symbol expander util

Author: borismarin

src/main/java/expr_parser/utils/SymbolExpander.java

@@ -0,0 +1,31 @@
+package expr_parser.utils;
+
+import java.util.LinkedHashMap;
+import java.util.LinkedList;
+import java.util.Queue;
+
+import expr_parser.visitors.AntlrExpressionParser;
+import expr_parser.visitors.ExpandSymbols;
+
+public class SymbolExpander {
+	public static final LinkedHashMap<String, String> expandSymbols(
+			LinkedHashMap<String, String> context) {
+		// we expect a toposorted context, ergo linkedHM
+		LinkedList<String> queue = new LinkedList<String>();
+		queue.addAll(context.keySet());
+		return expandSymbols(context, queue);
+	}
+
+	private static final LinkedHashMap<String, String> expandSymbols(
+			LinkedHashMap<String, String> context, Queue<String> queue) {
+		while (!queue.isEmpty()) {
+			String s = queue.remove();
+			AntlrExpressionParser p = new AntlrExpressionParser(context.get(s));
+			ExpandSymbols expander = new ExpandSymbols(context);
+			context.put(s, p.parseAndVisitWith(expander));
+			expandSymbols(context, queue);
+		}
+		return context;
+	}
+
+}