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author | Qt by Nokia <qt-info@nokia.com> | 2011-04-27 12:05:43 +0200 |
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committer | axis <qt-info@nokia.com> | 2011-04-27 12:05:43 +0200 |
commit | e1b2c9deb5943faae2b29be6a5c006f75bb73f06 (patch) | |
tree | fc79e45367c0a8fc71185e9afc33f7503a58653c /src/xmlpatterns/api/qxmlquery.cpp | |
download | qtxmlpatterns-e1b2c9deb5943faae2b29be6a5c006f75bb73f06.tar.gz |
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Branched from the monolithic repo, Qt master branch, at commit
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Diffstat (limited to 'src/xmlpatterns/api/qxmlquery.cpp')
-rw-r--r-- | src/xmlpatterns/api/qxmlquery.cpp | 1209 |
1 files changed, 1209 insertions, 0 deletions
diff --git a/src/xmlpatterns/api/qxmlquery.cpp b/src/xmlpatterns/api/qxmlquery.cpp new file mode 100644 index 0000000..d74a536 --- /dev/null +++ b/src/xmlpatterns/api/qxmlquery.cpp @@ -0,0 +1,1209 @@ +/**************************************************************************** +** +** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the QtXmlPatterns module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the Technology Preview License Agreement accompanying +** this package. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain additional +** rights. These rights are described in the Nokia Qt LGPL Exception +** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. +** +** If you have questions regarding the use of this file, please contact +** Nokia at qt-info@nokia.com. +** +** +** +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include <QtCore/QBuffer> +#include <QtCore/QStringList> +#include <QtXmlPatterns/QXmlFormatter> + +#include "qacceltreeresourceloader_p.h" +#include "qcommonvalues_p.h" +#include "qxmlresultitems.h" +#include "qxmlresultitems_p.h" +#include "qxmlserializer.h" +#include "qxpathhelper_p.h" + +#include "qxmlquery.h" +#include "qxmlquery_p.h" + +QT_BEGIN_NAMESPACE + +/*! + \class QXmlQuery + + \brief The QXmlQuery class performs XQueries on XML data, or on non-XML data modeled to look like XML. + + \reentrant + \since 4.4 + \ingroup xml-tools + + The QXmlQuery class compiles and executes queries written in the + \l {http://www.w3.org/TR/xquery/}{XQuery language}. QXmlQuery is + typically used to query XML data, but it can also query non-XML + data that has been modeled to look like XML. + + Using QXmlQuery to query XML data, as in the snippet below, is + simple because it can use the built-in \l {QAbstractXmlNodeModel} + {XML data model} as its delegate to the underlying query engine for + traversing the data. The built-in data model is specified in \l + {http://www.w3.org/TR/xpath-datamodel/} {XQuery 1.0 and XPath 2.0 + Data Model}. + + \snippet doc/src/snippets/code/src_xmlpatterns_api_qabstractxmlreceiver.cpp 0 + + The example uses QXmlQuery to match the first paragraph of an XML + document and then \l {QXmlSerializer} {output the result} to a + device as XML. + + Using QXmlQuery to query \e {non-XML} data requires writing a + subclass of QAbstractXmlNodeModel to use as a replacement for the + built-in XML data model. The custom data model will be able to + traverse the non-XML data as required by the QAbstractXmlNodeModel + interface. An instance of this custom data model then becomes the + delegate used by the query engine to traverse the non-XML data. For + an example of how to use QXmlQuery to query non-XML data, see the + documentation for QAbstractXmlNodeModel. + + \section1 Running XQueries + + To run a query set up with QXmlQuery, call one of the evaluation + functions. + + \list + + \o evaluateTo(QAbstractXmlReceiver *) is called with a pointer to an + XML \l {QAbstractXmlReceiver} {receiver}, which receives the query + results as a sequence of callbacks. The receiver callback class is + like the callback class used for translating the output of a SAX + parser. QXmlSerializer, for example, is a receiver callback class + for translating the sequence of callbacks for output as unformatted + XML text. + + \endlist + + \list + + \o evaluateTo(QXmlResultItems *) is called with a pointer to an + iterator for an empty sequence of query \l {QXmlResultItems} {result + items}. The Java-like iterator allows the query results to be + accessed sequentially. + + \endlist + + \list + + \o evaluateTo(QStringList *) is like evaluateTo(QXmlResultItems *), + but the query must evaluate to a sequence of strings. + + \endlist + + \section1 Running XPath Expressions + + The XPath language is a subset of the XQuery language, so + running an XPath expression is the same as running an XQuery + query. Pass the XPath expression to QXmlQuery using setQuery(). + + \section1 Running XSLT stylesheets + + Running an XSLT stylesheet is like running an XQuery, except that + when you construct your QXmlQuery, you must pass QXmlQuery::XSLT20 + to tell QXmlQuery to interpret whatever it gets from setQuery() as + an XSLT stylesheet instead of as an XQuery. You must also set the + input document by calling setFocus(). + + \snippet doc/src/snippets/code/src_xmlpatterns_api_qxmlquery.cpp 7 + + \note Currently, setFocus() must be called \e before setQuery() when + using XSLT. + + Another way to run an XSLT stylesheet is to use the \c xmlpatterns + command line utility. + + \code + xmlpatterns myStylesheet.xsl myInput.xml + \endcode + + \note For the current release, XSLT support should be considered + experimental. See section \l{XQuery#XSLT 2.0} {XSLT conformance} for + details. + + Stylesheet parameters are bound using bindVariable(). + + \section1 Binding A Query To A Starting Node + + When a query is run on XML data, as in the snippet above, the + \c{doc()} function returns the node in the built-in data model where + the query evaluation will begin. But when a query is run on a custom + node model containing non-XML data, one of the bindVariable() + functions must be called to bind a variable name to a starting node + in the custom model. A $variable reference is used in the XQuery + text to access the starting node in the custom model. It is not + necessary to declare the variable name external in the query. See + the example in the documentation for QAbstractXmlNodeModel. + + \section1 Reentrancy and Thread-Safety + + QXmlQuery is reentrant but not thread-safe. It is safe to use the + QxmlQuery copy constructor to create a copy of a query and run the + same query multiple times. Behind the scenes, QXmlQuery will reuse + resources such as opened files and compiled queries to the extent + possible. But it is not safe to use the same instance of QXmlQuery + in multiple threads. + + \section1 Error Handling + + Errors can occur during query evaluation. Examples include type + errors and file loading errors. When an error occurs: + + \list + + \o The error message is sent to the messageHandler(). + + \o QXmlResultItems::hasError() will return \c{true}, or + evaluateTo() will return \c{false}; + + \o The results of the evaluation are undefined. + + \endlist + + \section1 Resource Management + + When a query runs, it parses documents, allocating internal data + structures to hold them, and it may load other resources over the + network. It reuses these allocated resources when possible, to + avoid having to reload and reparse them. + + When setQuery() is called, the query text is compiled into an + internal data structure and optimized. The optimized form can + then be reused for multiple evaluations of the query. Since the + compile-and-optimize process can be expensive, repeating it for + the same query should be avoided by using a separate instance of + QXmlQuery for each query text. + + Once a document has been parsed, its internal representation is + maintained in the QXmlQuery instance and shared among multiple + QXmlQuery instances. + + An instance of QCoreApplication must exist before QXmlQuery can be + used. + + \section1 Event Handling + + When QXmlQuery accesses resources (e.g., calling \c fn:doc() to load a file, + or accessing a device via a bound variable), the event loop is used, which + means events will be processed. To avoid processing events when QXmlQuery + accesses resources, create your QXmlQuery instance in a separate thread. + */ + +/*! + \enum QXmlQuery::QueryLanguage + \since 4.5 + + Specifies whether you want QXmlQuery to interpret the input to + setQuery() as an XQuery or as an XSLT stylesheet. + + \value XQuery10 XQuery 1.0. + \value XSLT20 XSLT 2.0 + \omitvalue XmlSchema11IdentityConstraintSelector The selector, the restricted + XPath pattern found in W3C XML Schema 1.1 for uniqueness + contraints. Apart from restricting the syntax, the type check stage + for the expression assumes a sequence of nodes to be the focus. + \omitvalue XmlSchema11IdentityConstraintField The field, the restricted + XPath pattern found in W3C XML Schema 1.1 for uniqueness + contraints. Apart from restricting the syntax, the type check stage + for the expression assumes a sequence of nodes to be the focus. + \omitvalue XPath20 Signifies XPath 2.0. Has no effect in the public API, it's + used internally. As With XmlSchema11IdentityConstraintSelector and + XmlSchema11IdentityConstraintField, the type check stage + for the expression assumes a sequence of nodes to be the focus. + + \sa setQuery() + */ + +// ### Qt5: Merge constructor overloads +/*! + Constructs an invalid, empty query that cannot be used until + setQuery() is called. + + \note This constructor must not be used if you intend to use + this QXmlQuery