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ALXParser - a single expression dBase parser

, 9 Oct 2002
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A dBASE syntax parser of one expression. Functions and variables are supported.

Example of use parser

Introduction

This is a dBASE language parser with support of functions, variables, evaluation and processing of mistakes. The parser was was written by me and is contained in the CALXParser class. 

The process of calculation is broken on two stages: 

  1. syntactic analysis and filling of structures necessary for calculation, 
  2. execution of the prepared script. 

It has allowed a reduction in execution time when using the parser in the big cycles.

Base methods

These methods are necessary to get the results of analysis of expression.

void Parse(LPCSTR lpszExpression);
VARIANT* Execute();

Methods for work with variables

These methods are intended for definition of variables or change of values.

BOOL AddVariable(LPCSTR szName, VARIANT& varValue);
BOOL DelVariable(LPCSTR szName);
void DelUnusedVariables(LPCSTR szName);

BOOL SetVariableValue(LPCSTR szName, VARIANT& varValue);
BOOL SetVariableValue(VARIANT& varValue);
BOOL GetVariableValue(LPCSTR szName, VARIANT& varValue);
BOOL GetVariableValue(VARIANT& varValue);

LPCSTR GetFirstVariableName();
LPCSTR GetNextVariableName();	

Example

Example of use.

// pointer on result
VARIANT* pvarResult = NULL;

try
{
	// prepare script
	m_Parser.Parse(strExpression);
	// execute script
	pvarResult = m_Parser.Execute();
}
catch(CALXParserException* e)
{
	// processing of errors
	for(int i = 0; i < e->GetErrorCount(); i++)
	{
		e->GetErrorInfo(i);
		e->ReportError();
	}
	e->Delete();
	return;
}

// work with result
// ...

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

Alexey
Web Developer
Russian Federation Russian Federation
Year of birth - 1974.
Eeducation - was ended by Kaliningrad State University in 1997.
Now I work as the engineer-programmer in Kaliningrad (RUSSIA).

Comments and Discussions

 
GeneralSuper!!! Pinmemberins526-Jul-09 9:43 
Generalwhy you did now give a complete NFA and DFA diagram PinmemberMuhammad Rizwan Arif18-Dec-03 3:33 
GeneralRe: why you did now give a complete NFA and DFA diagram PinmemberAlexey18-Dec-03 4:43 
GeneralGreat job! PinmemberHolger Persch3-Sep-02 23:38 

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