584 lines
17 KiB
PHP
584 lines
17 KiB
PHP
<?php
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/**
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* An alternative abstract class for bridges utilizing XPath expressions
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*
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* This class is meant as an alternative base class for bridge implementations.
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* It offers preliminary functionality for generating feeds based on XPath
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* expressions.
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* As a minimum, extending classes should define XPath expressions pointing
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* to the feed items contents in the class constants below. In case there is
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* more manual fine tuning required, it offers a bunch of methods which can
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* be overridden, for example in order to specify formatting of field values
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* or more flexible definition of dynamic XPath expressions.
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*
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* This class extends {@see BridgeAbstract}, which means it incorporates and
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* extends all of its functionality.
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**/
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abstract class XPathAbstract extends BridgeAbstract {
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/**
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* Source Web page URL (should provide either HTML or XML content)
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* You can specify any website URL which serves data suited for display in RSS feeds
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* (for example a news blog).
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*
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* Use {@see XPathAbstract::getSourceUrl()} to read this parameter
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*/
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const FEED_SOURCE_URL = '';
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/**
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* XPath expression for extracting the feed title from the source page.
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* If this is left blank or does not provide any data {@see BridgeAbstract::getName()}
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* is used instead as the feed's title.
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*
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* Use {@see XPathAbstract::getExpressionTitle()} to read this parameter
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*/
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const XPATH_EXPRESSION_FEED_TITLE = './/title';
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/**
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* XPath expression for extracting the feed favicon URL from the source page.
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* If this is left blank or does not provide any data {@see BridgeAbstract::getIcon()}
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* is used instead as the feed's favicon URL.
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*
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* Use {@see XPathAbstract::getExpressionIcon()} to read this parameter
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*/
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const XPATH_EXPRESSION_FEED_ICON = './/link[@rel="icon"]/@href';
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/**
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* XPath expression for extracting the feed items from the source page
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* Enter an XPath expression matching a list of dom nodes, each node containing one
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* feed article item in total (usually a surrounding <div> or <span> tag). This will
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* be the context nodes for all of the following expressions. This expression usually
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* starts with a single forward slash.
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*
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* Use {@see XPathAbstract::getExpressionItem()} to read this parameter
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*/
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const XPATH_EXPRESSION_ITEM = '';
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/**
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* XPath expression for extracting an item title from the item context
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* This expression should match a node contained within each article item node
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* containing the article headline. It should start with a dot followed by two
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* forward slashes, referring to any descendant nodes of the article item node.
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*
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* Use {@see XPathAbstract::getExpressionItemTitle()} to read this parameter
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*/
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const XPATH_EXPRESSION_ITEM_TITLE = '';
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/**
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* XPath expression for extracting an item's content from the item context
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* This expression should match a node contained within each article item node
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* containing the article content or description. It should start with a dot
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* followed by two forward slashes, referring to any descendant nodes of the
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* article item node.
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*
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* Use {@see XPathAbstract::getExpressionItemContent()} to read this parameter
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*/
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const XPATH_EXPRESSION_ITEM_CONTENT = '';
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/**
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* XPath expression for extracting an item link from the item context
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* This expression should match a node's attribute containing the article URL
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* (usually the href attribute of an <a> tag). It should start with a dot
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* followed by two forward slashes, referring to any descendant nodes of
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* the article item node. Attributes can be selected by prepending an @ char
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* before the attributes name.
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*
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* Use {@see XPathAbstract::getExpressionItemUri()} to read this parameter
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*/
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const XPATH_EXPRESSION_ITEM_URI = '';
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/**
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* XPath expression for extracting an item author from the item context
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* This expression should match a node contained within each article item
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* node containing the article author's name. It should start with a dot
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* followed by two forward slashes, referring to any descendant nodes of
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* the article item node.
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*
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* Use {@see XPathAbstract::getExpressionItemAuthor()} to read this parameter
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*/
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const XPATH_EXPRESSION_ITEM_AUTHOR = '';
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/**
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* XPath expression for extracting an item timestamp from the item context
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* This expression should match a node or node's attribute containing the
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* article timestamp or date (parsable by PHP's strtotime function). It
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* should start with a dot followed by two forward slashes, referring to
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* any descendant nodes of the article item node. Attributes can be
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* selected by prepending an @ char before the attributes name.
