Schematron.php

<?php

namespace Milo;

use Milo\SchematronHelpers as Helpers;

use DOMDocument,
	DOMElement,
	DOMNode,
	DOMNodeList,
	DOMXPath;

use ErrorException,
	InvalidArgumentException,
	RuntimeException,
	stdClass;



/**
 * Implementation of ISO Schematron (http://www.schematron.com) validator with
 * Schematron 1.5 back compatibility.
 *
 * Class do not require XSLT extension nor additional XSLT documents. It works
 * with DOM extension only. It is a main purpose of this implementation.
 *
 * Schema validity is not checked completly, only self important things like
 * ID references and required attributes are checked. So, you should pass valid
 * schema.
 *
 * Presence of <sch:schema> is not required, so you can validate schematron in
 * Relax NG documents. But set ALLOW_MISSING_SCHEMA_ELEMENT option to enable it.
 *
 * Not implemented elements: let, diagnostic, diagnostics, dir, emph, flag, fpi,
 * icon, p, role, see, span, subject. Almost all of them are for documentation
 * purpose. Open issue on repository if you wish to be implemented.
 *
 * Example of usage:
 * <code>
 * use Milo\Schematron;
 *
 * $validator = new Schematron(Schematron::NS_ISO);
 * $validator->load('personal-schema.sch');
 *
 * $doc = new DOMDocument;
 * $doc->load($xmlDocument);
 *
 * $result = $validator->validate($doc, Schematron::RESULT_COMPLEX);
 * var_dump($result);
 * </code>
 *
 * You can choose one of four licences:
 * @licence  New BSD License
 * @licence  GNU General Public License version 2
 * @licence  GNU General Public License version 3
 * @licence  MIT
 *
 * @version  $Format:%m$
 * @see  https://github.com./milo/schematron
 *
 * @author  Miloslav Hůla (https://github.com./milo)
 */
class Schematron
{
	/** Class version */
	const
		VERSION = '1.0.0';

	/** Namespace of supported schematron versions */
	const
		NS_DETECT = NULL,
		NS_ISO = 'http://purl.oclc.org/dsdl/schematron',
		NS_1_5 = 'http://www.ascc.net/xml/schematron';

	/** Type of {@link self::validate()} return value */
	const
		RESULT_SIMPLE = 'simple',
		RESULT_COMPLEX = 'complex',
		RESULT_EXCEPTION = 'exception';

	/** Standardized validation phase */
	const
		PHASE_ALL = '#ALL',
		PHASE_DEFAULT = '#DEFAULT';

	/** Type of include URIs for {@link self::setAllowedInclude()} */
	const
		INCLUDE_URL = 0x01,
		INCLUDE_ABSOLUTE_PATH = 0x02,
		INCLUDE_RELATIVE_PATH = 0x04,
		INCLUDE_ALL = 0xFF;


	const
		/** Default options */
		DEFAULT_OPTIONS = 0x0000,

		/** Allow missing <sch:schema> (useful for Relax NG) */
		ALLOW_MISSING_SCHEMA_ELEMENT = 0x0001,

		/** Ignore <sch:include>, do not expand them */
		IGNORE_INCLUDE = 0x0002,

		/** Forbid <sch:include>, do not allow them */
		FORBID_INCLUDE = 0x0004,

		/** Skip <sch:rule> with same context as any rule before */
		SKIP_DUPLICIT_RULE_CONTEXT = 0x0008,

		/** Allow to <sch:schema> do not contain <sch::pattern> */
		ALLOW_EMPTY_SCHEMA = 0x0010,

		/** Allow to <sch:pattern> do not contain <sch:rule> */
		ALLOW_EMPTY_PATTERN = 0x0020,

		/** Allow to <sch:rule> do not contain <sch:assert> nor <sch:report> */
		ALLOW_EMPTY_RULE = 0x0040;



	/** XPath class used in this class */
	public static $xPathClass = 'Milo\SchematronXPath';

	/** @var bool  schema has been loaded */
	private $loaded = FALSE;

	/** @var int */
	private $options = self::DEFAULT_OPTIONS;

	/** @var string  schema namespace */
	private $ns;

	/** @var string|NULL  absolute path for <sch:include> relative paths */
	private $directory;

	/** @var int  LibXML options which were used for schema loading */
	private $domOptions;

	/** @var string|NULL  loaded from @schemaVersion in <sch:schema> */
	private $version;

