RosettaCodeData/Task/Queue-Definition/Action-/queue-definition-2.action

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CARD EndProg ;required for ALLOCATE.ACT
INCLUDE "D2:ALLOCATE.ACT" ;from the Action! Tool Kit. You must type 'SET EndProg=*' from the monitor after compiling, but before running this program!
DEFINE PTR="CARD"
DEFINE NODE_SIZE="3"
TYPE QueueNode=[BYTE data PTR nxt]
QueueNode POINTER queueFront,queueRear
BYTE FUNC IsEmpty()
IF queueFront=0 THEN
RETURN (1)
FI
RETURN (0)
PROC Push(BYTE v)
QueueNode POINTER node
node=Alloc(NODE_SIZE)
node.data=v
node.nxt=0
IF IsEmpty() THEN
queueFront=node
ELSE
queueRear.nxt=node
FI
queueRear=node
RETURN
BYTE FUNC Pop()
QueueNode POINTER node
BYTE v
IF IsEmpty() THEN
PrintE("Error: queue is empty!")
Break()
FI
node=queueFront
v=node.data
queueFront=node.nxt
Free(node,NODE_SIZE)
RETURN (v)
PROC TestIsEmpty()
IF IsEmpty() THEN
PrintE("Queue is empty")
ELSE
PrintE("Queue is not empty")
FI
RETURN
PROC TestPush(BYTE v)
PrintF("Push: %B%E",v)
Push(v)
RETURN
PROC TestPop()
BYTE v
Print("Pop: ")
v=Pop()
PrintBE(v)
RETURN
PROC Main()
AllocInit(0)
queueFront=0
queueRear=0
Put(125) PutE() ;clear screen
TestIsEmpty()
TestPush(10)
TestIsEmpty()
TestPush(31)
TestPop()
TestIsEmpty()
TestPush(5)
TestPop()
TestPop()
TestPop()
RETURN