greenplumn CParseHandlerScalarLimitOffset 源码

  • 2022-08-18
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greenplumn CParseHandlerScalarLimitOffset 代码

文件路径:/src/backend/gporca/libnaucrates/src/parser/CParseHandlerScalarLimitOffset.cpp

//---------------------------------------------------------------------------
//	Greenplum Database
//	Copyright (C) 2011 Greenplum, Inc.
//
//	@filename:
//		CParseHandlerScalarLimitOffset.cpp
//
//	@doc:
//		Implementation of the SAX parse handler class for parsing LimitOffset
//
//---------------------------------------------------------------------------

#include "naucrates/dxl/parser/CParseHandlerScalarLimitOffset.h"

#include "naucrates/dxl/operators/CDXLOperatorFactory.h"
#include "naucrates/dxl/operators/CDXLScalarLimitOffset.h"
#include "naucrates/dxl/parser/CParseHandlerFactory.h"
#include "naucrates/dxl/parser/CParseHandlerScalarOp.h"


using namespace gpdxl;


XERCES_CPP_NAMESPACE_USE

//---------------------------------------------------------------------------
//	@function:
//		CParseHandlerScalarLimitOffset::CParseHandlerScalarLimitOffset
//
//	@doc:
//		Constructor
//
//---------------------------------------------------------------------------
CParseHandlerScalarLimitOffset::CParseHandlerScalarLimitOffset(
	CMemoryPool *mp, CParseHandlerManager *parse_handler_mgr,
	CParseHandlerBase *parse_handler_root)
	: CParseHandlerScalarOp(mp, parse_handler_mgr, parse_handler_root)
{
}


//---------------------------------------------------------------------------
//	@function:
//		CParseHandlerScalarLimitOffset::StartElement
//
//	@doc:
//		Invoked by Xerces to process an opening tag
//
//---------------------------------------------------------------------------
void
CParseHandlerScalarLimitOffset::StartElement(
	const XMLCh *const element_uri, const XMLCh *const element_local_name,
	const XMLCh *const element_qname, const Attributes &attrs)
{
	if (0 == XMLString::compareString(
				 CDXLTokens::XmlstrToken(EdxltokenScalarLimitOffset),
				 element_local_name))
	{
		// parse and create scalar OpExpr
		CDXLScalarLimitOffset *dxl_op =
			(CDXLScalarLimitOffset *) CDXLOperatorFactory::MakeDXLLimitOffset(
				m_parse_handler_mgr->GetDXLMemoryManager(), attrs);
		m_dxl_node = GPOS_NEW(m_mp) CDXLNode(m_mp, dxl_op);
	}
	else
	{
		// we must have seen a LIMITOffset already and initialized its corresponding node
		if (nullptr == m_dxl_node)
		{
			CWStringDynamic *str = CDXLUtils::CreateDynamicStringFromXMLChArray(
				m_parse_handler_mgr->GetDXLMemoryManager(), element_local_name);
			GPOS_RAISE(gpdxl::ExmaDXL, gpdxl::ExmiDXLUnexpectedTag,
					   str->GetBuffer());
		}
		// install a scalar element parser for parsing the limit offset element
		CParseHandlerBase *child_parse_handler =
			CParseHandlerFactory::GetParseHandler(
				m_mp, CDXLTokens::XmlstrToken(EdxltokenScalar),
				m_parse_handler_mgr, this);
		m_parse_handler_mgr->ActivateParseHandler(child_parse_handler);

		// store parse handler
		this->Append(child_parse_handler);

		child_parse_handler->startElement(element_uri, element_local_name,
										  element_qname, attrs);
	}
}

//---------------------------------------------------------------------------
//	@function:
//		CParseHandlerScalarLimitOffset::EndElement
//
//	@doc:
//		Processes a Xerces end element event
//
//---------------------------------------------------------------------------
void
CParseHandlerScalarLimitOffset::EndElement(
	const XMLCh *const,	 // element_uri,
	const XMLCh *const element_local_name,
	const XMLCh *const	// element_qname
)
{
	if (0 != XMLString::compareString(
				 CDXLTokens::XmlstrToken(EdxltokenScalarLimitOffset),
				 element_local_name))
	{
		CWStringDynamic *str = CDXLUtils::CreateDynamicStringFromXMLChArray(
			m_parse_handler_mgr->GetDXLMemoryManager(), element_local_name);
		GPOS_RAISE(gpdxl::ExmaDXL, gpdxl::ExmiDXLUnexpectedTag,
				   str->GetBuffer());
	}

	const ULONG size = this->Length();
	if (0 < size)
	{
		GPOS_ASSERT(1 == size);
		// limit Offset node was not empty
		CParseHandlerScalarOp *child_parse_handler =
			dynamic_cast<CParseHandlerScalarOp *>((*this)[0]);

		AddChildFromParseHandler(child_parse_handler);
	}

	// deactivate handler
	m_parse_handler_mgr->DeactivateHandler();
}

// EOF

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