Lower.java revision 1176:ceed654a29a4
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.codegen; 27 28import static jdk.nashorn.internal.codegen.CompilerConstants.EVAL; 29import static jdk.nashorn.internal.codegen.CompilerConstants.RETURN; 30import static jdk.nashorn.internal.ir.Expression.isAlwaysTrue; 31 32import java.util.ArrayList; 33import java.util.Arrays; 34import java.util.Collections; 35import java.util.List; 36import java.util.ListIterator; 37import java.util.regex.Pattern; 38import jdk.nashorn.internal.ir.AccessNode; 39import jdk.nashorn.internal.ir.BaseNode; 40import jdk.nashorn.internal.ir.BinaryNode; 41import jdk.nashorn.internal.ir.Block; 42import jdk.nashorn.internal.ir.BlockLexicalContext; 43import jdk.nashorn.internal.ir.BlockStatement; 44import jdk.nashorn.internal.ir.BreakNode; 45import jdk.nashorn.internal.ir.CallNode; 46import jdk.nashorn.internal.ir.CaseNode; 47import jdk.nashorn.internal.ir.CatchNode; 48import jdk.nashorn.internal.ir.ContinueNode; 49import jdk.nashorn.internal.ir.EmptyNode; 50import jdk.nashorn.internal.ir.Expression; 51import jdk.nashorn.internal.ir.ExpressionStatement; 52import jdk.nashorn.internal.ir.ForNode; 53import jdk.nashorn.internal.ir.FunctionNode; 54import jdk.nashorn.internal.ir.FunctionNode.CompilationState; 55import jdk.nashorn.internal.ir.IdentNode; 56import jdk.nashorn.internal.ir.IfNode; 57import jdk.nashorn.internal.ir.IndexNode; 58import jdk.nashorn.internal.ir.JumpStatement; 59import jdk.nashorn.internal.ir.JumpToInlinedFinally; 60import jdk.nashorn.internal.ir.LabelNode; 61import jdk.nashorn.internal.ir.LexicalContext; 62import jdk.nashorn.internal.ir.LiteralNode; 63import jdk.nashorn.internal.ir.LiteralNode.PrimitiveLiteralNode; 64import jdk.nashorn.internal.ir.LoopNode; 65import jdk.nashorn.internal.ir.Node; 66import jdk.nashorn.internal.ir.ReturnNode; 67import jdk.nashorn.internal.ir.RuntimeNode; 68import jdk.nashorn.internal.ir.Statement; 69import jdk.nashorn.internal.ir.SwitchNode; 70import jdk.nashorn.internal.ir.Symbol; 71import jdk.nashorn.internal.ir.ThrowNode; 72import jdk.nashorn.internal.ir.TryNode; 73import jdk.nashorn.internal.ir.VarNode; 74import jdk.nashorn.internal.ir.WhileNode; 75import jdk.nashorn.internal.ir.WithNode; 76import jdk.nashorn.internal.ir.visitor.NodeOperatorVisitor; 77import jdk.nashorn.internal.ir.visitor.NodeVisitor; 78import jdk.nashorn.internal.parser.Token; 79import jdk.nashorn.internal.parser.TokenType; 80import jdk.nashorn.internal.runtime.Context; 81import jdk.nashorn.internal.runtime.JSType; 82import jdk.nashorn.internal.runtime.Source; 83import jdk.nashorn.internal.runtime.logging.DebugLogger; 84import jdk.nashorn.internal.runtime.logging.Loggable; 85import jdk.nashorn.internal.runtime.logging.Logger; 86 87/** 88 * Lower to more primitive operations. After lowering, an AST still has no symbols 89 * and types, but several nodes have been turned into more low level constructs 90 * and control flow termination criteria have been computed. 91 * 92 * We do things like code copying/inlining of finallies here, as it is much 93 * harder and context dependent to do any code copying after symbols have been 94 * finalized. 95 */ 96@Logger(name="lower") 97final class Lower extends NodeOperatorVisitor<BlockLexicalContext> implements Loggable { 98 99 private final DebugLogger log; 100 101 // Conservative pattern to test if element names consist of characters valid for identifiers. 102 // This matches any non-zero length alphanumeric string including _ and $ and not starting with a digit. 103 private static Pattern SAFE_PROPERTY_NAME = Pattern.compile("[a-zA-Z_$][\\w$]*"); 104 105 /** 106 * Constructor. 