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Diffstat (limited to 'src/include/xbexp.h')
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diff --git a/src/include/xbexp.h b/src/include/xbexp.h new file mode 100755 index 0000000..96413ac --- /dev/null +++ b/src/include/xbexp.h @@ -0,0 +1,215 @@ +/* xbexp.h + +XBase64 Software Library + +Copyright (c) 1997,2003,2014,2022 Gary A Kunkel + +The xb64 software library is covered under the terms of the GPL Version 3, 2007 license. + +Email Contact: + + XDB-devel@lists.sourceforge.net + XDB-users@lists.sourceforge.net + +*/ + + +#ifndef __XB_EXP_H__ +#define __XB_EXP_H__ + + +// #ifdef CMAKE_COMPILER_IS_GNUCC +// #pragma interface +// #endif + + + +#ifdef XB_FUNCTION_SUPPORT +#define XB_EXP_CHAR 'C' +#define XB_EXP_DATE 'D' +#define XB_EXP_LOGICAL 'L' +#define XB_EXP_NUMERIC 'N' +#define XB_EXP_UNKNOWN 'U' +#endif + +#ifdef XB_EXPRESSION_SUPPORT + +#define XB_EXP_CONSTANT 'C' +#define XB_EXP_FUNCTION 'F' +#define XB_EXP_FIELD 'D' +#define XB_EXP_OPERATOR 'O' +#define XB_EXP_NOTROOT 'N' // not root node, needs further parsing +#define XB_EXP_PRE_OPERATOR 'B' // (B)efore) pre increment, pre decrement +#define XB_EXP_POST_OPERATOR 'A' // (A)fter) post increment, pre decrement + +#define XB_END_OF_EXPRESSION -100 + +// #define XB_UNBALANCED_PARENS -101 +// #define XB_UNBALANCED_QUOTES -102 + + +namespace xb{ + +///@cond DOXYOFF +struct XBDLLEXPORT xbExpToken { + xbString sExpression; // in - expression to pull next token from + // out - remainder of the expression after token removed + xbString sToken; // next token pulled from the expression + char cNodeType; // one of XB_EXP_CONSTANT, XB_EXP_FUNCTION, XB_EXP_FIELD, XB_EXP_OPERATOR, XB_EXP_NOTROOT + char cReturnType; // one of XB_EXP_CHAR, XB_EXP_DATE, XB_EXP_LOGICAL, XB_EXP_NUMERIC, XB_EXP_UNKNOWN + xbInt16 iSts; // return status after retrieving or attempting next token from expression + // 0 = no error + // XB_END_OF_EXPRESSION + // XB_UNBALANCED_PARENS + // XB_UNBALANCED_QUOTES + char cPrevNodeType; // previous node type + char cPrevReturnType; // previous return type + + // constructor + xbExpToken() { cNodeType = 0; cReturnType = 0; iSts = 0; cPrevNodeType = 0; cPrevReturnType = 0; } +}; +///@endcond DOXYOFF + + +/************************************************************************/ + +//! @brief Class for handling expressions. +/*! +The xbExp class is used for parsing and evaluating expression. + +The Xbase64 library includes an expression parsing module which assists +application programmers by providing a high level data manipulation tool and +also allows for building complex index keys. + +The functions included were derived from dBASE III Plus, Dbase IV and Clipper.<br><br> + +<h3>Internal fuctioning</h3> +The expression module works in two phases. Firstly, method +<em>ParseExpression</em> is called and builds an expression tree from +all the components of the expression. The tree is made up of individual +nodes. The expression is checked for valid field names, literals, +operands and functions. Any field references are resolved. If fields +are used in an expression and the database name for the field is not +included in the name with the -> operand, the routines assume the +associated database has been successfully opened. +<br> +Secondly, method <em>ProcessExpression</em> is called to process the +expression tree created by ParseExpression(). The routine parses each +node in the expression tree, executing functions, processing operands +and manipulating data to produce the desired result.<br> + +If an expression will be processed repeatedly, it is best to pre-parse the +tree using <em>ParseExpression</em>, then for each new call to the expression, +execute method <em>ProcessExpression</em> which processes the tree.<br><br> + +<h3>Expression Return Types</h3> +Expressions will return a type of CHAR, NUMERIC, DATE or LOGICAL.