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*
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* Use {@see XPathAbstract::getExpressionItemTimestamp()} to read this parameter
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*/
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const XPATH_EXPRESSION_ITEM_TIMESTAMP = '';
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/**
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* XPath expression for extracting item enclosures (media content like
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* images or movies) from the item context
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* This expression should match a node's attribute containing an article
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* image URL (usually the src attribute of an <img> tag or a style
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* attribute). It should start with a dot followed by two forward slashes,
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* referring to any descendant nodes of the article item node. Attributes
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* can be selected by prepending an @ char before the attributes name.
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*
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* Use {@see XPathAbstract::getExpressionItemEnclosures()} to read this parameter
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*/
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const XPATH_EXPRESSION_ITEM_ENCLOSURES = '';
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/**
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* XPath expression for extracting an item category from the item context
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* This expression should match a node or node's attribute contained
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* within each article item node containing the article category. This
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* could be inside <div> or <span> tags or sometimes be hidden
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* in a data attribute. It should start with a dot followed by two
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* forward slashes, referring to any descendant nodes of the article
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* item node. Attributes can be selected by prepending an @ char
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* before the attributes name.
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*
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* Use {@see XPathAbstract::getExpressionItemCategories()} to read this parameter
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*/
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const XPATH_EXPRESSION_ITEM_CATEGORIES = '';
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/**
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* Fix encoding
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* Set this to true for fixing feed encoding by invoking PHP's utf8_decode
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* function on all extracted texts. Try this in case you see "broken" or
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* "weird" characters in your feed where you'd normally expect umlauts
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* or any other non-ascii characters.
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*
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* Use {@see XPathAbstract::getSettingFixEncoding()} to read this parameter
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*/
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const SETTING_FIX_ENCODING = false;
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/**
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* Internal storage for resulting feed name, automatically detected
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* @var string
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*/
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private $feedName;
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/**
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* Internal storage for resulting feed name, automatically detected
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* @var string
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*/
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private $feedUri;
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/**
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* Internal storage for resulting feed favicon, automatically detected
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* @var string
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*/
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private $feedIcon;
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public function getName(){
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return $this->feedName ?: parent::getName();
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}
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public function getURI() {
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return $this->feedUri ?: parent::getURI();
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}
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public function getIcon() {
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return $this->feedIcon ?: parent::getIcon();
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}
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/**
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* Source Web page URL (should provide either HTML or XML content)
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* @return string
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*/
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protected function getSourceUrl(){
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return static::FEED_SOURCE_URL;
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}
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/**
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* XPath expression for extracting the feed title from the source page
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* @return string
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*/
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protected function getExpressionTitle(){
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return static::XPATH_EXPRESSION_FEED_TITLE;
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}
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/**
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* XPath expression for extracting the feed favicon from the source page
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* @return string
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*/
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protected function getExpressionIcon(){
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return static::XPATH_EXPRESSION_FEED_ICON;
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}
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/**
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* XPath expression for extracting the feed items from the source page
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* @return string
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*/
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protected function getExpressionItem(){
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return static::XPATH_EXPRESSION_ITEM;
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}
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/**
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* XPath expression for extracting an item title from the item context
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* @return string
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*/
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protected function getExpressionItemTitle(){
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return static::XPATH_EXPRESSION_ITEM_TITLE;
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}
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/**
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* XPath expression for extracting an item's content from the item context
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* @return string
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*/
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protected function getExpressionItemContent(){
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return static::XPATH_EXPRESSION_ITEM_CONTENT;
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}
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/**
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* XPath expression for extracting an item link from the item context
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* @return string
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*/
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protected function getExpressionItemUri(){
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return static::XPATH_EXPRESSION_ITEM_URI;
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}
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/**
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* XPath expression for extracting an item author from the item context
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* @return string
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*/
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protected function getExpressionItemAuthor(){
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return static::XPATH_EXPRESSION_ITEM_AUTHOR;
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}
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/**
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* XPath expression for extracting an item timestamp from the item context
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* @return string
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*/
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protected function getExpressionItemTimestamp(){
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return static::XPATH_EXPRESSION_ITEM_TIMESTAMP;
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}
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/**
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* XPath expression for extracting item enclosures (media content like
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* images or movies) from the item context
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* @return string
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*/
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protected function getExpressionItemEnclosures(){
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return static::XPATH_EXPRESSION_ITEM_ENCLOSURES;
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}
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/**
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* XPath expression for extracting an item category from the item context
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* @return string
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*/
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protected function getExpressionItemCategories(){
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return static::XPATH_EXPRESSION_ITEM_CATEGORIES;
