460 lines
19 KiB
C++
460 lines
19 KiB
C++
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// Copyright (C) 2009-2012 Lorenzo Caminiti
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// Distributed under the Boost Software License, Version 1.0
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// (see accompanying file LICENSE_1_0.txt or a copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// Home at http://www.boost.org/libs/local_function
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#ifndef BOOST_LOCAL_FUNCTION_HPP_
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#define BOOST_LOCAL_FUNCTION_HPP_
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#ifndef DOXYGEN
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#include <boost/local_function/aux_/macro/decl.hpp>
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#include <boost/local_function/aux_/macro/name.hpp>
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#include <boost/local_function/aux_/macro/typeof.hpp>
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#include <boost/local_function/aux_/preprocessor/traits/decl.hpp>
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#include <boost/local_function/detail/preprocessor/line_counter.hpp>
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#include <boost/local_function/detail/preprocessor/void_list.hpp>
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#include <boost/config.hpp>
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// PUBLIC //
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#ifdef BOOST_NO_CXX11_VARIADIC_MACROS
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# define BOOST_LOCAL_FUNCTION_ID(id, declarations) \
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BOOST_LOCAL_FUNCTION_AUX_DECL(id, 0 /* not within template */, \
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BOOST_LOCAL_FUNCTION_AUX_PP_DECL_TRAITS( \
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BOOST_LOCAL_FUNCTION_DETAIL_PP_VOID_LIST( \
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declarations)))
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# define BOOST_LOCAL_FUNCTION(declarations) \
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BOOST_LOCAL_FUNCTION_ID( \
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BOOST_LOCAL_FUNCTION_DETAIL_PP_LINE_COUNTER, declarations)
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# define BOOST_LOCAL_FUNCTION_ID_TPL(id, declarations) \
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BOOST_LOCAL_FUNCTION_AUX_DECL(id, 1 /* within template */, \
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BOOST_LOCAL_FUNCTION_AUX_PP_DECL_TRAITS( \
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BOOST_LOCAL_FUNCTION_DETAIL_PP_VOID_LIST( \
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declarations)))
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# define BOOST_LOCAL_FUNCTION_TPL(declarations) \
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BOOST_LOCAL_FUNCTION_ID_TPL( \
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BOOST_LOCAL_FUNCTION_DETAIL_PP_LINE_COUNTER, declarations)
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#else // VARIADIC
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# define BOOST_LOCAL_FUNCTION_ID(id, ...) \
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BOOST_LOCAL_FUNCTION_AUX_DECL(id, 0 /* not within template */, \
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BOOST_LOCAL_FUNCTION_AUX_PP_DECL_TRAITS( \
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BOOST_LOCAL_FUNCTION_DETAIL_PP_VOID_LIST(__VA_ARGS__)))
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# define BOOST_LOCAL_FUNCTION(...) \
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BOOST_LOCAL_FUNCTION_ID( \
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BOOST_LOCAL_FUNCTION_DETAIL_PP_LINE_COUNTER, __VA_ARGS__)
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# define BOOST_LOCAL_FUNCTION_ID_TPL(id, ...) \
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BOOST_LOCAL_FUNCTION_AUX_DECL(id, 1 /* within template */, \
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BOOST_LOCAL_FUNCTION_AUX_PP_DECL_TRAITS( \
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BOOST_LOCAL_FUNCTION_DETAIL_PP_VOID_LIST(__VA_ARGS__)))
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# define BOOST_LOCAL_FUNCTION_TPL(...) \
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BOOST_LOCAL_FUNCTION_ID_TPL( \
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BOOST_LOCAL_FUNCTION_DETAIL_PP_LINE_COUNTER, __VA_ARGS__)
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#endif // VARIADIC
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#define BOOST_LOCAL_FUNCTION_NAME(qualified_name) \
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BOOST_LOCAL_FUNCTION_AUX_NAME(0 /* not within template */, qualified_name)
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#define BOOST_LOCAL_FUNCTION_NAME_TPL(qualified_name) \
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BOOST_LOCAL_FUNCTION_AUX_NAME(1 /* within template */, qualified_name)
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#define BOOST_LOCAL_FUNCTION_TYPEOF(bound_variable_name) \
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BOOST_LOCAL_FUNCTION_AUX_TYPEOF_TYPE(bound_variable_name)
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// DOCUMENTATION //
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#else // DOXYGEN
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/** @file
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@brief Local functions allow to program functions locally, within other
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functions, and directly within the scope where they are needed.