to process XSL-T stylesheets. The other constructor + must be used in that case. + */ +QXmlQuery::QXmlQuery() : d(new QXmlQueryPrivate()) +{ +} + +/*! + Constructs a QXmlQuery that is a copy of \a other. The new + instance will share resources with the existing query + to the extent possible. + */ +QXmlQuery::QXmlQuery(const QXmlQuery &other) : d(new QXmlQueryPrivate(*other.d)) +{ + /* First we have invoked QXmlQueryPrivate's synthesized copy constructor. + * Keep this section in sync with QXmlQuery::operator=(). */ + d->detach(); +} + +/*! + Constructs a query that will use \a np as its name pool. The query + cannot be evaluated until setQuery() has been called. + */ +QXmlQuery::QXmlQuery(const QXmlNamePool &np) : d(new QXmlQueryPrivate(np)) +{ +} + +/*! + + Constructs a query that will be used to run Xqueries or XSL-T + stylesheets, depending on the value of \a queryLanguage. It will use + \a np as its name pool. + + \note If your QXmlQuery will process XSL-T stylesheets, this + constructor must be used. The default constructor can only + create instances of QXmlQuery for running XQueries. + + \note The XSL-T support in this release is considered experimental. + See the \l{XQuery#XSLT 2.0} {XSLT conformance} for details. + + \since 4.5 + \sa queryLanguage() + */ +QXmlQuery::QXmlQuery(QueryLanguage queryLanguage, + const QXmlNamePool &np) : d(new QXmlQueryPrivate(np)) +{ + d->queryLanguage = queryLanguage; +} + +/*! + Destroys this QXmlQuery. + */ +QXmlQuery::~QXmlQuery() +{ + delete d; +} + +/*! + Assigns \a other to this QXmlQuery instance. + */ +QXmlQuery &QXmlQuery::operator=(const QXmlQuery &other) +{ + /* Keep this section in sync with QXmlQuery::QXmlQuery(const QXmlQuery &). + */ + if(d != other.d) + { + *d = *other.d; + d->detach(); + } + + return *this; +} + +/*! + Changes the \l {QAbstractMessageHandler}{message handler} for this + QXmlQuery to \a aMessageHandler. The query sends all compile and + runtime messages to this message handler. QXmlQuery does not take + ownership of \a aMessageHandler. + + Normally, the default message handler is sufficient. It writes + compile and runtime messages to \e stderr. The default message + handler includes color codes if \e stderr can render colors. + + Note that changing the message handler after the query has been + compiled has no effect, i.e. the query uses the same message handler + at runtime that it uses at compile time. + + When QXmlQuery calls QAbstractMessageHandler::message(), + the arguments are as follows: + + \table + \header + \o message() argument + \o Semantics + \row + \o QtMsgType type + \o Only QtWarningMsg and QtFatalMsg are used. The former + identifies a compile or runtime warning, while the + latter identifies a dynamic or static error. + \row + \o const QString & description + \o An XHTML document which is the actual message. It is translated + into the current language. + \row + \o const QUrl &identifier + \o Identifies the error with a URI, where the fragment is + the error code, and the rest of the URI is the error namespace. + \row + \o const QSourceLocation & sourceLocation + \o Identifies where the error occurred. + \endtable + + */ +void QXmlQuery::setMessageHandler(QAbstractMessageHandler *aMessageHandler) +{ + d->messageHandler = aMessageHandler; +} + +/*! + Returns the message handler that handles compile and runtime + messages for this QXmlQuery. + */ +QAbstractMessageHandler *QXmlQuery::messageHandler() const +{ + return d->messageHandler; +} + +/*! + Sets this QXmlQuery to an XQuery read from the \a sourceCode + device. The device must have been opened with at least + QIODevice::ReadOnly. + + \a documentURI represents the query obtained from the \a sourceCode + device. It is the base URI of the static context, as defined in the + \l {http://www.w3.org/TR/xquery/}{XQuery language}. It is used + internally to resolve relative URIs that appear in the query, and + for message reporting. \a documentURI can be empty. If it is empty, + the \l{QCoreApplication::applicationFilePath()} {application file + path} is used. If it is not empty, it may be either relative or + absolute. If it is relative, it is resolved itself against the + \l {QCoreApplication::applicationFilePath()} {application file + path} before it is used. If \a documentURI is neither a valid URI + nor empty, the result is undefined. + + If the query contains a static error (e.g. syntax error), an error + message is sent to the messageHandler(), and isValid() will return + \e false. + + Variables must be bound before setQuery() is called. + + The encoding of the XQuery in \a sourceCode is detected internally + using the rules for setting and detecting encoding of XQuery files, + which are explained in the \l {http://www.w3.org/TR/xquery/} + {XQuery language}. + + If \a sourceCode is \c null or not readable, or if \a documentURI is not + a valid URI, behavior is undefined. + \sa isValid() + */ +void QXmlQuery::setQuery(QIODevice *sourceCode, const QUrl &documentURI) +{ + if(!sourceCode) + { + qWarning("A null QIODevice pointer cannot be passed."); + return; + } + + if(!sourceCode->isReadable()) + { + qWarning("The device must be readable."); + return; + } + + d->queryURI = QPatternist::XPathHelper::normalizeQueryURI(documentURI); + d->expression(sourceCode); +} + +/*! + \overload + The behavior and requirements of this function are the same as for + setQuery(QIODevice*, const QUrl&), after the XQuery has been read + from the IO device into a string. Because \a sourceCode is already + a Unicode string, detection of its encoding is unnecessary. +*/ +void QXmlQuery::setQuery(const QString &sourceCode, const QUrl &documentURI) +{ + Q_ASSERT_X(documentURI.isEmpty() || documentURI.isValid(), Q_FUNC_INFO, + "The document URI must be valid."); + + QByteArray query(sourceCode.toUtf8()); + QBuffer buffer(&query); + buffer.open(QIODevice::ReadOnly); + + setQuery(&buffer, documentURI); +} + +/*! + Sets this QXmlQuery to the XQuery read from the \a queryURI. Use + isValid() after calling this function. If an error occurred reading + \a queryURI, e.g., the query does not exist, cannot be read, or is + invalid, isValid() will return \e false. + + The supported URI schemes are the same as those in the XQuery + function \c{fn:doc}, except that queryURI can be the object of + a variable binding. + + \a baseURI is the Base URI of the static context, as defined in the + \l {http://www.w3.org/TR/xquery/}{XQuery language}. It is used + internally to resolve relative URIs that appear in the query, and + for message reporting. If \a baseURI is empty, \a queryURI is used. + Otherwise, \a baseURI is used, and it is resolved against the \l + {QCoreApplication::applicationFilePath()} {application file path} if + it is relative. + + If \a queryURI is empty or invalid, or if \a baseURI is invalid, + the behavior of this function is undefined. + */ +void QXmlQuery::setQuery(const QUrl &queryURI, const QUrl &baseURI) +{ + Q_ASSERT_X(queryURI.isValid(), Q_FUNC_INFO, "The passed URI must be valid."); + + const QUrl canonicalURI(QPatternist::XPathHelper::normalizeQueryURI(queryURI)); + Q_ASSERT(canonicalURI.isValid()); + Q_ASSERT(!canonicalURI.isRelative()); + Q_ASSERT(baseURI.isValid() || baseURI.isEmpty()); + + d->queryURI = QPatternist::XPathHelper::normalizeQueryURI(baseURI.isEmpty() ? queryURI : baseURI); + + QPatternist::AutoPtr<QIODevice> result; + + try + { + result.reset(QPatternist::AccelTreeResourceLoader::load(canonicalURI, d->m_networkAccessDelegator, + d->staticContext())); + } + catch(const QPatternist::Exception) + { + /* We do nothing, result will be 0. */ + } + + if(result) + { + setQuery(result.data(), d->queryURI); + result->close(); + } + else + d->recompileRequired(); +} + +/*! + Binds the variable \a name to the \a value so that $\a name can be + used from within the query to refer to the \a value. + + \a name must not be \e null. \a {name}.isNull() must return false. + If \a name has already been bound by a previous bindVariable() call, + its previous binding will be overridden. + + If \a {value} is null so that \a {value}.isNull() returns true, and + \a {name} already has a binding, the effect is to remove the + existing binding for \a {name}. + + To bind a value of type QString or QUrl, wrap the value in a + QVariant such that QXmlItem's QVariant constructor is called. + + All strings processed by the query must be valid XQuery strings, + which means they must contain only XML 1.0 characters. However, + this requirement is not checked. If the query processes an invalid + string, the behavior is undefined. + + \sa QVariant::isValid(), {QtXDM}{How QVariant maps to XQuery's Data Model}, + QXmlItem::isNull() + */ +void QXmlQuery::bindVariable(const QXmlName &name, const QXmlItem &value) +{ + if(name.isNull()) + { + qWarning("The variable name cannot be null."); + return; + } + + const QPatternist::VariableLoader::Ptr vl(d->variableLoader()); + const QVariant variant(QVariant::fromValue(value)); + + /* If the type of the variable changed(as opposed to only the value), + * we will have to recompile. */ + if(vl->invalidationRequired(name, variant) || value.isNull()) + d->recompileRequired(); + + vl->addBinding(name, variant); +} + +/*! + \overload + + This function constructs a QXmlName from \a localName using the + query's \l {QXmlNamePool} {namespace}. The function then behaves as + the overloaded function. It is equivalent to the following snippet. + + \snippet doc/src/snippets/code/src_xmlpatterns_api_qxmlquery.cpp 0 + */ +void QXmlQuery::bindVariable(const QString &localName, const