ELAM::CharacterClassSettings Class Reference

This class holds the character classes used by an Engine. More...

#include <elamcharclass.h>

List of all members.

Public Member Functions
QString	operatorClass () const
	class of operator characters
void	setOperatorClass (QString)
	sets the class of operator characters
QPair< QString, QString >	nameClass () const
	returns the two name sub-classes nameClass().first refers to start characters, nameClass().second refers to all characters that can turn up anywhere in names
void	setNameClass (QString startchars, QString allchars)
	sets the two sub-classes of names
void	setNameClass (const QPair< QString, QString > &chars)
	convenience overload: sets the two sub-classes of names
QString	whitespaceClass () const
	returns all characters that are regarded as whitespace
void	setWhitespaceClass (QString)
	sets all characters that are regarded as whitespace
QString	literalStartClass () const
	returns all characters that start a literal, normally digits ' and "
void	setLiteralStartClass (QString)
	sets characters that can start a literal
QPair< QChar, QChar >	parenthesesChars () const
	returns the opening (first) and closing (second) character of parentheses
void	setParentheses (QChar open, QChar close)
	sets the characters used for parentheses
QPair< QChar, QChar >	assignmentChars () const
	returns the characters that designate an assignment
void	setAssignmentChars (QChar start, QChar end)
	sets the characters used for assignment operators
QChar	commaChar () const
	returns the character used as a comma (separator of function arguments)
void	setCommaChar (QChar)
	sets the character used as comma
bool	isConsistent () const
	true if the settings are internally consistent
Token::Type	charType (QChar ch, Token::Type oldtype) const
	returns the type of token the character belongs to
bool	isAssignment (QString) const
	returns true if the string contains any assignment operator
bool	isSimpleAssignment (QString) const
	returns true if the string contains exactly the simple assignment operator
bool	isName (QString) const
	returns true if the string can be interpreted as name
bool	isOperator (QString) const
	returns true if the string can be interpreted as operator
QString	toOperator (QString) const
	removes assignment chars from the token and returns the pure operator or an empty string if it was a pure assignment

---

Detailed Description

This class holds the character classes used by an Engine.

See also:

Engine::characterClasses()

There are three major classes of chracters:

• names
  • names can be variables, constants, functions
  • the names class has two sub-classes
    • start-of-names is characters that may start a name, usually letters and underscores
    • all-of-names is characters that may be contained anywhere in names, this class must include the complete start of names class
• operators
  • any sequence of these characters is interpreted as unary or binary operator
• whitespace
  • whitespace can separate other tokens, but is ignored itself

None of these three classes may overlap. There are several more minor classes:

• literals
  • the character class actually only contains characters that can start a literal, the continuation and end of literals is determines by a callback routine
  • characters in this class may overlap with names, but must not overlap with operators, whitespace and start-of-names
• parentheses
  • are two distinct characters that group expressions, none of them must be contained in any other class
• comma
  • a single character separating arguments in functions, the comma character must not be contained in any other class
• assignment
  • one or two characters that denote an assignment
  • both are optional, both must be contained in operators
  • one of the characters, if it exists, is the first character of an assignment
  • the other of the characters, if it exists, is the last character of an assignment
  • just those two characters are the simple assignment operator
  • both surrounding another operator combine the operation with assignment (e.g. a+=b is equivalent to a=a+b)

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Member Function Documentation

QPair<QChar,QChar> ELAM::CharacterClassSettings::assignmentChars

(

)

const

returns the characters that designate an assignment

• assignmentChars().first is the character that starts an assignment operator,
• assignmentChars().second is the character that ends it.

Token::Type ELAM::CharacterClassSettings::charType	(	QChar	ch,
		Token::Type	oldtype
	)			const

returns the type of token the character belongs to

Parameters:

	ch	the character to be checked
	oldtype	the type the previous character belongs to (set to Invalid if this is the first character)

Compares the character with the known settings for character classes and returns its probable token type. The old type of the previous character is necessary to check for context sensitive rules.

