function-closure.hpp File Reference

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Description

Partial function application and building a complete function closure.

This is a addendum to (and thin wrapper for) <functional>, supporting the case when a function should be closed over (partially or all) arguments, where especially the parameter values to close on are provided as a tuple. Additionally, we allow for composing (chaining) of two functions.

Because we have to deal with arbitrary functions and arbitrary parameter types, we need a lot of repetitive code to "catch" functions from zero to nine arguments. At the bottom of this header, you'll find a function-style interface, which wraps up all these technicalities.

Todo:

the implementation is able to handle partial application with N arguments, but currently we need just one argument, thus only this case was wrapped up into a convenient functions func::applyFirst and func::applyLast

11/23 these functor-utils were written at a time when support for handling generic functions in C++ was woefully inadequate; at that time, we neither had Lambda-support in the language, nor the ability to use variadic arguments. Providing a one-shot function-style interface for this kind of manipulations is still considered beneficial, and thus we should gradually modernise the tools we want to retain...

See also

control::CommandDef usage example

function.hpp

Definition in file function-closure.hpp.

#include "lib/meta/function.hpp"
#include "lib/meta/tuple-helper.hpp"
#include "lib/util.hpp"
#include <functional>
#include <utility>
#include <tuple>

Classes
struct	_Chain< FUN1, FUN2 >
struct	_Clo< SIG, ARG >
struct	_PapE< FUN >
struct	_PapS< FUN >
struct	_Sig< RET, ARG >
struct	Apply< n >
	this Helper with repetitive specialisations for up to nine arguments is used either to apply a function to arguments given as a tuple, or to create the actual closure (functor) over all function arguments. More...
struct	Apply< 0 >
	< Apply function without Arguments More...
struct	Apply< 1 >
	< Apply function with 1 Argument More...
struct	Apply< 2 >
	< Apply function with 2 Arguments More...
struct	Apply< 3 >
	< Apply function with 3 Arguments More...
struct	Apply< 4 >
	< Apply function with 4 Arguments More...
struct	Apply< 5 >
	< Apply function with 5 Arguments More...
struct	Apply< 6 >
	< Apply function with 6 Arguments More...
struct	Apply< 7 >
	< Apply function with 7 Arguments More...
struct	Apply< 8 >
	< Apply function with 8 Arguments More...
struct	Apply< 9 >
	< Apply function with 9 Arguments More...
class	BindToArgument< SIG, X, pos >
	Bind a specific argument to an arbitrary value. More...
class	FunctionClosure< SIG >
	Closing a function over its arguments. More...
struct	PartiallyInitTuple< SRC, TAR, start >::IndexMapper< idx, doPick >
struct	PartiallyInitTuple< SRC, TAR, start >::IndexMapper< idx, false >
class	PApply< SIG, VAL >
	Partial function application Takes a function and a value tuple, using the latter to close function arguments either from the front (left) or aligned to the end of the function argument list. More...
struct	PartiallyInitTuple< SRC, TAR, start >
	Builder for a tuple instance, where only some ctor parameters are supplied, while the remaining arguments will be default constructed. More...
struct	PlaceholderTuple< TYPES, i >
	Build a list of standard function argument placeholder types. More...
struct	PlaceholderTuple< Node< X, TAIL >, i >
struct	PlaceholderTuple< NullType, i >
class	TupleApplicator< SIG >
	Closure-creating template. More...

Functions
template<typename SIG , typename... ARG>
_Fun< SIG >::Ret	apply (SIG &f, std::tuple< ARG... > &args)
	apply the given function to the argument tuple More...
template<typename FUN , typename ARG >
auto	applyFirst (FUN &&fun, ARG &&arg)
	close the given function over the first argument. More...
template<typename FUN , typename ARG >
auto	applyLast (FUN &&fun, ARG &&arg)
	close the given function over the last argument
template<typename SIG , typename TERM >
_PapE< SIG >::FunType::Functor	bindLast (SIG &f, TERM const &arg)
	bind the last function argument to an arbitrary term, which especially might be a (nested) binder... More...
template<typename FUN1 , typename FUN2 >
auto	chained (FUN1 &&f1, FUN2 &&f2)
	build a functor chaining the given functions: feed the result of f1 into f2. More...
template<typename SIG , typename... ARG>
_Clo< SIG, Types< ARG... > >::Type	closure (SIG &f, std::tuple< ARG... > &args)
	close the given function over all arguments, using the values from the argument tuple. More...
template<typename... ARG>
_Sig< void, Types< ARG... > >::Applicator	tupleApplicator (std::tuple< ARG... > &args)
	build a TupleApplicator, which embodies the given argument tuple and can be used to apply them to various functions repeatedly.

