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