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}
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/**
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* Fix encoding
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* @return string
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*/
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protected function getSettingFixEncoding(){
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return static::SETTING_FIX_ENCODING;
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}
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/**
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* Internal helper method for quickly accessing all the user defined constants
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* in derived classes
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*
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* @param $name
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* @return bool|string
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*/
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private function getParam($name){
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switch($name) {
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case 'url':
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return $this->getSourceUrl();
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case 'feed_title':
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return $this->getExpressionTitle();
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case 'feed_icon':
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return $this->getExpressionIcon();
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case 'item':
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return $this->getExpressionItem();
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case 'title':
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return $this->getExpressionItemTitle();
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case 'content':
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return $this->getExpressionItemContent();
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case 'uri':
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return $this->getExpressionItemUri();
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case 'author':
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return $this->getExpressionItemAuthor();
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case 'timestamp':
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return $this->getExpressionItemTimestamp();
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case 'enclosures':
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return $this->getExpressionItemEnclosures();
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case 'categories':
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return $this->getExpressionItemCategories();
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case 'fix_encoding':
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return $this->getSettingFixEncoding();
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}
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}
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/**
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* Should provide the source website HTML content
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* can be easily overwritten for example if special headers or auth infos are required
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* @return string
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*/
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protected function provideWebsiteContent() {
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return getContents($this->feedUri);
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}
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/**
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* Should provide the feeds title
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*
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* @param DOMXPath $xpath
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* @return string
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*/
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protected function provideFeedTitle(DOMXPath $xpath) {
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$title = $xpath->query($this->getParam('feed_title'));
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if(count($title) === 1) {
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return $this->getItemValueOrNodeValue($title);
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}
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}
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/**
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* Should provide the URL of the feed's favicon
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*
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* @param DOMXPath $xpath
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* @return string
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*/
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protected function provideFeedIcon(DOMXPath $xpath) {
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$icon = $xpath->query($this->getParam('feed_icon'));
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if(count($icon) === 1) {
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return $this->cleanImageUrl($this->getItemValueOrNodeValue($icon));
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}
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}
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/**
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* Should provide the feed's items.
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*
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* @param DOMXPath $xpath
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* @return DOMNodeList
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*/
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protected function provideFeedItems(DOMXPath $xpath) {
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return @$xpath->query($this->getParam('item'));
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}
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public function collectData() {
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$this->feedUri = $this->getParam('url');
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$webPageHtml = new DOMDocument();
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libxml_use_internal_errors(true);
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$webPageHtml->loadHTML($this->provideWebsiteContent());
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libxml_clear_errors();
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libxml_use_internal_errors(false);
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$xpath = new DOMXPath($webPageHtml);
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$this->feedName = $this->provideFeedTitle($xpath);
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$this->feedIcon = $this->provideFeedIcon($xpath);
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$entries = $this->provideFeedItems($xpath);
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if($entries === false) {
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return;
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}
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foreach ($entries as $entry) {
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$item = new \FeedItem();
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foreach(array('title', 'content', 'uri', 'author', 'timestamp', 'enclosures', 'categories') as $param) {
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$expression = $this->getParam($param);
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if('' === $expression) {
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continue;
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}
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//can be a string or DOMNodeList, depending on the expression result
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$typedResult = @$xpath->evaluate($expression, $entry);
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if ($typedResult === false || ($typedResult instanceof DOMNodeList && count($typedResult) === 0)
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|| (is_string($typedResult) && strlen(trim($typedResult)) === 0)) {
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continue;
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}
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$item->__set($param, $this->formatParamValue($param, $this->getItemValueOrNodeValue($typedResult)));
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}
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$itemId = $this->generateItemId($item);
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if(null !== $itemId) {
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$item->setUid($itemId);
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}
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$this->items[] = $item;
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}
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}
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/**
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* @param $param
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* @param $value
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* @return string|array
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*/
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protected function formatParamValue($param, $value)
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{
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$value = $this->fixEncoding($value);
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switch ($param) {
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case 'title':
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return $this->formatItemTitle($value);
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case 'content':
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return $this->formatItemContent($value);
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case 'uri':
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return $this->formatItemUri($value);
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case 'author':
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return $this->formatItemAuthor($value);
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case 'timestamp':
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return $this->formatItemTimestamp($value);
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case 'enclosures':
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return array($this->cleanImageUrl($value));
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case 'categories':
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return array($this->fixEncoding($value));
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}
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return $value;
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}
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/**
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* Formats the title of a feed item. Takes extracted raw title and returns it formatted
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* as string.