107 */ 108 Lower(final Compiler compiler) { 109 super(new BlockLexicalContext() { 110 111 @Override 112 public List<Statement> popStatements() { 113 final List<Statement> newStatements = new ArrayList<>(); 114 boolean terminated = false; 115 116 final List<Statement> statements = super.popStatements(); 117 for (final Statement statement : statements) { 118 if (!terminated) { 119 newStatements.add(statement); 120 if (statement.isTerminal() || statement instanceof JumpStatement) { //TODO hasGoto? But some Loops are hasGoto too - why? 121 terminated = true; 122 } 123 } else { 124 statement.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) { 125 @Override 126 public boolean enterVarNode(final VarNode varNode) { 127 newStatements.add(varNode.setInit(null)); 128 return false; 129 } 130 }); 131 } 132 } 133 return newStatements; 134 } 135 136 @Override 137 protected Block afterSetStatements(final Block block) { 138 final List<Statement> stmts = block.getStatements(); 139 for(final ListIterator<Statement> li = stmts.listIterator(stmts.size()); li.hasPrevious();) { 140 final Statement stmt = li.previous(); 141 // popStatements() guarantees that the only thing after a terminal statement are uninitialized 142 // VarNodes. We skip past those, and set the terminal state of the block to the value of the 143 // terminal state of the first statement that is not an uninitialized VarNode. 144 if(!(stmt instanceof VarNode && ((VarNode)stmt).getInit() == null)) { 145 return block.setIsTerminal(this, stmt.isTerminal()); 146 } 147 } 148 return block.setIsTerminal(this, false); 149 } 150 }); 151 152 this.log = initLogger(compiler.getContext()); 153 } 154 155 @Override 156 public DebugLogger getLogger() { 157 return log; 158 } 159 160 @Override 161 public DebugLogger initLogger(final Context context) { 162 return context.getLogger(this.getClass()); 163 } 164 165 @Override 166 public boolean enterBreakNode(final BreakNode breakNode) { 167 addStatement(breakNode); 168 return false; 169 } 170 171 @Override 172 public Node leaveCallNode(final CallNode callNode) { 173 return checkEval(callNode.setFunction(markerFunction(callNode.getFunction()))); 174 } 175 176 @Override 177 public Node leaveCatchNode(final CatchNode catchNode) { 178 return addStatement(catchNode); 179 } 180 181 @Override 182 public boolean enterContinueNode(final ContinueNode continueNode) { 183 addStatement(continueNode); 184 return false; 185 } 186 187 @Override 188 public boolean enterJumpToInlinedFinally(final JumpToInlinedFinally jumpToInlinedFinally) { 189 addStatement(jumpToInlinedFinally); 190 return false; 191 } 192 193 @Override 194 public boolean enterEmptyNode(final EmptyNode emptyNode) { 195 return false; 196 } 197 198 @Override 199 public Node leaveIndexNode(final IndexNode indexNode) { 200 final String name = getConstantPropertyName(indexNode.getIndex()); 201 if (name != null) { 202 // If index node is a constant property name convert index node to access node. 203 assert Token.descType(indexNode.getToken()) == TokenType.LBRACKET; 204 return new AccessNode(indexNode.getToken(), indexNode.getFinish(), indexNode.getBase(), name); 205 } 206 return super.leaveIndexNode(indexNode); 207 } 208 209 // If expression is a primitive literal that is not an array index and does return its string value. Else return null. 210 private static String getConstantPropertyName(final Expression expression) { 211 if (expression instanceof LiteralNode.PrimitiveLiteralNode) { 212 final Object value = ((LiteralNode) expression).getValue(); 213 if (value instanceof String && SAFE_PROPERTY_NAME.matcher((String) value).matches()) { 214 return (String) value; 215 } 216 } 217 return null; 218 } 219 220 @Override 221 public Node leaveExpressionStatement(final ExpressionStatement expressionStatement) { 222 final Expression expr = expressionStatement.getExpression(); 223 ExpressionStatement node = expressionStatement; 224 225 final FunctionNode currentFunction = lc.getCurrentFunction(); 226 227 if (currentFunction.isProgram()) { 228 if (!isInternalExpression(expr) && !isEvalResultAssignment(expr)) { 229 node = expressionStatement.setExpression( 230 new BinaryNode( 231 Token.recast( 232 expressionStatement.getToken(), 233 TokenType.ASSIGN), 234 compilerConstant(RETURN), 235 expr)); 236 } 237 } 238 239 return addStatement(node); 240 } 241 242 @Override 243 public Node leaveBlockStatement(final BlockStatement blockStatement) { 244 return addStatement(blockStatement); 245 } 246 247 @Override 248 public Node leaveForNode(final ForNode forNode) { 249 ForNode newForNode = forNode; 250 251 final Expression test = forNode.getTest(); 252 if (!forNode.isForIn() && isAlwaysTrue(test)) { 253 newForNode = forNode.setTest(lc, null); 254 } 255 256 newForNode = checkEscape(newForNode); 257 if(newForNode.isForIn()) { 258 // Wrap it in a block so its internally created iterator is restricted in scope 259 addStatementEnclosedInBlock(newForNode); 260 } else { 261 addStatement(newForNode); 262 } 263 return newForNode; 264 } 265 266 @Override 267 public Node leaveFunctionNode(final FunctionNode functionNode) { 268 log.info("END FunctionNode: ", functionNode.getName()); 269 return functionNode.setState(lc, CompilationState.LOWERED); 270 } 271 272 @Override 273 public Node leaveIfNode(final IfNode ifNode) { 274 return addStatement(ifNode); 275 } 276 277 @Override 278 public Node leaveIN(final BinaryNode binaryNode) { 279 return new RuntimeNode(binaryNode); 280 } 281 282 @Override 283 public Node leaveINSTANCEOF(final BinaryNode binaryNode) { 284 return new RuntimeNode(binaryNode); 285 } 286 287 @Override 288 public Node leaveLabelNode(final LabelNode labelNode) { 289 return addStatement(labelNode); 290 } 291 292 @Override 293 public Node leaveReturnNode(final ReturnNode returnNode) { 294 addStatement(returnNode); //ReturnNodes are always terminal, marked as such in constructor 295 return returnNode; 296 } 297 298 @Override 299 public Node leaveCaseNode(final CaseNode caseNode) { 300 // Try to represent the case test as an integer 301 final Node test = caseNode.getTest(); 302 if (test instanceof LiteralNode) { 303 final LiteralNode<?> lit = (LiteralNode<?>)test; 304 if (lit.isNumeric() && !(lit.getValue() instanceof Integer)) { 305 if (JSType.isRepresentableAsInt(lit.getNumber())) { 306 return caseNode.setTest((Expression)LiteralNode.newInstance(lit, lit.getInt32()).accept(this)); 307 } 308 } 309 } 310 return caseNode; 311 } 312 313 @Override 314 public Node leaveSwitchNode(final SwitchNode switchNode) { 315 if(!switchNode.isUniqueInteger()) { 316 // Wrap it in a block so its internally created tag is restricted in scope 317 addStatementEnclosedInBlock(switchNode); 318 } else { 319 addStatement(switchNode); 320 } 321 return switchNode; 322 } 323 324 @Override 325 public Node leaveThrowNode(final ThrowNode throwNode) { 326 return addStatement(throwNode); //ThrowNodes are always terminal, marked as such in constructor 327 } 328 329 @SuppressWarnings("unchecked") 330 private static <T extends Node> T ensureUniqueNamesIn(final T node) { 331 return (T)node.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) { 332 @Override 333 public Node leaveFunctionNode(final FunctionNode functionNode) { 334 final String name = functionNode.getName(); 335 return functionNode.setName(lc, lc.getCurrentFunction().uniqueName(name)); 336 } 337 338 @Override 339 public Node leaveDefault(final Node labelledNode) { 340 return labelledNode.ensureUniqueLabels(lc); 341 } 342 }); 343 } 344 345 private static Block createFinallyBlock(final Block finallyBody) { 346 final List<Statement> newStatements = new ArrayList<>(); 347 for (final Statement statement : finallyBody.getStatements()) { 348 newStatements.add(statement); 349 if (statement.hasTerminalFlags()) { 350 break; 351 } 352 } 353 return finallyBody.setStatements(null, newStatements); 354 } 355 356 private Block catchAllBlock(final TryNode tryNode) { 357 final int lineNumber = tryNode.getLineNumber(); 358 final long token = tryNode.getToken(); 