	/** @var string|NULL  loaded from <sch:title> in <sch:schema> */
	private $title;

	/** @var string  default validation phase */
	private $defaultPhase = self::PHASE_ALL;

	/** @var int|FALSE|NULL  restrictions on <sch:include>; self::INCLUDE_* value/mask */
	private $allowedInclude = self::INCLUDE_RELATIVE_PATH;

	/** @var int  how deep can be <sch:include> */
	private $maxIncludeDepth = 10;


	/** @var SchematronXPath */
	protected $xPath;

	/** @var array[prefix => URI]  loaded from <sch:ns> */
	protected $namespaces = array();

	/** @var stdClass[]  {@see self::findPatterns()} */
	protected $patterns = array();

	/** @var array[id => value]  {@see self::findPhases()} */
	protected $phases = array();




	/**
	 * @param  string  schema namespace (self::NS_*)
	 * @throws InvalidArgumentException  when unsupported namespace passed
	 */
	public function __construct($namespace = self::NS_DETECT)
	{
		if (!in_array($namespace, array(self::NS_DETECT, self::NS_ISO, self::NS_1_5), TRUE)) {
			throw new InvalidArgumentException("Unsupported schema namespace '$namespace'.");
		}

		$this->ns = $namespace;
	}



	/**
	 * Loads schematron schema from file.
	 * @param  string  path/URI to schema file
	 * @param  int  LibXML options
	 * @throws SchematronException  when schema loading fails
	 */
	public function load($file, $options = NULL)
	{
		$this->domOptions = $options === NULL ? (LIBXML_NOENT | LIBXML_NOBLANKS) : $options;

		$doc = new DOMDocument;
		Helpers::handleXmlErrors();
		$doc->load($file, $this->domOptions);
		if ($e = Helpers::fetchXmlErrors()) {
			throw new SchematronException("Cannot load schema from file '$file'.", 0, $e);
		}

		if (is_file($file)) {
			$this->directory = dirname(realpath($file));
		}

		return $this->loadDom($doc);
	}



	/**
	 * Loads schematron schema from DOMDocument.
	 * @return self
	 * @throws SchematronException  when schema loading fails
	 * @throws RuntimeException  when <sch:include> expanding fails
	 */
	public function loadDom(DOMDocument $schema)
	{
		if ($this->ns === self::NS_DETECT) {
			$this->ns = $schema->getElementsByTagNameNS(self::NS_ISO, '*')->length
				? self::NS_ISO
				: self::NS_1_5;
		}

		$this->expandIncludes($schema);

		$this->xPath = new self::$xPathClass($schema);
		$this->xPath->registerNamespace('sch', $this->ns);

		$this->loadSchemaBasics($schema);
		$this->namespaces = $this->findNamespaces($schema);
		$this->patterns = $this->findPatterns($schema);
		if (!count($this->patterns) && !($this->options & self::ALLOW_EMPTY_SCHEMA)) {
			throw new SchematronException('None <sch:pattern> found in schema.');
		}
		$this->phases = $this->findPhases($schema);

		$this->loaded = TRUE;

		return $this;
	}



	/**
	 * Validate document over against loaded schema.
	 * @param  DOMDocument  document to validate
	 * @param  string  type of return value
	 * @param  string  validation phase
	 * @return array
	 * @throws RuntimeException  when schema has not been loaded yet
	 * @throws InvalidArgumentException  when validation $phase is not defined
	 * @throws SchematronException  when $result is RESULT_EXCEPTION and document is not valid
	 */
	public function validate(DOMDocument $doc, $result = self::RESULT_SIMPLE, $phase = self::PHASE_DEFAULT)
	{
		if (!$this->loaded) {
			throw new RuntimeException('Schema has not been loaded yet. Load it before validation.');
		}

		$xpath = new self::$xPathClass($doc);
		foreach ($this->namespaces as $prefix => $uri) {
			$xpath->registerNamespace($prefix, $uri);
		}

		if ($phase === self::PHASE_DEFAULT) {
			$phase = $this->defaultPhase;
		}

		if ($phase === self::PHASE_ALL) {
			$activePatternKeys = array_keys($this->patterns);
		} elseif (!array_key_exists($phase, $this->phases)) {
			throw new InvalidArgumentException("Validation phase '$phase' is not defined.");
		} else {
			$activePatternKeys = array_keys($this->phases[$phase]);
		}

