/interpreter/tags/at2dist130208/src/edu/vub/at/objects/ATTypeTag.java
Java | 85 lines | 8 code | 6 blank | 71 comment | 0 complexity | e84f3332b48eed10b91722ca97ee155e MD5 | raw file
1/** 2 * AmbientTalk/2 Project 3 * ATTypeTag.java created on 18-feb-2007 at 15:55:09 4 * (c) Programming Technology Lab, 2006 - 2007 5 * Authors: Tom Van Cutsem & Stijn Mostinckx 6 * 7 * Permission is hereby granted, free of charge, to any person 8 * obtaining a copy of this software and associated documentation 9 * files (the "Software"), to deal in the Software without 10 * restriction, including without limitation the rights to use, 11 * copy, modify, merge, publish, distribute, sublicense, and/or 12 * sell copies of the Software, and to permit persons to whom the 13 * Software is furnished to do so, subject to the following 14 * conditions: 15 * 16 * The above copyright notice and this permission notice shall be 17 * included in all copies or substantial portions of the Software. 18 * 19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 20 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 21 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 22 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT 23 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 24 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 25 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 26 * OTHER DEALINGS IN THE SOFTWARE. 27 */ 28package edu.vub.at.objects; 29 30import edu.vub.at.exceptions.InterpreterException; 31import edu.vub.at.objects.grammar.ATSymbol; 32 33/** 34 * The public interface to a native type tag object. 35 * <p> 36 * Type tags consist of two properties: 37 * <ul> 38 * <li>they have a unique name by which they can be identified across the network. 39 * In other words, the identity of a type is its name (= nominal typing). 40 * <li>they have a list of supertypes: a type is then a subtype of these supertypes. 41 * </ul> 42 * <p> 43 * Types have one important operation: one type can be tested to be a subtype of 44 * another type. 45 * <p> 46 * Type tags are very similar to empty Java-like interface types, and their main purpose 47 * lies in the *classification* of objects. AmbientTalk Objects can be tagged with zero 48 * or more type tags. 49 * 50 * @author tvcutsem 51 */ 52public interface ATTypeTag extends ATObject { 53 54 /** 55 * Returns the name of this type tag. 56 * 57 * @return an {@link ATSymbol} representing the unique name by which the type can be identified. 58 */ 59 public ATSymbol base_typeName() throws InterpreterException; 60 61 /** 62 * Returns a table with the supertypes of this type tag. 63 * 64 * @return an {@link ATTable} with the super types of the receiver type tags. 65 */ 66 public ATTable base_superTypes() throws InterpreterException; 67 68 /** 69 * Returns true if this type tag is a subtype of a given type tag. 70 * <p> 71 * More specifically, what the native implementation (expressed in AmbientTalk syntax) does is: 72 * <p> 73 * <code> 74 * def isSubtypeOf(supertype) { 75 * (supertype.name() == name).or: 76 * { (supertypes.find: { |stype| stype.isSubtypeOf(supertype) }) != nil } 77 * }; 78 * </code> 79 * 80 * @param other a type. 81 * @return true if the receiver type is a subtype of the other type. 82 */ 83 public ATBoolean base_isSubtypeOf(ATTypeTag other) throws InterpreterException; 84 85}