001    // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
002    // for details. All rights reserved. Use of this source code is governed by a
003    // BSD-style license that can be found in the LICENSE file.
004    
005    package com.google.dart.compiler.util;
006    
007    import com.google.dart.compiler.backend.js.ast.*;
008    import com.intellij.util.SmartList;
009    import org.jetbrains.annotations.NotNull;
010    import org.jetbrains.annotations.Nullable;
011    
012    import java.util.ArrayList;
013    import java.util.List;
014    
015    public final class AstUtil {
016        private AstUtil() {
017        }
018    
019        /**
020         * Returns a sequence of expressions (using the binary sequence operator).
021         *
022         * @param exprs - expressions to add to sequence
023         * @return a sequence of expressions.
024         */
025        public static JsBinaryOperation newSequence(JsExpression... exprs) {
026            if (exprs.length < 2) {
027                throw new RuntimeException("newSequence expects at least two arguments");
028            }
029            JsExpression result = exprs[exprs.length - 1];
030            for (int i = exprs.length - 2; i >= 0; i--) {
031                result = new JsBinaryOperation(JsBinaryOperator.COMMA, exprs[i], result);
032            }
033            return (JsBinaryOperation) result;
034        }
035    
036        @Nullable
037        public static <T extends JsNode> T deepCopy(@Nullable T node) {
038            if (node == null) return null;
039    
040            //noinspection unchecked
041            return (T) node.deepCopy();
042        }
043    
044        @NotNull
045        public static <T extends JsNode> List<T> deepCopy(@Nullable List<T> nodes) {
046            if (nodes == null) return new SmartList<T>();
047    
048            List<T> nodesCopy = new ArrayList<T>(nodes.size());
049            for (T node : nodes) {
050                nodesCopy.add(deepCopy(node));
051            }
052    
053            return nodesCopy;
054        }
055    }