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//
// NamespaceSupport.h
//
// Library: XML
// Package: SAX
// Module: SAX
//
// Namespace support for SAX2.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef SAX_NamespaceSupport_INCLUDED
#define SAX_NamespaceSupport_INCLUDED
#include "Poco/XML/XML.h"
#include "Poco/XML/XMLString.h"
#include <set>
#include <map>
#include <vector>
namespace Poco {
namespace XML {
class XML_API NamespaceSupport
/// Encapsulate Namespace logic for use by SAX drivers.
/// This class encapsulates the logic of Namespace processing:
/// it tracks the declarations currently in force for each context and
/// automatically processes qualified XML 1.0 names into their Namespace
/// parts; it can also be used in reverse for generating
/// XML 1.0 from Namespaces.
/// Namespace support objects are reusable, but the reset method
/// must be invoked between each session.
{
public:
typedef std::set<XMLString> PrefixSet;
NamespaceSupport();
/// Creates a NamespaceSupport object.
~NamespaceSupport();
/// Destroys a NamespaceSupport object.
bool declarePrefix(const XMLString& prefix, const XMLString& namespaceURI);
/// Declare a Namespace prefix. All prefixes must be declared before they are
/// referenced. For example, a SAX driver (parser) would scan an element's attributes
/// in two passes: first for namespace declarations, then a second pass using
/// processName() to interpret prefixes against (potentially redefined) prefixes.
///
/// This method declares a prefix in the current Namespace context; the prefix
/// will remain in force until this context is popped, unless it is shadowed
/// in a descendant context.
///
/// To declare the default element Namespace, use the empty string as the prefix.
///
/// Note that you must not declare a prefix after you've pushed and popped another
/// Namespace context, or treated the declarations phase as complete by processing
/// a prefixed name.
///
/// Returns true if the prefix was legal, false otherwise.
bool undeclarePrefix(const XMLString& prefix);
/// Remove the given namespace prefix.
void getDeclaredPrefixes(PrefixSet& prefixes) const;
/// Return an enumeration of all prefixes declared in this context.
///
/// The empty (default) prefix will be included in this enumeration; note that
/// this behaviour differs from that of getPrefix() and getPrefixes().
const XMLString& getPrefix(const XMLString& namespaceURI) const;
/// Return one of the prefixes mapped to a Namespace URI.
///
/// If more than one prefix is currently mapped to the same URI, this method
/// will make an arbitrary selection; if you want all of the prefixes, use the
/// getPrefixes() method instead.
bool isMapped(const XMLString& namespaceURI) const;
/// Returns true if the given namespaceURI has been mapped to a prefix,
/// false otherwise.
void getPrefixes(PrefixSet& prefixes) const;
/// Return an enumeration of all prefixes whose declarations are active in the
/// current context. This includes declarations from parent contexts that have
/// not been overridden.
///
/// Note: if there is a default prefix, it will not be returned in this enumeration;
/// check for the default prefix using the getURI with an argument of "".
void getPrefixes(const XMLString& namespaceURI, PrefixSet& prefixes) const;
/// Return an enumeration of all prefixes for a given URI whose declarations
/// are active in the current context. This includes declarations from parent
/// contexts that have not been overridden.
///
/// This method returns prefixes mapped to a specific Namespace URI. The xml:
/// prefix will be included. If you want only one prefix that's mapped to the
/// Namespace URI, and you don't care which one you get, use the getPrefix() method
/// instead.
///
/// Note: the empty (default) prefix is never included in this enumeration;
/// to check for the presence of a default Namespace, use the getURI() method
/// with an argument of "".
const XMLString& getURI(const XMLString& prefix) const;
/// Look up a prefix and get the currently-mapped Namespace URI.
///
/// This method looks up the prefix in the current context. Use the empty string
/// ("") for the default Namespace.
void pushContext();
/// Start a new Namespace context. The new context will automatically inherit
/// the declarations of its parent context, but it will also keep track of which
/// declarations were made within this context.
///
/// Event callback code should start a new context once per element. This means
/// being ready to call this in either of two places. For elements that don't
/// include namespace declarations, the ContentHandler::startElement() callback
/// is the right place. For elements with such a declaration, it'd done in the
/// first ContentHandler::startPrefixMapping() callback. A boolean flag can be
/// used to track whether a context has been started yet. When either of those
/// methods is called, it checks the flag to see if a new context needs to be
/// started. If so, it starts the context and sets the flag. After
/// ContentHandler::startElement() does that, it always clears the flag.
///
/// Normally, SAX drivers would push a new context at the beginning of each
/// XML element. Then they perform a first pass over the attributes to process
/// all namespace declarations, making ContentHandler::startPrefixMapping() callbacks.
/// Then a second pass is made, to determine the namespace-qualified names for
/// all attributes and for the element name. Finally all the information for
/// the ContentHandler::startElement() callback is available, so it can then
/// be made.
///
/// The Namespace support object always starts with a base context already in
/// force: in this context, only the "xml" prefix is declared.
void popContext();
/// Revert to the previous Namespace context.
///
/// Normally, you should pop the context at the end of each XML element. After
/// popping the context, all Namespace prefix mappings that were previously
/// in force are restored.
///
/// You must not attempt to declare additional Namespace prefixes after popping
/// a context, unless you push another context first.
bool processName(const XMLString& qname, XMLString& namespaceURI, XMLString& localName, bool isAttribute) const;
/// Process a raw XML 1.0 name.
/// This method processes a raw XML 1.0 name in the current context
/// by removing the prefix and looking it up among the
/// prefixes currently declared. The result will be returned in
/// namespaceURI and localName.
/// If the raw name has a prefix that has not been declared, then the return
/// value will be false, otherwise true.
///
/// Note that attribute names are processed differently than element names:
/// an unprefixed element name will receive the
/// default Namespace (if any), while an unprefixed attribute name will not.
void reset();
/// Reset this Namespace support object for reuse.
///
/// It is necessary to invoke this method before reusing the Namespace support
/// object for a new session. If namespace declaration URIs are to be supported,
/// that flag must also be set to a non-default value.
/// Reset this Namespace support object for reuse.
static const XMLString XML_NAMESPACE;
static const XMLString XML_NAMESPACE_PREFIX;
static const XMLString XMLNS_NAMESPACE;
static const XMLString XMLNS_NAMESPACE_PREFIX;
private:
NamespaceSupport(const NamespaceSupport&);
NamespaceSupport& operator = (const NamespaceSupport&);
typedef std::map<XMLString, XMLString> Context;
typedef std::vector<Context> ContextVec;
ContextVec _contexts;
static const XMLString EMPTY_STRING;
};
} } // namespace Poco::XML
#endif // SAX_NamespaceSupport_INCLUDED
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