X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/75142d452b7f6bc3b6be3d8a08c0f602fd157ec5..9b33de72cd2469bedac2b5f0a48a8782571ea9db:/src/LR0.c diff --git a/src/LR0.c b/src/LR0.c index 9f019223..945d41f8 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 + Free Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -15,75 +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 +#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; -int final_state; -static state_t *first_state = NULL; +typedef struct state_list +{ + struct state_list *next; + state *state; +} state_list; -static state_t *this_state = NULL; -static state_t *last_state = NULL; +static state_list *first_state = NULL; +static state_list *last_state = NULL; -static int nshifts; -static short *shift_symbol = NULL; -static short *redset = NULL; -static short *shiftset = NULL; +/*------------------------------------------------------------------. +| 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 = NULL; -static int *kernel_size = NULL; -static short *kernel_items = NULL; +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_HASH_SIZE 1009 -static state_t **state_hash = NULL; + node->next = NULL; + node->state = s; + + if (!first_state) + first_state = node; + if (last_state) + last_state->next = node; + last_state = node; + + 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++) @@ -93,7 +129,7 @@ allocate_itemsets (void) } free (symbol_count); - kernel_size = XCALLOC (int, nsyms); + kernel_size = xnmalloc (nsyms, sizeof *kernel_size); } @@ -102,9 +138,10 @@ allocate_storage (void) { allocate_itemsets (); - shiftset = XCALLOC (short, nsyms); - redset = XCALLOC (short, nrules + 1); - state_hash = XCALLOC (state_t *, STATE_HASH_SIZE); + shiftset = xnmalloc (nsyms, sizeof *shiftset); + redset = xnmalloc (nrules, sizeof *redset); + state_hash_new (); + shift_symbol = xnmalloc (nsyms, sizeof *shift_symbol); } @@ -116,386 +153,109 @@ 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. | +`---------------------------------------------------------------*/ 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); - shift_symbol = XCALLOC (short, nsyms); 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]++; - } - } + for (i = 0; i < nritemset; ++i) + if (ritem[itemset[i]] >= 0) + { + 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, tags[symbol]); - - 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++; - - 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, tags[symbol]); + 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 (!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); + if (trace_flag & trace_automaton) + fprintf (stderr, "Exiting get_state => %d\n", s->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; -} - - -/*------------------------------------------------------------------. -| Subroutine of augment_automaton. Create the next-to-final state, | -| to which a shift has already been made in the initial state. | -| | -| The task of this state consists in shifting (actually, it's a | -| goto, but shifts and gotos are both stored in SHIFTS) the start | -| symbols, hence the name. | -`------------------------------------------------------------------*/ - -static void -insert_start_shifting_state (void) -{ - state_t *statep; - shifts *sp; - - statep = STATE_ALLOC (0); - statep->number = nstates++; - - /* The distinctive feature of this state from the - eof_shifting_state, is that it is labeled as post-start-symbol - shifting. I fail to understand why this state, and the - post-start-start can't be merged into one. But it does fail if - you try. --akim */ - 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 = shifts_new (1); - statep->shifts = sp; - sp->shifts[0] = nstates; -} - - -/*-----------------------------------------------------------------. -| Subroutine of augment_automaton. Create the final state, which | -| shifts `0', the end of file. The initial state shifts the start | -| symbol, and goes to here. | -`-----------------------------------------------------------------*/ - -static void -insert_eof_shifting_state (void) -{ - state_t *statep; - shifts *sp; - - /* 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 = STATE_ALLOC (0); - statep->number = nstates++; - - last_state->next = statep; - last_state = statep; - - /* Make the shift from the final state to the termination state. */ - sp = shifts_new (1); - statep->shifts = sp; - sp->shifts[0] = nstates; -} - - -/*---------------------------------------------------------------. -| Subroutine of augment_automaton. Create the accepting state. | -`---------------------------------------------------------------*/ - -static void -insert_accepting_state (void) -{ - state_t *statep; - - /* Note that the variable `final_state' refers to what we sometimes - call the termination state. */ - final_state = nstates; - - /* Make the termination state. */ - statep = STATE_ALLOC (0); - statep->number = nstates++; - last_state->next = statep; - last_state = statep; -} - - - - - -/*------------------------------------------------------------------. -| 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. | -`------------------------------------------------------------------*/ - -static void -augment_automaton (void) -{ - if (!first_state->shifts->nshifts) { - /* The first state has no shifts. Make one shift, from the - initial state to the next-to-final state. */ - - shifts *sp = shifts_new (1); - first_state->shifts = sp; - sp->shifts[0] = nstates; - - /* Create the next-to-final state, with shift to - what will be the final state. */ - insert_start_shifting_state (); + symbol_number sym = shift_symbol[i]; + shiftset[i] = get_state (sym, kernel_size[sym], kernel_base[sym]); } - else - { - state_t *statep = first_state->next; - /* The states reached by shifts from FIRST_STATE are numbered - 1..(SP->NSHIFTS). Look for one reached by START_SYMBOL. - This is typical of `start: start ... ;': there is a state - with the item `start: start . ...'. We want to add a `shift - on EOF to eof-shifting state here. */ - while (statep->accessing_symbol != start_symbol - && statep->number < first_state->shifts->nshifts) - statep = statep->next; - - if (statep->accessing_symbol == start_symbol) - { - /* We already have STATEP, a next-to-final state for `start: - start . ...'. Make sure it has a shift to what will be - the final state. */ - int i; - - /* Find the shift of the inital state that leads to STATEP. */ - shifts *sp = statep->shifts; - - shifts *sp1 = shifts_new (sp->nshifts + 1); - statep->shifts = sp1; - sp1->shifts[0] = nstates; - for (i = sp->nshifts; i > 0; i--) - sp1->shifts[i] = sp->shifts[i - 1]; - - XFREE (sp); - - insert_eof_shifting_state (); - } - else - { - /* There is no state for `start: start . ...'. */ - int i, k; - shifts *sp = first_state->shifts; - shifts *sp1 = NULL; - - /* Add one more shift to the initial state, going to the - next-to-final state (yet to be made). */ - sp1 = shifts_new (sp->nshifts + 1); - first_state->shifts = sp1; - /* 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) - sp1->shifts[k++] = nstates; - sp1->shifts[k] = sp->shifts[i]; - statep = statep->next; - } - if (i == k) - sp1->shifts[k++] = nstates; - - XFREE (sp); - - /* Create the next-to-final state, with shift to what will - be the final state. Corresponds to `start: start . ...'. */ - insert_start_shifting_state (); - } - } - - insert_accepting_state (); } @@ -506,53 +266,66 @@ augment_automaton (void) `----------------------------------------------------------------*/ static void -save_reductions (void) +save_reductions (state *s) { - int count; - int i; + int count = 0; + size_t i; /* Find and count the active items that represent ends of rules. */ - - count = 0; - for (i = 0; i < nitemset; ++i) + for (i = 0; i < nritemset; ++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); } -/*--------------------. -| Build STATE_TABLE. | -`--------------------*/ +/*---------------. +| Build STATES. | +`---------------*/ static void -set_state_table (void) +set_states (void) { - state_t *sp; - state_table = 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); - - state_table[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. | @@ -561,42 +334,44 @@ set_state_table (void) void generate_states (void) { + item_number initial_core = 0; + state_list *list = NULL; allocate_storage (); - new_closure (nitems); - new_states (); + new_closure (nritems); - 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, tags[this_state->accessing_symbol]); + 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. */ - 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; + 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 */ free_closure (); free_storage (); - /* set up initial and final states as parser wants them */ - augment_automaton (); - - /* Set up STATE_TABLE. */ - set_state_table (); + /* Set up STATES. */ + set_states (); }