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
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_
} transitions_t;
-/* 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) \
+ (states[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] = 0)
-#define TRANSITION_IS_DISABLED(Transitions, Shift) \
- (Transitions->states[Shift] == 0)
+#define TRANSITION_IS_DISABLED(Transitions, Num) \
+ (Transitions->states[Num] == 0)
/* Return the state such these TRANSITIONS contain a shift/goto to it on
SYMBOL. Aborts if none found. */
typedef struct errs_s
{
- short nerrs;
- short errs[1];
+ short num;
+ symbol_number_t symbols[1];
} errs_t;
-errs_t *errs_new PARAMS ((int n));
-errs_t *errs_dup PARAMS ((errs_t *src));
+errs_t *errs_new PARAMS ((int num, symbol_number_t *tokens));
/*-------------.
typedef struct reductions_s
{
- short nreds;
- short rules[1];
+ short num;
+ rule_number_t rules[1];
} reductions_t;
{
state_number_t number;
symbol_number_t accessing_symbol;
- transitions_t *shifts;
+ transitions_t *transitions;
reductions_t *reductions;
errs_t *errs;
state_t *state_new PARAMS ((symbol_number_t accessing_symbol,
size_t core_size, item_number_t *core));
-/* Set the shifts of STATE. */
+/* Set the transitions of STATE. */
void state_transitions_set PARAMS ((state_t *state,
- int nshifts, state_number_t *shifts));
+ int num, state_number_t *transitions));
/* Set the reductions of STATE. */
void state_reductions_set PARAMS ((state_t *state,
- int nreductions, short *reductions));
+ int num, rule_number_t *reductions));
+
+/* Set the errs of STATE. */
+void state_errs_set PARAMS ((state_t *state,
+ int num, symbol_number_t *errs));
/* Print on OUT all the lookaheads such that this STATE wants to
reduce this RULE. */
projects / bison.git / blobdiff