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*/
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/**
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@brief This macro is used to start a local function declaration.
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This macro must be used within a declarative context, it must follow the local
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function result type, it must be followed by the local function body code, and
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then by the @RefMacro{BOOST_LOCAL_FUNCTION_NAME} macro (see the
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@RefSect{tutorial, Tutorial} and @RefSect{advanced_topics, Advanced Topics}
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sections):
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@code
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{ // Some declarative context.
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...
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result_type BOOST_LOCAL_FUNCTION(declarations) {
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... // Body code.
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} BOOST_LOCAL_FUNCTION_NAME(qualified_name)
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...
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}
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@endcode
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As usual, exceptions specifications can be optionally programmed just after the
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macro and before the body code block <c>{ ... }</c> (but the exception
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specifications will only apply to the body code and not to the library code
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automatically generated by the macro expansion, see the
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@RefSect{advanced_topics, Advanced Topics} section).
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Within templates, the special macros @RefMacro{BOOST_LOCAL_FUNCTION_TPL}
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and @RefMacro{BOOST_LOCAL_FUNCTION_NAME_TPL} must be used.
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@Params
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@Param{declarations,
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On compilers that support variadic macros\, the parameter declarations are
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defined by the following grammar:
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@code
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declarations:
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void | declaration_tuple | declaration_sequence
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declaration_tuple:
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declaration\, declaration\, ...
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declaration_sequence:
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(declaration) (declaration) ...
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declaration:
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bound_variable | parameter | default_value | result_type
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bound_variable:
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[const] bind [(variable_type)] [&] variable_name
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parameter:
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[auto | register] parameter_type parameter_name
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default_value:
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default parameter_default_value
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result_type:
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return function_result_type
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@endcode
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On compilers that do not support variadic macros\, <c>declaration_tuple</c>
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cannot be used:
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@code
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declarations:
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void | declaration_sequence
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@endcode
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(Lexical conventions: <c>token1 | token2</c> means either <c>token1</c> or
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<c>token2</c>; <c>[token]</c> means either <c>token</c> or nothing;
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<c>{expression}</c> means the token resulting from the expression.)
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}
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@EndParams
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Note that on compilers that support variadic macros, commas can be used to
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separate the declarations resembling more closely the usual C++ function
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declaration syntax (this is the preferred syntax).
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However, for portability, on all C++ compilers (with and without variadic
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macros) the same library macros also accept parameter declarations specified as
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a Boost.Preprocessor sequence separated by round parenthesis <c>()</c>.
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When binding the object <c>this</c>, the special symbol <c>this_</c> needs to
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be used instead of <c>this</c> as the name of the variable to bind and also
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within the local function body to access the object.
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(Mistakenly using <c>this</c> instead of <c>this_</c> might not always result in a compiler error and will in general result in undefined behaviour.)
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The result type must either be specified just before the macro or within the
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macro declarations prefixed by <c>return</c> (but not in both places).
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Within the local function body it possible to access the result type using <c>result_type</c>, the type of the first parameter using <c>arg1_type</c>, the type of the second parameter using <c>arg2_type</c>, etc.
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The bound variable types can be accessed using @RefMacro{BOOST_LOCAL_FUNCTION_TYPEOF}.
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This macro cannot be portably expanded multiple times on the same line.
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In these cases, use the @RefMacro{BOOST_LOCAL_FUNCTION_ID} macro instead.
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The maximum number of local function parameters (excluding bound variables) is
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specified by the configuration macro
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@RefMacro{BOOST_LOCAL_FUNCTION_CONFIG_ARITY_MAX}.
