X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/aa7815f5c6e8e07a85e47df9cd7b579468969efb..8b9e021fd1e3b03568d4b2167c47f33ba822a1c8:/src/state.h?ds=sidebyside

diff --git a/src/state.h b/src/state.h
index f4242555..a1ed9934 100644
--- a/src/state.h
+++ b/src/state.h
@@ -1,22 +1,22 @@
-/* Type definitions for nondeterministic finite state machine for bison,
-   Copyright 1984, 1989, 2000 Free Software Foundation, Inc.
+/* Type definitions for the finite state machine for Bison.
+
+   Copyright (C) 1984, 1989, 2000-2004, 2007, 2009-2010 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 <http://www.gnu.org/licenses/>.  */
 
 
 /* These type definitions are used to represent a nondeterministic
@@ -30,104 +30,245 @@
    state.  These symbols at these items are the allowable inputs that
    can follow now.
 
-   A core represents one state.  States are numbered in the number
+   A core represents one state.  States are numbered in the NUMBER
    field.  When generate_states is finished, the starting state is
-   state 0 and nstates is the number of states.  (A transition to a
-   state whose state number is nstates indicates termination.)  All
-   the cores are chained together and first_state points to the first
-   one (state 0).
+   state 0 and NSTATES is the number of states.  (FIXME: This sentence
+   is no longer true: A transition to a state whose state number is
+   NSTATES indicates termination.)  All the cores are chained together
+   and FIRST_STATE points to the first one (state 0).
 
    For each state there is a particular symbol which must have been
    the last thing accepted to reach that state.  It is the
-   accessing_symbol of the core.
-
-   Each core contains a vector of nitems items which are the indices
-   in the ritems vector of the items that are selected in this state.
+   ACCESSING_SYMBOL of the core.
 
-   The link field is used for chaining buckets that hash states by
-   their itemsets.  This is for recognizing equivalent states and
-   combining them when the states are generated.
+   Each core contains a vector of NITEMS items which are the indices
+   in the RITEM vector of the items that are selected in this state.
 
-   The two types of transitions are shifts (push the lookahead token
-   and read another) and reductions (combine the last n things on the
-   stack via a rule, replace them with the symbol that the rule
-   derives, and leave the lookahead token alone).  When the states are
-   generated, these transitions are represented in two other lists.
+   The two types of actions are shifts/gotos (push the lookahead token
+   and read another/goto to the state designated by a nterm) and
+   reductions (combine the last n things on the stack via a rule,
+   replace them with the symbol that the rule derives, and leave the
+   lookahead token alone).  When the states are generated, these
+   actions are represented in two other lists.
 
-   Each shifts structure describes the possible shift transitions out
-   of one state, the state whose number is in the number field.  The
-   shifts structures are linked through next and first_shift points to
-   them.  Each contains a vector of numbers of the states that shift
-   transitions can go to.  The accessing_symbol fields of those
-   states' cores say what kind of input leads to them.
+   Each transition structure describes the possible transitions out
+   of one state, the state whose number is in the number field.  Each
+   contains a vector of numbers of the states that transitions can go
+   to.  The accessing_symbol fields of those states' cores say what
+   kind of input leads to them.
 
-   A shift to state zero should be ignored.  Conflict resolution
-   deletes shifts by changing them to zero.
+   A transition to state zero should be ignored: conflict resolution
+   deletes transitions by having them point to zero.
 
    Each reductions structure describes the possible reductions at the
-   state whose number is in the number field.  The data is a list of
-   nreds rules, represented by their rule numbers.  first_reduction
-   points to the list of these structures.
+   state whose number is in the number field.  rules is an array of
+   num rules.  lookahead_tokens is an array of bitsets, one per rule.
 
    Conflict resolution can decide that certain tokens in certain
    states should explicitly be errors (for implementing %nonassoc).
    For each state, the tokens that are errors for this reason are
-   recorded in an errs structure, which has the state number in its
-   number field.  The rest of the errs structure is full of token
-   numbers.
+   recorded in an errs structure, which holds the token numbers.
 
-   There is at least one shift transition present in state zero.  It
+   There is at least one goto transition present in state zero.  It
    leads to a next-to-final state whose accessing_symbol is the
    grammar's start symbol.  The next-to-final state has one shift to
    the final state, whose accessing_symbol is zero (end of input).
-   The final state has one shift, which goes to the termination state
-   (whose number is nstates-1).  The reason for the extra state at the
-   end is to placate the parser's strategy of making all decisions one
-   token ahead of its actions.  */
+   The final state has one shift, which goes to the termination state.
+   The reason for the extra state at the end is to placate the
+   parser's strategy of making all decisions one token ahead of its
+   actions.  */
 
 #ifndef STATE_H_
 # define STATE_H_
 
-typedef struct core
+# include <bitset.h>
+
+# include "gram.h"
+# include "symtab.h"
+
+
+/*-------------------.
+| Numbering states.  |
+`-------------------*/
+
+typedef int state_number;
+# define STATE_NUMBER_MAXIMUM INT_MAX
+
+/* Be ready to map a state_number to an int.  */
+static inline int
+state_number_as_int (state_number s)
 {
-  struct core *next;
-  struct core *link;
-  short number;
-  short accessing_symbol;
-  short nitems;
-  short items[1];
+  return s;
 }
-core;
 
 
+typedef struct state state;
 
