| 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 | * ExpressionFunction.java |
| 29 | * --------------- |
| 30 | * Author: Volker Berlin |
| 31 | * |
| 32 | */ |
| 33 | package smallsql.database; |
| 34 | |
| 35 | import java.sql.*; |
| 36 | |
| 37 | |
| 38 | /** |
| 39 | * This is the base class for all functions. To add a new fuction you need<p> |
| 40 | * 1.) Add a new constant to the class SQLTokenizer.<p> |
| 41 | * 2.) Add a mapping of the function name keyword to the function constant in the class SQLTokenizer.<p> |
| 42 | * 3.) Extends a class from ExpressionFunction and implemets the function logic.<p> |
| 43 | * 4.) Add a case to the switch in SQLParser.function().<p> |
| 44 | */ |
| 45 | |
| 46 | abstract class ExpressionFunction extends Expression { |
| 47 | |
| 48 | Expression param1; |
| 49 | Expression param2; |
| 50 | Expression param3; |
| 51 | Expression param4; |
| 52 | |
| 53 | ExpressionFunction(){ |
| 54 | super(FUNCTION); |
| 55 | } |
| 56 | |
| 57 | // setzt die Funktionsnummer z.B. bei abs(5) --> SQLTokenizer.ABS |
| 58 | abstract int getFunction(); |
| 59 | |
| 60 | byte[] getBytes() throws Exception{ |
| 61 | return ExpressionValue.getBytes(getObject(), getDataType()); |
| 62 | } |
| 63 | |
| 64 | void setParams( Expression[] params ){ |
| 65 | super.setParams( params ); |
| 66 | if(params.length >0) param1 = params[0] ; |
| 67 | if(params.length >1) param2 = params[1] ; |
| 68 | if(params.length >2) param3 = params[2] ; |
| 69 | if(params.length >3) param4 = params[3] ; |
| 70 | } |
| 71 | |
| 72 | final void setParamAt( Expression param, int idx){ |
| 73 | switch(idx){ |
| 74 | case 0: |
| 75 | param1 = param; |
| 76 | break; |
| 77 | case 1: |
| 78 | param2 = param; |
| 79 | break; |
| 80 | case 2: |
| 81 | param3 = param; |
| 82 | break; |
| 83 | case 3: |
| 84 | param4 = param; |
| 85 | break; |
| 86 | } |
| 87 | super.setParamAt( param, idx ); |
| 88 | } |
| 89 | |
| 90 | |
| 91 | /** |
| 92 | * Is used in GroupResult. |
| 93 | */ |
| 94 | public boolean equals(Object expr){ |
| 95 | if(!super.equals(expr)) return false; |
| 96 | if(!(expr instanceof ExpressionFunction)) return false; |
| 97 | return ((ExpressionFunction)expr).getFunction() == getFunction(); |
| 98 | } |
| 99 | |
| 100 | |
| 101 | /** |
| 102 | * Create a SQLException that the current function does not support the specific data type. |
| 103 | * @param dataType A data type const from SQLTokenizer. |
| 104 | */ |
| 105 | SQLException createUnspportedDataType( int dataType ){ |
| 106 | return Utils.createSQLException("Unsupported data type '" + |
| 107 | SQLTokenizer.getKeyWord(dataType) + |
| 108 | "' for function " + |
| 109 | SQLTokenizer.getKeyWord(getFunction()) ); |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * Create a SQLException that the current function can not convert the specific data type. |
| 114 | * @param dataType A data type const from SQLTokenizer. |
| 115 | */ |
| 116 | SQLException createUnspportedConversion( int dataType ){ |
| 117 | return Utils.createSQLException("Unsupported conversion to data type '" + |
| 118 | SQLTokenizer.getKeyWord(dataType) + |
| 119 | "' for function " + |
| 120 | SQLTokenizer.getKeyWord(getFunction()) ); |
| 121 | } |
| 122 | |
| 123 | |
| 124 | |
| 125 | } |