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/*
 * Firebird Open Source JavaEE Connector - JDBC Driver
 *
 * Distributable under LGPL license.
 * You may obtain a copy of the License at http://www.gnu.org/copyleft/lgpl.html
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * LGPL License for more details.
 *
 * This file was created by members of the firebird development team.
 * All individual contributions remain the Copyright (C) of those
 * individuals.  Contributors to this file are either listed here or
 * can be obtained from a source control history command.
 *
 * All rights reserved.
 */
package org.firebirdsql.jdbc.escape;

/**
 * Implements the {@code LENGTH} JDBC escape.
 * 
 * The JDBC specification specifies Number of characters in string, excluding trailing blanks, we right-trim
 * ({@code TRIM(TRAILING FROM value)}) the string before passing the value to either {@code CHAR_LENGTH} or
 * {@code OCTETS_LENGTH}. As a result, the interpretation of what is a blank depends on the type of value. Is the value
 * a normal {@code (VAR)CHAR} (non-octets), then the blank is space (0x20), for a
 * {@code VAR(CHAR)CHARACTER SET OCTETS / (VAR)BINARY} the blank is NUL (0x00). This means that the optional
 * {@code CHARACTERS|OCTETS} parameter has no influence on which blanks are trimmed, but only whether we count
 * characters or bytes after trimming.
 * 
 *
 * @author Mark Rotteveel
 * @since 4.0
 */
final class LengthFunction implements SQLFunction {

    private static final SQLFunction TRIM_TRAILING = new PatternSQLFunction("TRIM(TRAILING FROM {0})");
    private static final SQLFunction CHARACTER_LENGTH = new CharacterLengthFunction();

    @Override
    public String apply(String... parameters) throws FBSQLParseException {
        if (parameters.length < 1 || parameters.length > 2) {
            throw new FBSQLParseException(
                    "Expected 1 or 2 parameters for LENGTH, received " + parameters.length);
        }
        String[] clonedParameters = parameters.clone();
        clonedParameters[0] = TRIM_TRAILING.apply(parameters);
        return CHARACTER_LENGTH.apply(clonedParameters);
    }

}