657 lines
21 KiB
PHP
657 lines
21 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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/**
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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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* Use raw item content
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* Whether to use the raw item content or to replace certain characters with
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* special significance in HTML by HTML entities (using the PHP function htmlspecialchars).
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*
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* Use {@see XPathAbstract::getSettingUseRawItemContent()} to read this parameter
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*/
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const SETTING_USE_RAW_ITEM_CONTENT = true;
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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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{
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return $this->feedName ?: parent::getName();
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}
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public function getURI()
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{
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return $this->feedUri ?: parent::getURI();
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}
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public function getIcon()
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{
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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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{
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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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{
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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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{
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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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{
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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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{
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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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{
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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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{
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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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{
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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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{
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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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{
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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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{
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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 bool
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*/
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protected function getSettingFixEncoding(): bool
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{
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return static::SETTING_FIX_ENCODING;
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}
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/**
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* Use raw item content
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* @return bool
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*/
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protected function getSettingUseRawItemContent(): bool
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{
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return static::SETTING_USE_RAW_ITEM_CONTENT;
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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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{
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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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case 'raw_content':
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return $this->getSettingUseRawItemContent();
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}
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}
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/**
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* Should provide the source website HTML content
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* can be easily overwritten for example if special headers or auth infos are required
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* @return string
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*/
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protected function provideWebsiteContent()
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{
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return getContents($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 $xpath)
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{
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$title = $xpath->query($this->getParam('feed_title'));
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if (count($title) === 1) {
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return $this->fixEncoding($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 $xpath)
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{
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$icon = $xpath->query($this->getParam('feed_icon'));
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if (count($icon) === 1) {
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return $this->cleanMediaUrl($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|false
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*/
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protected function provideFeedItems(\DOMXPath $xpath)
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{
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return @$xpath->query($this->getParam('item'));
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}
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public function collectData()
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{
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$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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// fix relative links
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defaultLinkTo($webPageHtml, $webPageHtml->baseURI ?? $this->feedUri);
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$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 ($entries === false) {
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// malformed
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return;
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}
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foreach ($entries as $entry) {
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$item = new FeedItem();
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foreach (['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, $entry);
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if (
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$typedResult === false || ($typedResult instanceof \DOMNodeList && count($typedResult) === 0)
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|| (is_string($typedResult) && strlen(trim($typedResult)) === 0)
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) {
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continue;
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}
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if ('categories' === $param && $typedResult instanceof \DOMNodeList) {
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$value = [];
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foreach ($typedResult as $domNode) {
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$value[] = $this->getItemValueOrNodeValue($domNode, false);
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}
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} else {
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$value = $this->getItemValueOrNodeValue($typedResult, 'content' === $param);
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}
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$item->__set($param, $this->formatParamValue($param, $value));
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}
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$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 = is_array($value) ? array_map('trim', $value) : trim($value);
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$value = is_array($value) ? array_map([$this, 'fixEncoding'], $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 $this->formatItemEnclosures($value);
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case 'categories':
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return $this->formatItemCategories($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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{
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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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{
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return $this->getParam('raw_content') ? $value : htmlspecialchars($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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{
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if (strlen($value) === 0) {
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return '';
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}
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if (
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strpos($value, 'http://') === 0
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|| strpos($value, 'https://') === 0
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) {
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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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{
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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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{
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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
|
|
* formatted as array.
|
|
* Can be easily overwritten for in case the values need to be transformed into something
|
|
* else.
|
|
* @param string $value
|
|
* @return array
|
|
*/
|
|
protected function formatItemEnclosures($value)
|
|
{
|
|
return [$this->cleanMediaUrl($value)];
|
|
}
|
|
|
|
/**
|
|
* Formats the categories of a feed item. Takes extracted raw categories and returns them
|
|
* formatted as array.
|
|
* Can be easily overwritten for in case the values need to be transformed into something
|
|
* else.
|
|
* @param string|array $value
|
|
* @return array
|
|
*/
|
|
protected function formatItemCategories($value)
|
|
{
|
|
return is_array($value) ? $value : [$value];
|
|
}
|
|
|
|
/**
|
|
* @param $mediaUrl
|
|
* @return string|void
|
|
*/
|
|
protected function cleanMediaUrl($mediaUrl)
|
|
{
|
|
$pattern = '~(?:http(?:s)?:)?[\/a-zA-Z0-9\-=_,\.\%]+\.(?:jpg|gif|png|jpeg|ico|mp3|webp){1}~i';
|
|
$result = preg_match($pattern, $mediaUrl, $matches);
|
|
if (1 !== $result) {
|
|
return;
|
|
}
|
|
return urljoin($this->feedUri, $matches[0]);
|
|
}
|
|
|
|
/**
|
|
* @param $typedResult
|
|
* @param bool $returnXML
|
|
* @param bool $escapeHtml
|
|
* @return string
|
|
* @throws Exception
|
|
*/
|
|
protected function getItemValueOrNodeValue($typedResult, $returnXML = false)
|
|
{
|
|
if ($typedResult instanceof \DOMNodeList) {
|
|
$typedResult = $typedResult->item(0);
|
|
}
|
|
|
|
if ($typedResult instanceof \DOMElement) {
|
|
return $returnXML ? ($typedResult->ownerDocument ?? $typedResult)->saveXML($typedResult) : $typedResult->nodeValue;
|
|
} elseif ($typedResult instanceof \DOMAttr) {
|
|
return $typedResult->value;
|
|
} elseif ($typedResult instanceof \DOMText) {
|
|
return $typedResult->wholeText;
|
|
} elseif (is_string($typedResult)) {
|
|
return $typedResult;
|
|
} elseif (null === $typedResult) {
|
|
return '';
|
|
}
|
|
|
|
throw new \Exception('Unknown type of XPath expression result: ' . gettype($typedResult));
|
|
}
|
|
|
|
/**
|
|
* Fixes feed encoding by invoking PHP's utf8_decode function on extracted texts.
|
|
* Useful in case of "broken" or "weird" characters in the feed where you'd normally
|
|
* expect umlauts.
|
|
*
|
|
* @param $input
|
|
* @return string
|
|
*/
|
|
protected function fixEncoding($input)
|
|
{
|
|
return $this->getParam('fix_encoding') ? utf8_decode($input) : $input;
|
|
}
|
|
|
|
/**
|
|
* Allows overriding default mechanism determining items Uid's
|
|
*
|
|
* @param FeedItem $item
|
|
* @return string|null
|
|
*/
|
|
protected function generateItemId(FeedItem $item)
|
|
{
|
|
return null;
|
|
}
|
|
}
|