Namespaces
	lib
	Implementation namespace for support and library code.

---

Class Documentation

lib::meta::func::anonymous_namespace{function-closure.hpp}::_Clo

struct lib::meta::func::anonymous_namespace{function-closure.hpp}::_Clo

Class Members
typedef _Fun< SIG >::Ret	Ret
typedef _Sig< Ret, ARG >::Type	Signature
typedef FunctionClosure < Signature >	Type

Collaboration diagram for _Clo< SIG, ARG >:

lib::meta::func::anonymous_namespace{function-closure.hpp}::_Sig

struct lib::meta::func::anonymous_namespace{function-closure.hpp}::_Sig

Class Members
typedef BuildFunType< RET, ARG > ::Sig	Type
typedef TupleApplicator< Type >	Applicator

Collaboration diagram for _Sig< RET, ARG >:

lib::meta::func::anonymous_namespace{function-closure.hpp}::Apply

struct lib::meta::func::anonymous_namespace{function-closure.hpp}::Apply

Collaboration diagram for Apply< n >:

lib::meta::func::anonymous_namespace{function-closure.hpp}::PlaceholderTuple

struct lib::meta::func::anonymous_namespace{function-closure.hpp}::PlaceholderTuple

Collaboration diagram for PlaceholderTuple< TYPES, i >:

lib::meta::func::anonymous_namespace{function-closure.hpp}::PlaceholderTuple< Node< X, TAIL >, i >

struct lib::meta::func::anonymous_namespace{function-closure.hpp}::PlaceholderTuple< Node< X, TAIL >, i >

Class Members
typedef typename PlaceholderTuple< TAIL, i+1 > ::List	TailPlaceholders
typedef Node< _Placeholder< i > , TailPlaceholders >	List

Collaboration diagram for PlaceholderTuple< Node< X, TAIL >, i >:

lib::meta::func::anonymous_namespace{function-closure.hpp}::PlaceholderTuple< NullType, i >

struct lib::meta::func::anonymous_namespace{function-closure.hpp}::PlaceholderTuple< NullType, i >

Class Members
typedef NullType	List

Collaboration diagram for PlaceholderTuple< NullType, i >:

Function Documentation

apply()

_Fun<SIG>::Ret lib::meta::func::apply ( SIG &  f, std::tuple< ARG... > &  args  )

inline

apply the given function to the argument tuple

Deprecated:

11/23 meanwhile provided by the standard lib!

Definition at line 839 of file function-closure.hpp.

References lib::meta::func::apply().

Referenced by lib::meta::func::apply().

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closure()

_Clo<SIG,Types<ARG...> >::Type lib::meta::func::closure ( SIG &  f, std::tuple< ARG... > &  args  )

inline

close the given function over all arguments, using the values from the argument tuple.

Returns

a closure object, which can be invoked later to yield the function result.

Definition at line 854 of file function-closure.hpp.

References lib::meta::func::closure().

Referenced by lib::meta::func::closure().

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applyFirst()

auto lib::meta::func::applyFirst ( FUN &&  fun, ARG &&  arg  )

inline

close the given function over the first argument.

Warning

never tie an ownership-managing object by-value!

Definition at line 865 of file function-closure.hpp.

References lib::meta::func::applyFirst().

Referenced by lib::meta::func::applyFirst().

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bindLast()

_PapE<SIG>::FunType::Functor lib::meta::func::bindLast ( SIG &  f, TERM const &  arg  )

inline

bind the last function argument to an arbitrary term, which especially might be a (nested) binder...

Definition at line 890 of file function-closure.hpp.

References lib::meta::func::bindLast().

Referenced by lib::meta::func::bindLast().

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chained()

auto lib::meta::func::chained ( FUN1 &&  f1, FUN2 &&  f2  )

inline

build a functor chaining the given functions: feed the result of f1 into f2.

Note

the mathematical notation would be chained ≔ f2 ∘f1

Definition at line 905 of file function-closure.hpp.

References lib::meta::func::chained().

Referenced by lib::meta::func::chained().

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