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Java > Open Source Codes > edu > rice > cs > util > sexp > Tokens


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45
46 package edu.rice.cs.util.sexp;
47
48 /**
49  * Provides a common namespace for the token classes.
50  */
51 public interface Tokens {
52   
53   /** These tokens are designed to be compared using the == operator for (, ), ", and \. Otherwise,
54   * the tokens may be compared using the .equals() method. This class is concrete only for testing
55   * purposes.
56   */
57   /* abstract */ class SExpToken {
58     protected String JavaDoc _rep;
59     
60     /** @param rep The string representation of this token */
61     public SExpToken(String JavaDoc rep) { _rep = rep; }
62     
63     /** @return the string representation of this token */
64     public String JavaDoc getText() { return _rep; }
65     
66     public boolean equals(Object JavaDoc o) {
67       return (o!=null && o.getClass() == getClass() && ((SExpToken)o)._rep.equals(_rep));
68     }
69     
70     public int hashCode() { return _rep.hashCode(); }
71     
72     public String JavaDoc toString() { return _rep; }
73   }
74   
75   ////////////// Symbol Tokens ///////////////////
76
77   class LeftParenToken extends SExpToken {
78     public static final LeftParenToken ONLY = new LeftParenToken();
79     private LeftParenToken(){ super("("); }
80   }
81   
82   class RightParenToken extends SExpToken {
83     public static final RightParenToken ONLY = new RightParenToken();
84     private RightParenToken(){ super(")"); }
85   }
86   
87   class BackSlashToken extends SExpToken {
88     public static final BackSlashToken ONLY = new BackSlashToken();
89     private BackSlashToken(){ super("\\"); }
90   }
91   
92   ////////////// General Tokens //////////////////
93
94   /** Words include any text (including symbols) that is not a number, a backslash, or a quote character. */
95   class WordToken extends SExpToken { public WordToken(String JavaDoc word) { super(word); } }
96   
97   /** This token is handled as a unit by the lexer. Any text between the pair of quotes is given
98   * in this QuotedTextToken.
99   */
100   class QuotedTextToken extends SExpToken {
101     // private String _txt;
102 public QuotedTextToken(String JavaDoc txt) { super(txt); }
103     public String JavaDoc getFullText() { return "\"" + _rep + "\""; }
104   }
105   
106   /**
107   * Words include any text (including symbols) that
108    * is not a number, a backslash, or a quote character
109    */
110   class BooleanToken extends SExpToken {
111     public static final BooleanToken TRUE = new BooleanToken(true);
112     public static final BooleanToken FALSE = new BooleanToken(false);
113     
114     private boolean _bool;
115     private BooleanToken(boolean bool){
116       super(""+bool);
117       _bool = bool;
118     }
119     public boolean getValue() { return _bool; }
120   }
121   
122   /**
123   * Numbers are string s of only digits (0-9)
124    */
125   class NumberToken extends SExpToken {
126     private double _num;
127     public NumberToken(double num){
128       // If it is a whole number, don't include
129 // the decimal in the string representation
130 super((num % 1 == 0) ? "" + (int)num : "" + num);
131       _num = num;
132     }
133     public double getValue() { return _num; }
134   }
135   
136 }
137
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