expression.java

hsql是很有名的嵌入式数据库

     * @param datatype data type
     * @param o data
     */
    Expression(int datatype, Object o) {

        exprType  = VALUE;
        dataType  = datatype;
        valueData = o;
    }

    /**
     * Creates a new (possibly PARAM) VALUE expression
     *
     * @param datatype initial datatype
     * @param o initial value
     * @param isParam true if this is to be a PARAM VALUE expression
     */
    Expression(int datatype, Object o, boolean isParam) {

        this(datatype, o);

        this.isParam = isParam;

        if (isParam) {
            paramMode = PARAM_IN;
        }
    }

    private void checkAggregate() {

        if (isAggregate(exprType)) {
            aggregateSpec = AGGREGATE_SELF;
        } else {
            aggregateSpec = AGGREGATE_NONE;

            if ((eArg != null) && eArg.isAggregate()) {
                aggregateSpec += AGGREGATE_LEFT;
            }

            if ((eArg2 != null) && eArg2.isAggregate()) {
                aggregateSpec += AGGREGATE_RIGHT;
            }
        }
    }

    public String describe(Session session) {
        return describe(session, 0);
    }

    static String getContextDDL(Expression expression) throws HsqlException {

        String ddl = expression.getDDL();

        if (expression.exprType != VALUE && expression.exprType != COLUMN
                && expression.exprType != FUNCTION
                && expression.exprType != ALTERNATIVE
                && expression.exprType != CASEWHEN
                && expression.exprType != CONVERT) {
            StringBuffer temp = new StringBuffer();

            ddl = temp.append('(').append(ddl).append(')').toString();
        }

        return ddl;
    }

    /**
     * For use with CHECK constraints. Under development.
     *
     * Currently supports a subset of expressions and is suitable for CHECK
     * search conditions that refer only to the inserted/updated row.
     *
     * For full DDL reporting of VIEW select queries and CHECK search
     * conditions, future improvements here are dependent upon improvements to
     * SELECT query parsing, so that it is performed in a number of passes.
     * An early pass should result in the query turned into an Expression tree
     * that contains the information in the original SQL without any
     * alterations, and with tables and columns all resolved. This Expression
     * can then be preserved for future use. Table and column names that
     * are not user-defined aliases should be kept as the HsqlName structures
     * so that table or column renaming is reflected in the precompiled
     * query.
     *
     * @return DDL
     * @throws HsqlException
     */
    String getDDL() throws HsqlException {

        StringBuffer buf   = new StringBuffer(64);
        String       left  = null;
        String       right = null;

        if (eArg != null) {
            left = Expression.getContextDDL(eArg);
        }

        if (eArg2 != null) {
            right = Expression.getContextDDL(eArg2);
        }

        switch (exprType) {

            case FUNCTION :
                return function.getDLL();

            case VALUE :
                try {
                    return Column.createSQLString(valueData, dataType);
                } catch (HsqlException e) {}

                return buf.toString();

            case COLUMN :

                // this is a limited solution
                Table table = tableFilter.getTable();

                if (tableName != null) {
                    buf.append(table.tableName.statementName);
                    buf.append('.');
                }

                buf.append(
                    table.getColumn(columnIndex).columnName.statementName);

                return buf.toString();

            case TRUE :
                return Token.T_TRUE;

            case FALSE :
                return Token.T_FALSE;

            case VALUELIST :
                for (int i = 0; i < valueList.length; i++) {
                    buf.append(valueList[i].getDDL());

                    if (i < valueList.length - 1) {
                        buf.append(',');
                    }
                }

                return buf.toString();

            case ASTERIX :
                buf.append('*');

                return buf.toString();

            case NEGATE :
                buf.append('-').append(left);

                return buf.toString();

            case ADD :
                buf.append(left).append('+').append(right);

                return buf.toString();

            case SUBTRACT :
                buf.append(left).append('-').append(right);

                return buf.toString();

            case MULTIPLY :
                buf.append(left).append('*').append(right);

                return buf.toString();

            case DIVIDE :
                buf.append(left).append('/').append(right);

                return buf.toString();

            case CONCAT :
                buf.append(left).append("||").append(right);

                return buf.toString();

            case NOT :
                if (eArg.exprType == IS_NULL) {
                    buf.append(getContextDDL(eArg.eArg)).append(' ').append(
                        Token.T_IS).append(' ').append(Token.T_NOT).append(
                        ' ').append(Token.T_NULL);

                    return buf.toString();
                }

                buf.append(Token.T_NOT).append(' ').append(left);

                return buf.toString();

            case EQUAL :
                buf.append(left).append('=').append(right);

                return buf.toString();

            case BIGGER_EQUAL :
                buf.append(left).append(">=").append(right);

                return buf.toString();

            case BIGGER :
                buf.append(left).append('>').append(right);

                return buf.toString();

            case SMALLER :
                buf.append(left).append('<').append(right);

                return buf.toString();

            case SMALLER_EQUAL :
                buf.append(left).append("<=").append(right);

                return buf.toString();

            case NOT_EQUAL :
                if (Token.T_NULL.equals(right)) {
                    buf.append(left).append(" IS NOT ").append(right);
                } else {
                    buf.append(left).append("!=").append(right);
                }

                return buf.toString();

            case LIKE :
                buf.append(left).append(' ').append(Token.T_LIKE).append(' ');
                buf.append(right);

