WithObject.java revision 1320:0e28af5ee013
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 26package jdk.nashorn.internal.runtime; 27 28import static jdk.nashorn.internal.lookup.Lookup.MH; 29 30import java.lang.invoke.MethodHandle; 31import java.lang.invoke.MethodHandles; 32import java.lang.invoke.MethodType; 33import java.lang.invoke.SwitchPoint; 34import jdk.internal.dynalink.CallSiteDescriptor; 35import jdk.internal.dynalink.linker.GuardedInvocation; 36import jdk.internal.dynalink.linker.LinkRequest; 37import jdk.internal.dynalink.support.CallSiteDescriptorFactory; 38import jdk.nashorn.api.scripting.AbstractJSObject; 39import jdk.nashorn.api.scripting.ScriptObjectMirror; 40import jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor; 41import jdk.nashorn.internal.runtime.linker.NashornGuards; 42 43/** 44 * This class supports the handling of scope in a with body. 45 * 46 */ 47public final class WithObject extends ScriptObject implements Scope { 48 private static final MethodHandle WITHEXPRESSIONGUARD = findOwnMH("withExpressionGuard", boolean.class, Object.class, PropertyMap.class, SwitchPoint.class); 49 private static final MethodHandle WITHEXPRESSIONFILTER = findOwnMH("withFilterExpression", Object.class, Object.class); 50 private static final MethodHandle WITHSCOPEFILTER = findOwnMH("withFilterScope", Object.class, Object.class); 51 private static final MethodHandle BIND_TO_EXPRESSION_OBJ = findOwnMH("bindToExpression", Object.class, Object.class, Object.class); 52 private static final MethodHandle BIND_TO_EXPRESSION_FN = findOwnMH("bindToExpression", Object.class, ScriptFunction.class, Object.class); 53 54 /** With expression object. */ 55 private final ScriptObject expression; 56 57 /** 58 * Constructor 59 * 60 * @param scope scope object 61 * @param expression with expression 62 */ 63 WithObject(final ScriptObject scope, final ScriptObject expression) { 64 super(scope, null); 65 setIsScope(); 66 this.expression = expression; 67 } 68 69 /** 70 * Delete a property based on a key. 71 * @param key Any valid JavaScript value. 72 * @param strict strict mode execution. 73 * @return True if deleted. 74 */ 75 @Override 76 public boolean delete(final Object key, final boolean strict) { 77 final ScriptObject self = expression; 78 final String propName = JSType.toString(key); 79 80 final FindProperty find = self.findProperty(propName, true); 81 82 if (find != null) { 83 return self.delete(propName, strict); 84 } 85 86 return false; 87 } 88 89 90 @Override 91 public GuardedInvocation lookup(final CallSiteDescriptor desc, final LinkRequest request) { 92 if (request.isCallSiteUnstable()) { 93 // Fall back to megamorphic invocation which performs a complete lookup each time without further relinking. 94 return super.lookup(desc, request); 95 } 96 97 // With scopes can never be observed outside of Nashorn code, so all call sites that can address it will of 98 // necessity have a Nashorn descriptor - it is safe to cast. 99 final NashornCallSiteDescriptor ndesc = (NashornCallSiteDescriptor)desc; 100 FindProperty find = null; 101 GuardedInvocation link = null; 102 ScriptObject self; 103 104 final boolean isNamedOperation; 105 final String name; 106 if (desc.getNameTokenCount() > 2) { 107 isNamedOperation = true; 108 name = desc.getNameToken(CallSiteDescriptor.NAME_OPERAND); 109 } else { 110 isNamedOperation = false; 111 name = null; 112 } 113 114 self = expression; 115 if (isNamedOperation) { 116 find = self.findProperty(name, true); 117 } 118 119 if (find != null) { 120 link = self.lookup(desc, request); 121 if (link != null) { 122 return fixExpressionCallSite(ndesc, link); 123 } 124 } 125 126 final ScriptObject scope = getProto(); 127 if (isNamedOperation) { 128 find = scope.findProperty(name, true); 129 } 130 131 if (find != null) { 132 return fixScopeCallSite(scope.lookup(desc, request), name, find.getOwner()); 133 } 134 135 // the property is not found - now check for 136 // __noSuchProperty__ and __noSuchMethod__ in expression 137 if (self != null) { 138 final String fallBack; 139 140 final String operator = CallSiteDescriptorFactory.tokenizeOperators(desc).get(0); 141 142 switch (operator) { 143 case "callMethod": 144 throw new AssertionError(); // Nashorn never emits callMethod 145 case "getMethod": 146 fallBack = NO_SUCH_METHOD_NAME; 147 break; 148 case "getProp": 149 case "getElem": 150 fallBack = NO_SUCH_PROPERTY_NAME; 151 break; 152 default: 153 fallBack = null; 154 break; 155 } 156 157 if (fallBack != null) { 158 find = self.findProperty(fallBack, true); 159 if (find != null) { 160 switch (operator) { 161 case "getMethod": 162 link = self.noSuchMethod(desc, request); 163 break; 164 case "getProp": 165 case "getElem": 166 link = self.noSuchProperty(desc, request); 167 break; 168 default: 169 break; 170 } 171 } 172 } 173 174 if (link != null) { 175 return fixExpressionCallSite(ndesc, link); 176 } 177 } 178 179 // still not found, may be scope can handle with it's own 180 // __noSuchProperty__, __noSuchMethod__ etc. 181 link = scope.lookup(desc, request); 182 183 if (link != null) { 184 return fixScopeCallSite(link, name, null); 185 } 186 187 return null; 188 } 189 190 /** 191 * Overridden to try to find the property first in the expression object (and its prototypes), and only then in this 192 * object (and its prototypes). 193 * 194 * @param key Property key. 195 * @param deep Whether the search should look up proto chain. 196 * @param start the object on which the lookup was originally initiated 197 * 198 * @return FindPropertyData or null if not found. 199 */ 200 @Override 201 protected FindProperty findProperty(final String key, final boolean deep, final ScriptObject start) { 202 // We call findProperty on 'expression' with 'expression' itself as start parameter. 203 // This way in ScriptObject.setObject we can tell the property is from a 'with' expression 204 // (as opposed from another non-scope object in the proto chain such as Object.prototype). 205 final FindProperty exprProperty = expression.findProperty(key, true, expression); 206 if (exprProperty != null) { 207 return exprProperty; 208 } 209 return super.findProperty(key, deep, start); 210 } 211 212 @Override 213 protected Object invokeNoSuchProperty(final String name, final int programPoint) { 214 FindProperty find = expression.findProperty(NO_SUCH_PROPERTY_NAME, true); 215 if (find != null) { 216 final Object func = find.getObjectValue(); 217 if (func instanceof ScriptFunction) { 218 return ScriptRuntime.apply((ScriptFunction)func, expression, name); 219 } 220 } 221 222 return getProto().invokeNoSuchProperty(name, programPoint); 223 } 224 225 @Override 226 public void setSplitState(final int state) { 227 ((Scope) getNonWithParent()).setSplitState(state); 228 } 229 230 @Override 231 public int getSplitState() { 232 return ((Scope) getNonWithParent()).getSplitState(); 233 } 234 235 @Override 236 public void addBoundProperties(final ScriptObject source, final Property[] properties) { 237 // Declared variables in nested eval go to first normal (non-with) parent scope. 238 getNonWithParent().addBoundProperties(source, properties); 239 } 240 241 /** 242 * Get first parent scope that is not an instance of WithObject. 243 */ 244 private ScriptObject getNonWithParent() { 245 ScriptObject proto = getProto(); 246 247 while (proto != null && proto instanceof WithObject) { 248 proto = proto.getProto(); 249 } 250 251 return proto; 252 } 253 254 private static GuardedInvocation fixReceiverType(final GuardedInvocation link, final MethodHandle filter) { 255 // The receiver may be an Object or a ScriptObject. 256 final MethodType invType = link.getInvocation().type(); 257 final MethodType newInvType = invType.changeParameterType(0, filter.type().returnType()); 258 return link.asType(newInvType); 259 } 260 261 private static GuardedInvocation fixExpressionCallSite(final NashornCallSiteDescriptor desc, final GuardedInvocation link) { 262 // If it's not a getMethod, just add an expression filter that converts WithObject in "this" position to its 263 // expression. 264 if (!"getMethod".equals(desc.getFirstOperator())) { 265 return fixReceiverType(link, WITHEXPRESSIONFILTER).filterArguments(0, WITHEXPRESSIONFILTER); 266 } 267 268 final MethodHandle linkInvocation = link.getInvocation(); 269 final MethodType linkType = linkInvocation.type(); 270 final boolean linkReturnsFunction = ScriptFunction.class.isAssignableFrom(linkType.returnType()); 271 272 return link.replaceMethods( 273 // Make sure getMethod will bind the script functions it receives to WithObject.expression 274 MH.foldArguments( 275 linkReturnsFunction ? 