shiboken2: Enable documentation generation with libxml2/libxslt

As QtXmlPatterns is deprecated in Qt 5.14, the documentation build
needs to be changed to work with libxml2/libxslt exclusively.

Split the XML functionality into separate files for libxslt and Qt and
provide an interface for XPATH queries and XSLT transformations in
xmlutils.h.

Adapt testmodifydocumentation to work on temporary files as libxslt
cannot handle Qt resources.

Change-Id: I923f5b2e7c1d2511f15788e4b80c7721daeb2bc3
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

1 files changed, 231 insertions, 0 deletions

diff --git a/sources/shiboken2/ApiExtractor/xmlutils_libxslt.cpp b/sources/shiboken2/ApiExtractor/xmlutils_libxslt.cpp
new file mode 100644
index 000000000..e1e185130
--- /dev/null
+++ b/sources/shiboken2/ApiExtractor/xmlutils_libxslt.cpp
@@ -0,0 +1,231 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt for Python.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "xmlutils_libxslt.h"
+#include "xmlutils.h"
+
+#include <QtCore/QByteArray>
+#include <QtCore/QCoreApplication>
+#include <QtCore/QDir>
+#include <QtCore/QFile>
+#include <QtCore/QString>
+
+#include <libxslt/xsltutils.h>
+#include <libxslt/transform.h>
+
+#include <libxml/xmlsave.h>
+#include <libxml/xpath.h>
+
+#include <cstdlib>
+#include <memory>
+
+static void cleanup()
+{
+    xsltCleanupGlobals();
+    xmlCleanupParser();
+}
+
+static void ensureInitialized()
+{
+    static bool initialized = false;
+    if (!initialized) {
+        initialized = true;
+        xmlInitParser();
+        xsltInit();
+        qAddPostRoutine(cleanup);
+    }
+}
+
+namespace {
+
+// RAI Helpers for cleaning up libxml2/libxslt data
+
+struct XmlDocDeleter // for std::unique_ptr<xmlDoc>
+{
+    void operator()(xmlDocPtr xmlDoc) { xmlFreeDoc(xmlDoc); }
+};
+
+struct XmlXPathObjectDeleter
+{
+    void operator()(xmlXPathObjectPtr xPathObject) { xmlXPathFreeObject(xPathObject); }
+};
+
+struct XmlStyleSheetDeleter // for std::unique_ptr<xsltStylesheet>
+{
+    void operator()(xsltStylesheetPtr xslt) { xsltFreeStylesheet(xslt); }
+};
+
+struct XmlXPathContextDeleter
+{
+    void operator()(xmlXPathContextPtr xPathContext) { xmlXPathFreeContext(xPathContext); }
+};
+
+} // namespace
+
+using XmlDocUniquePtr = std::unique_ptr<xmlDoc, XmlDocDeleter>;
+using XmlPathObjectUniquePtr = std::unique_ptr<xmlXPathObject, XmlXPathObjectDeleter>;
+using XmlStyleSheetUniquePtr = std::unique_ptr<xsltStylesheet, XmlStyleSheetDeleter>;
+using XmlXPathContextUniquePtr = std::unique_ptr<xmlXPathContext, XmlXPathContextDeleter>;
+
+// Helpers for formatting nodes obtained from XPATH queries
+
+static int qbXmlOutputWriteCallback(void *context, const char *buffer, int len)
+{
+    static_cast<QByteArray *>(context)->append(buffer, len);
+    return len;
+}
+
+static int qbXmlOutputCloseCallback(void * /* context */) { return 0; }
+
+static QByteArray formatNode(xmlNodePtr node, QString *errorMessage)
+{
+    QByteArray result;
+    xmlSaveCtxtPtr saveContext =
+        xmlSaveToIO(qbXmlOutputWriteCallback, qbXmlOutputCloseCallback,
+                    &result, "UTF-8", 0);
+    if (!saveContext) {
+        *errorMessage = QLatin1String("xmlSaveToIO() failed.");
+        return result;
+    }
+    const long saveResult = xmlSaveTree(saveContext, node);
+    xmlSaveClose(saveContext);
+    if (saveResult < 0)
+        *errorMessage = QLatin1String("xmlSaveTree() failed.");
+    return result;
+}
+
+// XPath expressions
+class LibXmlXQuery : public XQuery
+{
+public:
+    explicit LibXmlXQuery(XmlDocUniquePtr &doc, XmlXPathContextUniquePtr &xpathContext) :
+       m_doc(std::move(doc)), m_xpathContext(std::move(xpathContext))
+    {
+        ensureInitialized();
