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1 files changed, 253 insertions, 0 deletions

diff --git a/src/syntaxParser/java_cup/terminal_set.java b/src/syntaxParser/java_cup/terminal_set.java
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+++ b/src/syntaxParser/java_cup/terminal_set.java
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+
+package java_cup;
+
+import java.util.BitSet;
+
+/** A set of terminals implemented as a bitset. 
+ * @version last updated: 11/25/95
+ * @author  Scott Hudson
+ */
+public class terminal_set {
+
+  /*-----------------------------------------------------------*/
+  /*--- Constructor(s) ----------------------------------------*/
+  /*-----------------------------------------------------------*/
+
+  /** Constructor for an empty set. */
+  public terminal_set() 
+    { 
+      /* allocate the bitset at what is probably the right size */
+      _elements = new BitSet(terminal.number());
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Constructor for cloning from another set. 
+   * @param other the set we are cloning from.
+   */
+  public terminal_set(terminal_set other) 
+    throws internal_error
+    {
+      not_null(other);
+      _elements = (BitSet)other._elements.clone();
+    }
+
+  /*-----------------------------------------------------------*/
+  /*--- (Access to) Static (Class) Variables ------------------*/
+  /*-----------------------------------------------------------*/
+
+  /** Constant for the empty set. */
+  public static final terminal_set EMPTY = new terminal_set();
+
+  /*-----------------------------------------------------------*/
+  /*--- (Access to) Instance Variables ------------------------*/
+  /*-----------------------------------------------------------*/
+
+  /** Bitset to implement the actual set. */
+  protected BitSet _elements;
+
+  /*-----------------------------------------------------------*/
+  /*--- General Methods ----------------------------------------*/
+  /*-----------------------------------------------------------*/
+
+  /** Helper function to test for a null object and throw an exception if
+   *  one is found. 
+   * @param obj the object we are testing.
+   */
+  protected void not_null(Object obj) throws internal_error
+    {
+      if (obj == null) 
+	throw new internal_error("Null object used in set operation");
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Determine if the set is empty. */
+  public boolean empty()
+    {
+      return equals(EMPTY);
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Determine if the set contains a particular terminal. 
+   * @param sym the terminal symbol we are looking for.
+   */
+  public boolean contains(terminal sym) 
+    throws internal_error
+    {
+      not_null(sym); 
+      return _elements.get(sym.index());
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Given its index determine if the set contains a particular terminal. 
+   * @param indx the index of the terminal in question.
+   */
+  public boolean contains(int indx) 
+    {
+      return _elements.get(indx);
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Determine if this set is an (improper) subset of another.
+   * @param other the set we are testing against.
+   */
+  public boolean is_subset_of(terminal_set other)
+    throws internal_error
+    {
+      not_null(other);
+
+      /* make a copy of the other set */
+      BitSet copy_other = (BitSet)other._elements.clone();
+
+      /* and or in */
+      copy_other.or(_elements);
+
+      /* if it hasn't changed, we were a subset */
+      return copy_other.equals(other._elements);
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Determine if this set is an (improper) superset of another.
+   * @param other the set we are testing against.
+   */
+  public boolean is_superset_of(terminal_set other)
+    throws internal_error
+    {
+      not_null(other);
+      return other.is_subset_of(this);
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Add a single terminal to the set.  
+   * @param sym the terminal being added.
+   * @return true if this changes the set.
+   */
+  public boolean add(terminal sym) 
+    throws internal_error
+    {
+      boolean result;
+
+      not_null(sym); 
+
+      /* see if we already have this */ 
+      result = _elements.get(sym.index());
+
+      /* if not we add it */
+      if (!result)
+	_elements.set(sym.index());
+
+      return result;
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Remove a terminal if it is in the set.
+   * @param sym the terminal being removed.
+   */
+  public void remove(terminal sym) 
+    throws internal_error
+    {
+      not_null(sym); 
+      _elements.clear(sym.index());
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Add (union) in a complete set.  
+   * @param other the set being added.
+   * @return true if this changes the set.
+   */
+  public boolean add(terminal_set other)
+    throws internal_error
+    {
+      not_null(other);
+
+      /* make a copy */
+      BitSet copy = (BitSet)_elements.clone();
+
+      /* or in the other set */
+      _elements.or(other._elements);
+
+      /* changed if we are not the same as the copy */
+      return !_elements.equals(copy);
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Determine if this set intersects another.
+   * @param other the other set in question.
+   */
+   public boolean intersects(terminal_set other)
+     throws internal_error
+     {
+       not_null(other);
+
+       /* make a copy of the other set */
+       BitSet copy = (BitSet)other._elements.clone();
+
+       /* xor out our values */
+       copy.xor(this._elements);
+
+       /* see if its different */
+       return !copy.equals(other._elements);
+     }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Equality comparison. */
+  public boolean equals(terminal_set other)
+    {
+      if (other == null) 
+	return false;
+      else
+	return _elements.equals(other._elements);
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Generic equality comparison. */
+  public boolean equals(Object other)
+    {
+      if (!(other instanceof terminal_set))
+	return false;
+      else
+	return equals((terminal_set)other);
+    }
+
+  /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
+
+  /** Convert to string. */
+  public String toString()
+    {
+      String result;
+      boolean comma_flag;
+      
+      result = "{";
+      comma_flag = false;
+      for (int t = 0; t < terminal.number(); t++)
+	{
+	  if (_elements.get(t))
+	    {
+	      if (comma_flag)
+	        result += ", ";
+	      else
+	        comma_flag = true;
+
+	      result += terminal.find(t).name();
+	    }
+	}
+      result += "}";
+
+      return result;
+    }
+
+  /*-----------------------------------------------------------*/
+
+}
+