Method 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 StartElement(String, String, String, IAttributes) callback is the right place. For elements with such a declaration, it'd done in the first StartPrefixMapping(String, String) 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 StartElement(String, String, String, IAttributes) 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 StartPrefixMapping(String, String) 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 StartElement(String, String, String, IAttributes) 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.