001 // Copyright 2004, 2005 The Apache Software Foundation 002 // 003 // Licensed under the Apache License, Version 2.0 (the "License"); 004 // you may not use this file except in compliance with the License. 005 // You may obtain a copy of the License at 006 // 007 // http://www.apache.org/licenses/LICENSE-2.0 008 // 009 // Unless required by applicable law or agreed to in writing, software 010 // distributed under the License is distributed on an "AS IS" BASIS, 011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012 // See the License for the specific language governing permissions and 013 // limitations under the License. 014 015 package org.apache.hivemind.schema; 016 017 import org.apache.hivemind.Location; 018 import org.apache.hivemind.internal.Module; 019 020 /** 021 * Object which can translate a string into an object value. This is used to 022 * translate attribute values (or element content) from strings into 023 * numbers, booleans or other constructs before assigning the final value 024 * to a propery. Translation occurs after symbol substitution. 025 * 026 * <p> 027 * Translator classes should have a public constructor that takes no 028 * arguments. They may optionally have a second constructor 029 * that takes a single string as a parameter. When the 030 * {@link org.apache.hivemind.parse.DescriptorParser} encounters 031 * a <code>translator</code> of the form 032 * "<code><i>translator-id</i>,<i>initialization-string</i></code>" 033 * (example: "int,min=0") it will use the second constructor, passing 034 * the initialization string. 035 * 036 * <p> 037 * Generally, initializion strings are of the form 038 * <code><i>key</i>=<i>value</i>[,<i>key</i>=<i>value</i>]*</code>. 039 * Each initializer has a set of keys it recognizes, other keys are simply 040 * ignored. 041 * 042 * @author Howard Lewis Ship 043 */ 044 public interface Translator 045 { 046 /** 047 * Invoked by a {@link org.apache.hivemind.schema.Rule} 048 * to translate an inputValue into an appropriate object. 049 * Substitution symbols will already have been expanded before this method is 050 * invoked. 051 * 052 * @param contributingModule the module from which the input value originates 053 * @param propertyType the type of the property to be assigned by this translator; smart translators may 054 * be able to automatically convert from string to the correct type 055 * @param inputValue the value to be translated, either an attribute value or the content of the element 056 * @param location the location of the inputValue; used to set the location of created objects, 057 * or when reporting errors 058 */ 059 public Object translate( 060 Module contributingModule, 061 Class propertyType, 062 String inputValue, 063 Location location); 064 }