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Java > Open Source Codes > edu > rice > cs > drjava > config > OptionParser


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33
34 package edu.rice.cs.drjava.config;
35 import java.util.Hashtable JavaDoc;
36 /** The association of an OptionName with the ability to parse something to type T; the intended type
37  * parameterization is covariant: if U extends T, then OptionParser<U> extends OptionParser<T>.
38  */
39 public abstract class OptionParser<T> implements ParseStrategy<T> {
40     
41     /** The logical name of this configurable option (i.e. "indent.size") public because it's final,
42      * and a String is immutable.
43      */
44     public final String JavaDoc name;
45     private final T defaultValue;
46
47     /** An inner hashtable that maps DefaultOptionMaps to value T's. Part of the magic inner workings of this package.
48      */
49     final Hashtable JavaDoc<DefaultOptionMap,T> map = new Hashtable JavaDoc<DefaultOptionMap,T>();
50
51     /** Constructor that takes in a name
52      * @param name the name of this option (i.e. "indent.level");
53      */
54     public OptionParser(String JavaDoc name, T def) { this.name = name; defaultValue = def; }
55     
56     /** Accessor for name option
57      * @return name of this option (i.e. "indent.level")
58      */
59     public String JavaDoc getName() { return name; }
60
61     /** @return the default value */
62     public T getDefault() { return defaultValue; }
63
64     /** @return the default value as a string */
65     public abstract String JavaDoc getDefaultString();
66   
67     /** The ability to parse a string to an object of type T. All concrete versions of this class must override this
68      * method to provide some sort of parser implementation.
69      * @param value a String to parse
70      * @return the statically-typed representation of the string value.
71      */
72     public abstract T parse(String JavaDoc value);
73      
74     /* PACKAGE PRIVATE MAGIC STUFF
75      * This package-private magic stuff makes all of the config "magic" types work. Basically, it's achieved via a
76      * double-dispatch stunt, so that the type information is saved. */
77
78     abstract String JavaDoc getString(DefaultOptionMap om);
79     
80     /** Uses parse() and setOption() so that any changes in parsing will automatically be applied to setString(). */
81     T setString(DefaultOptionMap om, String JavaDoc val) { return setOption(om,parse(val)); }
82     
83     /** The accessor for the magic-typed hashtable stunt. */
84     T getOption(DefaultOptionMap om) { return map.get(om); }
85
86     /** The mutator for the magic-typed hashtable stunt. */
87     T setOption(DefaultOptionMap om, T val) { return map.put(om,val); }
88     
89     /** The destructor for a mapping in the magic-typed hashtable. */
90     T remove(DefaultOptionMap om) { return map.remove(om); }
91 }
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