| 1 | /* ============================================================= |
| 2 | * SmallSQL : a free Java DBMS library for the Java(tm) platform |
| 3 | * ============================================================= |
| 4 | * |
| 5 | * (C) Copyright 2004-2006, by Volker Berlin. |
| 6 | * |
| 7 | * Project Info: http://www.smallsql.de/ |
| 8 | * |
| 9 | * This library is free software; you can redistribute it and/or modify it |
| 10 | * under the terms of the GNU Lesser General Public License as published by |
| 11 | * the Free Software Foundation; either version 2.1 of the License, or |
| 12 | * (at your option) any later version. |
| 13 | * |
| 14 | * This library is distributed in the hope that it will be useful, but |
| 15 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 16 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
| 17 | * License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Lesser General Public |
| 20 | * License along with this library; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, |
| 22 | * USA. |
| 23 | * |
| 24 | * [Java is a trademark or registered trademark of Sun Microsystems, Inc. |
| 25 | * in the United States and other countries.] |
| 26 | * |
| 27 | * --------------- |
| 28 | * ExpressionFunctionSubstring.java |
| 29 | * --------------- |
| 30 | * Author: Volker Berlin |
| 31 | * |
| 32 | * Created on 23.06.2004 |
| 33 | */ |
| 34 | package smallsql.database; |
| 35 | |
| 36 | |
| 37 | /** |
| 38 | * @author Volker Berlin |
| 39 | */ |
| 40 | final class ExpressionFunctionSubstring extends ExpressionFunctionReturnP1StringAndBinary { |
| 41 | |
| 42 | |
| 43 | final int getFunction() { |
| 44 | return SQLTokenizer.SUBSTRING; |
| 45 | } |
| 46 | |
| 47 | |
| 48 | final boolean isNull() throws Exception { |
| 49 | return param1.isNull() || param2.isNull() || param3.isNull(); |
| 50 | } |
| 51 | |
| 52 | |
| 53 | final byte[] getBytes() throws Exception{ |
| 54 | if(isNull()) return null; |
| 55 | byte[] bytes = param1.getBytes(); |
| 56 | int byteLen = bytes.length; |
| 57 | int start = Math.min( Math.max( 0, param2.getInt() - 1), byteLen); |
| 58 | int length = param3.getInt(); |
| 59 | if(length < 0) |
| 60 | throw Utils.createSQLException("Invalid length '"+length + "' in function SUBSTRING"); |
| 61 | if(start == 0 && byteLen == length) return bytes; |
| 62 | if(byteLen > length + start){ |
| 63 | byte[] b = new byte[length]; |
| 64 | System.arraycopy(bytes, start, b, 0, length); |
| 65 | return b; |
| 66 | }else{ |
| 67 | byte[] b = new byte[byteLen - start]; |
| 68 | System.arraycopy(bytes, start, b, 0, b.length); |
| 69 | return b; |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | |
| 74 | final String getString() throws Exception { |
| 75 | if(isNull()) return null; |
| 76 | String str = param1.getString(); |
| 77 | int strLen = str.length(); |
| 78 | int start = Math.min( Math.max( 0, param2.getInt() - 1), strLen); |
| 79 | int length = param3.getInt(); |
| 80 | if(length < 0) |
| 81 | throw Utils.createSQLException("Invalid length '"+length + "' in function SUBSTRING"); |
| 82 | length = Math.min( length, strLen-start ); |
| 83 | return str.substring(start, start+length); |
| 84 | } |
| 85 | |
| 86 | |
| 87 | } |