		$return = array();
		foreach ($activePatternKeys as $patternKey) {
			$pattern = $this->patterns[$patternKey];
			foreach ($pattern->rules as $ruleKey => $rule) {
				foreach ($xpath->queryContext($rule->context, $doc) as $currentNode) {
					foreach ($rule->statements as $statement) {
						if ($statement->isAssert ^ $xpath->evaluate("boolean($statement->test)", $currentNode)) {
							$message = $this->statementToMessage($statement->node, $xpath, $currentNode);

							switch ($result) {
								case self::RESULT_EXCEPTION:
									throw new SchematronException($message);

								case self::RESULT_COMPLEX:
									if (!isset($return[$patternKey])) {
										$return[$patternKey] = (object) array(
											'title' => $pattern->title,
											'rules' => array(),
										);
									}

									if (!isset($return[$patternKey]->rules[$ruleKey])) {
										$return[$patternKey]->rules[$ruleKey] = (object) array(
											'context' => $rule->context,
											'errors' => array(),
										);
									}

									$return[$patternKey]->rules[$ruleKey]->errors[] = (object) array(
										'test' => $statement->test,
										'message' => $message,
										'path' => $currentNode->getNodePath(),
									);
									break;

								default:
									$return[] = $message;
									break;
							}
						} // test
					} // statements for context
				} // context elements
			} // rules
		} // patterns

		return $return;
	}



	/**
	 * Returns version loaded from @schemaVersion on <sch:schema>
	 * @return string|NULL
	 */
	public function getSchemaVersion()
	{
		return $this->version;
	}



	/**
	 * Returns title loaded from <sch:title> in <sch:schema>
	 * @return string|NULL
	 */
	public function getSchemaTitle()
	{
		return $this->title;
	}



	/**
	 * Set processing options, {@link self::DEFAULT_OPTIONS}
	 * @param  int  mask of options
	 * @return self
	 */
	public function setOptions($options = self::DEFAULT_OPTIONS)
	{
		$this->options = $options;
		return $this;
	}



	/**
	 * Returns processing options, {@link self::DEFAULT_OPTIONS}
	 * @return int
	 */
	public function getOptions()
	{
		return $this->options;
	}



	/**
	 * Has been schema loaded?
	 * @return bool
	 */
	public function isLoaded()
	{
		return $this->loaded;
	}



	/**
	 * Set which URIa are allowed for <sch:include> (self::INCLUDE_*)
	 * @param  int  mask of types
	 * @return self
	 */
	public function setAllowedInclude($mask)
	{
		$this->allowedInclude = $mask;
		return $this;
	}



	/**
	 * Returns which URIa are allowed for <sch:include> (self::INCLUDE_*)
	 * @return int
	 */
	public function getAllowedInclude()
	{
		return $this->allowedInclude;
	}



	/**
	 * Sets how deep can be <sch:include> in <sch:include> in <sch:include> ...
	 * @param  int  depth
	 * @return self
	 */
	public function setMaxIncludeDepth($depth)
	{
		$this->maxIncludeDepth = (int) $depth;
		return $this;
	}



	/**
	 * Returns how deep can be <sch:include> in <sch:include> in <sch:include> ...
	 * @param  int  depth
	 * @return self
	 */
	public function getMaxIncludeDepth()
	{
		return $this->maxIncludeDepth;
	}



	/**
	 * Sets include directory path for relative file paths in <sch:include>
	 * @param  string  directory path
	 * @return self
	 * @throws RuntimeException  when directory does not exist
	 */
	public function setIncludeDir($dir)
	{
		if (!is_dir($dir)) {
			throw new RuntimeException("Directory '$dir' does not exist.");
		}
		$this->directory = realpath($dir);

		return $this;
	}



	/**
	 * Returns path to directory which is used for relative file paths from <sch:include>
	 * @return string|NULL
	 */
	public function getIncludeDir()
	{
		return $this->directory;
	}



	/* ~~~ Schematron schema loading part ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
	/**
	 * Expands all <sch:include> in DOM.
	 * @param  DOMElement
	 * @param  int  include depth level
	 * @throws SchematronException
	 * @throws RuntimeException  when applied any include restriction
	 */
	protected function expandIncludes(DOMDocument $schema, $depth = 0)
	{
		if ($this->options & self::IGNORE_INCLUDE) {
			return;
		}

		if ($depth > $this->maxIncludeDepth) {
			throw new RuntimeException("Reached maximum ($this->maxIncludeDepth) include depth.");
		}