QXmlItem &value) +{ + bindVariable(QXmlName(d->namePool, localName), value); +} + +/*! + Binds the variable \a name to the \a device so that $\a name can be + used from within the query to refer to the \a device. The QIODevice + \a device is exposed to the query as a URI of type \c{xs:anyURI}, + which can be passed to the \c{fn:doc()} function to be read. E.g., + this function can be used to pass an XML document in memory to + \c{fn:doc}. + + \snippet doc/src/snippets/code/src_xmlpatterns_api_qxmlquery.cpp 1 + + The caller must ensure that \a device has been opened with at least + QIODevice::ReadOnly prior to this binding. Otherwise, behavior is + undefined. + + If the query will access an XML document contained in a QString, use + a QBuffer as shown in the following snippet. Suppose \e myQString + contains \c{<document>content</document>} + + \snippet doc/src/snippets/qxmlquery/bindingExample.cpp 0 + + \a name must not be \e null. \a {name}.isNull() must return false. + If \a name has already been bound, its previous binding will be + overridden. The URI that \a name evaluates to is arbitrary and may + change. + + If the type of the variable binding changes (e.g., if a previous + binding by the same name was a QVariant, or if there was no previous + binding), isValid() will return \c{false}, and recompilation of the + query text is required. To recompile the query, call setQuery(). For + this reason, bindVariable() should be called before setQuery(), if + possible. + + \note \a device must not be deleted while this QXmlQuery exists. +*/ +void QXmlQuery::bindVariable(const QXmlName &name, QIODevice *device) +{ + if(device && !device->isReadable()) + { + qWarning("A null, or readable QIODevice must be passed."); + return; + } + + if(name.isNull()) + { + qWarning("The variable name cannot be null."); + return; + } + + const QPatternist::VariableLoader::Ptr vl(d->variableLoader()); + + if(device) + { + const QVariant variant(QVariant::fromValue(device)); + + if(vl->invalidationRequired(name, variant)) + d->recompileRequired(); + + vl->addBinding(name, variant); + + /* We need to tell the resource loader to discard its document, because + * the underlying QIODevice has changed, but the variable name is the + * same which means that the URI is the same, and hence the resource + * loader will return the document for the old QIODevice. + */ + d->resourceLoader()->clear(QUrl(QLatin1String("tag:trolltech.com,2007:QtXmlPatterns:QIODeviceVariable:") + d->namePool.d->stringForLocalName(name.localName()))); + } + else + { + vl->removeBinding(name); + d->recompileRequired(); + } +} + +/*! + \overload + + If \a localName is a valid \l {QXmlName::isNCName()} {NCName}, this + function is equivalent to the following snippet. + + \snippet doc/src/snippets/code/src_xmlpatterns_api_qxmlquery.cpp 2 + + A QXmlName is constructed from \a localName, and is passed + to the appropriate overload along with \a device. + + \sa QXmlName::isNCName() + */ +void QXmlQuery::bindVariable(const QString &localName, QIODevice *device) +{ + bindVariable(QXmlName(d->namePool, localName), device); +} + +/*! + Evaluates this query and sends the result as a sequence of callbacks + to the \l {QAbstractXmlReceiver} {receiver} \a callback. QXmlQuery + does not take ownership of \a callback. + + If an error occurs during the evaluation, error messages are sent to + messageHandler() and \c false is returned. + + If this query \l {isValid()} {is invalid}, \c{false} is returned + and the behavior is undefined. If \a callback is null, + behavior is undefined. + + \sa QAbstractXmlReceiver, isValid() + */ +bool QXmlQuery::evaluateTo(QAbstractXmlReceiver *callback) const +{ + if(!callback) + { + qWarning("A non-null callback must be passed."); + return false; + } + + if(isValid()) + { + try + { + /* + * This order is significant. expression() might cause + * query recompilation, and as part of that it recreates + * the static context. However, if we create the dynamic + * context before the query recompilation has been + * triggered, it will use the old static context, and + * hence old source locations. + */ + const QPatternist::Expression::Ptr expr(d->expression()); + const QPatternist::DynamicContext::Ptr dynContext(d->dynamicContext(callback)); + callback->startOfSequence(); + expr->evaluateToSequenceReceiver(dynContext); + callback->endOfSequence(); + return true; + } + catch(const QPatternist::Exception) + { + return false; + } + } + else + return false; +} + +/*! + Attempts to evaluate the query and returns the results in the + \a target \l {QStringList} {string list}. + + If the query \l {isValid()} {is valid} and the evaluation succeeds, + true is returned. Otherwise, false is returned and the contents of + \a target are undefined. + + The query