diff -r e20de85af2ee -r ce057bb09d0b ossrv_pub/boost_apis/boost/lambda/closures.hpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ossrv_pub/boost_apis/boost/lambda/closures.hpp Fri Jun 04 16:20:51 2010 +0100 @@ -0,0 +1,274 @@ +/*============================================================================= + Adaptable closures + + Phoenix V0.9 + Copyright (c) 2001-2002 Joel de Guzman + + Distributed under the Boost Software License, Version 1.0. (See + accompanying file LICENSE_1_0.txt or copy at + http://www.boost.org/LICENSE_1_0.txt) + + URL: http://spirit.sourceforge.net/ + +==============================================================================*/ +#ifndef PHOENIX_CLOSURES_HPP +#define PHOENIX_CLOSURES_HPP + +/////////////////////////////////////////////////////////////////////////////// +#include "boost/lambda/core.hpp" +/////////////////////////////////////////////////////////////////////////////// +namespace boost { +namespace lambda { + +/////////////////////////////////////////////////////////////////////////////// +// +// Adaptable closures +// +// The framework will not be complete without some form of closures +// support. Closures encapsulate a stack frame where local +// variables are created upon entering a function and destructed +// upon exiting. Closures provide an environment for local +// variables to reside. Closures can hold heterogeneous types. +// +// Phoenix closures are true hardware stack based closures. At the +// very least, closures enable true reentrancy in lambda functions. +// A closure provides access to a function stack frame where local +// variables reside. Modeled after Pascal nested stack frames, +// closures can be nested just like nested functions where code in +// inner closures may access local variables from in-scope outer +// closures (accessing inner scopes from outer scopes is an error +// and will cause a run-time assertion failure). +// +// There are three (3) interacting classes: +// +// 1) closure: +// +// At the point of declaration, a closure does not yet create a +// stack frame nor instantiate any variables. A closure declaration +// declares the types and names[note] of the local variables. The +// closure class is meant to be subclassed. It is the +// responsibility of a closure subclass to supply the names for +// each of the local variable in the closure. Example: +// +// struct my_closure : closure { +// +// member1 num; // names the 1st (int) local variable +// member2 message; // names the 2nd (string) local variable +// member3 real; // names the 3rd (double) local variable +// }; +// +// my_closure clos; +// +// Now that we have a closure 'clos', its local variables can be +// accessed lazily using the dot notation. Each qualified local +// variable can be used just like any primitive actor (see +// primitives.hpp). Examples: +// +// clos.num = 30 +// clos.message = arg1 +// clos.real = clos.num * 1e6 +// +// The examples above are lazily evaluated. As usual, these +// expressions return composite actors that will be evaluated +// through a second function call invocation (see operators.hpp). +// Each of the members (clos.xxx) is an actor. As such, applying +// the operator() will reveal its identity: +// +// clos.num() // will return the current value of clos.num +// +// *** [note] Acknowledgement: Juan Carlos Arevalo-Baeza (JCAB) +// introduced and initilally implemented the closure member names +// that uses the dot notation. +// +// 2) closure_member +// +// The named local variables of closure 'clos' above are actually +// closure members. The closure_member class is an actor and +// conforms to its conceptual interface. member1..memberN are +// predefined typedefs that correspond to each of the listed types +// in the closure template parameters. +// +// 3) closure_frame +// +// When a closure member is finally evaluated, it should refer to +// an actual instance of the variable in the hardware stack. +// Without doing so, the process is not complete and the evaluated +// member will result to an assertion failure. Remember that the +// closure is just a declaration. The local variables that a +// closure refers to must still be instantiated. +// +// The closure_frame class does the actual instantiation of the +// local variables and links these variables with the closure and +// all its members. There can be multiple instances of +// closure_frames typically situated in the stack inside a +// function. