orxonox::ExprParser Class Reference

Parser for expressions like "3 * cos(5 + 4) / a" where a is a predeclared variable. More...

#include </home/jenkins/workspace/orxonox_doxygen_trunk/src/libraries/util/ExprParser.h>

Public Types
enum	binary_operator {   b_plus, b_minus, mal, durch,   modulo, hoch, undef, oder,   und, gleich, b_nicht, kleiner,   groesser, ungleich, kleinergleich, groessergleich }
enum	unary_operator { u_plus, u_minus, u_nicht }

Public Member Functions
	ExprParser ()
const std::string &	getRemains ()
float	getResult ()
bool	getSuccess ()
void	parse (const std::string &str)
void	setVariable (const std::string &varname, float value)

Private Member Functions
float	parse_argument ()
binary_operator	parse_binary_operator ()
float	parse_expr_1 ()
float	parse_expr_2 ()
float	parse_expr_3 ()
float	parse_expr_4 ()
float	parse_expr_5 ()
float	parse_expr_6 ()
float	parse_expr_7 ()
float	parse_expr_8 ()
float	parse_last_argument ()
unary_operator	parse_unary_operator ()
void	parse_word (char *str)

Private Attributes
bool	failed_
binary_operator	op
const char *	reading_stream
std::string	remains_
float	result_
std::map< std::string, float >	variables_

Detailed Description

Parser for expressions like "3 * cos(5 + 4) / a" where a is a predeclared variable.

Usage

Using it is rather simple:

std::string str("3 + 4");
ExprParser expr;
expr.parse(str);
if (expr.getSuccess())
{
    if (!expr.getRemains().empty())
    {
        orxout(user_warning) << "Expression could not be parsed to the end! Remains: '" << expr.getRemains() << '\'' << endl;
    }
    float result = expr.getResult();
}
else
    orxout(user_error) << "Cannot calculate expression: Parse error." << endl;

getRemains() returns the expression after what could be parsed. For instance "2*3 text" will return "text" as remains.

The implementation of this class is really old and sort of a trial for
a first C++ class by Reto. That explains why it looks more like C than
C++... Also some of the variable names are in German. <br>
Explaining how it works exactly is probably not possible anymore, but it
is based on recursively parsing the expression character by character.
That much I can remember.

Functions, operators and variables supported

• Variables:
  • e
  • pi
• Functions:
  • sin, asin, sinh, asinh
  • cos, acos, cosh, acosh
  • tan, atan, tanh, atanh
  • int, floor, ceil, abs, sign
  • pow, sqrt, exp, ln, log
  • mod, div
  • min, max
  • radians, degrees
• Operators:
  • +, -, ! (unary)
  • +, -, *, /, %, ^, |, &, !, <, >, !=, <=, >=, =

Note

Operators may not be very consistent with C++ rules, but using the class for plus and minus should be perfectly ok.

Member Enumeration Documentation

enum orxonox::ExprParser::binary_operator

Enumerator
b_plus
b_minus
mal
durch
modulo
hoch
undef
oder
und
gleich
b_nicht
kleiner
groesser
ungleich
kleinergleich
groessergleich

enum orxonox::ExprParser::unary_operator

Enumerator
u_plus
u_minus
u_nicht

Constructor & Destructor Documentation

orxonox::ExprParser::ExprParser

(

)

Member Function Documentation

const std::string& orxonox::ExprParser::getRemains ( )

inline

float orxonox::ExprParser::getResult ( )

inline

bool orxonox::ExprParser::getSuccess ( )

inline

void orxonox::ExprParser::parse

(

const std::string &

str

)

float orxonox::ExprParser::parse_argument ( )

private

ExprParser::binary_operator orxonox::ExprParser::parse_binary_operator ( )

private

float orxonox::ExprParser::parse_expr_1 ( )

private

float orxonox::ExprParser::parse_expr_2 ( )

private

float orxonox::ExprParser::parse_expr_3 ( )

private

float orxonox::ExprParser::parse_expr_4 ( )

private

float orxonox::ExprParser::parse_expr_5 ( )

private

float orxonox::ExprParser::parse_expr_6 ( )

private

float orxonox::ExprParser::parse_expr_7 ( )

private

float orxonox::ExprParser::parse_expr_8 ( )

private

float orxonox::ExprParser::parse_last_argument ( )

private

ExprParser::unary_operator orxonox::ExprParser::parse_unary_operator ( )

private

void orxonox::ExprParser::parse_word ( char *  str )

private

void orxonox::ExprParser::setVariable	(	const std::string &	varname,
		float	value
	)

Member Data Documentation

bool orxonox::ExprParser::failed_

private

binary_operator orxonox::ExprParser::op

private

const char* orxonox::ExprParser::reading_stream

private

std::string orxonox::ExprParser::remains_

private

float orxonox::ExprParser::result_

private

std::map<std::string, float> orxonox::ExprParser::variables_

private

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

• libraries/util/ExprParser.h
• libraries/util/ExprParser.cc