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1 /////////////////////////////////////////////////////////////////////////////// |
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2 // The FeedUpdateBroker class implements a simple RSS fetcher and parser. |
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3 // Adapted from WRTKit RssReader example |
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4 |
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5 // Constructor. |
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6 function FeedUpdateBroker() { |
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7 this.httpReq = null; |
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8 this.feedAddress = null; |
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9 this.callback = null; |
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10 this.ignoreContent = false; |
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11 this.cancelled = false; |
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12 this.responseParser = this.handleRssResponse; |
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13 this.startFromItem = 0; |
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14 this.maxItems = 0; |
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15 } |
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16 |
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17 // Fetches a feed from the specified URL and calls the callback when the feed |
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18 // has been fetched and parsed, or if the process results in an error. |
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19 FeedUpdateBroker.prototype.doFetchFeed = function(){ |
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20 // create new XML HTTP request |
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21 this.httpReq = new Ajax(); |
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22 |
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23 // set callback |
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24 var self = this; |
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25 this.httpReq.onreadystatechange = function() { self.readyStateChanged(); }; |
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26 |
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27 var fullURL = this.feedAddress; |
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28 if (fullURL.indexOf("?") == -1) { |
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29 fullURL += "?"; |
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30 } else { |
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31 fullURL += "&"; |
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32 } |
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33 fullURL += "nocache=" + (new Date().getTime()); |
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34 |
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35 // initiate the request |
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36 this.httpReq.open("GET", fullURL, true); |
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37 this.httpReq.send(null); |
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38 } |
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39 |
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40 // has been fetched and parsed, or if the process results in an error. |
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41 FeedUpdateBroker.prototype.fetchFeed = function(feedURL, callback) { |
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42 // remember callback |
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43 this.callback = callback; |
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44 this.feedAddress = feedURL; |
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45 this.doFetchFeed(); |
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46 } |
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47 |
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48 // Callback for ready-state change events in the XML HTTP request. |
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49 FeedUpdateBroker.prototype.readyStateChanged = function() { |
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50 // complete request? |
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51 if (this.httpReq.readyState == 4) { |
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52 // attempt to get response status |
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53 var responseStatus = null; |
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54 try { |
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55 responseStatus = this.httpReq.status; |
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56 } catch (noStatusException) {} |
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57 |
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58 // are we being prompted for login? |
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59 var text = this.httpReq.responseText; |
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60 if ( isLoginPrompt (text) ) { |
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61 var self = this; |
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62 login(function(){self.doFetchFeed();}); |
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63 return; |
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64 } |
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65 |
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66 // handle the response and call the registered callback object |
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67 var response = this.httpReq.responseXML; |
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68 if (response == null) { |
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69 // if the content type is not set correctly, we get the response as text |
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70 var xmlparser = new DOMParser(); |
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71 response = xmlparser.parseFromString(this.httpReq.responseText, "text/xml"); |
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72 } |
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73 this.callback.feedUpdateCompleted(this.handleResponse(responseStatus, response)); |
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74 } |
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75 } |
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76 |
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77 // Handles a completed response. |
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78 FeedUpdateBroker.prototype.handleResponse = function(responseStatus, xmlDoc){ |
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79 if (this.responseParser == null) { |
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80 return this.handleRssResponse(responseStatus, xmlDoc); |
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81 } |
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82 else { |
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83 return this.responseParser.call(this, this, responseStatus, xmlDoc); |
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84 } |
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85 } |
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86 |
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87 |
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88 FeedUpdateBroker.prototype.handleRssResponse = function(broker, responseStatus, xmlDoc){ |
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89 if ( this.cancelled ) { |
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90 return { status: "cancelled" }; |
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91 } |
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92 if (responseStatus == 200 && xmlDoc != null) { |
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93 // node ref for iterating |
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94 var node; |
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95 |
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96 // get last modified time - default to current time |
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97 var lastModified = new Date().getTime(); |
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98 var channelElements = xmlDoc.getElementsByTagName("channel"); |
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99 if (channelElements.length > 0) { |
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100 node = channelElements[0].firstChild; |
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101 while (node != null) { |
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102 if (node.nodeType == Node.ELEMENT_NODE) { |
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103 if (node.nodeName == "pubDate" || |
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104 node.nodeName == "lastBuildDate" || |
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105 node.nodeName == "dc:date") { |
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106 lastModified = getTextOfNode(node); |
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107 break; |