-typedef struct shifts
+/*--------------.
+| Transitions.  |
+`--------------*/
+
+typedef struct
 {
-  struct shifts *next;
-  short number;
-  short nshifts;
-  short shifts[1];
-}
-shifts;
+  int num;
+  state *states[1];
+} transitions;
+
+
+/* What is the symbol labelling the transition to
+   TRANSITIONS->states[Num]?  Can be a token (amongst which the error
+   token), or non terminals in case of gotos.  */
+
+#define TRANSITION_SYMBOL(Transitions, Num) \
+  (Transitions->states[Num]->accessing_symbol)
+
+/* Is the TRANSITIONS->states[Num] a shift? (as opposed to gotos).  */
 
+#define TRANSITION_IS_SHIFT(Transitions, Num) \
+  (ISTOKEN (TRANSITION_SYMBOL (Transitions, Num)))
 
+/* Is the TRANSITIONS->states[Num] a goto?. */
 
-typedef struct errs
+#define TRANSITION_IS_GOTO(Transitions, Num) \
+  (!TRANSITION_IS_SHIFT (Transitions, Num))
+
+/* Is the TRANSITIONS->states[Num] labelled by the error token?  */
+
+#define TRANSITION_IS_ERROR(Transitions, Num) \
+  (TRANSITION_SYMBOL (Transitions, Num) == errtoken->number)
+
+/* When resolving a SR conflicts, if the reduction wins, the shift is
+   disabled.  */
+
+#define TRANSITION_DISABLE(Transitions, Num) \
+  (Transitions->states[Num] = NULL)
+
+#define TRANSITION_IS_DISABLED(Transitions, Num) \
+  (Transitions->states[Num] == NULL)
+
+
+/* Iterate over each transition over a token (shifts).  */
+#define FOR_EACH_SHIFT(Transitions, Iter)			\
+  for (Iter = 0;						\
+       Iter < Transitions->num					\
+	 && (TRANSITION_IS_DISABLED (Transitions, Iter)		\
+	     || TRANSITION_IS_SHIFT (Transitions, Iter));	\
+       ++Iter)							\
+    if (!TRANSITION_IS_DISABLED (Transitions, Iter))
+
+
+/* Return the state such SHIFTS contain a shift/goto to it on SYM.
+   Abort if none found.  */
+struct state *transitions_to (transitions *shifts, symbol_number sym);
+
+
+/*-------.
+| Errs.  |
+`-------*/
+
+typedef struct
 {
-  short nerrs;
-  short errs[1];
-}
-errs;
+  int num;
+  symbol *symbols[1];
+} errs;
 
+errs *errs_new (int num, symbol **tokens);
 
 
-typedef struct reductions
+/*-------------.
+| Reductions.  |
+`-------------*/
+
+typedef struct
 {
-  struct reductions *next;
-  short number;
-  short nreds;
-  short rules[1];
-}
-reductions;
+  int num;
+  bitset *lookahead_tokens;
+  /* Sorted ascendingly on rule number.  */
+  rule *rules[1];
+} reductions;
+
+
+
+/*---------.
+| states.  |
+`---------*/
+
+struct state_list;
+
+struct state
+{
+  state_number number;
+  symbol_number accessing_symbol;
+  transitions *transitions;
+  reductions *reductions;
+  errs *errs;
+
+  /* When an includer (such as ielr.c) needs to store states in a list, the
+     includer can define struct state_list as the list node structure and can
+     store in this member a reference to the node containing each state.  */
+  struct state_list *state_list;
+
+  /* If non-zero, then no lookahead sets on reduce actions are needed to
+     decide what to do in state S.  */
+  char consistent;
+
+  /* If some conflicts were solved thanks to precedence/associativity,
+     a human readable description of the resolution.  */
+  const char *solved_conflicts;
+  const char *solved_conflicts_xml;
+
+  /* Its items.  Must be last, since ITEMS can be arbitrarily large.  Sorted
+     ascendingly on item index in RITEM, which is sorted on rule number.  */
+  size_t nitems;
+  item_number items[1];
+};
+
+extern state_number nstates;
+extern state *final_state;
+
+/* Create a new state with ACCESSING_SYMBOL for those items.  */
+state *state_new (symbol_number accessing_symbol,
+		  size_t core_size, item_number *core);
+state *state_new_isocore (state const *s);
+
+/* Set the transitions of STATE.  */
+void state_transitions_set (state *s, int num, state **trans);
+
+/* Set the reductions of STATE.  */
+void state_reductions_set (state *s, int num, rule **reds);
+
+int state_reduction_find (state *s, rule *r);
+
+/* Set the errs of STATE.  */
+void state_errs_set (state *s, int num, symbol **errors);
+
+/* Print on OUT all the lookahead tokens such that this STATE wants to
+   reduce R.  */
+void state_rule_lookahead_tokens_print (state *s, rule *r, FILE *out);
+void state_rule_lookahead_tokens_print_xml (state *s, rule *r,
+					    FILE *out, int level);
+
+/* Create/destroy the states hash table.  */
+void state_hash_new (void);
+void state_hash_free (void);
+
+/* Find the state associated to the CORE, and return it.  If it does
+   not exist yet, return NULL.  */
+state *state_hash_lookup (size_t core_size, item_number *core);
+
+/* Insert STATE in the state hash table.  */
+void state_hash_insert (state *s);
+
+/* Remove unreachable states, renumber remaining states, update NSTATES, and
+   write to OLD_TO_NEW a mapping of old state numbers to new state numbers such
+   that the old value of NSTATES is written as the new state number for removed
+   states.  The size of OLD_TO_NEW must be the old value of NSTATES.  */
+void state_remove_unreachable_states (state_number old_to_new[]);
+
+/* All the states, indexed by the state number.  */
+extern state **states;
+
+/* Free all the states.  */
+void states_free (void);
 
 #endif /* !STATE_H_ */