24 lines
2.4 KiB
Markdown
24 lines
2.4 KiB
Markdown
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# Specifications
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This section contains design specifications for some of the components in UML.txt. For the others, the UML should provide all of the information that you need.
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## The Label Class
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Label objects are used in label setting and label correcting algorithms. They maintain information about the shortest path to a particular Intersection that has been found thus far, including the length of the path and the incoming StreetSegment (i.e., the StreetSegment from the predecessor Intersection) on that path. The adjustValue() method must only update the value and predecessor if the possibleValue is less than the current value. Note that the isPermanent() and makePermanent() methods will only be used in label setting algorithms.
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## Classes that Realize the LabelManager Interface
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The adjustHeadValue() method in classes that realize the LabelManager interface must adjust the Label at the head node of the given StreetSegment. It must invoke the adjustValue() method of the appropriate Label object so that the Label is only updated if its value would be reduced.
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## Classes that Realize the CandidateLabelManager Interface
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The getCandidateLabel() method in classes that realize the CandidateLabelManager interface must return an appropriate candidate label. There are many ways to accomplish this; no particular algorithm has been specified.
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## Classes that Realize the PermnanentLabelManager Interface
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The getSmallestLabel() method in classes that realize the PermanentLabelManager interface must return a Label that has the minimum value among all non-permanent Label objects. A PermanentLabelList object must search through all non-permanent Label object in the List, a PermanentLabelHeap object must use a d-heap for this purpose, and a PermanentLabelBuckets object must use buckets for this purpose.
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## Classes that Extend the AbstractShortestPathAlgorithm Class
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Classes that extend the AbstractShortestPathAlgorithm class must use an appropriate LabelManager to manager the labels that are used in the findPath() method. The StreetSegment objects in the shortest path must be returned by the findPath() method. The findPath() method may (but is not required to) inform StreetSegmentObserver objects of StreetSegment objects that it has identified while performing the calculations. This functionality will not be used in the final product, but is useful when debugging and profililng.
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