//---------------------------------------------------------------------------
//	Greenplum Database
//	Copyright (C) 2010 Greenplum, Inc.
//
//	@filename:
//		CParseHandlerBase.h
//
//	@doc:
//		Base SAX parse handler class for DXL documents
//---------------------------------------------------------------------------

#ifndef GPDXL_CParseHandlerBase_H
#define GPDXL_CParseHandlerBase_H

#include <xercesc/sax2/DefaultHandler.hpp>

#include "gpos/base.h"

#include "naucrates/dxl/CDXLUtils.h"
#include "naucrates/dxl/operators/CDXLNode.h"
#include "naucrates/exception.h"

namespace gpdxl
{
using namespace gpos;

// fwd decl
class CParseHandlerManager;
class CParseHandlerBase;

// dynamic arrays of parse handlers
using CParseHandlerBaseArray =
	CDynamicPtrArray<CParseHandlerBase, CleanupDelete>;

XERCES_CPP_NAMESPACE_USE

// DXL parse handler type. Currently we only annotate the top-level parse handlers
// for the top-level DXL elements such as Plan, Query and Metadata
enum EDxlParseHandlerType
{
	EdxlphOptConfig,
	EdxlphEnumeratorConfig,
	EdxlphStatisticsConfig,
	EdxlphCTEConfig,
	EdxlphHint,
	EdxlphPlanHint,
	EdxlphWindowOids,
	EdxlphTraceFlags,
	EdxlphPlan,
	EdxlphQuery,
	EdxlphMetadata,
	EdxlphMetadataRequest,
	EdxlphStatistics,
	EdxlphSearchStrategy,
	EdxlphCostParams,
	EdxlphCostParam,
	EdxlphScalarExpr,
	EdxlphOther
};
//---------------------------------------------------------------------------
//	@class:
//		CParseHandlerBase
//
//	@doc:
//		Base SAX parse handler class for parsing DXL documents.
//		Implements Xerces required interface for SAX parse handlers.
//
//---------------------------------------------------------------------------
class CParseHandlerBase : public DefaultHandler
{
private:
	// array of parse handlers for child elements
	CParseHandlerBaseArray *m_parse_handler_base_array;

protected:
	// memory pool to create DXL objects in
	CMemoryPool *m_mp;

	// manager for transitions between parse handlers
	CParseHandlerManager *m_parse_handler_mgr;

	// add child parse handler
	inline void
	Append(CParseHandlerBase *parse_handler_base)
	{
		GPOS_ASSERT(nullptr != parse_handler_base);
		m_parse_handler_base_array->Append(parse_handler_base);
	};

	// number of children
	inline ULONG
	Length() const
	{
		return m_parse_handler_base_array->Size();
	}

	// shorthand to access children
	inline CParseHandlerBase *
	operator[](ULONG idx) const
	{
		return (*m_parse_handler_base_array)[idx];
	};

	// parse handler for root element
	CParseHandlerBase *m_parse_handler_root;

	// process the start of an element
	virtual void StartElement(
		const XMLCh *const element_uri,			// URI of element's namespace
		const XMLCh *const element_local_name,	// local part of element's name
		const XMLCh *const element_qname,		// element's qname
		const Attributes &attr					// element's attributes
		) = 0;

	// process the end of an element
	virtual void EndElement(
		const XMLCh *const element_uri,			// URI of element's namespace
		const XMLCh *const element_local_name,	// local part of element's name
		const XMLCh *const element_qname		// element's qname
		) = 0;

public:
	CParseHandlerBase(const CParseHandlerBase &) = delete;

	// ctor
	CParseHandlerBase(CMemoryPool *mp, CParseHandlerManager *parse_handler_mgr,
					  CParseHandlerBase *parse_handler_root);

	//dtor
	~CParseHandlerBase() override;

	virtual EDxlParseHandlerType GetParseHandlerType() const;

	// replaces a parse handler in the parse handler array with a new one
	void ReplaceParseHandler(CParseHandlerBase *parse_handler_base_old,
							 CParseHandlerBase *parse_handler_base_new);

	// Xerces parse handler interface method to eceive notification of the beginning of an element.
	void startElement(
		const XMLCh *const element_uri,			// URI of element's namespace
		const XMLCh *const element_local_name,	// local part of element's name
		const XMLCh *const element_qname,		// element's qname
		const Attributes &attr					// element's attributes
		) override;

	// Xerces parse handler interface method to eceive notification of the end of an element.
	void endElement(
		const XMLCh *const element_uri,			// URI of element's namespace
		const XMLCh *const element_local_name,	// local part of element's name
		const XMLCh *const element_qname		// element's qname
		) override;

	// process a parsing ProcessError
	void error(const SAXParseException &) override;
};
}  // namespace gpdxl

#endif	// !GPDXL_CParseHandlerBase_H

// EOF