276 BIND_TO_EXPRESSION_FN : 277 BIND_TO_EXPRESSION_OBJ, 278 filterReceiver( 279 linkInvocation.asType( 280 linkType.changeReturnType( 281 linkReturnsFunction ? 282 ScriptFunction.class : 283 Object.class). 284 changeParameterType( 285 0, 286 Object.class)), 287 WITHEXPRESSIONFILTER)), 288 filterGuardReceiver(link, WITHEXPRESSIONFILTER)); 289 // No clever things for the guard -- it is still identically filtered. 290 291 } 292 293 private GuardedInvocation fixScopeCallSite(final GuardedInvocation link, final String name, final ScriptObject owner) { 294 final GuardedInvocation newLink = fixReceiverType(link, WITHSCOPEFILTER); 295 final MethodHandle expressionGuard = expressionGuard(name, owner); 296 final MethodHandle filterGuardReceiver = filterGuardReceiver(newLink, WITHSCOPEFILTER); 297 return link.replaceMethods( 298 filterReceiver( 299 newLink.getInvocation(), 300 WITHSCOPEFILTER), 301 NashornGuards.combineGuards( 302 expressionGuard, 303 filterGuardReceiver)); 304 } 305 306 private static MethodHandle filterGuardReceiver(final GuardedInvocation link, final MethodHandle receiverFilter) { 307 final MethodHandle test = link.getGuard(); 308 if (test == null) { 309 return null; 310 } 311 312 final Class<?> receiverType = test.type().parameterType(0); 313 final MethodHandle filter = MH.asType(receiverFilter, 314 receiverFilter.type().changeParameterType(0, receiverType). 315 changeReturnType(receiverType)); 316 317 return filterReceiver(test, filter); 318 } 319 320 private static MethodHandle filterReceiver(final MethodHandle mh, final MethodHandle receiverFilter) { 321 //With expression filter == receiverFilter, i.e. receiver is cast to withobject and its expression returned 322 return MH.filterArguments(mh, 0, receiverFilter.asType(receiverFilter.type().changeReturnType(mh.type().parameterType(0)))); 323 } 324 325 /** 326 * Drops the WithObject wrapper from the expression. 327 * @param receiver WithObject wrapper. 328 * @return The with expression. 329 */ 330 public static Object withFilterExpression(final Object receiver) { 331 return ((WithObject)receiver).expression; 332 } 333 334 @SuppressWarnings("unused") 335 private static Object bindToExpression(final Object fn, final Object receiver) { 336 if (fn instanceof ScriptFunction) { 337 return bindToExpression((ScriptFunction) fn, receiver); 338 } else if (fn instanceof ScriptObjectMirror) { 339 final ScriptObjectMirror mirror = (ScriptObjectMirror)fn; 340 if (mirror.isFunction()) { 341 // We need to make sure correct 'this' is used for calls with Ident call 342 // expressions. We do so here using an AbstractJSObject instance. 343 return new AbstractJSObject() { 344 @Override 345 public Object call(final Object thiz, final Object... args) { 346 return mirror.call(withFilterExpression(receiver), args); 347 } 348 }; 349 } 350 } 351 352 return fn; 353 } 354 355 private static Object bindToExpression(final ScriptFunction fn, final Object receiver) { 356 return fn.makeBoundFunction(withFilterExpression(receiver), ScriptRuntime.EMPTY_ARRAY); 357 } 358 359 private MethodHandle expressionGuard(final String name, final ScriptObject owner) { 360 final PropertyMap map = expression.getMap(); 361 final SwitchPoint sp = expression.getProtoSwitchPoint(name, owner); 362 return MH.insertArguments(WITHEXPRESSIONGUARD, 1, map, sp); 363 } 364 365 @SuppressWarnings("unused") 366 private static boolean withExpressionGuard(final Object receiver, final PropertyMap map, final SwitchPoint sp) { 367 return ((WithObject)receiver).expression.getMap() == map && (sp == null || !sp.hasBeenInvalidated()); 368 } 369 370 /** 371 * Drops the WithObject wrapper from the scope. 372 * @param receiver WithObject wrapper. 373 * @return The with scope. 374 */ 375 public static Object withFilterScope(final Object receiver) { 376 return ((WithObject)receiver).getProto(); 377 } 378 379 /** 380 * Get the with expression for this {@code WithObject} 381 * @return the with expression 382 */ 383 public ScriptObject getExpression() { 384 return expression; 385 } 386 387 private static MethodHandle findOwnMH(final String name, final Class<?> rtype, final Class<?>... types) { 388 return MH.findStatic(MethodHandles.lookup(), WithObject.class, name, MH.type(rtype, types)); 389 } 390} 391