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The maximum number of bound variables is specified by the configuration macro
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@RefMacro{BOOST_LOCAL_FUNCTION_CONFIG_BIND_MAX}.
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The configuration macro
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@RefMacro{BOOST_LOCAL_FUNCTION_CONFIG_LOCALS_AS_TPARAMS} can be used to force
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optimizations that reduce the local function call run-time overhead.
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@Note Local functions are functors so they can be assigned to other functors
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like <c>boost::function</c> (see Boost.Function).
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@See @RefSect{tutorial, Tutorial} section,
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@RefSect{advanced_topics, Advanced Topics} section,
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@RefMacro{BOOST_LOCAL_FUNCTION_NAME}, @RefMacro{BOOST_LOCAL_FUNCTION_TPL},
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@RefMacro{BOOST_LOCAL_FUNCTION_NAME_TPL},
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@RefMacro{BOOST_LOCAL_FUNCTION_TYPEOF}, @RefMacro{BOOST_LOCAL_FUNCTION_ID},
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@RefMacro{BOOST_LOCAL_FUNCTION_CONFIG_ARITY_MAX},
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@RefMacro{BOOST_LOCAL_FUNCTION_CONFIG_BIND_MAX},
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@RefMacro{BOOST_LOCAL_FUNCTION_CONFIG_LOCALS_AS_TPARAMS}.
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*/
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#define BOOST_LOCAL_FUNCTION(declarations)
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/**
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@brief This macro is used to start a local function declaration within
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templates.
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This macro must be used instead of @RefMacro{BOOST_LOCAL_FUNCTION} when
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declaring a local function within a template.
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A part from that, this macro has the exact same syntax a
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@RefMacro{BOOST_LOCAL_FUNCTION} (see @RefMacro{BOOST_LOCAL_FUNCTION} for more
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information):
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@code
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{ // Some declarative context within a template.
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...
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result_type BOOST_LOCAL_FUNCTION_TPL(declarations) {
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... // Body code.
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} BOOST_LOCAL_FUNCTION_NAME_TPL(qualified_name)
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...
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}
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@endcode
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Note that @RefMacro{BOOST_LOCAL_FUNCTION_NAME_TPL} must be used with this
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macro instead of @RefMacro{BOOST_LOCAL_FUNCTION_NAME}.
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This macro cannot be portably expanded multiple times on the same line.
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In these cases, use the @RefMacro{BOOST_LOCAL_FUNCTION_ID_TPL} macro instead.
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@Note C++03 does not allow to use <c>typename</c> outside templates.
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This library internally manipulates types, these operations require
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<c>typename</c> but only within templates.
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This macro is used to indicate to the library when the enclosing scope is a
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template so the library can correctly use <c>typename</c>.
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@See @RefSect{tutorial, Tutorial} section, @RefMacro{BOOST_LOCAL_FUNCTION},
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@RefMacro{BOOST_LOCAL_FUNCTION_ID_TPL},
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@RefMacro{BOOST_LOCAL_FUNCTION_NAME_TPL}.
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*/
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#define BOOST_LOCAL_FUNCTION_TPL(declarations)
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/**
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@brief This macro allows to declare multiple local functions on the same line.
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This macro is equivalent to @RefMacro{BOOST_LOCAL_FUNCTION} but it can be
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expanded multiple times on the same line if different identifiers <c>id</c> are
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provided for each expansion (see the
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@RefSect{advanced_topics, Advanced Topics} section).
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@Params
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@Param{id,
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A unique identifier token which can be concatenated by the preprocessor
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(<c>__LINE__</c>\, <c>local_function_number_1_on_line_123</c>\, etc).
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}
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@Param{declarations,
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Same as the <c>declarations</c> parameter of the
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@RefMacro{BOOST_LOCAL_FUNCTION} macro.
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}
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@EndParams
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The @RefMacro{BOOST_LOCAL_FUNCTION_NAME} macro should be used to end each one
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of the multiple local function declarations as usual (and it will specify a
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unique name for each local function).
