Evaluates mathematical expressions. More...

#include <ec_engine.h>

Public Member Functions
wxArrayString	GetLog ()

	wxEcEngine ()

	~wxEcEngine ()

wxString	GetFormula ()

wxString	GetIndicator ()

int	GetLastError ()

double	GetLastResult ()

wxString	TranslateError (int code)

int	GetTrigonometricMode ()

void	SetTrigonometricMode (int trigmode)

void	Reset (bool formulaToo, bool constantsToo)

bool	DeleteConstant (wxString name)

bool	GetConstant (wxString expression, double *destination)

bool	GetConstant (wxString expression, double *destination, double defaultval)

bool	HasConstant (wxString expression)

int	GetConstantCount ()

bool	ListAllConstants (wxControlWithItems *destination, bool full=true)

bool	ListAllConstants (wxArrayString *destination, bool full=true)

bool	SetConstant (wxString name, wxDouble value)

void	ResetConstants (bool pDefault=true)

bool	ApplyFunction (wxString function, double value)

double	Compute ()

bool	Derivate (double where, double result, double storewhere=NULL)

bool	IsValid (wxString *expression)

bool	SetFormula (wxString expression)

void	Simplify (wxString *expression)

void	UseDebug (bool state)

Detailed Description

Evaluates mathematical expressions.

When the object is created, the radian mode is activated and you can compute directly. To do it, see the sample written on the main page of this documentation.

Constructor & Destructor Documentation

wxEcEngine::wxEcEngine ( )

The default constructor which takes no parameter.

wxEcEngine::~wxEcEngine ( )

The default destructor.

Member Function Documentation

bool wxEcEngine::ApplyFunction	(	wxString *	function,
		double *	value
	)

Applies a function on the given value.

Parameters

function	The pointer to the name of the function.
value	The pointer to the value which will be read and overwritten.

Returns: true on success, false if the function is unknown or not defined for the given value.

double wxEcEngine::Compute ( )

Evaluates the mathematical expression you have set with SetFormula(). To be sure of the result you must call GetLastError().

Returns: The result of the computation. Zero is the default value if it failed.

See also: GetLastResult()

bool wxEcEngine::DeleteConstant ( wxString name )

Deletes a constant.

Parameters

name	The name of the constant.

Returns: true on success, false on failure.

bool wxEcEngine::Derivate	(	double	where,
		double *	result,
		double *	storewhere = `NULL`
	)

Performs an approximation of the derivative of the loaded expression at a given point.

Parameters

where	The X-coordinate which must be evaluated.
result	The pointer to the floating number which will contain df(x)/dx. It must be valid.
storewhere	A pointer to store f(x) as a floating number.

Returns: true on success, false on failure (see GetLastError() to know more about).

See also: wxEcEngine::SetFormula(); wxECD_DXSTEP

bool wxEcEngine::GetConstant	(	wxString	expression,
		double *	destination
	)

Converts a constant or a floating number encoded as a wxString, and stores it into the destination.

Parameters

expression	Input to convert.
destination	Pointer to a double where to store the value.

Returns: true if the constant is found and converted, false if it is neither a valid constant nor a floating number.

Remarks: This function can be seen as a "wxString to Double converter". If wxString is the name of a constant, it will look for its value. Else it tries to convert into double in the destination.

bool wxEcEngine::GetConstant	(	wxString	expression,
		double *	destination,
		double	defaultval
	)

Variant method allowing to return a default value when the expression cannot be interpreted.

int wxEcEngine::GetConstantCount ( )

Gives the number of constants currently defined.

wxString wxEcEngine::GetFormula ( )

Reads the formula currently stored by the object.

See also: SetFormula()

wxString wxEcEngine::GetIndicator ( )

Returns the tip associated with the latest error. It helps you to track down a problem when GetLastError() does not return wxECE_NOERROR.

int wxEcEngine::GetLastError ( )

Returns the latest error obtained with Compute().

Returns: wxECE_NOERROR if no error occured.

