ts::Expressions Class Reference

Expression resolver based on the definition of symbols. More...

Public Member Functions
	Expressions (Report &report, int debug_level=Severity::Debug, const UString &debug_prefix=UString())
	Constructor. More...
bool	define (const UString &symbol, const UString &context=UString())
	Define a symbol in the internal repository. More...
bool	error () const
	Check if errors occured (invalid symbols, invalid expressions). More...
bool	evaluate (const UString &expression, const UString &context=UString())
	Evaluate a boolean expression using symbols. More...
bool	isDefined (const UString &symbol) const
	Check if a symbol is defined in the internal repository. More...
bool	isValidSymbolName (const UString &symbol, const UString &context=UString())
	Check if a string is valid symbol name and report an error if not. More...
void	resetError ()
	Reset the error indicator. More...
size_t	symbolCount () const
	Get the number of defined symbols. More...
bool	undefine (const UString &symbol, const UString &context=UString())
	Undefine a symbol from the internal repository. More...
void	undefineAll ()
	Undefine all symbols, clear the symbol database.

Static Public Member Functions
static bool	IsValidSymbolName (const UString &symbol)
	Check if a string is valid symbol name. More...

Detailed Description

Expression resolver based on the definition of symbols.

Symbols are words starting with a letter and made of alphanumerical characters and underscores. Symbol names are case sensitive. Symbols can be defined and undefined in an internal repository of the Expressions object.

Boolean expressions are evaluated based on the definition of symbols. A symbol evaluates to true when it is defined and false when it is not. The unary operator '!' is the negation. The binary operators '&&' and '||' can be used. Parentheses can be used to group sub-expressions.

Constructor & Destructor Documentation

Expressions()

ts::Expressions::Expressions ( Report &  report, int  debug_level = Severity::Debug, const UString &  debug_prefix = UString()  )

explicit

Constructor.

Parameters

[in,out]	report	Where to report errors.
[in]	debug_level	Severity level for debug messages.
[in]	debug_prefix	Prefix string for debug messages.

Member Function Documentation

define()

bool ts::Expressions::define	(	const UString &	symbol,
		const UString &	context = UString()
	)

Define a symbol in the internal repository.

Parameters

[in]	symbol	The symbol to add in the internal repository.
[in]	context	Optional context of the symbol, for error message only.

Returns

True if symbol is valid, false if it is not. A message is reported in error.

undefine()

bool ts::Expressions::undefine	(	const UString &	symbol,
		const UString &	context = UString()
	)

Undefine a symbol from the internal repository.

Parameters

[in]	symbol	The symbol to remove from the internal repository.
[in]	context	Optional context of the symbol, for error message only.

Returns

True if symbol is valid, false if it is not. A message is reported in error. Undefining a non-existent symbol is not an error, the function returns true.

symbolCount()

size_t ts::Expressions::symbolCount ( ) const

inline

Get the number of defined symbols.

Returns

The number of defined symbols.

isDefined()

bool ts::Expressions::isDefined ( const UString &  symbol ) const

inline

Check if a symbol is defined in the internal repository.

Parameters

[in]

symbol

The symbol to check.

Returns

True if symbol is defined, false if it is not.

isValidSymbolName()

bool ts::Expressions::isValidSymbolName	(	const UString &	symbol,
		const UString &	context = UString()
	)

Check if a string is valid symbol name and report an error if not.

Parameters

[in]	symbol	The symbol to check.
[in]	context	Optional context of the symbol, for error message only.

Returns

True if symbol is valid, false if it is not. A message is reported in error.

IsValidSymbolName()

static bool ts::Expressions::IsValidSymbolName ( const UString &  symbol )

static

Check if a string is valid symbol name.

Parameters

[in]

symbol

The name to check.

Returns

True if symbol is a valid name, false if it is not.

evaluate()

bool ts::Expressions::evaluate	(	const UString &	expression,
		const UString &	context = UString()
	)

Evaluate a boolean expression using symbols.

Parameters

[in]	expression	The expression to evaluate.
[in]	context	Optional context of the symbol, for error message only.

Returns

The boolean result of expression. In case of error, a message is reported and false is returned.

error()

bool ts::Expressions::error ( ) const

inline

Check if errors occured (invalid symbols, invalid expressions).

Returns

True if some error occurred.

See also

resetError()

resetError()

void ts::Expressions::resetError ( )

inline

Reset the error indicator.

See also

error()

---

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

• tsExpressions.h