Returns:

the type of this character:

• Invalid is returned if the character does not match any class, parsing should stop here
• If Literal is returned the calling engine must use specialized literal checking functions to find the end of the literal, the next character checke with this routine should be the first one behind the end of the literal
• Assignment characters are returned as Operator class
• Whitespace class characters should be ignored
• Special character types (Par*, Comma) must be tokenized separately
• Any other type (Name, Operator) must be concatenated until the return type changes

QChar ELAM::CharacterClassSettings::commaChar

(

)

const

returns the character used as a comma (separator of function arguments)

bool ELAM::CharacterClassSettings::isAssignment

(

QString

)

const

returns true if the string contains any assignment operator

bool ELAM::CharacterClassSettings::isConsistent

(

)

const

true if the settings are internally consistent

The character class settings are consistent if all constraints of class inclusion and exclusion are fullfilled.

bool ELAM::CharacterClassSettings::isName

(

QString

)

const

returns true if the string can be interpreted as name

bool ELAM::CharacterClassSettings::isOperator

(

QString

)

const

returns true if the string can be interpreted as operator

bool ELAM::CharacterClassSettings::isSimpleAssignment

(

QString

)

const

returns true if the string contains exactly the simple assignment operator

QString ELAM::CharacterClassSettings::literalStartClass

(

)

const

returns all characters that start a literal, normally digits ' and "

QPair<QString,QString> ELAM::CharacterClassSettings::nameClass

(

)

const

returns the two name sub-classes nameClass().first refers to start characters, nameClass().second refers to all characters that can turn up anywhere in names

QString ELAM::CharacterClassSettings::operatorClass

(

)

const

class of operator characters

QPair<QChar,QChar> ELAM::CharacterClassSettings::parenthesesChars

(

)

const

returns the opening (first) and closing (second) character of parentheses

void ELAM::CharacterClassSettings::setAssignmentChars	(	QChar	start,
		QChar	end
	)

sets the characters used for assignment operators

Parameters:

	start	if not '' the character that marks the start of an assignment
	end	if not '' the character that marks the end of an assignment

The combination of both characters along (without whitespace) is the direct assignment operator. In automatic assignment operator mode any operator that starts with the start character and ends with end character is regarded as an implicit assignment.

In the default configuration the start character is not set ('') and the end character is '=', so "a=1" will assign the value "1" to the variable "a" and "a += 1" is equivalent to "a = a + 1".

You can turn this automatism around by defining a start character only (e.g. start='=' and end=''). Then the assignment would still be "a = 1", but the combination of assignment and "+" would become "a =+ 1".

If you define both characters then both must be present in assignments. For example with start=':' and end='=' then assignment becomes "a:=1" and assignment with "+" becomes "a :+= 1".

If set, both characters must be part of the operator class.

If both start and end are '' it will be impossible to make assignments

void ELAM::CharacterClassSettings::setCommaChar

(

QChar

)

sets the character used as comma

The character must not be part of any other class.

void ELAM::CharacterClassSettings::setLiteralStartClass

(

QString

)

sets characters that can start a literal

void ELAM::CharacterClassSettings::setNameClass

(

const QPair< QString, QString > &

chars

)

[inline]

convenience overload: sets the two sub-classes of names

Parameters:

	chars.first	are characters that can start a name
	chars.second	are characters that can turn up anywhere in names, second must include all characters from first

void ELAM::CharacterClassSettings::setNameClass	(	QString	startchars,
		QString	allchars
	)

sets the two sub-classes of names

Parameters:

	startchars	are characters that can start a name
	allchars	are characters that can turn up anywhere in names, allchars must include all characters from startchars

void ELAM::CharacterClassSettings::setOperatorClass

(

QString

)

sets the class of operator characters

void ELAM::CharacterClassSettings::setParentheses	(	QChar	open,
		QChar	close
	)

sets the characters used for parentheses

Parameters:

	open	the character that opens/begins a parentheses structure, normally "("
	close	the character that closes/ends a parentheses structure, normally ")"

The parentheses characters must not be included in any other class.

void ELAM::CharacterClassSettings::setWhitespaceClass

(

QString

)

sets all characters that are regarded as whitespace

QString ELAM::CharacterClassSettings::toOperator

(

QString

)

const

removes assignment chars from the token and returns the pure operator or an empty string if it was a pure assignment

QString ELAM::CharacterClassSettings::whitespaceClass

(

)

const

returns all characters that are regarded as whitespace

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

• elamcharclass.h