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108 } |
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109 } |
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110 node = node.nextSibling; |
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111 } |
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112 } |
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113 |
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114 // init feed items array |
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115 var items = []; |
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116 |
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117 // we got the feed XML so now we'll parse it |
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118 var itemElements = xmlDoc.getElementsByTagName("item"); |
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119 |
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120 for (var i = this.startFromItem; i < itemElements.length; i++) { |
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121 if ( this.maxItems > 0 && this.maxItems < i ) { |
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122 break; |
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123 } |
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124 // iterate through child nodes of this item and gather |
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125 // all the data we need for a feed item |
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126 var title = null; |
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127 var date = null; |
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128 var description = null; |
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129 var url = null; |
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130 var author = null; |
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131 node = itemElements[i].firstChild; |
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132 while (node != null) { |
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133 if (node.nodeType == Node.ELEMENT_NODE) { |
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134 if (node.nodeName == "title") { |
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135 // item title |
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136 title = getTextOfNode(node); |
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137 } else if (node.nodeName == "pubDate" || node.nodeName == "dc:date") { |
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138 // item publishing date |
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139 date = getTextOfNode(node); |
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140 } else if (node.nodeName == "description" && !this.ignoreContent ) { |
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141 // item description |
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142 description = getTextOfNode(node); |
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143 } else if (node.nodeName == "link") { |
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144 // link URL |
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145 url = getTextOfNode(node); |
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146 } else if (node.nodeName == "dc:creator" ) { |
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147 author = getTextOfNode(node); |
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148 } |
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149 } |
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150 node = node.nextSibling; |
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151 } |
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152 |
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153 // create the item and add to the items array |
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154 items.push({ title: title, date: date, description: description, url: url, author: author }); |
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155 } |
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156 |
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157 // update was completed successfully |
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158 return { status: "ok", lastModified: lastModified, items: items }; |
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159 } else { |
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160 // update failed |
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161 return { status: "error" }; |
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162 } |
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163 } |
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164 |
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165 // Returns the text of a node. |
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166 function getTextOfNode(node) { |
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167 var buf = ""; |
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168 |
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169 // iterate through all child elements and collect all text to the buffer |
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170 var child = node.firstChild; |
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171 while (child != null) { |
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172 if (child.nodeType == Node.TEXT_NODE || child.nodeType == Node.CDATA_SECTION_NODE) { |
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173 // append text to buffer |
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174 if (buf != "") { |
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175 buf += " "; |
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176 } |
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177 buf += child.nodeValue; |
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178 } |
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179 child = child.nextSibling; |
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180 } |
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181 |
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182 // strip all tags from the buffer |
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183 var strippedBuf = ""; |
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184 var textStartPos = -1; |
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185 var tagBalance = 0; |
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186 |
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187 // iterate through the text and append all text to the stripped buffer |
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188 // that is at a tag balance of 0 |
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189 for (pos = 0; pos < buf.length; pos++) { |
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190 var c = buf.charAt(pos); |
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191 if (c == '<') { |
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192 // entering a tag |
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193 if (tagBalance == 0 && textStartPos != -1) { |
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194 // everything up to here was valid text |
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195 strippedBuf += buf.substring(textStartPos, pos); |
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196 textStartPos = -1; |
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197 } |
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198 tagBalance++; |
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199 } else if (c == '>') { |
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200 // leaving a tag |
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201 tagBalance--; |
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202 textStartPos = -1; |
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203 } else if (tagBalance == 0 && textStartPos == -1) { |
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204 // first char of text |
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205 textStartPos = pos; |
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206 } |
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207 } |
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208 |
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209 // add remaining text - if any |
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210 if (tagBalance == 0 && textStartPos != -1) { |
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211 strippedBuf += buf.substring(textStartPos, pos); |
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212 } |
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213 |
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214 return strippedBuf; |
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215 } |
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216 |
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217 FeedUpdateBroker.prototype.cancel = function() { |
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218 this.cancelled = true; |
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219 this.httpReq.abort(); |
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220 } |