expression< Type > Class Template Reference

#include <expression.h>

List of all members.

Public Member Functions
void	push_parsers (grammar_to_parser::parsers &l)
Type	evaluate ()
Type	evaluate (Type left_result)
Type	get_left_value ()
int	get_priority ()
Protected Attributes
grammar_to_parser::non_terminal< add >	m_add
grammar_to_parser::non_terminal< substract >	m_substract
grammar_to_parser::non_terminal< multiply >	m_multiply
grammar_to_parser::non_terminal< divide >	m_divide
grammar_to_parser::choice< subexpression >	m_subexpr
Private Types
typedef std::string	std_string
enum	priorities { plus_minus = 0, multiply_divide = 1, fnc_value_parenthesis = 2 }

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Detailed Description

template<class Type>
class expression< Type >

The class demonstrates how to declare parser class from grammar deinition. For recognizing arithmetic expressions is defined following grammar: E->S+E | S-E | S*E | S/E | S S->(E) | value | functions

Then: E is declared as class expression S as 'subexpression' S+E as 'add' S-E as 'substract', etc. To support non_terminal parser type, the method push_parsers() must be implemented, which defines the order of embedded symbols, i.e. add is used as non_terminal<add> and consists of choice< expression<Type> > and terminal<'+'> and choice< expression<Type> >.

'Type' is used for value parser and is filled using istream::>> operator functionality - in example is used Type=float

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The documentation for this class was generated from the following file:

• expression.h

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