LexQueue.def

(*!m2r10*) (* Copyright (c) 2015 B.Kowarsch. All rights reserved. *)

DEFINITION MODULE LexQueue;

(* Lexeme Queue for Modula-2 R10 Core Compiler *)

IMPORT Lexeme;


TYPE LexQueue = OPAQUE;

(* Constructor *)

PROCEDURE New ( VAR queue : LexQueue );
(* Allocates a new empty queue object and passes it back in queue.
   Passes NIL if the allocation failed. *)


(* Destructor *)

PROCEDURE Release ( VAR queue : LexQueue );
(* Releases queue and passes back NIL if successful. *)


(* Operations *)

PROCEDURE enqueue ( queue : LexQueue; lexeme : Lexeme ) : Queue;
(* Adds lexeme to the head of queue and returns queue, or NIL on failure. *)

PROCEDURE enqueueUnique ( queue : LexQueue; lexeme : Lexeme ) : Queue;
(* Adds lexeme to the head of queue if and only if the value is not already
 * present in queue.  Returns queue on success, or NIL on failure. *)

PROCEDURE dequeue ( queue : LexQueue ) : Lexeme;
(* Removes the lexeme at the tail queue and returns it, or NIL on failure. *)

PROCEDURE isEmpty ( queue : LexQueue ) : BOOLEAN;
(* Returns TRUE if queue is empty, otherwise FALSE. *)

PROCEDURE isElem ( queue : LexQueue; lexeme : Lexeme ) : BOOLEAN;
(* Returns TRUE if node is stored in queue, otherwise FALSE. *)

PROCEDURE count ( queue : LexQueue ) : CARDINAL;
(* Returns the number of nodes in queue. *)

PROCEDURE Reset ( queue : LexQueue ) : AST;
(* Removes all nodes from queue but does not deallocate it.
   Returns queue on success, or NIL if queue is NIL. *)


END LexQueue.