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+/* Type definitions for nondeterministic finite state machine for bison,
+   Copyright (C) 1984, 1989 Free Software Foundation, Inc.
+
+This file is part of Bison, the GNU Compiler Compiler.
+
+Bison is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+Bison is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+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, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+
+/* These type definitions are used to represent a nondeterministic
+   finite state machine that parses the specified grammar.
+   This information is generated by the function generate_states
+   in the file LR0.
+
+Each state of the machine is described by a set of items --
+particular positions in particular rules -- that are the possible
+places where parsing could continue when the machine is in this 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 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).
+
+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.
+
+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.
+
+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.
+
+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.
+
+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.
+
+There is at least one shift 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.  */
+
+
+typedef
+  struct core
+    {
+      struct core *next;
+      struct core *link;
+      short number;
+      short accessing_symbol;
+      short nitems;
+      short items[1];
+    }
+  core;
+
+
+
+typedef
+  struct shifts
+    {
+      struct shifts *next;
+      short number;
+      short nshifts;
+      short internalShifts[1];
+    }
+  shifts;
+
+
+
+typedef
+  struct errs
+    {
+      short nerrs;
+      short internalErrs[1];
+    }
+  errs;
+
+
+
+typedef
+  struct reductions
+    {
+      struct reductions *next;
+      short number;
+      short nreds;
+      short rules[1];
+    }
+  reductions;
+
+
+
+extern int nstates;
+extern core *first_state;
+extern shifts *first_shift;
+extern reductions *first_reduction;