		$list = $schema->getElementsByTagNameNS($this->ns, 'include');
		if ($list->length > 0 && ($this->options & self::FORBID_INCLUDE)) {
			throw new RuntimeException("Include functionality is disabled. Found $list->length <{$list->item(0)->nodeName}> elements, first on line {$list->item(0)->getLineNo()}.");
		}

		while ($list->length) { // do not foreach(), list is affected by replaceChild
			$element = $list->item(0);

			$href = $rawHref = Helpers::getAttribute($element, 'href');
			if (substr_compare($href, 'file://', 0, 7, TRUE) === 0) {
				$href = substr($href, 7);
			}

			$type = static::detectIncludeType($href, $typeStr);

			if (!($this->allowedInclude & $type)) {
				throw new RuntimeException("Including URI of type '$typeStr' referenced by <$element->nodeName> on line {$element->getLineNo()} is not allowed.");
			}

			if ($type === self::INCLUDE_RELATIVE_PATH) {
				if ($this->directory === NULL) {
					throw new RuntimeException("Cannot evaluate relative URI '$rawHref' referenced by <$element->nodeName> on line {$element->getLineNo()}, schema has not been loaded from file. Set schema directory by setIncludeDir() method.");
				}
				$href = $this->directory . DIRECTORY_SEPARATOR . $href;
			}

			$doc = new DOMDocument;
			Helpers::handleXmlErrors();
			$doc->load($href, $this->domOptions);
			if ($e = Helpers::fetchXmlErrors()) {
				throw new RuntimeException("Cannot load '$rawHref' referenced by <$element->nodeName> on line {$element->getLineNo()}.", 0, $e);
			}

			$this->expandIncludes($doc, $depth + 1);

			$element->parentNode->replaceChild(
				$schema->importNode($doc->documentElement, TRUE),
				$element
			);
		}
	}



	/**
	 * Fills object members by basics schema properties.
	 * @throws SchematronException
	 */
	protected function loadSchemaBasics(DOMDocument $schema)
	{
		$list = $this->xPath->query('//sch:schema', $schema);
		if ($list->length > 1) {
			throw new SchematronException("Only one <schema> element in document is allowed, but $list->length found.");

		} elseif ($list->length < 1) {
			if (!($this->options & self::ALLOW_MISSING_SCHEMA_ELEMENT)) {
				throw new SchematronException('<schema> element not found.');
			}

		} else {
			$element = $list->item(0);

			$this->version = Helpers::getAttribute($element, 'schemaVersion', NULL);
			$this->defaultPhase = Helpers::getAttribute($element, 'defaultPhase', self::PHASE_ALL);
			if (strtolower($binding = Helpers::getAttribute($element, 'queryBinding', 'xslt')) !== 'xslt') {
				throw new SchematronException("Query binding '$binding' is not supported.");
			}

			$titleElements = $this->xPath->query('sch:title', $element);
			if ($titleElements->length > 0) {
				$this->title = $titleElements->item(0)->textContent;
			}
		}
	}



	/**
	 * Search for all <sch:ns>.
	 * @return array[string prefix => string URI]
	 * @throws SchematronException
	 */
	protected function findNamespaces(DOMDocument $schema)
	{
		$namespaces = $elements = array();
		foreach ($this->xPath->query('//sch:ns', $schema) as $element) {
			$prefix = Helpers::getAttribute($element, 'prefix');
			$uri = Helpers::getAttribute($element, 'uri');

			if (array_key_exists($prefix, $elements)) {
				throw new SchematronException("Namespace prefix '$prefix' on line {$element->getLineNo()} is alredy declared on line {$elements[$prefix]->getLineNo()}.");
			}

			$elements[$prefix] = $element;
			$namespaces[$prefix] = $uri;
		}
		return $namespaces;
	}



	/**
	 * Search for all <sch:pattern>. Abstract patterns are instantized.
	 * @return stdClass[]
	 * @throws SchematronException
	 */
	protected function findPatterns(DOMDocument $schema)
	{
		$abstracts = $this->findPatternAbstracts($schema);

