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JavaCC is a parser/scanner generator for Java.
/* Copyright (c) 2006, Sun Microsystems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the Sun Microsystems, Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.javacc.parser;
import java.util.Iterator;
/**
* A set of routines that walk down the Expansion tree in
* various ways.
*/
public final class ExpansionTreeWalker {
private 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 (Iterator it = ((Choice)node).getChoices().iterator(); it.hasNext();) {
preOrderWalk((Expansion)it.next(), opObj);
}
} else if (node instanceof Sequence) {
for (Iterator it = ((Sequence)node).units.iterator(); it.hasNext();) {
preOrderWalk((Expansion)it.next(), 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).getLaExpansion();
if (!(nested_e instanceof Sequence && (Expansion)(((Sequence)nested_e).units.get(0)) == node)) {
preOrderWalk(nested_e, opObj);
}
} else if (node instanceof TryBlock) {
preOrderWalk(((TryBlock)node).exp, opObj);
} else if (node instanceof RChoice) {
for (Iterator it = ((RChoice)node).getChoices().iterator(); it.hasNext();) {
preOrderWalk((Expansion)it.next(), opObj);
}
} else if (node instanceof RSequence) {
for (Iterator it = ((RSequence)node).units.iterator(); it.hasNext();) {
preOrderWalk((Expansion)it.next(), 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 (Iterator it = ((Choice)node).getChoices().iterator(); it.hasNext();) {
postOrderWalk((Expansion)it.next(), opObj);
}
} else if (node instanceof Sequence) {
for (Iterator it = ((Sequence)node).units.iterator(); it.hasNext();) {
postOrderWalk((Expansion)it.next(), 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).getLaExpansion();
if (!(nested_e instanceof Sequence && (Expansion)(((Sequence)nested_e).units.get(0)) == node)) {
postOrderWalk(nested_e, opObj);
}
} else if (node instanceof TryBlock) {
postOrderWalk(((TryBlock)node).exp, opObj);
} else if (node instanceof RChoice) {
for (Iterator it = ((RChoice)node).getChoices().iterator(); it.hasNext();) {
postOrderWalk((Expansion)it.next(), opObj);
}
} else if (node instanceof RSequence) {
for (Iterator it = ((RSequence)node).units.iterator(); it.hasNext();) {
postOrderWalk((Expansion)it.next(), 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);
}
}