359 final int finish = tryNode.getFinish(); 360 361 final IdentNode exception = new IdentNode(token, finish, lc.getCurrentFunction().uniqueName(CompilerConstants.EXCEPTION_PREFIX.symbolName())); 362 363 final Block catchBody = new Block(token, finish, new ThrowNode(lineNumber, token, finish, new IdentNode(exception), true)); 364 assert catchBody.isTerminal(); //ends with throw, so terminal 365 366 final CatchNode catchAllNode = new CatchNode(lineNumber, token, finish, new IdentNode(exception), null, catchBody, true); 367 final Block catchAllBlock = new Block(token, finish, catchAllNode); 368 369 //catchallblock -> catchallnode (catchnode) -> exception -> throw 370 371 return (Block)catchAllBlock.accept(this); //not accepted. has to be accepted by lower 372 } 373 374 private IdentNode compilerConstant(final CompilerConstants cc) { 375 final FunctionNode functionNode = lc.getCurrentFunction(); 376 return new IdentNode(functionNode.getToken(), functionNode.getFinish(), cc.symbolName()); 377 } 378 379 private static boolean isTerminalFinally(final Block finallyBlock) { 380 return finallyBlock.getLastStatement().hasTerminalFlags(); 381 } 382 383 /** 384 * Splice finally code into all endpoints of a trynode 385 * @param tryNode the try node 386 * @param rethrow the rethrowing throw nodes from the synthetic catch block 387 * @param finallyBody the code in the original finally block 388 * @return new try node after splicing finally code (same if nop) 389 */ 390 private TryNode spliceFinally(final TryNode tryNode, final ThrowNode rethrow, final Block finallyBody) { 391 assert tryNode.getFinallyBody() == null; 392 393 final Block finallyBlock = createFinallyBlock(finallyBody); 394 final ArrayList<Block> inlinedFinallies = new ArrayList<>(); 395 final FunctionNode fn = lc.getCurrentFunction(); 396 final TryNode newTryNode = (TryNode)tryNode.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) { 397 398 @Override 399 public boolean enterFunctionNode(final FunctionNode functionNode) { 400 // do not enter function nodes - finally code should not be inlined into them 401 return false; 402 } 403 404 @Override 405 public Node leaveThrowNode(final ThrowNode throwNode) { 406 if (rethrow == throwNode) { 407 return new BlockStatement(prependFinally(finallyBlock, throwNode)); 408 } 409 return throwNode; 410 } 411 412 @Override 413 public Node leaveBreakNode(final BreakNode breakNode) { 414 return leaveJumpStatement(breakNode); 415 } 416 417 @Override 418 public Node leaveContinueNode(final ContinueNode continueNode) { 419 return leaveJumpStatement(continueNode); 420 } 421 422 private Node leaveJumpStatement(final JumpStatement jump) { 423 // NOTE: leaveJumpToInlinedFinally deliberately does not delegate to this method, only break and 424 // continue are edited. JTIF nodes should not be changed, rather the surroundings of 425 // break/continue/return that were moved into the inlined finally block itself will be changed. 426 427 // If this visitor's lc doesn't find the target of the jump, it means it's external to the try block. 428 if (jump.getTarget(lc) == null) { 429 return createJumpToInlinedFinally(fn, inlinedFinallies, prependFinally(finallyBlock, jump)); 430 } 431 return jump; 432 } 433 434 @Override 435 public Node leaveReturnNode(final ReturnNode returnNode) { 436 final Expression expr = returnNode.getExpression(); 437 if (isTerminalFinally(finallyBlock)) { 438 if (expr == null) { 439 // Terminal finally; no return expression. 440 return createJumpToInlinedFinally(fn, inlinedFinallies, ensureUniqueNamesIn(finallyBlock)); 441 } 442 // Terminal finally; has a return expression. 443 final List<Statement> newStatements = new ArrayList<>(2); 444 final int retLineNumber = returnNode.getLineNumber(); 445 final long retToken = returnNode.getToken(); 446 // Expression is evaluated for side effects. 