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33
34 package edu.rice.cs.drjava.model.definitions.indent;
35
36 import edu.rice.cs.drjava.model.AbstractDJDocument;
37
38 /**
39  * A question node in the decision tree for the indentation system.
40  * Calls to <code>indentLine</code> on an IndentRuleQuestion will
41  * make a decision based on context and call the same method on
42  * one of its children. The leaves of the tree are represented
43  * by IndentRuleAction objects.
44  * @version $Id: IndentRuleQuestion.java 3901 2006-06-30 05:28:11Z rcartwright $
45  */
46 public abstract class IndentRuleQuestion extends IndentRuleWithTrace {
47   /**
48    * Node in decision tree to use if the rule holds in this context.
49    */
50   private final IndentRule _yesRule;
51
52   /**
53    * Node in decision tree to use if the rule does not hold in this context.
54    */
55   private final IndentRule _noRule;
56
57   /**
58    * Constructs a new Question indent rule using the two given children.
59    * @param yesRule Rule to use if this rule holds
60    * @param noRule Rule to use if this rule does not hold
61    */
62   public IndentRuleQuestion(final IndentRule yesRule, final IndentRule noRule) {
63     _yesRule = yesRule;
64     _noRule = noRule;
65   }
66
67   /** Determines if the given rule holds in this context.
68    * @param doc AbstractDJDocument containing the line to be indented.
69    * @param reason - The reason that indentation was initiated, specified in Indenter
70    * @return true if this node's rule holds.
71    */
72   abstract boolean applyRule(AbstractDJDocument doc, int reason);
73
74   /** Determines if the given rule holds in this context.
75    * @param doc AbstractDJDocument containing the line to be indented.
76    * @param pos Position within line to be indented.
77    * @param reason - The reason that indentation was initiated, specified in Indenter
78    * @return true if this node's rule holds.
79    */
80   boolean applyRule(AbstractDJDocument doc, int pos, int reason) {
81     int oldPos = doc.getCurrentLocation();
82     doc.setCurrentLocation(pos);
83     boolean result = applyRule(doc, reason);
84     if (oldPos > doc.getLength()) {
85       oldPos = doc.getLength();
86     }
87     doc.setCurrentLocation(oldPos);
88     return result;
89   }
90
91   /**
92    * Determines if the given rule holds in this context and calls
93    * the same method on one of its child nodes.
94    * @param doc AbstractDJDocument containing the line to be indented.
95    * @param reason - The reason that indentation was initiated, specified in Indenter
96    * @return true if the caller should update the current location itself,
97    * false if the indenter has already handled this
98    */
99   public boolean indentLine(AbstractDJDocument doc, int reason) {
100     if (applyRule(doc, reason)) {
101       _addToIndentTrace(getRuleName(), YES, false);
102       return _yesRule.indentLine(doc, reason);
103     }
104     else {
105       _addToIndentTrace(getRuleName(), NO, false);
106       return _noRule.indentLine(doc, reason);
107     }
108   }
109 }
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