X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/97650f4efc420eb5eb0af124f28987875e10428a..e3fd1dcb8b0b55525876440410f71791d8b4c2f3:/src/LR0.c?ds=sidebyside
diff --git a/src/LR0.c b/src/LR0.c
index 2e347b55..a757f006 100644
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -1,106 +1,121 @@
-/* Generate the nondeterministic finite state machine for bison,
- Copyright 1984, 1986, 1989, 2000, 2001, 2002 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 "bitset.h"
-#include "quotearg.h"
-#include "symtab.h"
-#include "gram.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"
-typedef struct state_list_s
+typedef struct state_list
{
- struct state_list_s *next;
- state_t *state;
-} state_list_t;
+ struct state_list *next;
+ state *state;
+} state_list;
-static state_list_t *first_state = NULL;
-static state_list_t *last_state = NULL;
+static state_list *first_state = NULL;
+static state_list *last_state = NULL;
-static void
-state_list_append (state_t *state)
+
+/*------------------------------------------------------------------.
+| 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_t *node = XMALLOC (state_list_t, 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);
+
node->next = NULL;
- node->state = state;
+ 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_t *shift_symbol = NULL;
+static symbol_number *shift_symbol;
-static short *redset = NULL;
-static state_number_t *shiftset = NULL;
+static rule **redset;
+static state **shiftset;
-static item_number_t **kernel_base = NULL;
-static int *kernel_size = NULL;
-static item_number_t *kernel_items = NULL;
+static item_number **kernel_base;
+static int *kernel_size;
+static item_number *kernel_items;
static void
allocate_itemsets (void)
{
- symbol_number_t i;
- rule_number_t r;
- item_number_t *rhsp;
+ 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 (r = 1; r < nrules + 1; ++r)
+ 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
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 (item_number_t *, nsyms);
- if (count)
- kernel_items = XCALLOC (item_number_t, count);
+ kernel_base = xnmalloc (nsyms, sizeof *kernel_base);
+ kernel_items = xnmalloc (count, sizeof *kernel_items);
count = 0;
for (i = 0; i < nsyms; i++)
@@ -110,7 +125,7 @@ allocate_itemsets (void)
}
free (symbol_count);
- kernel_size = XCALLOC (int, nsyms);
+ kernel_size = xnmalloc (nsyms, sizeof *kernel_size);
}
@@ -119,10 +134,10 @@ allocate_storage (void)
{
allocate_itemsets ();
- shiftset = XCALLOC (state_number_t, nsyms);
- redset = XCALLOC (short, nrules + 1);
+ shiftset = xnmalloc (nsyms, sizeof *shiftset);
+ redset = xnmalloc (nrules, sizeof *redset);
state_hash_new ();
- shift_symbol = XCALLOC (symbol_number_t, nsyms);
+ shift_symbol = xnmalloc (nsyms, sizeof *shift_symbol);
}
@@ -134,7 +149,7 @@ free_storage (void)
free (shiftset);
free (kernel_base);
free (kernel_size);
- XFREE (kernel_items);
+ free (kernel_items);
state_hash_free ();
}
@@ -142,7 +157,7 @@ free_storage (void)
/*---------------------------------------------------------------.
-| Find which symbols can be shifted in STATE, and for each one |
+| 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. |
| |
@@ -150,144 +165,100 @@ 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_t *state)
+new_itemsets (state *s)
{
- int i;
+ size_t i;
- if (trace_flag)
- fprintf (stderr, "Entering new_itemsets, state = %d\n",
- 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 < nritemset; ++i)
- if (ritem[itemset[i]] >= 0)
+ for (i = 0; i < nitemset; ++i)
+ if (item_number_is_symbol_number (ritem[itemset[i]]))
{
- symbol_number_t symbol
- = item_number_as_symbol_number (ritem[itemset[i]]);
- if (!kernel_size[symbol])
- {
- shift_symbol[nshifts] = symbol;
- nshifts++;
- }
-
- kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1;
- kernel_size[symbol]++;
+ 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 (symbol_number_t symbol, size_t core_size, item_number_t *core)
-{
- state_t *res;
-
- if (trace_flag)
- fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",
- nstates, symbol, symbols[symbol]->tag);
-
- res = state_new (symbol, core_size, core);
- state_hash_insert (res);
-
- /* If this is the eoftoken, and this is not the initial state, then
- this is the final state. */
- if (symbol == 0 && first_state)
- final_state = res;
-
- state_list_append (res);
- return res;
-}
-
-
/*--------------------------------------------------------------.