447 newStatements.add(new ExpressionStatement(retLineNumber, retToken, returnNode.getFinish(), expr)); 448 newStatements.add(createJumpToInlinedFinally(fn, inlinedFinallies, ensureUniqueNamesIn(finallyBlock))); 449 return new BlockStatement(retLineNumber, new Block(retToken, finallyBlock.getFinish(), newStatements)); 450 } else if (expr == null || expr instanceof PrimitiveLiteralNode<?> || (expr instanceof IdentNode && RETURN.symbolName().equals(((IdentNode)expr).getName()))) { 451 // Nonterminal finally; no return expression, or returns a primitive literal, or returns :return. 452 // Just move the return expression into the finally block. 453 return createJumpToInlinedFinally(fn, inlinedFinallies, prependFinally(finallyBlock, returnNode)); 454 } else { 455 // We need to evaluate the result of the return in case it is complex while still in the try block, 456 // store it in :return, and return it afterwards. 457 final List<Statement> newStatements = new ArrayList<>(); 458 final int retLineNumber = returnNode.getLineNumber(); 459 final long retToken = returnNode.getToken(); 460 final int retFinish = returnNode.getFinish(); 461 final Expression resultNode = new IdentNode(expr.getToken(), expr.getFinish(), RETURN.symbolName()); 462 // ":return = <expr>;" 463 newStatements.add(new ExpressionStatement(retLineNumber, retToken, retFinish, new BinaryNode(Token.recast(returnNode.getToken(), TokenType.ASSIGN), resultNode, expr))); 464 // inline finally and end it with "return :return;" 465 newStatements.add(createJumpToInlinedFinally(fn, inlinedFinallies, prependFinally(finallyBlock, returnNode.setExpression(resultNode)))); 466 return new BlockStatement(retLineNumber, new Block(retToken, retFinish, newStatements)); 467 } 468 } 469 }); 470 addStatement(inlinedFinallies.isEmpty() ? newTryNode : newTryNode.setInlinedFinallies(lc, inlinedFinallies)); 471 // TODO: if finallyStatement is terminal, we could just have sites of inlined finallies jump here. 472 addStatement(new BlockStatement(finallyBlock)); 473 474 return newTryNode; 475 } 476 477 private static JumpToInlinedFinally createJumpToInlinedFinally(final FunctionNode fn, final List<Block> inlinedFinallies, final Block finallyBlock) { 478 final String labelName = fn.uniqueName(":finally"); 479 final long token = finallyBlock.getToken(); 480 final int finish = finallyBlock.getFinish(); 481 inlinedFinallies.add(new Block(token, finish, new LabelNode(finallyBlock.getFirstStatementLineNumber(), 482 token, finish, labelName, finallyBlock))); 483 return new JumpToInlinedFinally(labelName); 484 } 485 486 private static Block prependFinally(final Block finallyBlock, final Statement statement) { 487 final Block inlinedFinally = ensureUniqueNamesIn(finallyBlock); 488 if (isTerminalFinally(finallyBlock)) { 489 return inlinedFinally; 490 } 491 final List<Statement> stmts = inlinedFinally.getStatements(); 492 final List<Statement> newStmts = new ArrayList<>(stmts.size() + 1); 493 newStmts.addAll(stmts); 494 newStmts.add(statement); 495 return new Block(inlinedFinally.getToken(), statement.getFinish(), newStmts); 496 } 497 498 @Override 499 public Node leaveTryNode(final TryNode tryNode) { 500 final Block finallyBody = tryNode.getFinallyBody(); 501 TryNode newTryNode = tryNode.setFinallyBody(lc, null); 502 503 // No finally or empty finally 504 if (finallyBody == null || finallyBody.getStatementCount() == 0) { 505 final List<CatchNode> catches = newTryNode.getCatches(); 506 if (catches == null || catches.isEmpty()) { 507 // A completely degenerate try block: empty finally, no catches. Replace it with try body. 508 return addStatement(new BlockStatement(tryNode.getBody())); 509 } 510 return addStatement(ensureUnconditionalCatch(newTryNode)); 511 } 512 513 /* 514 * create a new trynode 515 * if we have catches: 516 * 517 * try try 518 * x try 519 * catch x 520 * y catch 521 * finally z y 522 * catchall 523 * rethrow 524 * 525 * otheriwse 526 * 527 * try try 528 * x x 529 * finally catchall 530 * y rethrow 531 * 532 * 533 * now splice in finally code wherever needed 534 * 535 */ 536 final Block catchAll = catchAllBlock(tryNode); 537 538 final List<ThrowNode> rethrows = new ArrayList<>(1); 539 catchAll.