X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/2cec70b9f139dd207022c35fdbe8b49fd1cf230d..72cd9a913f6d282c5e24990505c2c820bda2bf1b:/src/LR0.c
diff --git a/src/LR0.c b/src/LR0.c
index 4f771d21..a757f006 100644
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -1,89 +1,121 @@
-/* Generate the nondeterministic finite state machine for bison,
- Copyright 1984, 1986, 1989, 2000, 2001 Free Software Foundation, Inc.
+/* Generate the LR(0) parser states for Bison.
+
+ 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 "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 "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 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);
+
+ 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;
+
+ return s;
+}
+
+static int nshifts;
+static symbol_number *shift_symbol;
-#define STATE_HASH_SIZE 1009
-static state_t **state_hash = NULL;
+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; ritem[i]; ++i)
- if (ritem[i] > 0)
+ for (r = 0; r < nrules; ++r)
+ for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
{
- count++;
- symbol_count[ritem[i]]++;
+ 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 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 +125,7 @@ allocate_itemsets (void)
}
free (symbol_count);
- kernel_size = XCALLOC (int, nsyms);
+ kernel_size = xnmalloc (nsyms, sizeof *kernel_size);
}
@@ -102,9 +134,10 @@ 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 +149,113 @@ 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);
- 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]++;
- }
- }
+ 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, 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;
-
- if (trace_flag)
- fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n",
- this_state->number, symbol, tags[symbol]);
+ state *s;
- /* 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];
+ if (trace_flag & trace_automaton)
+ fprintf (stderr, "Entering get_state, symbol = %d (%s)\n",
+ sym, symbols[sym]->tag);
- 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);
- }
+ s = state_hash_lookup (core_size, core);
+ if (!s)
+ s = state_list_append (sym, core_size, core);
- 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 ();
- }
- 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 ();
- }
+ symbol_number sym = shift_symbol[i];
+ shiftset[i] = get_state (sym, kernel_size[sym], kernel_base[sym]);
}
-
- insert_accepting_state ();
}
@@ -506,101 +266,110 @@ 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)
{
- 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. */
-
- if (count)
- {
- reductions *p = REDUCTIONS_ALLOC (count);
- p->nreds = count;
- shortcpy (p->rules, redset, count);
-
- this_state->reductions = p;
- }
+ 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)
{
- /* Pessimization, but simplification of the code: make sure all
- the states have a shifts and errs, even if reduced to 0. */
- if (!sp->shifts)
- sp->shifts = shifts_new (0);
- if (!sp->errs)
- sp->errs = errs_new (0);
+ state_list *this = first_state;
- state_table[sp->number] = sp;
+ /* 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 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 (nitems);
- new_states ();
+ new_closure (nritems);
+
+ /* 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);
- while (this_state)
+ /* States are queued when they are created; process them all. */
+ for (list = first_state; list; list = list->next)
{
- if (trace_flag)
- fprintf (stderr, "Processing state %d (reached by %s)\n",
- this_state->number, tags[this_state->accessing_symbol]);
- /* 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;
+ 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);
}
/* 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 ();
}