expression.java

一个用java写的开源的数据库系统

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package org.hsqldb;

import java.sql.SQLException;
import java.sql.Types;
import java.util.Hashtable;
import java.util.Vector;

// fredt@users 20020215 - patch 1.7.0 by fredt
// to preserve column size etc. when SELECT INTO TABLE is used

/**
 * Expression class declaration
 *
 *
 * @version    1.7.0
 */
class Expression {

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

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

    // logical operations
    static final 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
    static final int COUNT      = 40,
                     SUM        = 41,
                     MIN        = 42,
                     MAX        = 43,
                     AVG        = 44,
                     DIST_COUNT = 45;

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

    // temporary used during paring
    static final 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 boolean   hListHasNull;
    private int       iDataType;

    // QUERY (correlated subquery)
    private Select sSelect;

    // FUNCTION
    private Function fFunction;

    // LIKE
    private char cLikeEscape;

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

// rougier@users 20020522 - patch 552830 - COUNT(DISTINCT)
    // {COUNT|SUM|MIN|MAX|AVG}(distinct ...)
    private boolean      isDistinctAggregate;
    static final Integer INTEGER_0 = new Integer(0);
    static final Integer INTEGER_1 = new Integer(1);

    /**
     * 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 = Types.VARCHAR;

        int len = v.size();

        hList = new Hashtable(len, 1);

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

            if (o != null) {
                hList.put(o, this.INTEGER_1);
            } else {
                this.hListHasNull = true;
            }
        }
    }

    /**
     * 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;
        }
    }

    Expression(String table, String column, boolean isquoted) {

        sTable = table;

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

    /**
     * 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() {
        return isAggregate(iType);
    }

    static boolean isAggregate(int type) {

        if ((type == COUNT) || (type == MAX) || (type == MIN)
                || (type == SUM) || (type == AVG) || (type == DIST_COUNT)) {
            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, boolean isquoted) {
        sAlias      = s;
        aliasQuoted = isquoted;
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    String getAlias() {

        if (sAlias != null) {
            return sAlias;
        }

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

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

// fredt@users 20020130 - patch 497872 by Nitin Chauhan - modified
// return column name for aggregates without alias
        if (isAggregate()) {
            return eArg.getColumnName();
        }

        return "";
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    boolean isAliasQuoted() {

        if (sAlias != null) {
            return aliasQuoted;
        }

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

        if (isAggregate()) {
            return eArg.columnQuoted;
        }

        return false;
    }

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

    /**
     * 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) {

// fredt@users 20011110 - fix for 471711 - subselects
                    // todo: other error message: multiple tables are possible
                    Trace.check(
                        tFilter == null
                        || tFilter.getName().equals(
                            f.getName()), Trace.COLUMN_NOT_FOUND, sColumn);

                    tFilter      = f;
                    iColumn      = i;
                    sTable       = f.getName();
                    iDataType    = f.getTable().getColumn(i).getType();
                    iColumnSize  = f.getTable().getColumn(i).getSize();
                    iColumnScale = f.getTable().getColumn(i).getScale();
                }
            }
        }

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

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