<br> + +An expression return type can be determined with method <em> +GetExpressionResultType</em> after parsing it.<br> + +Expressions returning a return type of CHAR are limited to a 200 byte internal +buffer. There is also a 100 byte limit for NDX index key support. If +the 200 byte limit is not large enough for your application, adjust field +<em>enum { WorkBufMaxLen = 200 };</em> in file <em>exp.h</em>.<br><br> + +<h3>Expression Functions</h3> +Each expression function also has a corresponding C++ function. It is +slightly more efficient to call the C++ functions directly, rather than +execute the expression parsing routines.<br><br> + +<h3>Expression Components</h3> +Expressions are made up of one or more tokens. A token is one of literal, +database field, operand or function. Literals are either numeric or character. +Character literals are enclosed in 'single' or "double" quotes. numeric +literals are a series of one or more contiguous numerals, ".", "+" or "-'". +<br><br> +A field is simply a field name in the default database, or is in the form +of database->fieldname. + +*/ + +class XBDLLEXPORT xbExp{ + + public: + xbExp( xbXBase * ); + xbExp( xbXBase *, xbDbf * ); + virtual ~xbExp(); + void ClearTreeHandle(); + + + #ifdef XB_DEBUG_SUPPORT + void DumpTree( xbInt16 iOption ); + void DumpToken( xbExpToken &t, xbInt16 iOption = 0 ); + #endif + + xbInt16 GetResultLen() const; + char GetReturnType() const; + xbInt16 GetBoolResult( xbBool &bResult ); + xbInt16 GetDateResult( xbDate &dtResult ); + xbInt16 GetNumericResult( xbDouble &dResult ); + xbInt16 GetStringResult( xbString &sResult ); + xbInt16 GetStringResult( char * vpResult, xbUInt32 ulLen ); + xbExpNode *GetTreeHandle(); + xbInt16 ParseExpression( const xbString &sExpression ); + xbInt16 ParseExpression( xbDbf *dbf, const xbString &sExpression ); + xbInt16 ProcessExpression(); + xbInt16 ProcessExpression( xbInt16 iRecBufSw ); + + + protected: + xbInt16 GetNextToken( xbExpToken &t ); + xbInt16 OperatorWeight( const xbString &sOperator ); + xbExpNode *GetNextNode( xbExpNode * n ) const; // traverses the tree from bottom left node, right, then up + + private: // methods + + // xbInt16 CalcExpressionResultLen(); + xbInt16 CalcFunctionResultLen( xbExpNode *n ) const; + xbInt16 CalcCharNodeLen( xbExpNode *n ); + xbInt16 CheckParensAndQuotes( const xbString &sExpression ); + xbInt16 GetExpressionResultLen() const; + + xbInt16 GetTokenCharConstant ( xbExpToken &t ); + xbInt16 GetTokenDatabaseField ( xbExpToken &t ); + xbInt16 GetTokenDateConstant ( xbExpToken &t ); + xbInt16 GetTokenFunction ( xbExpToken &t ); + xbInt16 GetTokenLogicalConstant( xbExpToken &t ); + xbInt16 GetTokenNumericConstant( xbExpToken &t ); + xbInt16 GetTokenOperator ( xbExpToken &t ); + xbInt16 GetTokenParen ( xbExpToken &t ); + + xbBool IsFunction ( const xbString &sExp, char &cReturnType ); + xbBool IsLogicalConstant ( const xbString &sExp ); + xbBool IsNumericConstant ( const xbString &sExp, char cPrevNodeType ); + xbBool IsOperator ( const xbString &sExp ); + char IsTokenSeparator ( char c ); + xbBool IsWhiteSpace ( char c ); + + xbInt16 ParseExpression ( const xbString &sExpression, xbInt16 iWeight ); + xbInt16 ParseExpressionConstant( xbExpToken &t, xbExpNode *n ); + xbInt16 ParseExpressionFunction( xbExpToken &t, xbExpNode *n, xbInt16 iWeight ); + xbInt16 ParseExpressionFunctionParms( const xbString &sParms, xbLinkList<xbString> &llParms ); + xbInt16 ParseExpressionField ( xbExpToken &t, xbExpNode *n ); + xbInt16 ParseExpressionOperator( xbExpToken &t, xbExpNode *n, xbInt16 iWeight ); + + xbInt16 ProcessExpressionFunction( xbExpNode *n, xbInt16 iRecBufSw = 0 ); + xbInt16 ProcessExpressionOperator( xbExpNode *n ); + + private: // fields + xbXBase *xbase; + xbDbf *dbf; + xbExpNode *nTree; // pointer to tree of expNodes + // xbInt16 iExpLen; // size of expression result + + +}; + +/* Expression handler */ + + +}; +#endif // XB_EXPRESSION_SUPPORT +#endif // __XB_EXP_H__ + + |