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Updates NilChkResolver with several fixes:
- Method calls remove any assumption about the nullness of non-local variable, since the method call might modify such variables. - Improves the scope stack for better management of various control flow patterns. - Fixes handling of break, continue, return and exception throwing. - Uses the result of null checks within loop conditions. Extracts LabelRewriter from Rewriter and run this translation after NilChkResolver. Updates EnhancedForRewriter to handle loop labels. Change on 2016/02/18 by kstanger <kstanger@google.com> ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=114972263
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translator/src/main/java/com/google/devtools/j2objc/translate/LabelRewriter.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,141 @@ | ||
| /* | ||
| * Copyright 2011 Google Inc. All Rights Reserved. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
|
||
| package com.google.devtools.j2objc.translate; | ||
|
|
||
| import com.google.devtools.j2objc.ast.Block; | ||
| import com.google.devtools.j2objc.ast.BreakStatement; | ||
| import com.google.devtools.j2objc.ast.ContinueStatement; | ||
| import com.google.devtools.j2objc.ast.DoStatement; | ||
| import com.google.devtools.j2objc.ast.EmptyStatement; | ||
| import com.google.devtools.j2objc.ast.EnhancedForStatement; | ||
| import com.google.devtools.j2objc.ast.ForStatement; | ||
| import com.google.devtools.j2objc.ast.LabeledStatement; | ||
| import com.google.devtools.j2objc.ast.MethodDeclaration; | ||
| import com.google.devtools.j2objc.ast.SimpleName; | ||
| import com.google.devtools.j2objc.ast.Statement; | ||
| import com.google.devtools.j2objc.ast.TreeUtil; | ||
| import com.google.devtools.j2objc.ast.TreeVisitor; | ||
| import com.google.devtools.j2objc.ast.WhileStatement; | ||
|
|
||
| import java.util.HashMap; | ||
| import java.util.Map; | ||
|
|
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| /** | ||
| * Rewrites multiple labels that have the same name. | ||
| * Rewrites labeled break and continue statements, converting them to goto for | ||
| * the correct control flow. | ||
| * | ||
| * @author Tom Ball, Keith Stanger | ||
| */ | ||
| public class LabelRewriter extends TreeVisitor { | ||
|
|
||
| @Override | ||
| public boolean visit(MethodDeclaration node) { | ||
| // Rename any labels that have the same names; legal in Java but not C. | ||
| final Map<String, Integer> labelCounts = new HashMap<>(); | ||
| node.accept(new TreeVisitor() { | ||
| @Override | ||
| public void endVisit(LabeledStatement labeledStatement) { | ||
| final String name = labeledStatement.getLabel().getIdentifier(); | ||
| int value = labelCounts.containsKey(name) ? labelCounts.get(name) + 1 : 1; | ||
| labelCounts.put(name, value); | ||
| if (value > 1) { | ||
| final String newName = name + '_' + value; | ||
| labeledStatement.setLabel(new SimpleName(newName)); | ||
| // Update references to this label. | ||
| labeledStatement.accept(new TreeVisitor() { | ||
| @Override | ||
| public void endVisit(ContinueStatement node) { | ||
| if (node.getLabel() != null && node.getLabel().getIdentifier().equals(name)) { | ||
| node.setLabel(new SimpleName(newName)); | ||
| } | ||
| } | ||
| @Override | ||
| public void endVisit(BreakStatement node) { | ||
| if (node.getLabel() != null && node.getLabel().getIdentifier().equals(name)) { | ||
| node.setLabel(new SimpleName(newName)); | ||
| } | ||
| } | ||
| }); | ||
|
|
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| } | ||
| } | ||
| }); | ||
| return true; | ||
| } | ||
|
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| private static Statement getLoopBody(Statement s) { | ||
| if (s instanceof DoStatement) { | ||
| return ((DoStatement) s).getBody(); | ||
| } else if (s instanceof EnhancedForStatement) { | ||
| return ((EnhancedForStatement) s).getBody(); | ||
| } else if (s instanceof ForStatement) { | ||
| return ((ForStatement) s).getBody(); | ||
| } else if (s instanceof WhileStatement) { | ||
| return ((WhileStatement) s).getBody(); | ||
| } | ||
| return null; | ||
| } | ||
|
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| @Override | ||
| public void endVisit(LabeledStatement node) { | ||
| Statement loopBody = getLoopBody(node.getBody()); | ||
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| final String labelIdentifier = node.getLabel().getIdentifier(); | ||
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| final boolean[] hasContinue = new boolean[1]; | ||
| final boolean[] hasBreak = new boolean[1]; | ||
| node.accept(new TreeVisitor() { | ||
| @Override | ||
| public void endVisit(ContinueStatement node) { | ||
| if (node.getLabel() != null && node.getLabel().getIdentifier().equals(labelIdentifier)) { | ||
| hasContinue[0] = true; | ||
| node.setLabel(new SimpleName("continue_" + labelIdentifier)); | ||
| } | ||
| } | ||
| @Override | ||
| public void endVisit(BreakStatement node) { | ||
| if (node.getLabel() != null && node.getLabel().getIdentifier().equals(labelIdentifier)) { | ||
| hasBreak[0] = true; | ||
| node.setLabel(new SimpleName("break_" + labelIdentifier)); | ||
| } | ||
| } | ||
| }); | ||
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| if (hasContinue[0]) { | ||
| assert loopBody != null : "Continue statements must be inside a loop."; | ||
| LabeledStatement newLabelStmt = new LabeledStatement("continue_" + labelIdentifier); | ||
| newLabelStmt.setBody(new EmptyStatement()); | ||
| // Put the loop body into an inner block so the continue label is outside | ||
| // the scope of any variable initializations. | ||
| Block newBlock = new Block(); | ||
| loopBody.replaceWith(newBlock); | ||
| newBlock.getStatements().add(loopBody); | ||
| newBlock.getStatements().add(newLabelStmt); | ||
| } | ||
| if (hasBreak[0]) { | ||
| LabeledStatement newLabelStmt = new LabeledStatement("break_" + labelIdentifier); | ||
| newLabelStmt.setBody(new EmptyStatement()); | ||
| TreeUtil.insertAfter(node, newLabelStmt); | ||
| } | ||
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| if (hasContinue[0] || hasBreak[0]) { | ||
| // Replace this node with its statement, thus deleting the label. | ||
| node.replaceWith(TreeUtil.remove(node.getBody())); | ||
| } | ||
| } | ||
| } |
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