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csjavacc/parser/RChoice.java

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+/*
+ * Copyright © 2002 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * California 95054, U.S.A. All rights reserved.  Sun Microsystems, Inc. has
+ * intellectual property rights relating to technology embodied in the product
+ * that is described in this document. In particular, and without limitation,
+ * these intellectual property rights may include one or more of the U.S.
+ * patents listed at http://www.sun.com/patents and one or more additional
+ * patents or pending patent applications in the U.S. and in other countries.
+ * U.S. Government Rights - Commercial software. Government users are subject
+ * to the Sun Microsystems, Inc. standard license agreement and applicable
+ * provisions of the FAR and its supplements.  Use is subject to license terms.
+ * Sun,  Sun Microsystems,  the Sun logo and  Java are trademarks or registered
+ * trademarks of Sun Microsystems, Inc. in the U.S. and other countries.  This
+ * product is covered and controlled by U.S. Export Control laws and may be
+ * subject to the export or import laws in other countries.  Nuclear, missile,
+ * chemical biological weapons or nuclear maritime end uses or end users,
+ * whether direct or indirect, are strictly prohibited.  Export or reexport
+ * to countries subject to U.S. embargo or to entities identified on U.S.
+ * export exclusion lists, including, but not limited to, the denied persons
+ * and specially designated nationals lists is strictly prohibited.
+ */
+
+package csjavacc.parser;
+import java.util.Vector;
+
+import csjavacc.struct.Nfa;
+import csjavacc.struct.RJustName;
+import csjavacc.struct.RegularExpression;
+
+
+/**
+ * Describes regular expressions which are choices from
+ * from among included regular expressions.
+ */
+
+public class RChoice extends RegularExpression {
+
+  /**
+   * The list of choices of this regular expression.  Each
+   * Vector component will narrow to RegularExpression.
+   */
+  public java.util.Vector choices = new java.util.Vector();
+
+  public Nfa GenerateNfa(boolean ignoreCase)
+  {
+     CompressCharLists();
+
+     if (choices.size() == 1)
+        return ((RegularExpression)choices.elementAt(0)).GenerateNfa(ignoreCase);
+
+     Nfa retVal = new Nfa();
+     NfaState startState = retVal.start;
+     NfaState finalState = retVal.end;
+
+     for (int i = 0; i < choices.size(); i++)
+     {
+        Nfa temp;
+        RegularExpression curRE = (RegularExpression)choices.elementAt(i);
+
+        temp = curRE.GenerateNfa(ignoreCase);
+
+        startState.AddMove(temp.start);
+        temp.end.AddMove(finalState);
+     }
+
+     return retVal;
+  }
+
+  void CompressCharLists()
+  { 
+     CompressChoices(); // Unroll nested choices
+     RegularExpression curRE;
+     RCharacterList curCharList = null;
+
+     for (int i = 0; i < choices.size(); i++)
+     {
+        curRE = (RegularExpression)choices.elementAt(i);
+
+        while (curRE instanceof RJustName)
+           curRE = ((RJustName)curRE).regexpr;
+
+        if (curRE instanceof RStringLiteral &&
+            ((RStringLiteral)curRE).image.length() == 1)
+           choices.setElementAt(curRE = new RCharacterList(
+                      ((RStringLiteral)curRE).image.charAt(0)), i);
+
+        if (curRE instanceof RCharacterList)
+        {
+           if (((RCharacterList)curRE).negated_list)
+              ((RCharacterList)curRE).RemoveNegation();
+
+           Vector tmp = ((RCharacterList)curRE).descriptors;
+
+           if (curCharList == null)
+              choices.setElementAt(curRE = curCharList =
+                                    new RCharacterList(), i);
+           else
+              choices.removeElementAt(i--);
+
+           for (int j = tmp.size(); j-- > 0;)
+              curCharList.descriptors.addElement(tmp.elementAt(j));
+         }
+
+     }
+  }
+
+  void CompressChoices()
+  {
+     RegularExpression curRE;
+
+     for (int i = 0; i < choices.size(); i++)
+     {
+        curRE = (RegularExpression)choices.elementAt(i);
+
+        while (curRE instanceof RJustName)
+           curRE = ((RJustName)curRE).regexpr;
+
+        if (curRE instanceof RChoice)
+        {
+           choices.removeElementAt(i--);
+           for (int j = ((RChoice)curRE).choices.size(); j-- > 0;)
+              choices.addElement(((RChoice)curRE).choices.elementAt(j));
+        }
+     }
+  }
+
+  public void CheckUnmatchability()
+  {
+     RegularExpression curRE;
+     int numStrings = 0;
+
+     for (int i = 0; i < choices.size(); i++)
+     {
+        if (!(curRE = (RegularExpression)choices.elementAt(i)).private_rexp &&
+            //curRE instanceof RJustName &&
+            curRE.ordinal > 0 && curRE.ordinal < ordinal &&
+            LexGen.lexStates[curRE.ordinal] == LexGen.lexStates[ordinal])
+        {
+           if (label != null)
+              CSJavaCCErrors.warning(this, "Regular Expression choice : " +
+                 curRE.label + " can never be matched as : " + label);
+           else
+              CSJavaCCErrors.warning(this, "Regular Expression choice : " +
+                 curRE.label + " can never be matched as token of kind : " +
+                                                                      ordinal);
+        }
+
+        if (!curRE.private_rexp && curRE instanceof RStringLiteral)
+           numStrings++;
+     }
+  }
+
+}