X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/53d4308dbbc73ad186d076a7503e2a11fb0462dc..c0cac722f7e5d7498528a67a37477cdf9ed1745c:/src/state.h

diff --git a/src/state.h b/src/state.h
index 08d9fa36..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"
 
 
 /*-------------------.
@@ -97,52 +95,68 @@ 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_s
+typedef struct state_s state_t;
+
+/*--------------.
+| Transitions.  |
+`--------------*/
+
+typedef struct transtion_s
 {
-  short nshifts;
-  state_number_t shifts[1];
-} shifts_t;
+  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 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 SHIFT_IS_DISABLED(Shifts, Shift) \
-  (Shifts->shifts[Shift] == 0)
 
-/* Return the state such these SHIFTS contain a shift/goto to it on
+/* Return the state such these TRANSITIONS contain a shift/goto to it on
    SYMBOL.  Aborts if none found.  */
 struct state_s;
-struct state_s *shifts_to PARAMS ((shifts_t *shifts, symbol_number_t s));
+struct state_s *transitions_to PARAMS ((transitions_t *state,
+					symbol_number_t s));
+
 
 /*-------.
 | Errs.  |
@@ -150,12 +164,11 @@ struct state_s *shifts_to PARAMS ((shifts_t *shifts, symbol_number_t s));
 
 typedef struct errs_s
 {
-  short nerrs;
-  short errs[1];
+  short num;
+  symbol_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_t **tokens));
 
 
 /*-------------.
@@ -164,38 +177,28 @@ errs_t *errs_dup PARAMS ((errs_t *src));
 
 typedef struct reductions_s
 {
-  short nreds;
-  short rules[1];
+  short num;
+  bitset *lookaheads;
+  rule_t *rules[1];
 } reductions_t;
 
 
 
-/*----------.
-| State_t.  |
-`----------*/
+/*---------.
+| States.  |
+`---------*/
 
-typedef struct state_s
+struct state_s
 {
   state_number_t number;
   symbol_number_t accessing_symbol;
-  shifts_t     *shifts;
+  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).
-
-     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;
@@ -204,7 +207,7 @@ typedef struct state_s
      */
   unsigned short nitems;
   item_number_t items[1];
-} state_t;
+};
 
 extern state_number_t nstates;
 extern state_t *final_state;
@@ -213,13 +216,19 @@ extern state_t *final_state;
 state_t *state_new PARAMS ((symbol_number_t accessing_symbol,
 			    size_t core_size, item_number_t *core));
 
-/* Set the shifts of STATE.  */
-void state_shifts_set PARAMS ((state_t *state,
-			       int nshifts, state_number_t *shifts));
+/* 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 nreductions, short *reductions));
+				   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.  */