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Within templates, the special macros @RefMacro{BOOST_LOCAL_FUNCTION_ID_TPL}
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must be used.
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@Note This macro can be useful when the local function macros are expanded
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within user-defined macros (because macros all expand on the same line).
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On some compilers (e.g., MSVC which supports the non-standard
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<c>__COUNTER__</c> macro) it might not be necessary to use this macro but
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the use of this macro when expanding multiple local function macros on the same
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line is always necessary to ensure portability (this is because this library
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can only portably use <c>__LINE__</c> to internally generate unique
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identifiers).
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@See @RefSect{advanced_topics, Advanced Topics} section,
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@RefMacro{BOOST_LOCAL_FUNCTION}, @RefMacro{BOOST_LOCAL_FUNCTION_NAME},
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@RefMacro{BOOST_LOCAL_FUNCTION_ID_TPL}.
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*/
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#define BOOST_LOCAL_FUNCTION_ID(id, declarations)
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/**
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@brief This macro allows to declare multiple local functions on the same line
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within templates.
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This macro must be used instead of @RefMacro{BOOST_LOCAL_FUNCTION_TPL} when
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declaring multiple local functions on the same line within a template.
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A part from that, this macro has the exact same syntax as
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@RefMacro{BOOST_LOCAL_FUNCTION_TPL} (see @RefMacro{BOOST_LOCAL_FUNCTION_TPL}
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for more information).
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@Params
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@Param{id,
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A unique identifier token which can be concatenated by the preprocessor
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(<c>__LINE__</c>\, <c>local_function_number_1_on_line_123</c>\, etc).
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}
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@Param{declarations,
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Same as the <c>declarations</c> parameter of the
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@RefMacro{BOOST_LOCAL_FUNCTION_TPL} macro.
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}
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@EndParams
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The @RefMacro{BOOST_LOCAL_FUNCTION_NAME} macro should be used to end each one
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of the multiple local function declarations as usual (and it will specify a
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unique name for each local function).
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Outside template, the macro @RefMacro{BOOST_LOCAL_FUNCTION_ID} should be used
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to declare multiple local functions on the same line.
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@Note This macro can be useful when the local function macros are expanded
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within user-defined macros (because macros all expand on the same line).
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On some compilers (e.g., MSVC which supports the non-standard
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<c>__COUNTER__</c> macro) it might not be necessary to use this macro but
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the use of this macro when expanding multiple local function macros on the same
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line is always necessary to ensure portability (this is because this library
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can only portably use <c>__LINE__</c> to internally generate unique
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identifiers).
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@See @RefSect{advanced_topics, Advanced Topics} section,
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@RefMacro{BOOST_LOCAL_FUNCTION_TPL}, @RefMacro{BOOST_LOCAL_FUNCTION_NAME},
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@RefMacro{BOOST_LOCAL_FUNCTION_ID}.
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*/
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#define BOOST_LOCAL_FUNCTION_ID_TPL(id, declarations)
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/**
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@brief This macro is used to end a local function declaration specifying its
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name.
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This macro must follow the local function body code block <c>{ ... }</c>:
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@code
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{ // Some declarative context.
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...
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result_type BOOST_LOCAL_FUNCTION(declarations) {
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... // Body code.
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} BOOST_LOCAL_FUNCTION_NAME(qualified_name)
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...
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}
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@endcode
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Within templates, the special macros @RefMacro{BOOST_LOCAL_FUNCTION_TPL} and
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@RefMacro{BOOST_LOCAL_FUNCTION_NAME_TPL} must be used.
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@Params
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@Param{qualified_name,
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The name of the local function optionally qualified as follow:
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@code
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name:
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[inline] [recursive] local_function_name
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@endcode
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(Lexical conventions: <c>token1 | token2</c> means either <c>token1</c> or
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<c>token2</c>; <c>[token]</c> means either <c>token</c> or nothing;
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<c>{expression}</c> means the token resulting from the expression.)
