1 /* 2 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package jdk.nashorn.internal.runtime; 27 28 import static jdk.nashorn.internal.lookup.Lookup.MH; 29 30 import java.lang.invoke.MethodHandle; 31 import java.lang.invoke.MethodHandles; 32 import java.lang.invoke.MethodType; 33 import jdk.internal.dynalink.CallSiteDescriptor; 34 import jdk.internal.dynalink.linker.GuardedInvocation; 35 import jdk.internal.dynalink.linker.LinkRequest; 36 import jdk.internal.dynalink.support.CallSiteDescriptorFactory; 37 import jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor; 38 39 40 /** 41 * This class supports the handling of scope in a with body. 42 * 43 */ 44 public final class WithObject extends ScriptObject implements Scope { 45 46 private static final MethodHandle WITHEXPRESSIONFILTER = findOwnMH("withFilterExpression", Object.class, Object.class); 47 private static final MethodHandle WITHSCOPEFILTER = findOwnMH("withFilterScope", Object.class, Object.class); 48 private static final MethodHandle BIND_TO_EXPRESSION_OBJ = findOwnMH("bindToExpression", Object.class, Object.class, Object.class); 49 private static final MethodHandle BIND_TO_EXPRESSION_FN = findOwnMH("bindToExpression", Object.class, ScriptFunction.class, Object.class); 50 51 /** With expression object. */ 52 private final Object expression; 53 54 /** 55 * Constructor 56 * 57 * @param scope scope object 58 * @param expression with expression 59 */ 60 WithObject(final ScriptObject scope, final Object expression) { 61 super(scope, null); 62 setIsScope(); 63 this.expression = expression; 64 } 65 66 /** 67 * Delete a property based on a key. 68 * @param key Any valid JavaScript value. 69 * @param strict strict mode execution. 70 * @return True if deleted. 71 */ 72 @Override 73 public boolean delete(final Object key, final boolean strict) { 74 if (expression instanceof ScriptObject) { 75 final ScriptObject self = (ScriptObject)expression; 76 final String propName = JSType.toString(key); 77 78 final FindProperty find = self.findProperty(propName, true); 79 80 if (find != null) { 81 return self.delete(propName, strict); 82 } 83 } 84 85 return false; 86 } 87 88 89 @Override 90 public GuardedInvocation lookup(final CallSiteDescriptor desc, final LinkRequest request) { 91 // With scopes can never be observed outside of Nashorn code, so all call sites that can address it will of 92 // necessity have a Nashorn descriptor - it is safe to cast. 93 final NashornCallSiteDescriptor ndesc = (NashornCallSiteDescriptor)desc; 94 FindProperty find = null; 95 GuardedInvocation link = null; 96 ScriptObject self = null; 97 98 final boolean isNamedOperation; 99 final String name; 100 if(desc.getNameTokenCount() > 2) { 101 isNamedOperation = true; 102 name = desc.getNameToken(CallSiteDescriptor.NAME_OPERAND); 103 } else { 104 isNamedOperation = false; 105 name = null; 106 } 107 108 if (expression instanceof ScriptObject) { 109 self = (ScriptObject)expression; 110 if (isNamedOperation) { 111 find = self.findProperty(name, true); 112 } 113 114 if (find != null) { 115 link = self.lookup(desc, request); 116 117 if (link != null) { 118 return fixExpressionCallSite(ndesc, link); 119 } 120 } 121 } 122 123 final ScriptObject scope = getProto(); 124 if (isNamedOperation) { 125 find = scope.findProperty(name, true); 126 } 127 128 if (find != null) { 129 return fixScopeCallSite(scope.lookup(desc, request)); 130 } 131 132 // the property is not found - now check for 133 // __noSuchProperty__ and __noSuchMethod__ in expression 134 if (self != null) { 135 final String fallBack; 136 137 final String operator = CallSiteDescriptorFactory.tokenizeOperators(desc).get(0); 138 139 switch (operator) { 140 case "callMethod": 141 throw new AssertionError(); // Nashorn never emits callMethod 142 case "getMethod": 143 fallBack = NO_SUCH_METHOD_NAME; 144 break; 145 case "getProp": 146 case "getElem": 147 fallBack = NO_SUCH_PROPERTY_NAME; 148 break; 149 default: 150 fallBack = null; 151 break; 152 } 153 154 if (fallBack != null) { 155 find = self.findProperty(fallBack, true); 156 if (find != null) { 157 switch (operator) { 158 case "getMethod": 159 link = self.noSuchMethod(desc, request); 160 break; 161 case "getProp": 162 case "getElem": 163 link = self.noSuchProperty(desc, request); 164 break; 165 default: 166 break; 167 } 168 } 169 } 170 171 if (link != null) { 172 return fixExpressionCallSite(ndesc, link); 173 } 174 } 175 176 // still not found, may be scope can handle with it's own 177 // __noSuchProperty__, __noSuchMethod__ etc. 178 link = scope.lookup(desc, request); 179 180 if (link != null) { 181 return fixScopeCallSite(link); 182 } 183 184 return null; 185 } 186 187 /** 188 * Overridden to try to find the property first in the expression object (and its prototypes), and only then in this 189 * object (and its prototypes). 