001/*
002// $Id: ParseTreeNode.java 482 2012-01-05 23:27:27Z jhyde $
003//
004// Licensed to Julian Hyde under one or more contributor license
005// agreements. See the NOTICE file distributed with this work for
006// additional information regarding copyright ownership.
007//
008// Julian Hyde licenses this file to you under the Apache License,
009// Version 2.0 (the "License"); you may not use this file except in
010// compliance with the License. You may obtain a copy of the License at:
011//
012// http://www.apache.org/licenses/LICENSE-2.0
013//
014// Unless required by applicable law or agreed to in writing, software
015// distributed under the License is distributed on an "AS IS" BASIS,
016// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017// See the License for the specific language governing permissions and
018// limitations under the License.
019*/
020package org.olap4j.mdx;
021
022import org.olap4j.type.Type;
023
024/**
025 * Node in a parse tree representing a parsed MDX statement.
026 *
027 * <p>To convert a parse tree to an MDX string, use a {@link ParseTreeWriter}
028 * and the {@link #unparse(ParseTreeWriter)} method.
029 *
030 * @author jhyde
031 * @version $Id: ParseTreeNode.java 482 2012-01-05 23:27:27Z jhyde $
032 * @since Jun 4, 2007
033 */
034public interface ParseTreeNode {
035    /**
036     * Accepts a visitor to this MDX parse tree node.
037     *
038     * <p>The implementation should generally dispatches to the
039     * {@link ParseTreeVisitor#visit} method appropriate to the type of expression.
040     *
041     * @param visitor Visitor
042     * @return T, the specific return type of the visitor
043     */
044    <T> T accept(ParseTreeVisitor<T> visitor);
045
046    /**
047     * Returns the type of this expression.
048     *
049     * <p>Returns null if this node is not an expression, for instance a
050     * <code>SELECT</code> node.
051     *
052     * @return type of this expression
053     */
054    Type getType();
055
056    /**
057     * Converts this node into MDX text.
058     *
059     * @param writer Parse tree writer
060     */
061    void unparse(ParseTreeWriter writer);
062
063    /**
064     * Returns the region of the source code which this node was created from,
065     * if it was created by parsing.
066     *
067     * <p>A non-leaf node's region will encompass the regions of all of its
068     * children. For example, a the region of a function call node
069     * <code>Crossjoin([Gender], {[Store].[USA]})</code> stretches from
070     * the first character of the function name to the closing parenthesis.
071     *
072     * <p>Region may be null, if the node was created programmatically, not
073     * from a piece of source code.
074     *
075     * @return Region of the source code this node was created from, if it was
076     * created by parsing
077     */
078    ParseRegion getRegion();
079
080    /**
081     * Creates a deep copy of this ParseTreeNode object.
082     *
083     * <p>Note: implementing classes can return the concrete type instead
084     * of ParseTreeNode (using Java 1.5 covariant return types)
085     *
086     * @return The deep copy of this ParseTreeNode
087     */
088    ParseTreeNode deepCopy();
089
090}
091
092// End ParseTreeNode.java