ast::eval< T > Struct Template Reference

AST evaluator. More...

#include <attribute_mapper_ast_eval.hpp>

Public Types
using	result_type = boost::optional< T >

Public Member Functions
	eval (const attribute_store::attribute context=0)
	Construct a new eval object. More...
result_type	operator() (const nil &) const
	the undefined keyword More...
result_type	operator() (const uint32_t n) const
	a literal number More...
result_type	operator() (const float n) const
	a literal number More...
result_type	operator() (const operation &x, result_type lhs) const
	An operation. More...
result_type	operator() (const signed_ &x) const
	Unary operation. More...
result_type	operator() (const expression &x) const
	Condition. More...
result_type	operator() (const condition &x) const
	The normal entry point of the evaluator. More...
result_type	operator() (const attribute &a) const
	an attribute read from the attribute store More...
result_type	operator() (const function_invokation &f) const
	Evaluates Function invokation. More...

Private Attributes
attribute_store::attribute	context

Detailed Description

template<typename T>
struct ast::eval< T >

AST evaluator.

This evaluator walks though the AST. Usually the evaluator is use to evaluate a toplevel expression, but this can also be applied to other AST nodes.

The evaluation is done in a context such that all attribute paths will be evaluated relative to the context (a common parent node in the attribute store).

The AST evaluator returns a std::optional, because evaluation is not always possible if the the needed attribute are not found within the context.

If the evaluation context is an invalid attribute all evaluations involving an attribute will return no value.

The AST evaluators are implemented as a functor (a function object). This because this allows us to use the boost::apply_visitor, which is able to evaluate the boost::variant objects using functors, through the operator() overloading. The use of the boost::apply_visitor is boost::apply_visitor( functor, variant ), this will call the appropiate operator() overloading for the data type in the variant. See https://www.boost.org/doc/libs/1_76_0/doc/html/boost/apply_visitor.html for details.

Member Typedef Documentation

result_type

template<typename T >

using ast::eval< T >::result_type = boost::optional<T>

Constructor & Destructor Documentation

eval()

template<typename T >

ast::eval< T >::eval ( const attribute_store::attribute  context = 0 )

inlineexplicit

Construct a new eval object.

Parameters

context

Context in which this evaluator should work.

Member Function Documentation

operator()() [1/9]

template<typename T >

result_type ast::eval< T >::operator() ( const attribute &  a ) const

inline

an attribute read from the attribute store

operator()() [2/9]

template<typename T >

result_type ast::eval< T >::operator() ( const condition &  x ) const

inline

The normal entry point of the evaluator.

operator()() [3/9]

template<typename T >

result_type ast::eval< T >::operator() ( const expression &  x ) const

inline

Condition.

for if statements

operator()() [4/9]

template<typename T >

result_type ast::eval< T >::operator() ( const float  n ) const

inline

a literal number

operator()() [5/9]

template<typename T >

result_type ast::eval< T >::operator() ( const function_invokation &  f ) const

inline

Evaluates Function invokation.

operator()() [6/9]

template<typename T >

result_type ast::eval< T >::operator() ( const nil &  ) const

inline

the undefined keyword

operator()() [7/9]

template<typename T >

result_type ast::eval< T >::operator() ( const operation &  x, result_type  lhs  ) const

inline

An operation.

An operation which should be applied to the current result, can be any operation +,-,*,/,&,| etc.

Parameters

x	The operation
lhs	Left hand side of the operation

operator()() [8/9]

template<typename T >

result_type ast::eval< T >::operator() ( const signed_ &  x ) const

inline

Unary operation.

operator()() [9/9]

template<typename T >

result_type ast::eval< T >::operator() ( const uint32_t  n ) const

inline

a literal number

Member Data Documentation

context

template<typename T >

attribute_store::attribute ast::eval< T >::context

private

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

• components/uic_attribute_mapper/src/attribute_mapper_ast_eval.hpp