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csjavacc/parser/ExpansionTreeWalker.java

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+/*
+ * Copyright © 2002 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * California 95054, U.S.A. All rights reserved.  Sun Microsystems, Inc. has
+ * intellectual property rights relating to technology embodied in the product
+ * that is described in this document. In particular, and without limitation,
+ * these intellectual property rights may include one or more of the U.S.
+ * patents listed at http://www.sun.com/patents and one or more additional
+ * patents or pending patent applications in the U.S. and in other countries.
+ * U.S. Government Rights - Commercial software. Government users are subject
+ * to the Sun Microsystems, Inc. standard license agreement and applicable
+ * provisions of the FAR and its supplements.  Use is subject to license terms.
+ * Sun,  Sun Microsystems,  the Sun logo and  Java are trademarks or registered
+ * trademarks of Sun Microsystems, Inc. in the U.S. and other countries.  This
+ * product is covered and controlled by U.S. Export Control laws and may be
+ * subject to the export or import laws in other countries.  Nuclear, missile,
+ * chemical biological weapons or nuclear maritime end uses or end users,
+ * whether direct or indirect, are strictly prohibited.  Export or reexport
+ * to countries subject to U.S. embargo or to entities identified on U.S.
+ * export exclusion lists, including, but not limited to, the denied persons
+ * and specially designated nationals lists is strictly prohibited.
+ */
+
+package csjavacc.parser;
+
+import csjavacc.struct.Choice;
+import csjavacc.struct.Expansion;
+import csjavacc.struct.Lookahead;
+import csjavacc.struct.ROneOrMore;
+import csjavacc.struct.RRepetitionRange;
+import csjavacc.struct.RSequence;
+import csjavacc.struct.RZeroOrMore;
+import csjavacc.struct.RZeroOrOne;
+import csjavacc.struct.TreeWalkerOp;
+import csjavacc.struct.TryBlock;
+import csjavacc.struct.ZeroOrMore;
+import csjavacc.struct.ZeroOrOne;
+
+/**
+ * A set of routines that walk down the Expansion tree in
+ * various ways.
+ */
+public class ExpansionTreeWalker {
+
+  /**
+   * Visits the nodes of the tree rooted at "node" in pre-order.
+   * i.e., it executes opObj.action first and then visits the
+   * children.
+   */
+  static void preOrderWalk(Expansion node, TreeWalkerOp opObj) {
+    opObj.action(node);
+    if (opObj.goDeeper(node)) {
+      if (node instanceof Choice) {
+        for (java.util.Enumeration anEnum = ((Choice)node).choices.elements(); anEnum.hasMoreElements();) {
+          preOrderWalk((Expansion)anEnum.nextElement(), opObj);
+        }
+      } else if (node instanceof Sequence) {
+        for (java.util.Enumeration anEnum = ((Sequence)node).units.elements(); anEnum.hasMoreElements();) {
+          preOrderWalk((Expansion)anEnum.nextElement(), opObj);
+        }
+      } else if (node instanceof OneOrMore) {
+        preOrderWalk(((OneOrMore)node).expansion, opObj);
+      } else if (node instanceof ZeroOrMore) {
+        preOrderWalk(((ZeroOrMore)node).expansion, opObj);
+      } else if (node instanceof ZeroOrOne) {
+        preOrderWalk(((ZeroOrOne)node).expansion, opObj);
+      } else if (node instanceof Lookahead) {
+        Expansion nested_e = ((Lookahead)node).la_expansion;
+        if (!(nested_e instanceof Sequence && (Expansion)(((Sequence)nested_e).units.elementAt(0)) == node)) {
+          preOrderWalk(nested_e, opObj);
+        }
+      } else if (node instanceof TryBlock) {
+        preOrderWalk(((TryBlock)node).exp, opObj);
+      } else if (node instanceof RChoice) {
+        for (java.util.Enumeration anEnum = ((RChoice)node).choices.elements(); anEnum.hasMoreElements();) {
+          preOrderWalk((Expansion)anEnum.nextElement(), opObj);
+        }
+      } else if (node instanceof RSequence) {
+        for (java.util.Enumeration anEnum = ((RSequence)node).units.elements(); anEnum.hasMoreElements();) {
+          preOrderWalk((Expansion)anEnum.nextElement(), opObj);
+        }
+      } else if (node instanceof ROneOrMore) {
+        preOrderWalk(((ROneOrMore)node).regexpr, opObj);
+      } else if (node instanceof RZeroOrMore) {
+        preOrderWalk(((RZeroOrMore)node).regexpr, opObj);
+      } else if (node instanceof RZeroOrOne) {
+        preOrderWalk(((RZeroOrOne)node).regexpr, opObj);
+      } else if (node instanceof RRepetitionRange) {
+        preOrderWalk(((RRepetitionRange)node).regexpr, opObj);
+      }
+    }
+  }
+
+  /**
+   * Visits the nodes of the tree rooted at "node" in post-order.
+   * i.e., it visits the children first and then executes
+   * opObj.action.
+   */
+  static void postOrderWalk(Expansion node, TreeWalkerOp opObj) {
+    if (opObj.goDeeper(node)) {
+      if (node instanceof Choice) {
+        for (java.util.Enumeration anEnum = ((Choice)node).choices.elements(); anEnum.hasMoreElements();) {
+          postOrderWalk((Expansion)anEnum.nextElement(), opObj);
+        }
+      } else if (node instanceof Sequence) {
+        for (java.util.Enumeration anEnum = ((Sequence)node).units.elements(); anEnum.hasMoreElements();) {
+          postOrderWalk((Expansion)anEnum.nextElement(), opObj);
+        }
+      } else if (node instanceof OneOrMore) {
+        postOrderWalk(((OneOrMore)node).expansion, opObj);
+      } else if (node instanceof ZeroOrMore) {
+        postOrderWalk(((ZeroOrMore)node).expansion, opObj);
+      } else if (node instanceof ZeroOrOne) {
+        postOrderWalk(((ZeroOrOne)node).expansion, opObj);
+      } else if (node instanceof Lookahead) {
+        Expansion nested_e = ((Lookahead)node).la_expansion;
+        if (!(nested_e instanceof Sequence && (Expansion)(((Sequence)nested_e).units.elementAt(0)) == node)) {
+          postOrderWalk(nested_e, opObj);
+        }
+      } else if (node instanceof TryBlock) {
+        postOrderWalk(((TryBlock)node).exp, opObj);
+      } else if (node instanceof RChoice) {
+        for (java.util.Enumeration anEnum = ((RChoice)node).choices.elements(); anEnum.hasMoreElements();) {
+          postOrderWalk((Expansion)anEnum.nextElement(), opObj);
+        }
+      } else if (node instanceof RSequence) {
+        for (java.util.Enumeration anEnum = ((RSequence)node).units.elements(); anEnum.hasMoreElements();) {
+          postOrderWalk((Expansion)anEnum.nextElement(), opObj);
+        }
+      } else if (node instanceof ROneOrMore) {
+        postOrderWalk(((ROneOrMore)node).regexpr, opObj);
+      } else if (node instanceof RZeroOrMore) {
+        postOrderWalk(((RZeroOrMore)node).regexpr, opObj);
+      } else if (node instanceof RZeroOrOne) {
+        postOrderWalk(((RZeroOrOne)node).regexpr, opObj);
+      } else if (node instanceof RRepetitionRange) {
+        postOrderWalk(((RRepetitionRange)node).regexpr, opObj);
+      }
+    }
+    opObj.action(node);
+  }
+
+}