X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/a70083a3ed3fc3f69e0bed00220614f9d8263994..eb1b07409f0ccad9970c8a60ded9f2a56d205b9c:/src/state.h diff --git a/src/state.h b/src/state.h index 43e6809b..390ab8af 100644 --- a/src/state.h +++ b/src/state.h @@ -1,5 +1,7 @@ -/* Type definitions for nondeterministic finite state machine for bison, - Copyright (C) 1984, 1989, 2000 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 @@ -30,109 +32,234 @@ 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 + +# 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; + +/*--------------. +| Transitions. | +`--------------*/ -typedef struct shifts +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?. */ + +#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); -typedef struct errs +/*-------. +| Errs. | +`-------*/ + +typedef struct { - short nerrs; - short errs[1]; -} -errs; + int num; + symbol *symbols[1]; +} errs; + +errs *errs_new (int num, symbol **tokens); +/*-------------. +| Reductions. | +`-------------*/ -typedef struct 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 +{ + state_number number; + symbol_number accessing_symbol; + transitions *transitions; + reductions *reductions; + errs *errs; + + /* 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; + + /* 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); + +/* 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); + +/* 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; -extern int nstates; -extern core *first_state; -extern shifts *first_shift; -extern reductions *first_reduction; +/* Free all the states. */ +void states_free (void); #endif /* !STATE_H_ */