/interpreter/tags/at2dist170907/src/edu/vub/at/objects/natives/NATTypeTag.java
Java | 192 lines | 94 code | 25 blank | 73 comment | 11 complexity | cbf1b050e101ffc9332a61b4c2fd266e MD5 | raw file
1/** 2 * AmbientTalk/2 Project 3 * NATTypeTag.java created on 18-feb-2007 at 15:59:20 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.natives; 29 30import edu.vub.at.exceptions.InterpreterException; 31import edu.vub.at.objects.ATBoolean; 32import edu.vub.at.objects.ATObject; 33import edu.vub.at.objects.ATTable; 34import edu.vub.at.objects.ATTypeTag; 35import edu.vub.at.objects.coercion.NativeTypeTags; 36import edu.vub.at.objects.grammar.ATSymbol; 37import edu.vub.at.objects.mirrors.NativeClosure; 38import edu.vub.at.objects.natives.grammar.AGSymbol; 39 40/** 41 * The native implementation of AmbientTalk type tag objects. 42 * 43 * In principle, care should be taken that all objects implementing the 44 * type tag interface are isolates, because type tags are usually attributed 45 * to messages which are isolates themselves. 46 * 47 * @author tvcutsem 48 */ 49public class NATTypeTag extends NATByCopy implements ATTypeTag { 50 51 private final ATSymbol typeName_; 52 private final ATTable parentTypes_; 53 54 public static ATTypeTag[] toTypeTagArray(ATTable types) throws InterpreterException { 55 if (types == NATTable.EMPTY) { 56 return NATObject._NO_TYPETAGS_; 57 } 58 ATObject[] unwrapped = types.asNativeTable().elements_; 59 ATTypeTag[] unwrappedTypes = new ATTypeTag[unwrapped.length]; 60 for (int i = 0; i < unwrappedTypes.length; i++) { 61 unwrappedTypes[i] = unwrapped[i].asTypeTag(); 62 } 63 return unwrappedTypes; 64 } 65 66 public static NATTypeTag atValue(String typeName) { 67 return atValue(AGSymbol.jAlloc(typeName)); 68 } 69 70 public static NATTypeTag atValue(ATSymbol typeName) { 71 return new NATTypeTag(typeName, 72 NATTable.atValue(new ATObject[] { OBJRootType._INSTANCE_ })); 73 } 74 75 public static NATTypeTag atValue(String typeName, NATTypeTag singleParent) { 76 return new NATTypeTag(AGSymbol.jAlloc(typeName), 77 NATTable.atValue(new ATObject[] { singleParent })); 78 } 79 80 /** 81 * Types should not be created directly because it should be verified 82 * that their list of parent types is never empty. Types created 83 * with an empty parent list automatically get assigned the root type 84 * as their single parent. 85 */ 86 public static NATTypeTag atValue(ATSymbol typeName, ATTable parentTypes) { 87 if (parentTypes == NATTable.EMPTY) { 88 return new NATTypeTag(typeName, NATTable.atValue(new ATObject[] { OBJRootType._INSTANCE_ })); 89 } else { 90 return new NATTypeTag(typeName, parentTypes); 91 } 92 } 93 94 /** 95 * The constructor is declared protected such that it cannot be used externally, 96 * but can be used by the OBJRootType class to create a type with an empty 97 * parent table, which is normally not allowed. Hence, by construction the only 98 * type with an empty parent table is the root type. 99 */ 100 protected NATTypeTag(ATSymbol typeName, ATTable parentTypes) { 101 typeName_ = typeName; 102 parentTypes_ = parentTypes; 103 } 104 105 public ATSymbol base_typeName() throws InterpreterException { 106 return typeName_; 107 } 108 109 public ATTable base_superTypes() throws InterpreterException { 110 return parentTypes_; 111 } 112 113 /** 114 * Native implementation of: 115 * 116 * def isSubtypeOf(supertype) { 117 * (supertype.name() == name).or: 118 * { (supertypes.find: { |type| 119 * type.isSubtypeOf(supertype) }) != nil } 120 * }; 121 */ 122 public ATBoolean base_isSubtypeOf(final ATTypeTag supertype) throws InterpreterException { 123 if (supertype.base_typeName().equals(typeName_)) { 124 return NATBoolean._TRUE_; 125 } else { 126 ATObject found = parentTypes_.base_find_(new NativeClosure(this) { 127 public ATObject base_apply(ATTable args) throws InterpreterException { 128 ATTypeTag type = get(args, 1).asTypeTag(); 129 return type.base_isSubtypeOf(supertype); 130 } 131 }); 132 return NATBoolean.atValue(found != OBJNil._INSTANCE_); 133 } 134 } 135 136 /** 137 * Identity of types is based on their name 138 */ 139 public ATBoolean base__opeql__opeql_(ATObject comparand) throws InterpreterException { 140 if (comparand.isTypeTag()) { 141 return comparand.asTypeTag().base_typeName().base__opeql__opeql_(typeName_); 142 } else { 143 return NATBoolean._FALSE_; 144 } 145 } 146 147 public boolean isTypeTag() { return true; } 148 149 public ATTypeTag asTypeTag() { return this; } 150 151 public NATText meta_print() throws InterpreterException { 152 return NATText.atValue("<type tag:"+typeName_+">"); 153 } 154 155 /** 156 * Types are singletons 157 */ 158 public ATObject meta_clone() throws InterpreterException { 159 return this; 160 } 161 162 public ATTable meta_typeTags() throws InterpreterException { 163 return NATTable.of(NativeTypeTags._TYPETAG_, NativeTypeTags._ISOLATE_); 164 } 165 166 /** 167 * The root type of the type hierarchy: every type eventually 168 * has this type as its parent. 169 */ 170 public static class OBJRootType extends NATTypeTag implements ATTypeTag { 171 172 private final static AGSymbol _ROOT_NAME_ = AGSymbol.jAlloc("Type"); 173 174 public static final OBJRootType _INSTANCE_ = new OBJRootType(); 175 176 /** 177 * The root type is named `Type and has no parent types 178 */ 179 private OBJRootType() { 180 super(_ROOT_NAME_, NATTable.EMPTY); 181 } 182 183 /** 184 * The root type is only a subtype of the root type itself 185 */ 186 public ATBoolean base_isSubtypeOf(ATTypeTag supertype) throws InterpreterException { 187 return NATBoolean.atValue(supertype.base_typeName().equals(_ROOT_NAME_)); 188 } 189 190 } 191 192}