/interpreter/tags/at2-build190607/src/edu/vub/at/objects/natives/NATTypeTag.java
Java | 188 lines | 94 code | 25 blank | 69 comment | 11 complexity | 401506260d31a7753b04293307d2d0c4 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 * @author tvcutsem 44 */ 45public class NATTypeTag extends NATByCopy implements ATTypeTag { 46 47 private final ATSymbol typeName_; 48 private final ATTable parentTypes_; 49 50 public static ATTypeTag[] toTypeTagArray(ATTable types) throws InterpreterException { 51 if (types == NATTable.EMPTY) { 52 return NATObject._NO_TYPETAGS_; 53 } 54 ATObject[] unwrapped = types.asNativeTable().elements_; 55 ATTypeTag[] unwrappedTypes = new ATTypeTag[unwrapped.length]; 56 for (int i = 0; i < unwrappedTypes.length; i++) { 57 unwrappedTypes[i] = unwrapped[i].asTypeTag(); 58 } 59 return unwrappedTypes; 60 } 61 62 public static NATTypeTag atValue(String typeName) { 63 return atValue(AGSymbol.jAlloc(typeName)); 64 } 65 66 public static NATTypeTag atValue(ATSymbol typeName) { 67 return new NATTypeTag(typeName, 68 NATTable.atValue(new ATObject[] { OBJRootType._INSTANCE_ })); 69 } 70 71 public static NATTypeTag atValue(String typeName, NATTypeTag singleParent) { 72 return new NATTypeTag(AGSymbol.jAlloc(typeName), 73 NATTable.atValue(new ATObject[] { singleParent })); 74 } 75 76 /** 77 * Types should not be created directly because it should be verified 78 * that their list of parent types is never empty. Types created 79 * with an empty parent list automatically get assigned the root type 80 * as their single parent. 81 */ 82 public static NATTypeTag atValue(ATSymbol typeName, ATTable parentTypes) { 83 if (parentTypes == NATTable.EMPTY) { 84 return new NATTypeTag(typeName, NATTable.atValue(new ATObject[] { OBJRootType._INSTANCE_ })); 85 } else { 86 return new NATTypeTag(typeName, parentTypes); 87 } 88 } 89 90 /** 91 * The constructor is declared protected such that it cannot be used externally, 92 * but can be used by the OBJRootType class to create a type with an empty 93 * parent table, which is normally not allowed. Hence, by construction the only 94 * type with an empty parent table is the root type. 95 */ 96 protected NATTypeTag(ATSymbol typeName, ATTable parentTypes) { 97 typeName_ = typeName; 98 parentTypes_ = parentTypes; 99 } 100 101 public ATSymbol base_getTypeName() throws InterpreterException { 102 return typeName_; 103 } 104 105 public ATTable base_getSuperTypes() throws InterpreterException { 106 return parentTypes_; 107 } 108 109 /** 110 * Native implementation of: 111 * 112 * def isSubtypeOf(supertype) { 113 * (supertype.name() == name).or: 114 * { (supertypes.find: { |type| 115 * type.isSubtypeOf(supertype) }) != nil } 116 * }; 117 */ 118 public ATBoolean base_isSubtypeOf(final ATTypeTag supertype) throws InterpreterException { 119 if (supertype.base_getTypeName().equals(typeName_)) { 120 return NATBoolean._TRUE_; 121 } else { 122 ATObject found = parentTypes_.base_find_(new NativeClosure(this) { 123 public ATObject base_apply(ATTable args) throws InterpreterException { 124 ATTypeTag type = get(args, 1).asTypeTag(); 125 return type.base_isSubtypeOf(supertype); 126 } 127 }); 128 return NATBoolean.atValue(found != NATNil._INSTANCE_); 129 } 130 } 131 132 /** 133 * Identity of types is based on their name 134 */ 135 public ATBoolean base__opeql__opeql_(ATObject comparand) throws InterpreterException { 136 if (comparand.isTypeTag()) { 137 return comparand.asTypeTag().base_getTypeName().base__opeql__opeql_(typeName_); 138 } else { 139 return NATBoolean._FALSE_; 140 } 141 } 142 143 public boolean isTypeTag() { return true; } 144 145 public ATTypeTag asTypeTag() { return this; } 146 147 public NATText meta_print() throws InterpreterException { 148 return NATText.atValue("<type tag:"+typeName_+">"); 149 } 150 151 /** 152 * Types are singletons 153 */ 154 public ATObject meta_clone() throws InterpreterException { 155 return this; 156 } 157 158 public ATTable meta_getTypeTags() throws InterpreterException { 159 return NATTable.of(NativeTypeTags._TYPETAG_); 160 } 161 162 /** 163 * The root type of the type hierarchy: every type eventually 164 * has this type as its parent. 165 */ 166 public static class OBJRootType extends NATTypeTag implements ATTypeTag { 167 168 private final static AGSymbol _ROOT_NAME_ = AGSymbol.jAlloc("Type"); 169 170 public static final OBJRootType _INSTANCE_ = new OBJRootType(); 171 172 /** 173 * The root type is named `Type and has no parent types 174 */ 175 private OBJRootType() { 176 super(_ROOT_NAME_, NATTable.EMPTY); 177 } 178 179 /** 180 * The root type is only a subtype of the root type itself 181 */ 182 public ATBoolean base_isSubtypeOf(ATTypeTag supertype) throws InterpreterException { 183 return NATBoolean.atValue(supertype.base_getTypeName().equals(_ROOT_NAME_)); 184 } 185 186 } 187 188}