expression.java

Java写的含有一个jdbc驱动的小型数据库数据库引擎

/*
 * Expression.java
 *
 * Copyright (c) 2001, The HSQL Development Group
 * 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 HSQL Development Group 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 REGENTS 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.
 *
 * This package is based on HypersonicSQL, originally developed by Thomas Mueller.
 *
 */
package org.hsqldb;

import java.sql.*;
import java.util.*;

/**
 * Expression class declaration
 *
 *
 * @version 1.0.0.1
 */
class Expression {

    // leaf types
    final static int    VALUE = 1, COLUMN = 2, QUERY = 3, TRUE = 4,
			VALUELIST = 5, ASTERIX = 6, FUNCTION = 7;

    // operations
    final static int    NEGATE = 9, ADD = 10, SUBTRACT = 11, MULTIPLY = 12,
			DIVIDE = 14, CONCAT = 15;

    // logical operations
    final static int    NOT = 20, EQUAL = 21, BIGGER_EQUAL = 22, BIGGER = 23,
			SMALLER = 24, SMALLER_EQUAL = 25, NOT_EQUAL = 26,
			LIKE = 27, AND = 28, OR = 29, IN = 30, EXISTS = 31;

    // aggregate functions
    final static int    COUNT = 40, SUM = 41, MIN = 42, MAX = 43, AVG = 44;

    // system functions
    final static int    IFNULL = 60, CONVERT = 61, CASEWHEN = 62;

    // temporary used during paring
    final static int    PLUS = 100, OPEN = 101, CLOSE = 102, SELECT = 103,
			COMMA = 104, STRINGCONCAT = 105, BETWEEN = 106,
			CAST = 107, END = 108;
    private int		iType;

    // nodes
    private Expression  eArg, eArg2;

    // VALUE, VALUELIST
    private Object      oData;
    private Hashtable   hList;
    private int		iDataType;

    // QUERY (correlated subquery)
    private Select      sSelect;

    // FUNCTION
    private Function    fFunction;

    // LIKE
    private char	cLikeEscape;

    // COLUMN
    private String      sTable, sColumn;
    private TableFilter tFilter;	// null if not yet resolved
    private int		iColumn;
    private String      sAlias;    // if it is a column of a select column list
    private boolean     bDescending;    // if it is a column in a order by

    /**
     * Constructor declaration
     *
     *
     * @param f
     */
    Expression(Function f) {
	iType = FUNCTION;
	fFunction = f;
    }

    /**
     * Constructor declaration
     *
     *
     * @param e
     */
    Expression(Expression e) {
	iType = e.iType;
	iDataType = e.iDataType;
	eArg = e.eArg;
	eArg2 = e.eArg2;
	cLikeEscape = e.cLikeEscape;
	sSelect = e.sSelect;
	fFunction = e.fFunction;
    }

    /**
     * Constructor declaration
     *
     *
     * @param s
     */
    Expression(Select s) {
	iType = QUERY;
	sSelect = s;
    }

    /**
     * Constructor declaration
     *
     *
     * @param v
     */
    Expression(Vector v) {
	iType = VALUELIST;
	iDataType = Column.VARCHAR;

	int len = v.size();

	hList = new Hashtable(len);

	for (int i = 0; i < len; i++) {
	    Object o = v.elementAt(i);

	    if (o != null) {
		hList.put(o, this);    // todo: don't use such dummy objects
	    }
	}
    }

    /**
     * Constructor declaration
     *
     *
     * @param type
     * @param e
     * @param e2
     */
    Expression(int type, Expression e, Expression e2) {
	iType = type;
	eArg = e;
	eArg2 = e2;
    }

    /**
     * Constructor declaration
     *
     *
     * @param table
     * @param column
     */
    Expression(String table, String column) {
	sTable = table;

	if (column == null) {
	    iType = ASTERIX;
	} else {
	    iType = COLUMN;
	    sColumn = column;
	}
    }

    /**
     * Constructor declaration
     *
     *
     * @param datatype
     * @param o
     */
    Expression(int datatype, Object o) {
	iType = VALUE;
	iDataType = datatype;
	oData = o;
    }

    /**
     * Method declaration
     *
     *
     * @param c
     */
    void setLikeEscape(char c) {
	cLikeEscape = c;
    }

    /**
     * Method declaration
     *
     *
     * @param type
     */
    void setDataType(int type) {
	iDataType = type;
    }

    /**
     * Method declaration
     *
     */
    void setTrue() {
	iType = TRUE;
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    boolean isAggregate() {
	if (iType == COUNT || iType == MAX || iType == MIN || iType == SUM
		|| iType == AVG) {
	    return true;
	}

	// todo: recurse eArg and eArg2; maybe they are grouped.
	// grouping 'correctly' would be quite complex
	return false;
    }

    /**
     * Method declaration
     *
     */
    void setDescending() {
	bDescending = true;
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    boolean isDescending() {
	return bDescending;
    }

    /**
     * Method declaration
     *
     *
     * @param s
     */
    void setAlias(String s) {
	sAlias = s;
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    String getAlias() {
	if (sAlias != null) {
	    return sAlias;
	}

	if (iType == VALUE) {
	    return "";
	}

	if (iType == COLUMN) {
	    return sColumn;
	}

	// todo
	return "";
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    int getType() {
	return iType;
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    int getColumnNr() {
	return iColumn;
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    Expression getArg() {
	return eArg;
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    Expression getArg2() {
	return eArg2;
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    TableFilter getFilter() {
	return tFilter;
    }

    /**
     * Method declaration
     *
     *
     * @throws SQLException
     */
    void checkResolved() throws SQLException {
	Trace.check(iType != COLUMN || tFilter != null,
		    Trace.COLUMN_NOT_FOUND, sColumn);

	if (eArg != null) {
	    eArg.checkResolved();
	}

	if (eArg2 != null) {
	    eArg2.checkResolved();
	}

	if (sSelect != null) {
	    sSelect.checkResolved();
	}

	if (fFunction != null) {
	    fFunction.checkResolved();
	}
    }

    /**
     * Method declaration
     *
     *
     * @param f
     *
     * @throws SQLException
     */
    void resolve(TableFilter f) throws SQLException {
	if (f != null && iType == COLUMN) {
	    if (sTable == null || f.getName().equals(sTable)) {
		int i = f.getTable().searchColumn(sColumn);

		if (i != -1) {

		    // todo: other error message: multiple tables are possible
		    Trace.check(tFilter == null || tFilter == f,
				Trace.COLUMN_NOT_FOUND, sColumn);

		    tFilter = f;
		    iColumn = i;
		    sTable = f.getName();
		    iDataType = f.getTable().getColumnType(i);
		}
	    }
	}

	// currently sets only data type
	// todo: calculate fixed expressions if possible
	if (eArg != null) {
	    eArg.resolve(f);
	}

	if (eArg2 != null) {
	    eArg2.resolve(f);
	}

	if (sSelect != null) {
	    sSelect.resolve(f, false);
	    sSelect.resolve();
	}

	if (fFunction != null) {
	    fFunction.resolve(f);
	}

	if (iDataType != 0) {
	    return;
	}

	switch (iType) {

	case FUNCTION:
	    iDataType = fFunction.getReturnType();

	    break;

	case QUERY:
	    iDataType = sSelect.eColumn[0].iDataType;

	    break;

	case NEGATE:
	    iDataType = eArg.iDataType;

	    break;

	case ADD:

	case SUBTRACT:

	case MULTIPLY:

	case DIVIDE:
	    iDataType = eArg.iDataType;

	    break;

	case CONCAT:
	    iDataType = Column.VARCHAR;