/* Type definitions for nondeterministic finite state machine for bison,
- Copyright (C) 1984, 1989 Free Software Foundation, Inc.
+ Copyright 1984, 1989, 2000, 2001 Free Software Foundation, Inc.
-This file is part of Bison, the GNU Compiler Compiler.
+ This file is part of Bison, the GNU Compiler Compiler.
-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.
+ 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.
-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.
+ 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.
-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. */
+ 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. */
/* These type definitions are used to represent a nondeterministic
- finite state machine that parses the specified grammar.
- This information is generated by the function generate_states
- in the file LR0.
-
-Each state of the machine is described by a set of items --
-particular positions in particular rules -- that are the possible
-places where parsing could continue when the machine is in this 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 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).
-
-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.
-
-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.
-
-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.
-
-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.
-
-A shift to state zero should be ignored. Conflict resolution
-deletes shifts by changing them 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.
-
-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.
-
-There is at least one shift 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. */
-
-
-typedef
- struct core
- {
- struct core *next;
- struct core *link;
- short number;
- short accessing_symbol;
- short nitems;
- short items[1];
- }
- core;
-
-
-
-typedef
- struct shifts
- {
- struct shifts *next;
- short number;
- short nshifts;
- short shifts[1];
- }
- shifts;
-
-
-
-typedef
- struct errs
- {
- short nerrs;
- short errs[1];
- }
- errs;
-
-
-
-typedef
- struct reductions
- {
- struct reductions *next;
- short number;
- short nreds;
- short rules[1];
- }
- reductions;
-
-
-
-extern int nstates;
-extern core *first_state;
-extern shifts *first_shift;
-extern reductions *first_reduction;
+ finite state machine that parses the specified grammar. This
+ information is generated by the function generate_states in the
+ file LR0.
+
+ Each state of the machine is described by a set of items --
+ particular positions in particular rules -- that are the possible
+ places where parsing could continue when the machine is in this
+ 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
+ field. When generate_states is finished, the starting state is
+ 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.
+
+ The link field is used for chaining symbols that hash states by
+ their itemsets. This is for recognizing equivalent states and
+ combining them when the states are generated.
+
+ 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.
+
+ 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.
+
+ A shift to state zero should be ignored. Conflict resolution
+ deletes shifts by changing them 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.
+
+ 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.
+
+ There is at least one shift 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. */
+
+#ifndef STATE_H_
+# define STATE_H_
+
+# include "bitsetv.h"
+
+/*---------.
+| Shifts. |
+`---------*/
+
+typedef struct shifts
+{
+ short nshifts;
+ short shifts[1];
+} shifts;
+
+shifts *shifts_new PARAMS ((int n));
+
+
+/* What is the symbol which is shifted by SHIFTS->shifts[Shift]? Can
+ be a token (amongst which the error token), or non terminals in
+ case of gotos. */
+
+#define SHIFT_SYMBOL(Shifts, Shift) \
+ (states[Shifts->shifts[Shift]]->accessing_symbol)
+
+/* Is the SHIFTS->shifts[Shift] a real shift? (as opposed to gotos.) */
+
+#define SHIFT_IS_SHIFT(Shifts, Shift) \
+ (ISTOKEN (SHIFT_SYMBOL (Shifts, Shift)))
+
+/* Is the SHIFTS->shifts[Shift] a goto?. */
+
+#define SHIFT_IS_GOTO(Shifts, Shift) \
+ (!SHIFT_IS_SHIFT (Shifts, Shift))
+
+/* Is the SHIFTS->shifts[Shift] then handling of the error token?. */
+
+#define SHIFT_IS_ERROR(Shifts, Shift) \
+ (SHIFT_SYMBOL (Shifts, Shift) == errtoken->number)
+
+/* When resolving a SR conflicts, if the reduction wins, the shift is
+ disabled. */
+
+#define SHIFT_DISABLE(Shifts, Shift) \
+ (Shifts->shifts[Shift] = 0)
+
+#define SHIFT_IS_DISABLED(Shifts, Shift) \
+ (Shifts->shifts[Shift] == 0)
+
+
+/*-------.
+| Errs. |
+`-------*/
+
+typedef struct errs
+{
+ short nerrs;
+ short errs[1];
+} errs;
+
+errs *errs_new PARAMS ((int n));
+errs *errs_dup PARAMS ((errs *src));
+
+
+/*-------------.
+| Reductions. |
+`-------------*/
+
+typedef struct reductions
+{
+ short nreds;
+ short rules[1];
+} reductions;
+
+reductions *reductions_new PARAMS ((int n));
+
+
+/*----------.
+| State_t. |
+`----------*/
+
+typedef struct state_s
+{
+ struct state_s *next;
+ struct state_s *link;
+
+ short number;
+ symbol_number_t accessing_symbol;
+ shifts *shifts;
+ reductions *reductions;
+ errs *errs;
+
+ /* Nonzero if no lookahead is needed to decide what to do in state S. */
+ char consistent;
+
+ /* Used in LALR, not LR(0). */
+ int nlookaheads;
+ bitsetv lookaheads;
+ rule_t **lookaheads_rule;
+
+ /* If some conflicts were solved thanks to precedence/associativity,
+ a human readable description of the resolution. */
+ const char *solved_conflicts;
+
+ /* Its items. Must be last, since ITEMS can be arbitrarily large.
+ */
+ unsigned short nitems;
+ item_number_t items[1];
+} state_t;
+
+#define STATE_ALLOC(Nitems) \
+ (state_t *) xcalloc ((unsigned) (sizeof (state_t) \
+ + (Nitems - 1) * sizeof (item_number_t)), 1)
+
+/* Print on OUT all the lookaheads such that this STATE wants to
+ reduce this RULE. */
+
+void state_rule_lookaheads_print PARAMS ((state_t *state, rule_t *rule,
+ FILE *out));
+
+#endif /* !STATE_H_ */
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