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}
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@EndParams
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The local function name can be qualified by prefixing it with the keyword
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<c>inline</c> (see the @RefSect{advanced_topics, Advanced Topics} section):
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@code
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BOOST_LOCAL_FUNCTION_NAME(inline local_function_name)
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@endcode
|
||
|
|
This increases the chances that the compiler will be able to inline the local
|
||
|
|
function calls (thus reducing run-time).
|
||
|
|
However, inline local functions cannot be passed as template parameters (e.g., to <c>std::for_each</c>) or assigned to other functors (e.g., to
|
||
|
|
<c>boost::function</c>).
|
||
|
|
That is true on C++03 compilers but inline local functions can instead be
|
||
|
|
passed as template parameters on C++11 compilers.
|
||
|
|
On C++11 compilers, there is no need to declare a local function lined because
|
||
|
|
this library will automatically use C++11 specific features to inline the local
|
||
|
|
function while always allowing to pass it as a template parameter.
|
||
|
|
This optimization is automatically enabled when the Boost.Config macro
|
||
|
|
<c>BOOST_NO_CXX11_LOCAL_CLASS_TEMPLATE_PARAMETERS</c> is not defined but it also be
|
||
|
|
forced using @RefMacro{BOOST_LOCAL_FUNCTION_CONFIG_LOCALS_AS_TPARAMS}.
|
||
|
|
|
||
|
|
The local function name can also be qualified by prefixing it with the
|
||
|
|
"keyword" <c>recursive</c> (see the
|
||
|
|
@RefSect{advanced_topics, Advanced Topics} section):
|
||
|
|
@code
|
||
|
|
BOOST_LOCAL_FUNCTION_NAME(recursive local_function_name)
|
||
|
|
@endcode
|
||
|
|
This allows the local function to recursively call itself from its body (as
|
||
|
|
usual in C++).
|
||
|
|
However, recursive local functions should only be called within their
|
||
|
|
declaration scope (otherwise the result is undefined behaviour).
|
||
|
|
Finally, compilers have not been observed to be able to inline recursive local
|
||
|
|
function calls, not even when the recursive local function is also declared
|
||
|
|
inline:
|
||
|
|
@code
|
||
|
|
BOOST_LOCAL_FUNCTION(inline recursive local_function_name)
|
||
|
|
@endcode
|
||
|
|
|
||
|
|
@Note The local function name cannot be the name of an operator
|
||
|
|
<c>operator...</c> and it cannot be the same name of another local function
|
||
|
|
declared within the same enclosing scope (but <c>boost::overloaded_function</c>
|
||
|
|
can be used to overload local functions, see
|
||
|
|
Boost.Functional/OverloadedFunction and the
|
||
|
|
@RefSect{advanced_topics, Advanced Topics} section).
|
||
|
|
|
||
|
|
@See @RefSect{tutorial, Tutorial} section,
|
||
|
|
@RefSect{advanced_topics, Advanced Topics} section,
|
||
|
|
@RefMacro{BOOST_LOCAL_FUNCTION},
|
||
|
|
@RefMacro{BOOST_LOCAL_FUNCTION_NAME_TPL}.
|
||
|
|
*/
|
||
|
|
#define BOOST_LOCAL_FUNCTION_NAME(qualified_name)
|
||
|
|
|
||
|
|
/**
|
||
|
|
@brief This macro is used to end a local function declaration specifying its
|
||
|
|
name within templates.
|
||
|
|
|
||
|
|
This macro must be used instead of @RefMacro{BOOST_LOCAL_FUNCTION_NAME} when
|
||
|
|
declaring a local function within a template.
|
||
|
|
A part from that, this macro has the exact same syntax a
|
||
|
|
@RefMacro{BOOST_LOCAL_FUNCTION_NAME} (see @RefMacro{BOOST_LOCAL_FUNCTION_NAME}
|
||
|
|
for more information):
|
||
|
|
@code
|
||
|
|
{ // Some declarative context within a template.
|
||
|
|
...
|
||
|
|
result_type BOOST_LOCAL_FUNCTION_TPL(declarations) {
|
||
|
|
... // Body code.