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) { 540 @Override 541 public boolean enterThrowNode(final ThrowNode throwNode) { 542 rethrows.add(throwNode); 543 return true; 544 } 545 }); 546 assert rethrows.size() == 1; 547 548 if (!tryNode.getCatchBlocks().isEmpty()) { 549 final Block outerBody = new Block(newTryNode.getToken(), newTryNode.getFinish(), ensureUnconditionalCatch(newTryNode)); 550 newTryNode = newTryNode.setBody(lc, outerBody).setCatchBlocks(lc, null); 551 } 552 553 newTryNode = newTryNode.setCatchBlocks(lc, Arrays.asList(catchAll)); 554 555 /* 556 * Now that the transform is done, we have to go into the try and splice 557 * the finally block in front of any statement that is outside the try 558 */ 559 return (TryNode)lc.replace(tryNode, spliceFinally(newTryNode, rethrows.get(0), finallyBody)); 560 } 561 562 private TryNode ensureUnconditionalCatch(final TryNode tryNode) { 563 final List<CatchNode> catches = tryNode.getCatches(); 564 if(catches == null || catches.isEmpty() || catches.get(catches.size() - 1).getExceptionCondition() == null) { 565 return tryNode; 566 } 567 // If the last catch block is conditional, add an unconditional rethrow block 568 final List<Block> newCatchBlocks = new ArrayList<>(tryNode.getCatchBlocks()); 569 570 newCatchBlocks.add(catchAllBlock(tryNode)); 571 return tryNode.setCatchBlocks(lc, newCatchBlocks); 572 } 573 574 @Override 575 public Node leaveVarNode(final VarNode varNode) { 576 addStatement(varNode); 577 if (varNode.getFlag(VarNode.IS_LAST_FUNCTION_DECLARATION) && lc.getCurrentFunction().isProgram()) { 578 new ExpressionStatement(varNode.getLineNumber(), varNode.getToken(), varNode.getFinish(), new IdentNode(varNode.getName())).accept(this); 579 } 580 return varNode; 581 } 582 583 @Override 584 public Node leaveWhileNode(final WhileNode whileNode) { 585 final Expression test = whileNode.getTest(); 586 final Block body = whileNode.getBody(); 587 588 if (isAlwaysTrue(test)) { 589 //turn it into a for node without a test. 590 final ForNode forNode = (ForNode)new ForNode(whileNode.getLineNumber(), whileNode.getToken(), whileNode.getFinish(), body, 0).accept(this); 591 lc.replace(whileNode, forNode); 592 return forNode; 593 } 594 595 return addStatement(checkEscape(whileNode)); 596 } 597 598 @Override 599 public Node leaveWithNode(final WithNode withNode) { 600 return addStatement(withNode); 601 } 602 603 /** 604 * Given a function node that is a callee in a CallNode, replace it with 605 * the appropriate marker function. This is used by {@link CodeGenerator} 606 * for fast scope calls 607 * 608 * @param function function called by a CallNode 609 * @return transformed node to marker function or identity if not ident/access/indexnode 610 */ 611 private static Expression markerFunction(final Expression function) { 612 if (function instanceof IdentNode) { 613 return ((IdentNode)function).setIsFunction(); 614 } else if (function instanceof BaseNode) { 615 return ((BaseNode)function).setIsFunction(); 616 } 617 return function; 618 } 619 620 /** 621 * Calculate a synthetic eval location for a node for the stacktrace, for example src#17<eval> 622 * @param node a node 623 * @return eval location 624 */ 625 private String evalLocation(final IdentNode node) { 626 final Source source = lc.getCurrentFunction().getSource(); 627 final int pos = node.position(); 628 return new StringBuilder(). 629 append(source.getName()). 630 append('#'). 631 append(source.getLine(pos)). 632 append(':'). 633 append(source.getColumn(pos)). 634 append("<eval>"). 