NotEnoughItems/src/main/java/codechicken/nei/KeyManager.java

package codechicken.nei;

import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map.Entry;

/**
 * Good old down/held/up keystate tracker
 */
public class KeyManager {
    public static interface IKeyStateTracker {
        public void tickKeyStates();
    }

    public static class KeyState {
        public boolean down;
        public boolean held;
        public boolean up;
    }

    public static HashMap<String, KeyState> keyStates = new HashMap<>();
    public static LinkedList<IKeyStateTracker> trackers = new LinkedList<>();

    public static void tickKeyStates() {
        for (Entry<String, KeyState> entry : keyStates.entrySet()) {
            final boolean down = NEIClientConfig.isKeyHashDown(entry.getKey());
            final KeyState state = entry.getValue();

            if (down) {
                state.down = !state.held;
                state.up = false;
            } else {
                state.up = state.held;
                state.down = false;
            }

            state.held = down;
        }

        for (IKeyStateTracker tracker : trackers) tracker.tickKeyStates();
    }
}