X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/c7ca99d4b03860bb258914fbc228272031eec77c..f377f69fec28013c79db4efe12bbb9d48987fb2c:/src/state.h diff --git a/src/state.h b/src/state.h index 524bfc9c..f63cc4f8 100644 --- a/src/state.h +++ b/src/state.h @@ -44,21 +44,21 @@ 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 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. + 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 @@ -68,23 +68,21 @@ 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 "bitset.h" /*-------------------. @@ -97,100 +95,110 @@ typedef short state_number_t; /* Be ready to map a state_number_t to an int. */ # define state_number_as_int(Tok) ((int) (Tok)) -/*---------. -| Shifts. | -`---------*/ -typedef struct shifts -{ - short nshifts; - state_number_t shifts[1]; -} shifts; +typedef struct state_s state_t; -shifts *shifts_new PARAMS ((int n)); +/*--------------. +| Transitions. | +`--------------*/ + +typedef struct transtion_s +{ + short num; + state_t *states[1]; +} transitions_t; -/* 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. */ +/* 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 SHIFT_SYMBOL(Shifts, Shift) \ - (states[Shifts->shifts[Shift]]->accessing_symbol) +#define TRANSITION_SYMBOL(Transitions, Num) \ + (Transitions->states[Num]->accessing_symbol) -/* Is the SHIFTS->shifts[Shift] a real shift? (as opposed to gotos.) */ +/* Is the TRANSITIONS->states[Num] a shift? (as opposed to gotos). */ -#define SHIFT_IS_SHIFT(Shifts, Shift) \ - (ISTOKEN (SHIFT_SYMBOL (Shifts, Shift))) +#define TRANSITION_IS_SHIFT(Transitions, Num) \ + (ISTOKEN (TRANSITION_SYMBOL (Transitions, Num))) -/* Is the SHIFTS->shifts[Shift] a goto?. */ +/* Is the TRANSITIONS->states[Num] a goto?. */ -#define SHIFT_IS_GOTO(Shifts, Shift) \ - (!SHIFT_IS_SHIFT (Shifts, Shift)) +#define TRANSITION_IS_GOTO(Transitions, Num) \ + (!TRANSITION_IS_SHIFT (Transitions, Num)) -/* Is the SHIFTS->shifts[Shift] then handling of the error token?. */ +/* Is the TRANSITIONS->states[Num] labelled by the error token? */ -#define SHIFT_IS_ERROR(Shifts, Shift) \ - (SHIFT_SYMBOL (Shifts, 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 SHIFT_DISABLE(Shifts, Shift) \ - (Shifts->shifts[Shift] = 0) +#define TRANSITION_DISABLE(Transitions, Num) \ + (Transitions->states[Num] = NULL) -#define SHIFT_IS_DISABLED(Shifts, Shift) \ - (Shifts->shifts[Shift] == 0) +#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 +typedef struct errs_s { - short nerrs; - short errs[1]; -} errs; + short num; + symbol_t *symbols[1]; +} errs_t; -errs *errs_new PARAMS ((int n)); -errs *errs_dup PARAMS ((errs *src)); +errs_t *errs_new PARAMS ((int num, symbol_t **tokens)); /*-------------. | Reductions. | `-------------*/ -typedef struct reductions +typedef struct reductions_s { - short nreds; - short rules[1]; -} reductions; + short num; + bitset *lookaheads; + rule_t *rules[1]; +} reductions_t; -reductions *reductions_new PARAMS ((int n)); -/*----------. -| State_t. | -`----------*/ +/*---------. +| States. | +`---------*/ -typedef struct state_s +struct state_s { - struct state_s *next; - state_number_t number; symbol_number_t accessing_symbol; - shifts *shifts; - reductions *reductions; - errs *errs; + 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; - /* 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; @@ -199,19 +207,31 @@ typedef struct state_s */ unsigned short nitems; item_number_t items[1]; -} state_t; +}; 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));