+    }
+
+protected:
+    QString doEvaluate(const QString &xPathExpression, QString *errorMessage) override;
+
+private:
+    XmlDocUniquePtr m_doc;
+    XmlXPathContextUniquePtr m_xpathContext;
+};
+
+QString LibXmlXQuery::doEvaluate(const QString &xPathExpression, QString *errorMessage)
+{
+    const QByteArray xPathExpressionB = xPathExpression.toUtf8();
+    auto xPathExpressionX = reinterpret_cast<const xmlChar *>(xPathExpressionB.constData());
+
+    XmlPathObjectUniquePtr xPathObject(xmlXPathEvalExpression(xPathExpressionX, m_xpathContext.get()));
+    if (!xPathObject) {
+         *errorMessage = QLatin1String("xmlXPathEvalExpression() failed for \"") + xPathExpression
+                         + QLatin1Char('"');
+        return QString();
+    }
+    QString result;
+    if (xmlNodeSetPtr nodeSet = xPathObject->nodesetval) {
+        for (int n = 0, count = nodeSet->nodeNr; n < count; ++n) {
+            auto node = nodeSet->nodeTab[n];
+            if (node->type == XML_ELEMENT_NODE) {
+                result += QString::fromLocal8Bit(formatNode(node, errorMessage));
+                if (!errorMessage->isEmpty())
+                    return QString();
+            }
+        }
+    }
+    return result;
+}
+
+QSharedPointer<XQuery> libXml_createXQuery(const QString &focus, QString *errorMessage)
+{
+    XmlDocUniquePtr doc(xmlParseFile(QFile::encodeName(focus).constData()));
+    if (!doc) {
+        *errorMessage = QLatin1String("libxml2: Cannot set focus to ") + QDir::toNativeSeparators(focus);
+        return {};
+    }
+    XmlXPathContextUniquePtr xpathContext(xmlXPathNewContext(doc.get()));
+    if (!xpathContext) {
+        *errorMessage = QLatin1String("libxml2: xmlXPathNewContext() failed");
+        return {};
+    }
+    return QSharedPointer<XQuery>(new LibXmlXQuery(doc, xpathContext));
+}
+
+// XSLT transformation
+
+static const char xsltPrefix[] = R"(<?xml version="1.0" encoding="UTF-8" ?>
+    <xsl:transform version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
+)";
+
+QString libXslt_transform(const QString &xml, QString xsl, QString *errorMessage)
+{
+    ensureInitialized();
+    // Read XML data
+    if (!xsl.startsWith(QLatin1String("<?xml"))) {
+        xsl.prepend(QLatin1String(xsltPrefix));
+        xsl.append(QLatin1String("</xsl:transform>"));
+    }
+    const QByteArray xmlData = xml.toUtf8();
+    XmlDocUniquePtr xmlDoc(xmlParseMemory(xmlData.constData(), xmlData.size()));
+    if (!xmlDoc) {
+        *errorMessage = QLatin1String("xmlParseMemory() failed for XML.");
+        return xml;
+    }
+
+    // Read XSL data as a XML file
+    const QByteArray xslData = xsl.toUtf8();
+    // xsltFreeStylesheet will delete this pointer
+    xmlDocPtr xslDoc = xmlParseMemory(xslData.constData(), xslData.size());
+    if (!xslDoc) {
+        *errorMessage = QLatin1String("xmlParseMemory() failed for XSL \"")
+            + xsl + QLatin1String("\".");
+        return xml;
+    };
+
+    // Parse XSL data
+    XmlStyleSheetUniquePtr xslt(xsltParseStylesheetDoc(xslDoc));
+    if (!xslt) {
+        *errorMessage = QLatin1String("xsltParseStylesheetDoc() failed.");
+        return xml;
+    }
+
+    // Apply XSL
+    XmlDocUniquePtr xslResult(xsltApplyStylesheet(xslt.get(), xmlDoc.get(), nullptr));
+    xmlChar *buffer = nullptr;
+    int bufferSize;
+    QString result;
+    if (xsltSaveResultToString(&buffer, &bufferSize, xslResult.get(), xslt.get()) == 0) {
+        result = QString::fromUtf8(reinterpret_cast<char*>(buffer), bufferSize);
+        std::free(buffer);
+    } else {
+        *errorMessage = QLatin1String("xsltSaveResultToString() failed.");
+        result = xml;
+    }
+    return result.trimmed();
+}