-| 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 state_number_t
-get_state (symbol_number_t symbol, size_t core_size, item_number_t *core)
+static state *
+get_state (symbol_number sym, size_t core_size, item_number *core)
{
- state_t *sp;
+ state *s;
- if (trace_flag)
+ if (trace_flag & trace_automaton)
fprintf (stderr, "Entering get_state, symbol = %d (%s)\n",
- symbol, symbols[symbol]->tag);
+ sym, symbols[sym]->tag);
- sp = state_hash_lookup (core_size, core);
- if (!sp)
- sp = new_state (symbol, core_size, core);
+ 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 STATE. |
-| |
-| TRANSITIONSET 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 (state_t *state)
+append_states (state *s)
{
int i;
- int j;
- symbol_number_t symbol;
- if (trace_flag)
- fprintf (stderr, "Entering append_states, state = %d\n",
- 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++)
{
- symbol = shift_symbol[i];
- shiftset[i] = get_state (symbol,
- kernel_size[symbol], kernel_base[symbol]);
+ symbol_number sym = shift_symbol[i];
+ shiftset[i] = get_state (sym, kernel_size[sym], kernel_base[sym]);
}
}
-static void
-new_states (void)
-{
- /* 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 (new_state (0, kernel_size[0], kernel_base[0]));
-}
-
-
-
/*----------------------------------------------------------------.
| Find which rules can be used for reduction transitions from the |
| current state and make a reductions structure for the state to |
@@ -295,26 +266,30 @@ new_states (void)
`----------------------------------------------------------------*/
static void
-save_reductions (state_t *state)
+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 (final_state && state->number == final_state->number)
- return;
+ 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++] = -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. */
- state_reductions_set (state, count, redset);
+ state_reductions_set (s, count, redset);
}
@@ -325,24 +300,23 @@ save_reductions (state_t *state)
static void
set_states (void)
{
- states = XCALLOC (state_t *, nstates);
+ states = xcalloc (nstates, sizeof *states);
while (first_state)
{
- state_list_t *this = 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. */
- state_t *state = this->state;
- if (!state->shifts)
- state_transitions_set (state, 0, 0);
- if (!state->errs)
- state->errs = errs_new (0);
- if (!state->reductions)
- state_reductions_set (state, 0, 0);
-
- states[state->number] = state;
+ 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);
@@ -353,45 +327,43 @@ 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)
{
- state_list_t *list = NULL;
+ item_number initial_core = 0;
+ state_list *list = NULL;
allocate_storage ();
new_closure (nritems);
- new_states ();
- list = first_state;
- while (list)
+ /* 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)
{
- state_t *state = list->state;
- if (trace_flag)
- fprintf (stderr, "Processing state %d (reached by %s)\n",
- state->number,
- symbols[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 (state->items, state->nitems);
+ 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 (state);
+ save_reductions (s);
/* Find the itemsets of the states that shifts can reach. */
- new_itemsets (state);
+ new_itemsets (s);
/* Find or create the core structures for those states. */
- append_states (state);
+ 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 (state, nshifts, shiftset);
-
- /* States are queued when they are created; process them all.
- */
- list = list->next;
+ now that the state numbers transitioning to are known. */
+ state_transitions_set (s, nshifts, shiftset);
}
/* discard various storage */