Nuria::LazyCondition Class Reference

LazyCondition offers lazily evaluated conditions for C++. More...

#include <lazyevaluation.hpp>

Public Types
enum	Type {   Empty = 0, Single, Equal, NonEqual,   Greater, GreaterEqual, Less, LessEqual,   LogicAnd, LogicOr }

Public Member Functions
	LazyCondition ()
	LazyCondition (const Field &field)
	LazyCondition (const QVariant &single)
	LazyCondition (const LazyCondition &other)
	LazyCondition (const QVariant &left, Type type, const QVariant &right)
	~LazyCondition ()
void	compile (AbstractConditionEvaluator *evaluator=nullptr)
bool	evaluate (const QVariantList &arguments) const
bool	isValid () const
const QVariant &	left () const
	operator QVariant () const
LazyCondition	operator&& (const LazyCondition &other)
template<typename... Args>
bool	operator() (const Args &...args)
LazyCondition &	operator= (const LazyCondition &other)
LazyCondition	operator|| (const LazyCondition &other)
const QVariant &	right () const
Type	type () const

Detailed Description

LazyCondition offers lazily evaluated conditions for C++.

Usage

LazyCondition tries to be as simple to use as possible, thus it mimics the behaviour to C++. This means that you can write conditions like you're used to from C++. Please be aware of possible problems when mixing lazy and strict evaluation by accident. Expressions that are written without telling the compiler about LazyCondition will be evaluated before it is passed to LazyCondition! For this reason, you need to use Nuria::val to start a lazy condition.

This class also acts as functor, meaning that you can later call it like a method. This also means that you can pass a instance to every function which expects a functor, like STL algorithms.

You can reference to arguments by index (Starting from 0) using Nuria::arg.

Example

The following example removes the first two elements from 'list' using std::remove_if and a lazy condition:

QList< int > list { 1, 2, 3, 4, 5 };
std::remove_if (list.begin (), list.end (), arg(0) < 3);
qDebug() << list;

Member Enumeration Documentation

enum Nuria::LazyCondition::Type

Available types of conditions.

Enumerator
Single	Invalid instance, evaluates to false.
Equal	Evaluates to (left).
NonEqual	Evaluates to (left == right).
Greater	Evaluates to (left != right).
GreaterEqual	Evaluates to (left > right).
Less	Evaluates to (left >= right).
LessEqual	Evaluates to (left < right).
LogicAnd	Evaluates to (left <= right).
LogicOr	Evaluates to (left && right). Evaluates to (left || right).

Constructor & Destructor Documentation

Nuria::LazyCondition::LazyCondition

(

)

Constructs a instance of type Empty.

Nuria::LazyCondition::~LazyCondition

(

)

Destructor.

Nuria::LazyCondition::LazyCondition

(

const Field &

field

)

Constructs a instance of type Single.

Nuria::LazyCondition::LazyCondition

(

const QVariant &

single

)

Constructs a instance of type Single.

Nuria::LazyCondition::LazyCondition

(

const LazyCondition &

other

)

Copy constructor.

Nuria::LazyCondition::LazyCondition	(	const QVariant &	left,
		Type	type,
		const QVariant &	right
	)

Constructor.

Member Function Documentation

void Nuria::LazyCondition::compile

(

AbstractConditionEvaluator *

evaluator = nullptr

)

Compiles the condition using evaluator. If no evaluator is given, the default implementation will be used. Ownership of evaluator will be transferred to this instance.

See also

AbstractConditionEvaluator ConditionEvaluator

Note

You only need to use this method explicitly if you want to use a custom evaluator.

bool Nuria::LazyCondition::evaluate

(

const QVariantList &

arguments

)

const

Evaluates the condition with arguments as input. If not already done the condition will be first compiled.

See also

compile

bool Nuria::LazyCondition::isValid

(

)

const

Returns true if the type of this condition is not Empty.

const QVariant& Nuria::LazyCondition::left

(

)

const

Returns the left-hand side value of the condition.

Nuria::LazyCondition::operator QVariant

(

)

const

Allow implicit conversion to QVariant.

LazyCondition Nuria::LazyCondition::operator&&

(

const LazyCondition &

other

)

Returns a LazyCondition with a logical and conjunction between this instance (on the left-hand side) and other (on the right-hand side).

template<typename... Args>

bool Nuria::LazyCondition::operator() ( const Args &...  args )

inline

Evaluates the condition.

LazyCondition& Nuria::LazyCondition::operator=

(

const LazyCondition &

other

)

Assignment operator.

LazyCondition Nuria::LazyCondition::operator||

(

const LazyCondition &

other

)

Returns a LazyCondition with a logical or conjunction between this instance (on the left-hand side) and other (on the right-hand side).

const QVariant& Nuria::LazyCondition::right

(

)

const

Returns the right-hand side value of the condition.

Type Nuria::LazyCondition::type

(

)

const

Returns the type of this instance.

See also

Type

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

• lazyevaluation.hpp