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// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package com.google.dart.compiler.backend.js;

import com.google.dart.compiler.backend.js.ast.*;
import org.jetbrains.annotations.NotNull;

/**
 * Determines if a statement at the end of a block requires a semicolon.
 * 

* For example, the following statements require semicolons:
*

    *
  • if (cond);
  • *
  • while (cond);
  • *
*

* The following do not require semicolons:
*

    *
  • return 1
  • *
  • do {} while(true)
  • *
*/ public class JsRequiresSemiVisitor extends JsVisitor { private boolean needsSemicolon; private JsRequiresSemiVisitor() { } public static boolean exec(JsStatement lastStatement) { JsRequiresSemiVisitor visitor = new JsRequiresSemiVisitor(); visitor.accept(lastStatement); return visitor.needsSemicolon; } @Override public void visitFor(@NotNull JsFor x) { if (x.getBody() instanceof JsEmpty) { needsSemicolon = true; } } @Override public void visitForIn(@NotNull JsForIn x) { if (x.getBody() instanceof JsEmpty) { needsSemicolon = true; } } @Override public void visitIf(@NotNull JsIf x) { JsStatement thenStmt = x.getThenStatement(); JsStatement elseStmt = x.getElseStatement(); JsStatement toCheck = thenStmt; if (elseStmt != null) { toCheck = elseStmt; } if (toCheck instanceof JsEmpty) { needsSemicolon = true; } else { // Must recurse to determine last statement (possible if-else chain). accept(toCheck); } } @Override public void visitLabel(@NotNull JsLabel x) { if (x.getStatement() instanceof JsEmpty) { needsSemicolon = true; } } @Override public void visitWhile(@NotNull JsWhile x) { if (x.getBody() instanceof JsEmpty) { needsSemicolon = true; } } }




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