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 
  26 package jdk.nashorn.internal.runtime.arrays;
  27 
  28 import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;
  29 

  30 import jdk.nashorn.internal.runtime.Context;
  31 import jdk.nashorn.internal.runtime.ScriptFunction;
  32 import jdk.nashorn.internal.runtime.ScriptRuntime;
  33 
  34 /**
  35  * Helper class for the various map/apply functions in {@link jdk.nashorn.internal.objects.NativeArray}.
  36  * @param <T> element type of results from application callback
  37  */
  38 public abstract class IteratorAction<T> {
  39     /** Self object */
  40     protected final Object self;
  41 
  42     /** This for the callback invocation */
  43     protected Object thisArg;
  44 
  45     /** Callback function to be applied to elements */
  46     protected final Object callbackfn;
  47 
  48     /** Result of array iteration */
  49     protected T result;
  50 
  51     /** Current array index of iterator */
  52     protected long index;
  53 
  54     /** Iterator object */
  55     private final ArrayLikeIterator<Object> iter;
  56 
  57     /**
  58      * Constructor
  59      *
  60      * @param self          self reference to array object
  61      * @param callbackfn    callback function for each element
  62      * @param thisArg       the reference
  63      * @param initialResult result accumulator initialization
  64      */
  65     public IteratorAction(final Object self, final Object callbackfn, final Object thisArg, final T initialResult) {
  66         this(self, callbackfn, thisArg, initialResult, ArrayLikeIterator.arrayLikeIterator(self));
  67     }
  68 
  69     /**
  70      * Constructor
  71      *
  72      * @param self          self reference to array object
  73      * @param callbackfn    callback function for each element
  74      * @param thisArg       the reference
  75      * @param initialResult result accumulator initialization
  76      * @param iter          custom element iterator
  77      */
  78     public IteratorAction(final Object self, final Object callbackfn, final Object thisArg, final T initialResult, final ArrayLikeIterator<Object> iter) {
  79         this.self       = self;
  80         this.callbackfn = callbackfn;
  81         this.result     = initialResult;
  82         this.iter       = iter;
  83         this.thisArg    = thisArg;
  84     }
  85 
  86     /**
  87      * An action to be performed once at the start of the apply loop
  88      * @param iterator array element iterator
  89      */
  90     protected void applyLoopBegin(final ArrayLikeIterator<Object> iterator) {
  91         //empty
  92     }
  93 
  94     /**
  95      * Apply action main loop.
  96      * @return result of apply
  97      */
  98     public final T apply() {
  99         if (!(callbackfn instanceof ScriptFunction)) {






 100             throw typeError("not.a.function", ScriptRuntime.safeToString(callbackfn));
 101         }
 102         final ScriptFunction func = ((ScriptFunction)callbackfn);
 103         // for non-strict callback, need to translate undefined thisArg to be global object
 104         thisArg = (thisArg == ScriptRuntime.UNDEFINED && !func.isStrict()) ? Context.getGlobal() : thisArg;
 105 
 106         applyLoopBegin(iter);
 107         final boolean reverse = iter.isReverse();
 108         while (iter.hasNext()) {
 109 
 110             final Object val = iter.next();
 111             index = iter.nextIndex() + (reverse ? 1 : -1);
 112 
 113             try {
 114                 if (!forEach(val, index)) {
 115                     return result;
 116                 }
 117             } catch (final RuntimeException | Error e) {
 118                 throw e;
 119             } catch (final Throwable t) {
 120                 throw new RuntimeException(t);
 121             }
 122         }
 123 
 124         return result;
 125     }
 126 
 127     /**
 128      * For each callback
 129      *
 130      * @param val value
 131      * @param i   position of value
 132      *
 133      * @return true if callback invocation return true
 134      *
 135      * @throws Throwable if invocation throws an exception/error
 136      */
 137     protected abstract boolean forEach(final Object val, final long i) throws Throwable;
 138 
 139 }
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