/* 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, 675 Mass Ave, Cambridge, MA 02139, 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 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 transition_t 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 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.
+
+ 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 holds the token numbers.
+
+ 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.
+ 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 "bitset.h"
+
+
+/*-------------------.
+| Numbering states. |
+`-------------------*/
+
+typedef short state_number_t;
+# define STATE_NUMBER_MAX ((state_number_t) SHRT_MAX)
+
+/* Be ready to map a state_number_t to an int. */
+# define state_number_as_int(Tok) ((int) (Tok))
+
+
+typedef struct state_s state_t;
+
+/*--------------.
+| Transitions. |
+`--------------*/
+
+typedef struct transtion_s
+{
+ short num;
+ state_t *states[1];
+} transitions_t;
+
+
+/* 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?. */
+
+#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 these TRANSITIONS contain a shift/goto to it on
+ SYMBOL. Aborts if none found. */
+struct state_s;
+struct state_s *transitions_to PARAMS ((transitions_t *state,
+ symbol_number_t s));
+
+
+/*-------.
+| Errs. |
+`-------*/
+
+typedef struct errs_s
+{
+ short num;
+ symbol_t *symbols[1];
+} errs_t;
+
+errs_t *errs_new PARAMS ((int num, symbol_t **tokens));
+
+
+/*-------------.
+| Reductions. |
+`-------------*/
+
+typedef struct reductions_s
+{
+ short num;
+ bitset *lookaheads;
+ rule_t *rules[1];
+} reductions_t;
+
+
+
+/*---------.
+| States. |
+`---------*/
+
+struct state_s
+{
+ state_number_t number;
+ symbol_number_t accessing_symbol;
+ transitions_t *transitions;
+ reductions_t *reductions;
+ errs_t *errs;
+
+ /* Nonzero if no lookahead is 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;
+
+ /* Its items. Must be last, since ITEMS can be arbitrarily large.
+ */
+ unsigned short nitems;
+ item_number_t items[1];
+};
+
+extern state_number_t nstates;
+extern state_t *final_state;
+
+/* Create a new state with ACCESSING_SYMBOL for those items. */
+state_t *state_new PARAMS ((symbol_number_t accessing_symbol,
+ size_t core_size, item_number_t *core));
+
+/* Set the transitions of STATE. */
+void state_transitions_set PARAMS ((state_t *state,
+ int num, state_t **transitions));
+
+/* Set the reductions of STATE. */
+void state_reductions_set PARAMS ((state_t *state,
+ int num, rule_t **reductions));
+
+int state_reduction_find PARAMS ((state_t *state, rule_t *rule));
+
+/* Set the errs of STATE. */
+void state_errs_set PARAMS ((state_t *state,
+ int num, symbol_t **errs));
+
+/* 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));
+
+/* Create/destroy the states hash table. */
+void state_hash_new PARAMS ((void));
+void state_hash_free PARAMS ((void));
+
+/* Find the state associated to the CORE, and return it. If it does
+ not exist yet, return NULL. */
+state_t *state_hash_lookup PARAMS ((size_t core_size, item_number_t *core));
+
+/* Insert STATE in the state hash table. */
+void state_hash_insert PARAMS ((state_t *state));
+
+/* All the states, indexed by the state number. */
+extern state_t **states;
+
+/* Free all the states. */
+void states_free PARAMS ((void));
+#endif /* !STATE_H_ */
projects / bison.git / blobdiff