src/third_party/WebKit/Source/devtools/front_end/sources/SimpleHistoryManager.js

   1 /*
   2  * Copyright (C) 2014 Google Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  *     * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *     * Redistributions in binary form must reproduce the above
  11  * copyright notice, this list of conditions and the following disclaimer
  12  * in the documentation and/or other materials provided with the
  13  * distribution.
  14  *     * Neither the name of Google Inc. nor the names of its
  15  * contributors may be used to endorse or promote products derived from
  16  * this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 /**
  32  * @interface
  33  */
  34 WebInspector.HistoryEntry = function() { }
  35
  36 WebInspector.HistoryEntry.prototype = {
  37     /**
  38      * @return {boolean}
  39      */
  40     valid: function() { },
  41
  42     reveal: function() { }
  43 };
  44
  45 /**
  46  * @constructor
  47  * @param {number} historyDepth
  48  */
  49 WebInspector.SimpleHistoryManager = function(historyDepth)
  50 {
  51     this._entries = [];
  52     this._activeEntryIndex = -1;
  53     this._coalescingReadonly = 0;
  54     this._historyDepth = historyDepth;
  55 }
  56
  57 WebInspector.SimpleHistoryManager.prototype = {
  58     readOnlyLock: function()
  59     {
  60         ++this._coalescingReadonly;
  61     },
  62
  63     releaseReadOnlyLock: function()
  64     {
  65         --this._coalescingReadonly;
  66     },
  67
  68     /**
  69      * @return {boolean}
  70      */
  71     readOnly: function()
  72     {
  73         return !!this._coalescingReadonly;
  74     },
  75
  76     /**
  77      * @param {!function(!WebInspector.HistoryEntry):boolean} filterOutCallback
  78      */
  79     filterOut: function(filterOutCallback)
  80     {
  81         if (this.readOnly())
  82             return;
  83         var filteredEntries = [];
  84         var removedBeforeActiveEntry = 0;
  85         for (var i = 0; i < this._entries.length; ++i) {
  86             if (!filterOutCallback(this._entries[i])) {
  87                 filteredEntries.push(this._entries[i]);
  88             } else if (i <= this._activeEntryIndex)
  89                 ++removedBeforeActiveEntry;
  90         }
  91         this._entries = filteredEntries;
  92         this._activeEntryIndex = Math.max(0, this._activeEntryIndex - removedBeforeActiveEntry);
  93     },
  94
  95     /**
  96      * @return {boolean}
  97      */
  98     empty: function()
  99     {
 100         return !this._entries.length;
 101     },
 102
 103     /**
 104      * @return {?WebInspector.HistoryEntry}
 105      */
 106     active: function()
 107     {
 108         return this.empty() ? null : this._entries[this._activeEntryIndex];
 109     },
 110
 111     /**
 112      * @param {!WebInspector.HistoryEntry} entry
 113      */
 114     push: function(entry)
 115     {
 116         if (this.readOnly())
 117             return;
 118         if (!this.empty())
 119             this._entries.splice(this._activeEntryIndex + 1);
 120         this._entries.push(entry);
 121         if (this._entries.length > this._historyDepth)
 122             this._entries.shift();
 123         this._activeEntryIndex = this._entries.length - 1;
 124     },
 125
 126     /**
 127      * @return {boolean}
 128      */
 129     rollback: function()
 130     {
 131         if (this.empty())
 132             return false;
 133
 134         var revealIndex = this._activeEntryIndex - 1;
 135         while (revealIndex >= 0 && !this._entries[revealIndex].valid())
 136             --revealIndex;
 137         if (revealIndex < 0)
 138             return false;
 139
 140         this.readOnlyLock();
 141         this._entries[revealIndex].reveal();
 142         this.releaseReadOnlyLock();
 143
 144         this._activeEntryIndex = revealIndex;
 145         return true;
 146     },
 147
 148     /**
 149      * @return {boolean}
 150      */
 151     rollover: function()
 152     {
 153         var revealIndex = this._activeEntryIndex + 1;
 154
 155         while (revealIndex < this._entries.length && !this._entries[revealIndex].valid())
 156             ++revealIndex;
 157         if (revealIndex >= this._entries.length)
 158             return false;
 159
 160         this.readOnlyLock();
 161         this._entries[revealIndex].reveal();
 162         this.releaseReadOnlyLock();
 163
 164         this._activeEntryIndex = revealIndex;
 165         return true;
 166     },
 167 };