190 * 191 * @param key Property key. 192 * @param deep Whether the search should look up proto chain. 193 * @param stopOnNonScope should a deep search stop on the first non-scope object? 194 * @param start the object on which the lookup was originally initiated 195 * 196 * @return FindPropertyData or null if not found. 197 */ 198 @Override 199 FindProperty findProperty(final String key, final boolean deep, final boolean stopOnNonScope, final ScriptObject start) { 200 if (expression instanceof ScriptObject) { 201 final FindProperty exprProperty = ((ScriptObject)expression).findProperty(key, deep, stopOnNonScope, start); 202 if(exprProperty != null) { 203 return exprProperty; 204 } 205 } 206 return super.findProperty(key, deep, stopOnNonScope, start); 207 } 208 209 @Override 210 public void setSplitState(final int state) { 211 getNonWithParent().setSplitState(state); 212 } 213 214 @Override 215 public int getSplitState() { 216 return getNonWithParent().getSplitState(); 217 } 218 219 /** 220 * Get first parent scope that is not an instance of WithObject. 221 */ 222 private Scope getNonWithParent() { 223 ScriptObject proto = getProto(); 224 225 while (proto != null && proto instanceof WithObject) { 226 proto = proto.getProto(); 227 } 228 229 assert proto instanceof Scope : "with scope without parent scope"; 230 return (Scope) proto; 231 } 232 233 private static GuardedInvocation fixReceiverType(final GuardedInvocation link, final MethodHandle filter) { 234 // The receiver may be an Object or a ScriptObject. 235 final MethodType invType = link.getInvocation().type(); 236 final MethodType newInvType = invType.changeParameterType(0, filter.type().returnType()); 237 return link.asType(newInvType); 238 } 239 240 private static GuardedInvocation fixExpressionCallSite(final NashornCallSiteDescriptor desc, final GuardedInvocation link) { 241 // If it's not a getMethod, just add an expression filter that converts WithObject in "this" position to its 242 // expression. 243 if(!"getMethod".equals(desc.getFirstOperator())) { 244 return fixReceiverType(link, WITHEXPRESSIONFILTER).filterArguments(0, WITHEXPRESSIONFILTER); 245 } 246 247 final MethodHandle linkInvocation = link.getInvocation(); 248 final MethodType linkType = linkInvocation.type(); 249 final boolean linkReturnsFunction = ScriptFunction.class.isAssignableFrom(linkType.returnType()); 250 return link.replaceMethods( 251 // Make sure getMethod will bind the script functions it receives to WithObject.expression 252 MH.foldArguments(linkReturnsFunction ? BIND_TO_EXPRESSION_FN : BIND_TO_EXPRESSION_OBJ, 253 filter(linkInvocation.asType(linkType.changeReturnType( 254 linkReturnsFunction ? ScriptFunction.class : Object.class)), WITHEXPRESSIONFILTER)), 255 // No clever things for the guard -- it is still identically filtered. 256 filterGuard(link, WITHEXPRESSIONFILTER)); 257 } 258 259 private static GuardedInvocation fixScopeCallSite(final GuardedInvocation link) { 260 final GuardedInvocation newLink = fixReceiverType(link, WITHSCOPEFILTER); 261 return link.replaceMethods(filter(newLink.getInvocation(), WITHSCOPEFILTER), filterGuard(newLink, WITHSCOPEFILTER)); 262 } 263 264 private static MethodHandle filterGuard(final GuardedInvocation link, final MethodHandle filter) { 265 final MethodHandle test = link.getGuard(); 266 return test == null ? null : filter(test, filter); 267 } 268 269 private static MethodHandle filter(final MethodHandle mh, final MethodHandle filter) { 270 return MH.filterArguments(mh, 0, filter); 271 } 272 273 /** 274 * Drops the WithObject wrapper from the expression. 275 * @param receiver WithObject wrapper. 276 * @return The with expression. 277 */ 278 public static Object withFilterExpression(final Object receiver) { 279 return ((WithObject)receiver).expression; 280 } 281 282 283 @SuppressWarnings("unused") 284 private static Object bindToExpression(final Object fn, final Object receiver) { 285 return fn instanceof ScriptFunction ? bindToExpression((ScriptFunction) fn, receiver) : fn; 286 } 287 288 private static Object bindToExpression(final ScriptFunction fn, final Object receiver) { 289 return fn.makeBoundFunction(withFilterExpression(receiver), new Object[0]); 290 } 291 292 /** 293 * Drops the WithObject wrapper from the scope. 294 * @param receiver WithObject wrapper. 295 * @return The with scope. 296 */ 297 public static Object withFilterScope(final Object receiver) { 298 return ((WithObject)receiver).getProto(); 299 } 300 301 /** 302 * Get the with expression for this {@code WithObject} 303 * @return the with expression 304 */ 305 public Object getExpression() { 306 return expression; 307 } 308 309 private static MethodHandle findOwnMH(final String name, final Class<?> rtype, final Class<?>... types) { 310 return MH.findStatic(MethodHandles.lookup(), WithObject.class, name, MH.type(rtype, types)); 311 } 312 }