PerformanceTests/JetStream2/cdjs/collision_detector.js

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// Copyright (C) 2015 Apple Inc. All rights reserved.
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function CollisionDetector() {
    this._state = new RedBlackTree();
}

CollisionDetector.prototype.handleNewFrame = function(frame) {
    var motions = [];
    var seen = new RedBlackTree();
    
    for (var i = 0; i < frame.length; ++i) {
        var aircraft = frame[i];
        
        var oldPosition = this._state.put(aircraft.callsign, aircraft.position);
        var newPosition = aircraft.position;
        seen.put(aircraft.callsign, true);
        
        if (!oldPosition) {
            // Treat newly introduced aircraft as if they were stationary.
            oldPosition = newPosition;
        }
        
        motions.push(new Motion(aircraft.callsign, oldPosition, newPosition));
    }
    
    // Remove aircraft that are no longer present.
    var toRemove = [];
    this._state.forEach(function(callsign, position) {
        if (!seen.get(callsign))
            toRemove.push(callsign);
    });
    for (var i = 0; i < toRemove.length; ++i)
        this._state.remove(toRemove[i]);
    
    var allReduced = reduceCollisionSet(motions);
    var collisions = [];
    for (var reductionIndex = 0; reductionIndex < allReduced.length; ++reductionIndex) {
        var reduced = allReduced[reductionIndex];
        for (var i = 0; i < reduced.length; ++i) {
            var motion1 = reduced[i];
            for (var j = i + 1; j < reduced.length; ++j) {
                var motion2 = reduced[j];
                var collision = motion1.findIntersection(motion2);
                if (collision)
                    collisions.push(new Collision([motion1.callsign, motion2.callsign], collision));
            }
        }
    }
    
    return collisions;
};