package org.simantics.scl.runtime.chr;

import java.util.Arrays;

class PriorityContainer {
    private static final boolean CLEANUP_ENABLED = true;
    
    final int priority;
    Fact[] facts = new Fact[4];
    int size;

    public PriorityContainer(int priority) {
        this.priority = priority;
    }
    
    public void push(Fact item) {
        if(size == facts.length)
            increaseCapacity();
        facts[size++] = item;
    }

    private void increaseCapacity() {
        if(CLEANUP_ENABLED) {
            // Cleanup dead facts
            int j=0;
            for(int i=0;i<size;++i) {
                Fact fact = facts[i];
                if(fact.isAlive())
                    facts[j++] = fact;
            }
            size = j;
        }
        
        // Resize if necessary
        if(size >= facts.length*3/4)
            facts = Arrays.copyOf(facts, size*2);
    }

    public Fact pop() {
        return facts[--size];
    }
}