X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/d257636504fc23c24be818a34f55a226bb29b719..75ad86eebd3f49dff81976eb83036eb7b7793e68:/src/state.h?ds=sidebyside diff --git a/src/state.h b/src/state.h index 6e3b2b3a..e0aa6b75 100644 --- a/src/state.h +++ b/src/state.h @@ -1,5 +1,7 @@ -/* Type definitions for nondeterministic finite state machine for bison, - Copyright 1984, 1989, 2000, 2001 Free Software Foundation, Inc. +/* Type definitions for nondeterministic finite state machine for Bison. + + Copyright (C) 1984, 1989, 2000, 2001, 2002, 2003, 2004, 2007 Free + Software Foundation, Inc. This file is part of Bison, the GNU Compiler Compiler. @@ -15,8 +17,8 @@ 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. */ + the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, + Boston, MA 02110-1301, USA. */ /* These type definitions are used to represent a nondeterministic @@ -42,206 +44,225 @@ 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. + 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_ -# include "bitsetv.h" +# include + +# include "gram.h" +# include "symtab.h" /*-------------------. | Numbering states. | `-------------------*/ -typedef short state_number_t; -# define STATE_NUMBER_MAX ((state_number_t) SHRT_MAX) +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) +{ + return s; +} + -/* Be ready to map a state_number_t to an int. */ -# define state_number_as_int(Tok) ((int) (Tok)) +typedef struct state state; /*--------------. | Transitions. | `--------------*/ -typedef struct transtion_s +typedef struct { - short num; - state_number_t states[1]; -} transitions_t; + int num; + state *states[1]; +} transitions; -/* What is the symbol which is shifted by TRANSITIONS->states[Shift]? Can - be a token (amongst which the error token), or non terminals in - case of gotos. */ +/* 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, Shift) \ - (states[Transitions->states[Shift]]->accessing_symbol) +#define TRANSITION_SYMBOL(Transitions, Num) \ + (Transitions->states[Num]->accessing_symbol) -/* Is the TRANSITIONS->states[Shift] a real shift? (as opposed to gotos.) */ +/* Is the TRANSITIONS->states[Num] a shift? (as opposed to gotos). */ -#define TRANSITION_IS_SHIFT(Transitions, Shift) \ - (ISTOKEN (TRANSITION_SYMBOL (Transitions, Shift))) +#define TRANSITION_IS_SHIFT(Transitions, Num) \ + (ISTOKEN (TRANSITION_SYMBOL (Transitions, Num))) -/* Is the TRANSITIONS->states[Shift] a goto?. */ +/* Is the TRANSITIONS->states[Num] a goto?. */ -#define TRANSITION_IS_GOTO(Transitions, Shift) \ - (!TRANSITION_IS_SHIFT (Transitions, Shift)) +#define TRANSITION_IS_GOTO(Transitions, Num) \ + (!TRANSITION_IS_SHIFT (Transitions, Num)) -/* Is the TRANSITIONS->states[Shift] then handling of the error token?. */ +/* Is the TRANSITIONS->states[Num] labelled by the error token? */ -#define TRANSITION_IS_ERROR(Transitions, Shift) \ - (TRANSITION_SYMBOL (Transitions, Shift) == errtoken->number) +#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, Shift) \ - (Transitions->states[Shift] = 0) +#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)) -#define TRANSITION_IS_DISABLED(Transitions, Shift) \ - (Transitions->states[Shift] == 0) -/* 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)); +/* 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 errs_s +typedef struct { - short num; - symbol_number_t symbols[1]; -} errs_t; + int num; + symbol *symbols[1]; +} errs; -errs_t *errs_new PARAMS ((int n)); -errs_t *errs_dup PARAMS ((errs_t *src)); +errs *errs_new (int num, symbol **tokens); /*-------------. | Reductions. | `-------------*/ -typedef struct reductions_s +typedef struct { - short num; - rule_number_t rules[1]; -} reductions_t; + int num; + bitset *lookahead_tokens; + rule *rules[1]; +} reductions; -/*----------. -| State_t. | -`----------*/ +/*---------. +| states. | +`---------*/ -typedef struct state_s +struct state { - state_number_t number; - symbol_number_t accessing_symbol; - transitions_t *shifts; - reductions_t *reductions; - errs_t *errs; + state_number number; + symbol_number accessing_symbol; + transitions *transitions; + 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). - - When a state is not consistent (there is an S/R or R/R conflict), - lookaheads are needed to enable the reductions. NLOOKAHEADS is - the number of lookahead guarded reductions of the - LOOKAHEADS_RULE. For each rule LOOKAHEADS_RULE[R], LOOKAHEADS[R] - is the bitset of the lookaheads enabling this reduction. */ - 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; + /* Conflict resolution sometimes makes states unreachable. Initialized to 0 + in state_new and then used by state_remove_unreachable_states after + conflicts_solve. */ + bool reachable; + /* Its items. Must be last, since ITEMS can be arbitrarily large. */ - unsigned short nitems; - item_number_t items[1]; -} state_t; + size_t nitems; + item_number items[1]; +}; -extern state_number_t nstates; -extern state_t *final_state; +extern state_number nstates; +extern state *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)); +state *state_new (symbol_number accessing_symbol, + size_t core_size, item_number *core); -/* Set the shifts of STATE. */ -void state_transitions_set PARAMS ((state_t *state, - int nshifts, state_number_t *shifts)); +/* Set the transitions of STATE. */ +void state_transitions_set (state *s, int num, state **trans); /* Set the reductions of STATE. */ -void state_reductions_set PARAMS ((state_t *state, - int nreductions, short *reductions)); +void state_reductions_set (state *s, int num, rule **reds); + +int state_reduction_find (state *s, rule *r); -/* 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)); +/* 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); /* Create/destroy the states hash table. */ -void state_hash_new PARAMS ((void)); -void state_hash_free PARAMS ((void)); +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_t *state_hash_lookup PARAMS ((size_t core_size, item_number_t *core)); +state *state_hash_lookup (size_t core_size, item_number *core); /* Insert STATE in the state hash table. */ -void state_hash_insert PARAMS ((state_t *state)); +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_t **states; +extern state **states; /* Free all the states. */ -void states_free PARAMS ((void)); +void states_free (void); + #endif /* !STATE_H_ */