                /** @todo fredt - scripting of non-ascii escapes needs changes to general script logging */
                if (likeObject.escapeChar != null) {
                    buf.append(' ').append(Token.T_ESCAPE).append(' ').append(
                        '\'');
                    buf.append(likeObject.escapeChar.toString()).append('\'');
                    buf.append(' ');
                }

                return buf.toString();

            case AND :
                buf.append(left).append(' ').append(Token.T_AND).append(
                    ' ').append(right);

                return buf.toString();

            case OR :
                buf.append(left).append(' ').append(Token.T_OR).append(
                    ' ').append(right);

                return buf.toString();

            case ALL :
                buf.append(left).append(' ').append(Token.T_ALL).append(
                    ' ').append(right);

                return buf.toString();

            case ANY :
                buf.append(left).append(' ').append(Token.T_ANY).append(
                    ' ').append(right);

                return buf.toString();

            case IN :
                buf.append(left).append(' ').append(Token.T_IN).append(
                    ' ').append(right);

                return buf.toString();

            case CONVERT :
                buf.append(' ').append(Token.T_CONVERT).append('(');
                buf.append(left).append(',');
                buf.append(Types.getTypeString(dataType, precision, scale));
                buf.append(')');

                return buf.toString();

            case CASEWHEN :
                buf.append(' ').append(Token.T_CASEWHEN).append('(');
                buf.append(left).append(',').append(right).append(')');

                return buf.toString();

            case IS_NULL :
                buf.append(left).append(' ').append(Token.T_IS).append(
                    ' ').append(Token.T_NULL);

                return buf.toString();

            case ALTERNATIVE :
                buf.append(left).append(',').append(right);

                return buf.toString();

            case QUERY :
/*
                buf.append('(');
                buf.append(subSelect.getDDL());
                buf.append(')');
*/
                break;

            case EXISTS :
                buf.append(' ').append(Token.T_EXISTS).append(' ');
                break;

            case COUNT :
                buf.append(' ').append(Token.T_COUNT).append('(');
                break;

            case SUM :
                buf.append(' ').append(Token.T_SUM).append('(');
                buf.append(left).append(')');
                break;

            case MIN :
                buf.append(' ').append(Token.T_MIN).append('(');
                buf.append(left).append(')');
                break;

            case MAX :
                buf.append(' ').append(Token.T_MAX).append('(');
                buf.append(left).append(')');
                break;

            case AVG :
                buf.append(' ').append(Token.T_AVG).append('(');
                buf.append(left).append(')');
                break;

            case EVERY :
                buf.append(' ').append(Token.T_EVERY).append('(');
                buf.append(left).append(')');
                break;

            case SOME :
                buf.append(' ').append(Token.T_SOME).append('(');
                buf.append(left).append(')');
                break;

            case STDDEV_POP :
                buf.append(' ').append(Token.T_STDDEV_POP).append('(');
                buf.append(left).append(')');
                break;

            case STDDEV_SAMP :
                buf.append(' ').append(Token.T_STDDEV_SAMP).append('(');
                buf.append(left).append(')');
                break;

            case VAR_POP :
                buf.append(' ').append(Token.T_VAR_POP).append('(');
                buf.append(left).append(')');
                break;

            case VAR_SAMP :
                buf.append(' ').append(Token.T_VAR_SAMP).append('(');
                buf.append(left).append(')');
                break;
        }

        throw Trace.error(Trace.EXPRESSION_NOT_SUPPORTED);
    }

    private String describe(Session session, int blanks) {

        int          lIType;
        StringBuffer buf = new StringBuffer(64);

        buf.append('\n');

        for (int i = 0; i < blanks; i++) {
            buf.append(' ');
        }

        if (oldIType != -1) {
            buf.append("SET TRUE, WAS: ");
        }

        lIType = oldIType == -1 ? exprType
                                : oldIType;

        switch (lIType) {

            case FUNCTION :
                buf.append("FUNCTION ");
                buf.append(function.describe(session));

                return buf.toString();

            case VALUE :
                if (isParam) {
                    buf.append("PARAM ");
                }

                buf.append("VALUE = ").append(valueData);
                buf.append(", TYPE = ").append(Types.getTypeString(dataType));

                return buf.toString();

            case COLUMN :
                buf.append("COLUMN ");

                if (tableName != null) {
                    buf.append(tableName);
                    buf.append('.');
                }

                buf.append(columnName);

                return buf.toString();

            case QUERY :
                buf.append("QUERY ");
                buf.append(subQuery.select.describe(session));

                return buf.toString();

            case TRUE :
                buf.append("TRUE ");
                break;

            case FALSE :
                buf.append("FALSE ");
                break;

            case VALUELIST :
                buf.append("VALUELIST ");
                buf.append(" TYPE = ").append(Types.getTypeString(dataType));

                if (valueList != null) {
                    for (int i = 0; i < valueList.length; i++) {
                        buf.append(valueList[i].describe(session,
                                                         blanks + blanks));
                        buf.append(' ');
                    }
                }
                break;

            case ASTERIX :
                buf.append("* ");
                break;

            case NEGATE :
                buf.append("NEGATE ");
                break;

            case ADD :
                buf.append("ADD ");
                break;

            case SUBTRACT :
                buf.append("SUBTRACT ");
                break;

            case MULTIPLY :
                buf.append("MULTIPLY ");
                break;