1 files changed, 89 insertions, 0 deletions
diff --git a/sources/scalac/symtab/SymSet.java b/sources/scalac/symtab/SymSet.java
new file mode 100644
index 0000000000..f72b9764f5
--- /dev/null
+++ b/sources/scalac/symtab/SymSet.java
@@ -0,0 +1,89 @@
+/*     ____ ____  ____ ____  ______                                     *\
+**    / __// __ \/ __// __ \/ ____/    SOcos COmpiles Scala             **
+**  __\_ \/ /_/ / /__/ /_/ /\_ \       (c) 2002, LAMP/EPFL              **
+** /_____/\____/\___/\____/____/                                        **
+\*                                                                      */
+
+// $Id$
+
+package scalac.symtab;
+
+/** Sets of symbols, implemented as binary trees.
+ */
+public class SymSet {
+    private SymSet l, r;
+    private Symbol sym;
+
+    public SymSet() {}
+
+    private SymSet(Symbol sym, SymSet l, SymSet r) {
+	this.sym = sym; this.l = l; this.r = r;
+    }
+
+    /** Union of this set and `{sym}'.
+     */
+    public SymSet incl(Symbol sym) {
+	if (this == EMPTY) {
+	    return new SymSet(sym, EMPTY, EMPTY);
+	} else if (sym == this.sym) {
+	    return this;
+	} else if (sym.isLess(this.sym)) {
+	    return new SymSet(this.sym, l.incl(sym), r);
+	} else {
+	    assert this.sym.isLess(sym);
+	    return new SymSet(this.sym, l, r.incl(sym));
+	}
+    }
+
+    /** Is `sym' an element of this set?
+     */
+    public boolean contains(Symbol sym) {
+	if (this == EMPTY) {
+	    return false;
+	} else if (sym == this.sym) {
+	    return true;
+	} else if (sym.isLess(this.sym)) {
+	    return l.contains(sym);
+	} else {
+	    assert this.sym.isLess(sym);
+	    return r.contains(sym);
+	}
+    }
+
+    /** The number of elements in ths set.
+     */
+    public int size() {
+	if (this == EMPTY) {
+	    return 0;
+	} else {
+	    return 1 + l.size() + r.size();
+	}
+    }
+
+    /** Copy elements of this set into `ss', starting at index `from'.
+     *  Return index one past last element copied.
+     */
+    public int copyToArray(Symbol[] ss, int from) {
+	if (this == EMPTY) {
+	    return from;
+	} else {
+	    from = l.copyToArray(ss, from);
+	    ss[from] = sym;
+	    return r.copyToArray(ss, from + 1);
+	}
+    }
+
+    /** Return all elements of this set as an array.
+     */
+    public Symbol[] toArray() {
+	int s = size();
+	if (s == 0) return Symbol.EMPTY_ARRAY;
+	Symbol[] ss = new Symbol[s];
+	copyToArray(ss, 0);
+	return ss;
+    }
+
+    /** The empty set.
+     */
+    public final static SymSet EMPTY = new SymSet();
+}