635 toString(); 636 } 637 638 /** 639 * Check whether a call node may be a call to eval. In that case we 640 * clone the args in order to create the following construct in 641 * {@link CodeGenerator} 642 * 643 * <pre> 644 * if (calledFuntion == buildInEval) { 645 * eval(cloned arg); 646 * } else { 647 * cloned arg; 648 * } 649 * </pre> 650 * 651 * @param callNode call node to check if it's an eval 652 */ 653 private CallNode checkEval(final CallNode callNode) { 654 if (callNode.getFunction() instanceof IdentNode) { 655 656 final List<Expression> args = callNode.getArgs(); 657 final IdentNode callee = (IdentNode)callNode.getFunction(); 658 659 // 'eval' call with at least one argument 660 if (args.size() >= 1 && EVAL.symbolName().equals(callee.getName())) { 661 final List<Expression> evalArgs = new ArrayList<>(args.size()); 662 for(final Expression arg: args) { 663 evalArgs.add((Expression)ensureUniqueNamesIn(arg).accept(this)); 664 } 665 return callNode.setEvalArgs(new CallNode.EvalArgs(evalArgs, evalLocation(callee))); 666 } 667 } 668 669 return callNode; 670 } 671 672 /** 673 * Helper that given a loop body makes sure that it is not terminal if it 674 * has a continue that leads to the loop header or to outer loops' loop 675 * headers. This means that, even if the body ends with a terminal 676 * statement, we cannot tag it as terminal 677 * 678 * @param loopBody the loop body to check 679 * @return true if control flow may escape the loop 680 */ 681 private static boolean controlFlowEscapes(final LexicalContext lex, final Block loopBody) { 682 final List<Node> escapes = new ArrayList<>(); 683 684 loopBody.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) { 685 @Override 686 public Node leaveBreakNode(final BreakNode node) { 687 escapes.add(node); 688 return node; 689 } 690 691 @Override 692 public Node leaveContinueNode(final ContinueNode node) { 693 // all inner loops have been popped. 694 if (lex.contains(node.getTarget(lex))) { 695 escapes.add(node); 696 } 697 return node; 698 } 699 }); 700 701 return !escapes.isEmpty(); 702 } 703 704 @SuppressWarnings("unchecked") 705 private <T extends LoopNode> T checkEscape(final T loopNode) { 706 final boolean escapes = controlFlowEscapes(lc, loopNode.getBody()); 707 if (escapes) { 708 return (T)loopNode. 709 setBody(lc, loopNode.getBody().setIsTerminal(lc, false)). 710 setControlFlowEscapes(lc, escapes); 711 } 712 return loopNode; 713 } 714 715 716 private Node addStatement(final Statement statement) { 717 lc.appendStatement(statement); 718 return statement; 719 } 720 721 private void addStatementEnclosedInBlock(final Statement stmt) { 722 BlockStatement b = BlockStatement.createReplacement(stmt, Collections.<Statement>singletonList(stmt)); 723 if(stmt.isTerminal()) { 724 b = b.setBlock(b.getBlock().setIsTerminal(null, true)); 725 } 726 addStatement(b); 727 } 728 729 /** 730 * An internal expression has a symbol that is tagged internal. Check if 731 * this is such a node 732 * 733 * @param expression expression to check for internal symbol 734 * @return true if internal, false otherwise 735 */ 736 private static boolean isInternalExpression(final Expression expression) { 737 if (!(expression instanceof IdentNode)) { 738 return false; 739 } 740 final Symbol symbol = ((IdentNode)expression).getSymbol(); 741 return symbol != null && symbol.isInternal(); 742 } 743 744 /** 745 * Is this an assignment to the special variable that hosts scripting eval 746 * results, i.e. __return__? 747 * 748 * @param expression expression to check whether it is $evalresult = X 749 * @return true if an assignment to eval result, false otherwise 750 */ 751 private static boolean isEvalResultAssignment(final Node expression) { 752 final Node e = expression; 753 if (e instanceof BinaryNode) { 754 final Node lhs = ((BinaryNode)e).lhs(); 755 if (lhs instanceof IdentNode) { 756 return ((IdentNode)lhs).getName().equals(RETURN.symbolName()); 757 } 758 } 759 return false; 760 } 761} 762