must evaluate to a sequence of \c{xs:string} values. If + the query does not evaluate to a sequence of strings, the values can + often be converted by adding a call to \c{string()} at the end of + the XQuery. + + If \a target is null, the behavior is undefined. + */ +bool QXmlQuery::evaluateTo(QStringList *target) const +{ + if(!target) + { + qWarning("A non-null callback must be passed."); + return false; + } + + if(isValid()) + { + try + { + /* + * This order is significant. expression() might cause + * query recompilation, and as part of that it recreates + * the static context. However, if we create the dynamic + * context before the query recompilation has been + * triggered, it will use the old static context, and + * hence old source locations. + */ + const QPatternist::Expression::Ptr expr(d->expression()); + if(!expr) + return false; + + QPatternist::DynamicContext::Ptr dynContext(d->dynamicContext()); + + if(!QPatternist::BuiltinTypes::xsString->xdtTypeMatches(expr->staticType()->itemType())) + return false; + + const QPatternist::Item::Iterator::Ptr it(expr->evaluateSequence(dynContext)); + QPatternist::Item next(it->next()); + + while(!next.isNull()) + { + target->append(next.stringValue()); + next = it->next(); + } + + return true; + } + catch(const QPatternist::Exception) + { + return false; + } + } + else + return false; +} + +/*! + Evaluates the query or stylesheet, and writes the output to \a target. + + QXmlSerializer is used to write the output to \a target. In a future + release, it is expected that this function will be changed to + respect serialization options set in the stylesheet. + + If an error occurs during the evaluation, error messages are sent to + messageHandler() and \c false is returned. + + If \a target is \c null, or is not opened in at least + QIODevice::WriteOnly mode, the behavior is undefined. QXmlQuery + does not take ownership of \a target. + + \since 4.5 + \overload + */ +bool QXmlQuery::evaluateTo(QIODevice *target) const +{ + if(!target) + { + qWarning("The pointer to the device cannot be null."); + return false; + } + + if(!target->isWritable()) + { + qWarning("The device must be writable."); + return false; + } + + QXmlSerializer serializer(*this, target); + return evaluateTo(&serializer); +} + +/*! + Starts the evaluation and makes it available in \a result. If \a + result is null, the behavior is undefined. The evaluation takes + place incrementally (lazy evaluation), as the caller uses + QXmlResultItems::next() to get the next result. + + \sa QXmlResultItems::next() +*/ +void QXmlQuery::evaluateTo(QXmlResultItems *result) const +{ + if(!result) + { + qWarning("A null pointer cannot be passed."); + return; + } + + if(isValid()) + { + try + { + /* + * We don't have the d->expression() calls and + * d->dynamicContext() calls in the same order as seen in + * QXmlQuery::evaluateTo(), and the reason to why + * that isn't a problem, is that we call isValid(). + */ + const QPatternist::DynamicContext::Ptr dynContext(d->dynamicContext()); + result->d_ptr->setDynamicContext(dynContext); + result->d_ptr->iterator = d->expression()->evaluateSequence(dynContext); + } + catch(const QPatternist::Exception) + { + result->d_ptr->iterator = QPatternist::CommonValues::emptyIterator; + result->d_ptr->hasError = true; + } + } + else + { + result->d_ptr->iterator= QPatternist::CommonValues::emptyIterator; + result->d_ptr->hasError = true; + } +} + +/*! + Evaluates the query, and serializes the output as XML to \a output. + + If an error occurs during the evaluation, error messages are sent to + messageHandler(), the content of \a output is undefined and \c false is + returned, otherwise \c true is returned. + + If \a output is \c null behavior is undefined. QXmlQuery + does not take ownership of \a output. + + Internally, the class QXmlFormatter is used for this. + \since 4.5 + */ +bool QXmlQuery::evaluateTo(QString *output) const +{ + Q_ASSERT_X(output, Q_FUNC_INFO, + "The input cannot be null"); + + QBuffer outputDevice; + outputDevice.open(QIODevice::ReadWrite); + + QXmlFormatter formatter(*this, &outputDevice); + const bool success = evaluateTo(&formatter); + + outputDevice.close(); + *output = QString::fromUtf8(outputDevice.data().constData()); + + return success; +} + +/*! + Returns true if this query is valid. Examples of invalid queries + are ones that contain syntax errors or that have not had setQuery() + called for them yet. + */ +bool QXmlQuery::isValid() const +{ + return d->isValid(); +} + +/*! + Sets the URI resolver to \a resolver. QXmlQuery does not take + ownership of \a resolver. + + \sa uriResolver() + */ +void QXmlQuery::setUriResolver(const QAbstractUriResolver *resolver) +{ + d->uriResolver = resolver; +} + +/*! + Returns the query's URI resolver. If no