		$patterns = array();
		foreach ($this->xPath->query('//sch:pattern[not(@abstract) or @abstract!="true"]', $schema) as $element) {
			if (($isA = Helpers::getAttribute($element, 'is-a', NULL)) !== NULL) {
				if (!array_key_exists($isA, $abstracts)) {
					throw new SchematronException("<$element->nodeName> on line {$element->getLineNo()} references to undefined abstract pattern by ID '$isA'.");
				}
				$pattern = $this->instantiatePattern($abstracts[$isA], $this->findParams($element));

			} else {
				$pattern = (object) array(
					'title' => $this->xPath->evaluate('boolean(sch:title)', $element)
						? $this->xPath->evaluate('string(sch:title)', $element)
						: Helpers::getAttribute($element, 'name', NULL), // Schematron v1.5
					'rules' => $rules = $this->findRules($element),
				);

				if (!count($rules) && !($this->options & self::ALLOW_EMPTY_PATTERN)) {
					throw new SchematronException("Missing rules for <$element->nodeName> on line {$element->getLineNo()}.");
				}
			}
			$pattern->id = Helpers::getAttribute($element, 'id', NULL);

			if ($pattern->id === NULL) {
				$patterns[] = $pattern;
			} else {
				$patterns["#$pattern->id"] = $pattern;
			}
		}

		return $patterns;
	}



	/**
	 * Search for all <sch:pattern abstract="TRUE">
	 * @return array[id => stdClass]
	 * @throws SchematronException
	 */
	protected function findPatternAbstracts(DOMDocument $schema)
	{
		$patterns = array();
		foreach ($this->xPath->query('//sch:pattern[@abstract="true"]', $schema) as $element) {
			if ($element->hasAttribute('is-a')) {
				throw new SchematronException("An abstract <$element->nodeName> on line {$element->getLineNo()} shall not have a 'is-a' attribute.");
			}

			$id = Helpers::getAttribute($element, 'id');
			$patterns[$id] = (object) array(
				'title' => $this->xPath->evaluate('boolean(sch:title)', $element)
					? $this->xPath->evaluate('string(sch:title)', $element)
					: Helpers::getAttribute($element, 'name', NULL), // Schematron v1.5
				'rules' => $rules = $this->findRules($element),
			);

			if (!count($rules) && !($this->options & self::ALLOW_EMPTY_PATTERN)) {
				throw new SchematronException("Missing rules for <$element->nodeName> on line {$element->getLineNo()}.");
			}
		}
		return $patterns;
	}



	/**
	 * Returns callable for replacing parameters in XPath expressions.
	 * @return  callable(string $expression, array $parameters)
	 */
	protected function getReplaceCb()
	{
		static $replaceCb;

		if ($replaceCb === NULL) {
			$replaceCb = function ($expression, $parameters) {
				foreach ($parameters as $name => $value) {
					$expression = str_replace("\$$name", $value, $expression);
				}

				return $expression;
			};
		}
		return $replaceCb;
	}



	/**
	 * Creates pattern instance from abstract pattern.
	 * @param  stdClass  abstract pattern
	 * @param  array[name => value]  parameters
	 * @return stdClass
	 */
	private function instantiatePattern(stdClass $abstract, array $parameters)
	{
		$instance = clone $abstract;
		foreach ($instance->rules as & $rule) {
			$rule = clone $rule;
			$rule->context = call_user_func($this->getReplaceCb(), $rule->context, $parameters);
			foreach ($rule->statements as & $stmt) {
				$stmt = clone $stmt;
				$stmt->test = call_user_func($this->getReplaceCb(), $stmt->test, $parameters);
			}
		}
		return $instance;
	}



	/**
	 * Search for all <sch:param>.
	 * @return array[string name => string value]
	 * @throws SchematronException
	 */
	protected function findParams(DOMElement $pattern)
	{
		$params = $elements = array();
		foreach ($this->xPath->query('sch:param', $pattern) as $element) {
			$name = Helpers::getAttribute($element, 'name');
			$value = Helpers::getAttribute($element, 'value');

			if (array_key_exists($name, $elements)) {
				throw new SchematronException("Parameter '$name' is already defined on line {$elements[$name]->getLineNo()}.");
			}

			$elements[$name] = $element;
			$params[$name] = $value;
		}
		return $params;
	}



	/**
	 * Search for all <sch:rule>.
	 * @return stdClass[]
	 * @throws SchematronException
	 */
	protected function findRules(DOMElement $pattern)
	{
		$abstracts = $this->findRuleAbstracts($pattern);