|
||
|
|
} BOOST_LOCAL_FUNCTION_NAME_TPL(qualified_name)
|
||
|
|
...
|
||
|
|
}
|
||
|
|
@endcode
|
||
|
|
|
||
|
|
Note that @RefMacro{BOOST_LOCAL_FUNCTION_TPL} must be used with this macro
|
||
|
|
instead of @RefMacro{BOOST_LOCAL_FUNCTION}.
|
||
|
|
|
||
|
|
@Note C++03 does not allow to use <c>typename</c> outside templates.
|
||
|
|
This library internally manipulates types, these operations require
|
||
|
|
<c>typename</c> but only within templates.
|
||
|
|
This macro is used to indicate to the library when the enclosing scope is a
|
||
|
|
template so the library can correctly use <c>typename</c>.
|
||
|
|
|
||
|
|
@See @RefSect{tutorial, Tutorial} section,
|
||
|
|
@RefMacro{BOOST_LOCAL_FUNCTION_NAME}, @RefMacro{BOOST_LOCAL_FUNCTION_TPL}.
|
||
|
|
*/
|
||
|
|
#define BOOST_LOCAL_FUNCTION_NAME_TPL(name)
|
||
|
|
|
||
|
|
/**
|
||
|
|
@brief This macro expands to the type of the specified bound variable.
|
||
|
|
|
||
|
|
This macro can be used within the local functions body to refer to the bound
|
||
|
|
variable types so to declare local variables, check concepts (using
|
||
|
|
Boost.ConceptCheck), etc (see the @RefSect{advanced_topics, Advanced Topics}
|
||
|
|
section).
|
||
|
|
This way the local function can be programmed entirely without explicitly
|
||
|
|
specifying the bound variable types thus facilitating maintenance (e.g., if
|
||
|
|
the type of a bound variable changes in the enclosing scope, the local function
|
||
|
|
code does not have to change).
|
||
|
|
|
||
|
|
@Params
|
||
|
|
@Param{bound_variable_name,
|
||
|
|
The name of one of the local function's bound variables.
|
||
|
|
}
|
||
|
|
@EndParams
|
||
|
|
|
||
|
|
The type returned by the macro is fully qualified in that it contains the extra
|
||
|
|
constant and reference qualifiers when the specified variable is bound by
|
||
|
|
constant and by reference.
|
||
|
|
For example, if a variable named <c>t</c> of type <c>T</c> is:
|
||
|
|
@li Bound by value using <c>bind t</c> then
|
||
|
|
<c>BOOST_LOCAL_FUNCTION_TYPEOF(t)</c> is <c>T</c>.
|
||
|
|
@li Bound by constant value using <c>const bind t</c> then
|
||
|
|
<c>BOOST_LOCAL_FUNCTION_TYPEOF(t)</c> is <c>const T</c>.
|
||
|
|
@li Bound by reference using <c>bind& t</c> then
|
||
|
|
<c>BOOST_LOCAL_FUNCTION_TYPEOF(t)</c> is <c>T&</c>.
|
||
|
|
@li Bound by constant reference using <c>const bind& t</c> then
|
||
|
|
<c>BOOST_LOCAL_FUNCTION_TYPEOF(t)</c> is <c>const T&</c>.
|
||
|
|
|
||
|
|
This macro must be prefixed by <c>typename</c> when used within templates.
|
||
|
|
|
||
|
|
@Note It is best to use this macro instead of Boost.Typeof so to reduce the
|
||
|
|
number of times Boost.Typeof is used to deduce types (see the
|
||
|
|
@RefSect{advanced_topics, Advanced Topics} section).
|
||
|
|
|
||
|
|
@See @RefSect{advanced_topics, Advanced Topics} section,
|
||
|
|
@RefMacro{BOOST_LOCAL_FUNCTION}.
|
||
|
|
*/
|
||
|
|
#define BOOST_LOCAL_FUNCTION_TYPEOF(bound_variable_name)
|
||
|
|
|
||
|
|
#endif // DOXYGEN
|
||
|
|
|
||
|
|
#endif // #include guard
|
||
|
|
|