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* Can be easily overwritten for in case the value needs to be transformed into something
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* else.
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* @param string $value
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* @return string
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*/
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protected function formatItemTitle($value) {
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return $value;
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}
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/**
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* Formats the timestamp of a feed item. Takes extracted raw timestamp and returns unix
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* timestamp as integer.
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* Can be easily overwritten for example if a special format has to be expected on the
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* source website.
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* @param string $value
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* @return string
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*/
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protected function formatItemContent($value) {
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return $value;
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}
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/**
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* Formats the URI of a feed item. Takes extracted raw URI and returns it formatted
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* as string.
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* Can be easily overwritten for in case the value needs to be transformed into something
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* else.
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* @param string $value
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* @return string
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*/
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protected function formatItemUri($value) {
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if(strlen($value) === 0) {
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return '';
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}
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if(strpos($value, 'http://') === 0 || strpos($value, 'https://') === 0) {
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return $value;
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}
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return urljoin($this->feedUri, $value);
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}
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/**
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* Formats the author of a feed item. Takes extracted raw author and returns it formatted
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* as string.
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* Can be easily overwritten for in case the value needs to be transformed into something
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* else.
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* @param string $value
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* @return string
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*/
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protected function formatItemAuthor($value) {
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return $value;
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}
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/**
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* Formats the timestamp of a feed item. Takes extracted raw timestamp and returns unix
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* timestamp as integer.
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* Can be easily overwritten for example if a special format has to be expected on the
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* source website.
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* @param string $value
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* @return false|int
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*/
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protected function formatItemTimestamp($value) {
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return strtotime($value);
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}
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/**
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* Formats the enclosures of a feed item. Takes extracted raw enclosures and returns them
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* formatted as array.
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* Can be easily overwritten for in case the values need to be transformed into something
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* else.
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* @param string $value
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* @return array
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*/
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protected function formatItemEnclosures($value) {
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return array($this->cleanImageUrl($value));
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}
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/**
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* Formats the categories of a feed item. Takes extracted raw categories and returns them
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* formatted as array.
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* Can be easily overwritten for in case the values need to be transformed into something
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* else.
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* @param string $value
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* @return array
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*/
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protected function formatItemCategories($value) {
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return array($value);
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}
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/**
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* @param $imageUrl
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* @return string|void
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*/
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protected function cleanImageUrl($imageUrl)
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{
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$result = preg_match('~(?:http(?:s)?:)?[\/a-zA-Z0-9\-_\.]+\.(?:jpg|gif|png|jpeg|ico){1}~', $imageUrl, $matches);
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if(1 !== $result) {
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return;
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}
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return urljoin($this->feedUri, $matches[0]);
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}
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/**
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* @param $typedResult
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* @return string
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*/
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protected function getItemValueOrNodeValue($typedResult)
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{
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if($typedResult instanceof DOMNodeList) {
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$item = $typedResult->item(0);
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if ($item instanceof DOMElement) {
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return trim($item->nodeValue);
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} elseif ($item instanceof DOMAttr) {
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return trim($item->value);
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}
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} elseif(is_string($typedResult) && strlen($typedResult) > 0) {
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return trim($typedResult);
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}
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returnServerError('Unknown type of XPath expression result.');
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}
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/**
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|
* Fixes feed encoding by invoking PHP's utf8_decode function on extracted texts.
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* Useful in case of "broken" or "weird" characters in the feed where you'd normally
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* expect umlauts.
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*
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|
* @param $input
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* @return string
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*/
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protected function fixEncoding($input)
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|
{
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|
return $this->getParam('fix_encoding') ? utf8_decode($input) : $input;
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|
}
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|
|
/**
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|
* Allows overriding default mechanism determining items Uid's
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|
*
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|
* @param FeedItem $item
|
|
* @return string|null
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|
*/
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|
protected function generateItemId(\FeedItem $item) {
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|
return null; //auto generation
|
|
}
|
|
}
|