		$rules = $contexts = array();
		foreach ($this->xPath->query('sch:rule[not(@abstract) or @abstract!="true"]', $pattern) as $element) {
			$context = Helpers::getAttribute($element, 'context');

			if (array_key_exists($context, $contexts) && ($this->options & self::SKIP_DUPLICIT_RULE_CONTEXT)) {
				continue;
			}
			$contexts[$context] = TRUE;

			$rules[] = (object) array(
				'context' => $context,
				'statements' => $statements = $this->findStatements($element, $abstracts),
			);

			if (!count($statements) && !($this->options & self::ALLOW_EMPTY_RULE)) {
				throw new SchematronException("Asserts nor reports not found for <$element->nodeName> on line {$element->getLineNo()}.");
			}
		}
		return $rules;
	}



	/**
	 * Search for all <sch:rule abstract="TRUE">.
	 * @return stdClass[]
	 * @throws SchematronException
	 */
	protected function findRuleAbstracts(DOMElement $pattern)
	{
		$rules = array();
		foreach ($this->xPath->query('sch:rule[@abstract="true"]', $pattern) as $element) {
			$id = Helpers::getAttribute($element, 'id');
			if ($element->hasAttribute('context')) {
				throw new SchematronException("An abstract rule on line {$element->getLineNo()} shall not have a 'context' attribute.");
			}

			$rules[$id] = (object) array(
				'statements' => $this->findStatements($element),
			);
		}
		return $rules;
	}



	/**
	 * Search for all <sch:assert> and <sch:report>.
	 * @return stdClass[]
	 * @throws SchematronException
	 */
	protected function findStatements(DOMElement $rule, array $abstractRules = array())
	{
		$statements = array();
		foreach ($this->xPath->query('sch:assert | sch:report | sch:extends', $rule) as $node) {
			if ($node->localName === 'extends') {
				$idRule = Helpers::getAttribute($node, 'rule');
				if (!isset($abstractRules[$idRule])) {
					throw new SchematronException("<$node->nodeName> on line {$node->getLineNo()} references to undefined abstract rule by ID '$idRule'.");
				}

				$statements = array_merge($statements, $abstractRules[$idRule]->statements);

			} else {
				$statements[] = (object) array(
					'test' => Helpers::getAttribute($node, 'test'),
					'isAssert' => $node->localName === 'assert',
					'node' => $node,
				);
			}
		}
		return $statements;
	}



	/**
	 * Search for all <sch:phase> and check existency of defaultPhase if set in <sch:schema>.
	 * @return array[id => array[idPattern]]
	 * @throws SchematronException
	 */
	protected function findPhases(DOMDocument $schema)
	{
		$phases = $elements = array();
		foreach ($this->xPath->query('//sch:phase', $schema) as $element) {
			$id = Helpers::getAttribute($element, 'id');
			if (isset($elements[$id])) {
				throw new SchematronException("<$element->nodeName> with id '$id' is already defined on line {$elements[$id]->getLineNo()}.");
			}
			$elements[$id] = $element;
			$phases[$id] = $this->findActives($element);
		}

		if ($this->defaultPhase !== self::PHASE_ALL && !array_key_exists($this->defaultPhase, $phases)) {
			throw new SchematronException("Default validation phase '$this->defaultPhase' is not defined.");
		}

		return $phases;
	}



	/**
	 * Search for all <sch:active>.
	 * @return string[]  list of <sch:pattern> IDs
	 * @throws SchematronException
	 */
	protected function findActives(DOMElement $phase)
	{
		$actives = array();
		foreach ($this->xPath->query('sch:active', $phase) as $element) {
			$idPattern = Helpers::getAttribute($element, 'pattern');
			if (!isset($this->patterns["#$idPattern"])) {
				throw new SchematronException("<$element->nodeName> on line {$element->getLineNo()} references to undefined pattern by ID '$idPattern'.");
			}
			$actives["#$idPattern"] = $idPattern;
		}
		return $actives;
	}



	/**
	 * Expands <sch:name> and <sch:value-of> in assertion/report message.
	 * @return string
	 */
	protected function statementToMessage(DOMElement $stmt, SchematronXPath $xPath, DOMNode $current)
	{
		$message = '';
		foreach ($stmt->childNodes as $node) {
			if ($node->nodeType === XML_ELEMENT_NODE && $node->namespaceURI === $this->ns) {
				if ($node->localName === 'name') {
					$message .= $xPath->evaluate('name(' . Helpers::getAttribute($node, 'path', '') . ')', $current);