URI resolver has been set, + QtXmlPatterns will use the URIs in queries as they are. + + The URI resolver provides a level of abstraction, or \e{polymorphic + URIs}. A resolver can rewrite \e{logical} URIs to physical ones, or + it can translate obsolete or invalid URIs to valid ones. + + QtXmlPatterns calls the URI resolver for all URIs it encounters, + except for namespaces. Specifically, all builtin functions that deal + with URIs (\c{fn:doc()}, and \c{fn:doc-available()}). + + In the case of \c{fn:doc()}, the absolute URI is the base URI in the + static context (which most likely is the location of the query). + Rather than use the URI the user specified, the return value of + QAbstractUriResolver::resolve() will be used. + + When QtXmlPatterns calls QAbstractUriResolver::resolve() the + absolute URI is the URI mandated by the XQuery language, and the + relative URI is the URI specified by the user. + + \sa setUriResolver() + */ +const QAbstractUriResolver *QXmlQuery::uriResolver() const +{ + return d->uriResolver; +} + +/*! + Returns the name pool used by this QXmlQuery for constructing \l + {QXmlName} {names}. There is no setter for the name pool, because + mixing name pools causes errors due to name confusion. + */ +QXmlNamePool QXmlQuery::namePool() const +{ + return d->namePool; +} + +/*! + Sets the focus to \a item. The focus is the set of items that the + context item expression and path expressions navigate from. For + example, in the expression \e p/span, the element that \e p + evaluates to is the focus for the following expression, \e span. + + The focus can be accessed using the context item expression, i.e., + dot ("."). + + By default, the focus is not set and is undefined. It will + therefore result in a dynamic error, \c XPDY0002, if the focus + is attempted to be accessed. The focus must be set before the + query is set with setQuery(). + + There is no behavior defined for setting an item which is null. + + */ +void QXmlQuery::setFocus(const QXmlItem &item) +{ + d->contextItem = item; +} + +/** + * This function should be a private member function of QXmlQuery, + * but we don't dare that due to our weird compilers. + * @internal + * @relates QXmlQuery + */ +template<typename TInputType> +bool setFocusHelper(QXmlQuery *const queryInstance, + const TInputType &focusValue) +{ + /* We call resourceLoader(), so we have ensured that we have a resourceLoader + * that we will share in our copy. */ + queryInstance->d->resourceLoader(); + + QXmlQuery focusQuery(*queryInstance); + + /* Now we use the same, so we own the loaded document. */ + focusQuery.d->m_resourceLoader = queryInstance->d->m_resourceLoader; + + /* The copy constructor doesn't allow us to copy an existing QXmlQuery and + * changing the language at the same time so we need to use private API. */ + focusQuery.d->queryLanguage = QXmlQuery::XQuery10; + + Q_ASSERT(focusQuery.queryLanguage() == QXmlQuery::XQuery10); + focusQuery.bindVariable(QChar::fromLatin1('u'), focusValue); + focusQuery.setQuery(QLatin1String("doc($u)")); + Q_ASSERT(focusQuery.isValid()); + + QXmlResultItems focusResult; + + queryInstance->d->m_resourceLoader = focusQuery.d->m_resourceLoader; + + focusQuery.evaluateTo(&focusResult); + const QXmlItem focusItem(focusResult.next()); + + if(focusItem.isNull() || focusResult.hasError()) + return false; + else + { + queryInstance->setFocus(focusItem); + return true; + } +} + +/*! + \since 4.5 + \overload + + Sets the focus to be the document located at \a documentURI and + returns true. If \a documentURI cannot be loaded, false is returned. + It is undefined at what time the document may be loaded. When + loading the document, the message handler and URI resolver set on + this QXmlQuery are used. + + If \a documentURI is empty or is not a valid URI, the behavior of + this function is undefined. + */ +bool QXmlQuery::setFocus(const QUrl &documentURI) +{ + Q_ASSERT_X(documentURI.isValid() && !documentURI.isEmpty(), + Q_FUNC_INFO, + "The URI passed must be valid."); + + return setFocusHelper(this, QVariant(documentURI)); +} + +/*! + + Sets the focus to be the \a document read from the QIODevice and + returns true. If \a document cannot be loaded, false is returned. + + QXmlQuery does not take ownership of \a document. The user + guarantees that a document is available from the \a document device + and that the document is not empty. The device must be opened in at + least read-only mode. \a document must stay in scope as long as the + current query is active. + + \since 4.5 + \overload + */ +bool QXmlQuery::setFocus(QIODevice *document) +{ + if(!document) + { + qWarning("A null QIODevice pointer cannot be passed."); + return false; + } + + if(!document->isReadable()) + { + qWarning("The device must be readable."); + return