File	Doc	Category	Size	Date	Package
symbol_set.java	API Doc	Java SE 5 API	6373	Fri Aug 26 14:54:54 BST 2005	com.sun.java_cup.internal

symbol_set

• java.lang.Object

Fields Summary
protected Hashtable	_all A hash table to hold the set. Symbols are keyed using their name string.

Constructors Summary
public symbol_set() Constructor for an empty set.
public symbol_set(symbol_set other) Constructor for cloning from another set. param other the set we are cloning from. not_null(other); _all = (Hashtable)other._all.clone();

Methods Summary
public boolean	add(com.sun.java_cup.internal.symbol_set other) Add (union) in a complete set. param other the set we are adding in. return true if this changes the set. boolean result = false; not_null(other); /* walk down the other set and do the adds individually */ for (Enumeration e = other.all(); e.hasMoreElements(); ) result = add((symbol)e.nextElement()) || result; return result;
public boolean	add(symbol sym) Add a single symbol to the set. param sym the symbol we are adding. return true if this changes the set. Object previous; not_null(sym); /* put the object in */ previous = _all.put(sym.name(),sym); /* if we had a previous, this is no change */ return previous == null;
public java.util.Enumeration	all() Access to all elements of the set. return _all.elements();
public boolean	contains(symbol sym) Determine if the set contains a particular symbol. param sym the symbol we are looking for. return _all.containsKey(sym.name());
public boolean	equals(com.sun.java_cup.internal.symbol_set other) Equality comparison. if (other == null || other.size() != size()) return false; /* once we know they are the same size, then improper subset does test */ try { return is_subset_of(other); } catch (internal_error e) { /* can't throw the error (because super class doesn't), so we crash */ e.crash(); return false; }
public boolean	equals(java.lang.Object other) Generic equality comparison. if (!(other instanceof symbol_set)) return false; else return equals((symbol_set)other);
public int	hashCode() Compute a hash code. int result = 0; int cnt; Enumeration e; /* hash together codes from at most first 5 elements */ for (e = all(), cnt=0 ; e.hasMoreElements() && cnt<5; cnt++) result ^= ((symbol)e.nextElement()).hashCode(); return result;
public boolean	is_subset_of(com.sun.java_cup.internal.symbol_set other) Determine if this set is an (improper) subset of another. param other the set we are testing against. not_null(other); /* walk down our set and make sure every element is in the other */ for (Enumeration e = all(); e.hasMoreElements(); ) if (!other.contains((symbol)e.nextElement())) return false; /* they were all there */ return true;
public boolean	is_superset_of(com.sun.java_cup.internal.symbol_set other) Determine if this set is an (improper) superset of another. param other the set we are are testing against. not_null(other); return other.is_subset_of(this);
protected void	not_null(java.lang.Object obj) Helper function to test for a null object and throw an exception if one is found. param obj the object we are testing. if (obj == null) throw new internal_error("Null object used in set operation");
public void	remove(symbol sym) Remove a single symbol if it is in the set. param sym the symbol we are removing. not_null(sym); _all.remove(sym.name());
public void	remove(com.sun.java_cup.internal.symbol_set other) Remove (set subtract) a complete set. param other the set we are removing. not_null(other); /* walk down the other set and do the removes individually */ for (Enumeration e = other.all(); e.hasMoreElements(); ) remove((symbol)e.nextElement());
public int	size() size of the set return _all.size();
public java.lang.String	toString() Convert to a string. String result; boolean comma_flag; result = "{"; comma_flag = false; for (Enumeration e = all(); e.hasMoreElements(); ) { if (comma_flag) result += ", "; else comma_flag = true; result += ((symbol)e.nextElement()).name(); } result += "}"; return result;