Add range locations

Range locations contains the left and right poistions in the source code where something is found.

src/main/java/parse/Loc.java

@@ -0,0 +1,46 @@
+package parse;
+
+import java_cup.runtime.ComplexSymbolFactory.Location;
+
+public class Loc {
+
+   public final Location left;
+   public final Location right;
+
+   private Loc(Location left, Location right) {
+      this.left = left;
+      this.right = right;
+   }
+
+   public static Loc loc() {
+      return loc(new Location(-1, -1));
+   }
+
+   public static Loc loc(Location left) {
+      return loc(left, left);
+   }
+
+   public static Loc loc(Location left, Location right) {
+      return new Loc(left, right);
+   }
+
+   @Override
+   public String toString() {
+      if (left.getUnit().equals("unknown") && right.getUnit().equals("unknown"))
+         return String.format("%d/%d-%d/%d",
+                              left.getLine(), left.getColumn(),
+                              right.getLine(), right.getColumn());
+      else if (left.getUnit().equals(right.getUnit()))
+         return String.format("%s:%d/%d-%d/%d",
+                              left.getUnit(),
+                              left.getLine(), left.getColumn(),
+                              right.getLine(), right.getColumn());
+      else
+         return String.format("%s:%d/%d-%s:%d/%d",
+                              left.getUnit(),
+                              left.getLine(), left.getColumn(),
+                              right.getUnit(),
+                              right.getLine(), right.getColumn());
+   }
+
+}