See also: ec_defs.h; GetIndicator(); TranslateError()

double wxEcEngine::GetLastResult ( )

Returns the latest result obtained with Compute().

See also: GetLastError()

wxArrayString wxEcEngine::GetLog ( )

Returns the log generated by the evaluation of the formula.

Remarks: This function is only available if wxECM_USEDEBUG is defined. To use it, code like this :
#ifdef wxECM_USEDEBUG

wxArrayString myLog = myEngine->GetLog();

#endif

See also: wxECM_USEDEBUG

int wxEcEngine::GetTrigonometricMode ( )

inline

Returns the trigonometric mode used for cosine, sine and tangent.

Returns: The current mode. wxECA_RADIAN should be the default value.

See also: ec_defs.h

bool wxEcEngine::HasConstant ( wxString expression )

Tells if the expression exists as a variable or a number.

Parameters

expression Input to look for.

Returns: true if the constant is found and converted, false if it is neither a valid constant nor a floating number.

bool wxEcEngine::IsValid ( wxString * expression )

Checks the validity of an expression. The method is based on a set of criteria, such as the number of brackets. The symbols used in the expression will not be validated.

Parameters

expression A pointer to the expression to check.

Returns: true if the expression appears logically correct, false in the other cases.

bool wxEcEngine::ListAllConstants	(	wxControlWithItems *	destination,
		bool	full = `true`
	)

Makes a dump of all the constants into a wxControlWithItems, it can be wxListBox, wxComboBox...

Parameters

destination	A pointer to the control which will receive the data.
full	Tells if the value should also be included.

Returns: true on success, false on failure.

Remarks: If the result is true, it does not presume that at least 1 item has been added. You have to make sure on your own.

bool wxEcEngine::ListAllConstants	(	wxArrayString *	destination,
		bool	full = `true`
	)

Makes a dump of all the constants into a wxArrayString.

Parameters

destination	A pointer to the array which will receive the data.
full	Tells if the value should also be included.

Returns: true on success, false on failure.

Remarks: This function has to be used for non-GUI applications.

void wxEcEngine::Reset	(	bool	formulaToo,
		bool	constantsToo
	)

Resets the engine.

Parameters

formulaToo	Will clear the formula set with SetFormula().
constantsToo	Will restore the default constants.

void wxEcEngine::ResetConstants ( bool pDefault = true )

Deletes all the constants, and sets the default ones if requested.

bool wxEcEngine::SetConstant	(	wxString	name,
		wxDouble	value
	)

Defines a new constant. If the constant already exists, it will be overwritten.

Warning: The name of the constant cannot begin with a figure

Parameters

name	The name of the new constant.
value	The value of the new constant.

Returns: true if the constant has been (re)defined, false on failure.

bool wxEcEngine::SetFormula ( wxString expression )

Stores the internal formula which will be used for all the computations. If the formula is rejected, wxECE_SYNTAX will be returned by GetLastError().

Remarks: The expression will be simplified and checked before being stored.

Parameters

expression The formula you want to use.

Returns: true if the formula is accepted, false if it is rejected.

void wxEcEngine::SetTrigonometricMode ( int trigmode )

inline

Sets the trigonometric mode to be used for cosine, sine and tangent.

Parameters

trigmode A mode defined in ec_defs.h (wxECA_*).

void wxEcEngine::Simplify ( wxString * expression )

Performs the simplifications required to make the expression readable by the interpreter. You cannot expect all inputs to be valid after this operation. It depends on the quality of the input (in terms of wrong syntax).

Parameters

expression A pointer to a string which will be read and rewritten.

wxString wxEcEngine::TranslateError ( int code )

Returns a string describing the meaning of an error code.

Parameters

code	An error code defined in ec_defs.h (wxECE_*).

void wxEcEngine::UseDebug ( bool state )

inline

Enables or disable the storage of debug information in LogAction(). This function is useless if wxECM_USEDEBUG is not defined.

See also: wxECM_USEDEBUG; wxEcEngine::LogAction()

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

ec_engine.h
ec_engine.cpp

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation