Sync

Task/Queue-Definition/00DESCRIPTION

@@ -11,3 +11,5 @@ Errors:
 * handle the error of trying to pop from an empty queue (behavior depends on the language and platform)
 
 See [[Queue/Usage]] for the built-in FIFO or queue of your language or standard library.
+
+{{Template:See also lists}}

Task/Queue-Definition/ALGOL-68/queue-definition.alg

@@ -0,0 +1,73 @@
+# -*- coding: utf-8 -*- #
+CO REQUIRES:
+  MODE OBJLINK = STRUCT(
+    REF OBJLINK next,
+    REF OBJLINK prev,
+    OBJVALUE value # ... etc. required #
+  );
+  PROC obj link new = REF OBJLINK: ~;
+  PROC obj link free = (REF OBJLINK free)VOID: ~
+END CO
+
+# actually a pointer to the last LINK, there ITEMs are ADDED/get #
+MODE OBJQUEUE = REF OBJLINK;
+
+OBJQUEUE obj queue empty = NIL;
+
+BOOL obj queue par = FALSE; # make code thread safe #
+SEMA obj queue sema = LEVEL ABS obj queue par;
+# Warning: 1 SEMA for all queues of type obj, i.e. not 1 SEMA per queue #
+
+PROC obj queue init = (REF OBJQUEUE self)REF OBJQUEUE:
+  self := obj queue empty;
+
+PROC obj queue put = (REF OBJQUEUE self, OBJVALUE obj)REF OBJQUEUE: (
+  REF OBJLINK out = obj link new;
+  IF obj queue par THEN DOWN obj queue sema FI;
+  IF self IS obj queue empty THEN
+    out := (out, out, obj) # self referal #
+  ELSE # join into list #
+    out := (self, prev OF self, obj);
+    next OF prev OF out := prev OF next OF out := out
+  FI;
+  IF obj queue par THEN UP obj queue sema FI;
+  self := out
+);
+
+# define a useful prepend/put/plusto (+=:) operator... #
+PROC obj queue plusto = (OBJVALUE obj, REF OBJQUEUE self)OBJQUEUE: obj queue put(self,obj);
+OP +=: = (OBJVALUE obj, REF OBJQUEUE self)REF OBJQUEUE: obj queue put(self,obj);
+# a potential append/plusab (+:=) operator...
+OP (REF OBJQUEUE, OBJVALUE)OBJQUEUE +:= = obj queue plusab;
+#
+
+# see if the program/coder wants the OBJ problem mended... #
+PROC (REF OBJQUEUE #self#)BOOL obj queue index error mended
+  := (REF OBJQUEUE self)BOOL: (abend("obj queue index error"); stop);
+
+PROC on obj queue index error = (REF OBJQUEUE self, PROC(REF OBJQUEUE #self#)BOOL mended)VOID:
+  obj queue index error mended := mended;
+
+PROC obj queue get = (REF OBJQUEUE self)OBJVALUE: (
+# DOWN obj queue sema; #
+  IF self IS obj queue empty THEN
+    IF NOT obj queue index error mended(self) THEN abend("obj stack index error") FI FI;
+  OBJQUEUE old tail = prev OF self;
+  IF old tail IS self THEN # free solo member #
+    self := obj queue empty
+  ELSE # free self/tail member #
+    OBJQUEUE new tail = prev OF old tail;
+    next OF new tail := self;
+    prev OF self := new tail
+  FI;
+#;UP obj queue sema #
+  OBJVALUE out = value OF old tail;
+# give a recovery hint to the garbage collector #
+  obj link free(old tail);
+  out
+);
+
+PROC obj queue is empty = (REF OBJQUEUE self)BOOL:
+  self IS obj queue empty;
+
+SKIP

Task/Queue-Definition/Component-Pascal/queue-definition-1.component

@@ -0,0 +1,63 @@
+MODULE Queue;
+IMPORT StdLog,Boxes;
+
+TYPE
+	Queue* = POINTER TO RECORD
+		first,last: LONGINT;
+		queue: POINTER TO ARRAY OF Boxes.Object;
+	END;
+	
+	PROCEDURE NewQueue*(cap: LONGINT): Queue;
+	VAR
+		q: Queue;
+	BEGIN
+		NEW(q);q.first := 0; q.last := 0;
+		NEW(q.queue,cap);
+		RETURN q		
+	END NewQueue;
+	
+	PROCEDURE (q: Queue) IsEmpty*(): BOOLEAN, NEW;
+	VAR
+	BEGIN
+		RETURN (q.first = q.last)
+	END IsEmpty;
+	
+	PROCEDURE (q: Queue) Push*(o: Boxes.Object),NEW;
+	VAR
+		i,j,oldSize,newSize: LONGINT;
+		queue: POINTER TO ARRAY OF Boxes.Object;
+	BEGIN
+		IF q.IsEmpty() THEN
+			q.queue[q.last] := o;
+			q.last := (q.last + 1) MOD LEN(q.queue)
+		ELSE
+			q.queue[q.last] := o;
+			q.last := (q.last + 1) MOD LEN(q.queue);
+			IF q.first = q.last THEN
+				(* grow queue *)
+				newSize := LEN(q.queue) + (LEN(q.queue) DIV 2);
+				(* new queue*)
+				NEW(queue,newSize);
+				(* move data from old queue to new queue *)
+				i := q.first; j := 0;oldSize := LEN(q.queue) - q.first + q.last;
+				WHILE (j < oldSize ) & (j < LEN(queue) - 1) DO
+					queue[j] := q.queue[i];
+					i := (i + 1) MOD LEN(q.queue);INC(j)
+				END;
+				q.queue := queue;q.first := 0;q.last := j
+			END
+		END;
+	END Push;
+	
+	PROCEDURE (q: Queue) Pop*(): Boxes.Object, NEW;
+	VAR
+		o: Boxes.Object;
+	BEGIN
+		ASSERT(~q.IsEmpty());
+		o := q.queue[q.first];
+		q.queue[q.first] := NIL;
+		q.first := (q.first + 1) MOD LEN(q.queue);
+		RETURN o;
+	END Pop;
+
+END Queue.

Task/Queue-Definition/Component-Pascal/queue-definition-2.component

@@ -0,0 +1,14 @@
+DEFINITION Queue;
+
+	IMPORT Boxes;
+
+	TYPE
+		Queue = POINTER TO RECORD
+			(q: Queue) IsEmpty (): BOOLEAN, NEW;
+			(q: Queue) Pop (): Boxes.Object, NEW;
+			(q: Queue) Push (o: Boxes.Object), NEW
+		END;
+
+	PROCEDURE NewQueue (cap: LONGINT): Queue;
+
+END Queue.

Task/Queue-Definition/Nimrod/queue-definition.nimrod

@@ -0,0 +1,18 @@
+import queues
+
+# defining push & pop (obviously optional)
+proc push*[T](q: var TQueue[T]; item: T) =
+    add(q,item)
+proc pop*[T](q: var TQueue[T]): T =
+    result = dequeue(q)
+
+var fifo: TQueue[int] = initQueue[int]()
+
+fifo.push(26)
+fifo.push(99)
+fifo.push(2)
+echo("Fifo size: ", fifo.len())
+echo("Popping: ", fifo.pop())
+echo("Popping: ", fifo.pop())
+echo("Popping: ", fifo.pop())
+#echo("Popping: ", fifo.pop())     # popping an empty stack raises [EAssertionFailed]