as yet. */ - /* Add one more shift in first_shift, - going to the next-to-final state (yet to be made). */ - sp = first_shift; - - sp2 = (shifts *) xmalloc(sizeof(shifts) - + sp->nshifts * sizeof(short)); - sp2->nshifts = sp->nshifts + 1; - - /* Stick this shift into the vector at the proper place. */ - statep = first_state->next; - for (k = 0, i = 0; i < sp->nshifts; k++, i++) - { - if (statep->accessing_symbol > start_symbol && i == k) - sp2->shifts[k++] = nstates; - sp2->shifts[k] = sp->shifts[i]; - statep = statep->next; - } - if (i == k) - sp2->shifts[k++] = nstates; - - /* Patch sp2 into the chain of shifts - in place of sp, at the beginning. */ - sp2->next = sp->next; - first_shift = sp2; - if (last_shift == sp) - last_shift = sp2; - - FREE(sp); - - /* Create the next-to-final state, with shift to - what will be the final state. */ - insert_start_shift(); - } - } - else - { - /* The initial state didn't even have any shifts. - Give it one shift, to the next-to-final state. */ - sp = NEW(shifts); - sp->nshifts = 1; - sp->shifts[0] = nstates; - - /* Patch sp into the chain of shifts at the beginning. */ - sp->next = first_shift; - first_shift = sp; - - /* Create the next-to-final state, with shift to - what will be the final state. */ - insert_start_shift(); - } - } - else + /* States are queued when they are created; process them all. */ + for (list = first_state; list; list = list->next) { - /* There are no shifts for any state. - Make one shift, from the initial state to the next-to-final state. */ - - sp = NEW(shifts); - sp->nshifts = 1; - sp->shifts[0] = nstates; - - /* Initialize the chain of shifts with sp. */ - first_shift = sp; - last_shift = sp; - - /* Create the next-to-final state, with shift to - what will be the final state. */ - insert_start_shift(); + 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 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); } - /* Make the final state--the one that follows a shift from the - next-to-final state. - The symbol for that shift is 0 (end-of-file). */ - statep = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short))); - statep->number = nstates; - last_state->next = statep; - last_state = statep; - - /* Make the shift from the final state to the termination state. */ - sp = NEW(shifts); - sp->number = nstates++; - sp->nshifts = 1; - sp->shifts[0] = nstates; - last_shift->next = sp; - last_shift = sp; - - /* Note that the variable `final_state' refers to what we sometimes call - the termination state. */ - final_state = nstates; - - /* Make the termination state. */ - statep = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short))); - statep->number = nstates++; - last_state->next = statep; - last_state = statep; -} - - -/* subroutine of augment_automaton. - Create the next-to-final state, to which a shift has already been made in - the initial state. */ -void -insert_start_shift (void) -{ - register core *statep; - register shifts *sp; - - statep = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short))); - statep->number = nstates; - statep->accessing_symbol = start_symbol; - - last_state->next = statep; - last_state = statep; - - /* Make a shift from this state to (what will be) the final state. */ - sp = NEW(shifts); - sp->number = nstates++; - sp->nshifts = 1; - sp->shifts[0] = nstates; + /* discard various storage */ + free_closure (); + free_storage (); - last_shift->next = sp; - last_shift = sp; + /* Set up STATES. */ + set_states (); }