false; + } + + return setFocusHelper(this, document); +} + +/*! + This function behaves identically to calling the setFocus() overload with a + QIODevice whose content is \a focus encoded as UTF-8. That is, \a focus is + treated as if it contained an XML document. + + Returns the same result as the overload. + + \overload + \since 4.6 + */ +bool QXmlQuery::setFocus(const QString &focus) +{ + QBuffer device; + device.setData(focus.toUtf8()); + device.open(QIODevice::ReadOnly); + + return setFocusHelper(this, &device); +} + +/*! + Returns a value indicating what this QXmlQuery is being used for. + The default is QXmlQuery::XQuery10, which means the QXmlQuery is + being used for running XQuery and XPath queries. QXmlQuery::XSLT20 + can also be returned, which indicates the QXmlQuery is for running + XSL-T spreadsheets. + + \since 4.5 + */ +QXmlQuery::QueryLanguage QXmlQuery::queryLanguage() const +{ + return d->queryLanguage; +} + +/*! + Sets the \a name of the initial template. The initial template is + the one the processor calls first, instead of attempting to match a + template to the context node (if any). If an initial template is not + set, the standard order of template invocation will be used. + + This function only applies when using QXmlQuery to process XSL-T + stylesheets. The name becomes part of the compiled stylesheet. + Therefore, this function must be called before calling setQuery(). + + If the stylesheet has no template named \a name, the processor will + use the standard order of template invocation. + + \since 4.5 + \sa initialTemplateName() + */ +void QXmlQuery::setInitialTemplateName(const QXmlName &name) +{ + d->initialTemplateName = name; +} + +/*! + \overload + + Sets the name of the initial template to \a localName, which must be + a valid \l{QXmlName::localName()} {local name}. The initial template + is the one the processor calls first, instead of attempting to match + a template to the context node (if any). If an initial template is + not set, the standard order of template invocation will be used. + + This function only applies when using QXmlQuery to process XSL-T + stylesheets. The name becomes part of the compiled stylesheet. + Therefore, this function must be called before calling setQuery(). + + If \a localName is not a valid \l{QXmlName::localName()} {local + name}, the effect is undefined. If the stylesheet has no template + named \a localName, the processor will use the standard order of + template invocation. + + \since 4.5 + \sa initialTemplateName() + */ +void QXmlQuery::setInitialTemplateName(const QString &localName) +{ + Q_ASSERT_X(QXmlName::isNCName(localName), + Q_FUNC_INFO, + "The name passed must be a valid NCName."); + setInitialTemplateName(QXmlName(d->namePool, localName)); +} + +/*! + Returns the name of the XSL-T stylesheet template that the processor + will call first when running an XSL-T stylesheet. This function only + applies when using QXmlQuery to process XSL-T stylesheets. By + default, no initial template is set. In that case, a default + constructed QXmlName is returned. + + \since 4.5 + */ +QXmlName QXmlQuery::initialTemplateName() const +{ + return d->initialTemplateName; +} + +/*! + Sets the network manager to \a newManager. + QXmlQuery does not take ownership of \a newManager. + + \sa networkAccessManager() + \since 4.5 + */ +void QXmlQuery::setNetworkAccessManager(QNetworkAccessManager *newManager) +{ + d->m_networkAccessDelegator->m_genericManager = newManager; +} + +/*! + Returns the network manager, or 0 if it has not been set. + + \sa setNetworkAccessManager() + \since 4.5 + */ +QNetworkAccessManager *QXmlQuery::networkAccessManager() const +{ + return d->m_networkAccessDelegator->m_genericManager; +} + +/*! + Binds the result of the query \a query, to a variable by name \a name. + + Evaluation of \a query will be commenced when this function is called. + + If \a query is invalid, behavior is undefined. \a query will be copied. + + \since 4.5 + \sa isValid() + */ +void QXmlQuery::bindVariable(const QXmlName &name, const QXmlQuery &query) +{ + Q_ASSERT_X(query.isValid(), Q_FUNC_INFO, "The query being bound must be valid."); + + const QPatternist::VariableLoader::Ptr vl(d->variableLoader()); + const QVariant variant(QVariant::fromValue(query)); + + if(vl->invalidationRequired(name, variant)) + d->recompileRequired(); + + vl->addBinding(name, variant); +} + +/*! + \overload + + Has the same behavior and effects as the function being overloaded, but takes + the variable name \a localName as a QString. \a query is used as in the + overloaded function. + + \since 4.5 + */ +void QXmlQuery::bindVariable(const QString &localName, const QXmlQuery &query) +{ + return bindVariable(QXmlName(d->namePool, localName), query); +} + +QT_END_NAMESPACE |