				} elseif ($node->localName === 'value-of') {
					$message .= $xPath->evaluate('string(' . Helpers::getAttribute($node, 'select') . ')', $current);

				} else {
					/** @todo warning? */
					$message .= $node->textContent;
				}

			} else {
				$message .= $node->textContent;
			}
		}

		$message = preg_replace('#\s+#', ' ', trim($message));

		return $message;
	}



	/**
	 * Detects include URI type.
	 * @return int
	 */
	protected static function detectIncludeType($uri, & $typeStr = NULL)
	{
		$absolutePathRe = substr_compare(PHP_OS, 'WIN', 0, 3, TRUE) === 0
			? '#^[A-Z]:#i'
			: '#^/#';

		if (preg_match('#^[a-z-]+://#i', $uri)) {
			$type = self::INCLUDE_URL;
			$typeStr = 'URL';

		} elseif (preg_match($absolutePathRe, $uri)) {
			$type = self::INCLUDE_ABSOLUTE_PATH;
			$typeStr = 'Absolute file path';

		} else {
			$type = self::INCLUDE_RELATIVE_PATH;
			$typeStr = 'Relative file path';
		}

		return $type;
	}

}



/**
 * Helpers for work with LibXML and DOM.
 *
 * @author  Miloslav Hůla (https://github.com./milo)
 */
class SchematronHelpers
{
	/** @var array */
	private static $handleXmlErrors = array();



	/**
	 * Enable LibXML internal error handling.
	 * @param  bool  clear existing errors
	 */
	public static function handleXmlErrors($clear = TRUE)
	{
		self::$handleXmlErrors[] = libxml_use_internal_errors(TRUE);
		$clear && libxml_clear_errors();
	}



	/**
	 * Fetch all LibXML errors.
	 * @param  bool
	 * @return NULL|ErrorException  all errors chained in exceptions
	 */
	public static function fetchXmlErrors($restoreHandling = TRUE)
	{
		$e = NULL;
		foreach (array_reverse(libxml_get_errors()) as $error) {
			$e = new ErrorException(trim($error->message), $error->code, $error->level, $error->file, $error->line, $e);
		}
		libxml_clear_errors();
		$restoreHandling && self::restoreErrorHandling();
		return $e;
	}



	/**
	 * Restore LibXML internal error handling previously enabled by self::handleXmlErrors()
	 */
	public static function restoreErrorHandling()
	{
		libxml_use_internal_errors(array_pop(self::$handleXmlErrors));
	}



	/**
	 * Returns value of element attribute.
	 * @param  DOMElement
	 * @param  string  attribute name
	 * @param  mixed  default value if attribude does not exist
	 * @return mixed
	 * @throws SchematronException  when attribute does not exist and default value is not specified
	 */
	public static function getAttribute(DOMElement $element, $name)
	{
		if ($element->hasAttribute($name)) {
			return $element->getAttribute($name);

		} elseif (count($args = func_get_args()) > 2) {
			return $args[2];
		}

		throw new SchematronException("Missing required attribute '$name' for element <$element->nodeName> on line {$element->getLineNo()}.");
	}

}



/**
 * DOMXPath envelope.
 *
 * @author  Miloslav Hůla (https://github.com./milo)
 */
class SchematronXPath extends DOMXPath
{
	/**
	 * ($registerNodeNS is FALSE in opposition to DOMXPath default value)
	 */
	public function query($expression, DOMNode $context = NULL, $registerNodeNS = FALSE)
	{
		return parent::query($expression, $context, $registerNodeNS);
	}



	/**
	 * ($registerNodeNS is FALSE in opposition to DOMXPath default value)
	 */
	public function evaluate($expression, DOMNode $context = NULL, $registerNodeNS = FALSE)
	{
		return parent::evaluate($expression, $context, $registerNodeNS);
	}



	public function queryContext($expression, DOMNode $context = NULL, $registerNodeNS = FALSE)
	{
		if (isset($expression[0]) && $expression[0] !== '.' && $expression[0] !== '/') {
			$expression = "//$expression";
		}
		return $this->query($expression, $context, $registerNodeNS);
	}

}



/**
 * Thrown when schematron schema source is malformed (not well-formed).
 *
 * @author  Miloslav Hůla (https://github.com./milo)
 */
class SchematronException extends \RuntimeException
{
}