InstructionCache

lib/common/src/instruction.rs

@@ -33,6 +33,42 @@ impl<I,T,X> InstructionFeedback<I,T> for X
 		X:InstructionEmitter<I,TimeInner=T>+InstructionConsumer<I,TimeInner=T>,
 {}
 
+pub struct InstructionCache<S,I,T>{
+	instruction_machine:S,
+	cached_instruction:Option<TimedInstruction<I,T>>,
+	time_limit:Time<T>,
+}
+impl<S,I,T> InstructionCache<S,I,T>
+	where
+		Time<T>:Copy+Ord,
+		Option<TimedInstruction<I,T>>:Clone,
+		S:InstructionEmitter<I,TimeInner=T>+InstructionConsumer<I,TimeInner=T>
+{
+	pub fn new(
+		instruction_machine:S,
+	)->Self{
+		Self{
+			instruction_machine,
+			cached_instruction:None,
+			time_limit:Time::MIN,
+		}
+	}
+	pub fn next_instruction_cached(&mut self,time_limit:Time<T>)->Option<TimedInstruction<I,T>>{
+		if time_limit<self.time_limit{
+			return self.cached_instruction.clone();
+		}
+		let next_instruction=self.instruction_machine.next_instruction(time_limit);
+		self.cached_instruction=next_instruction.clone();
+		self.time_limit=time_limit;
+		next_instruction
+	}
+	pub fn process_instruction(&mut self,instruction:TimedInstruction<I,T>){
+		// invalidate cache
+		self.time_limit=Time::MIN;
+		self.instruction_machine.process_instruction(instruction);
+	}
+}
+
 //PROPER PRIVATE FIELDS!!!
 pub struct InstructionCollector<I,T>{
 	time:Time<T>,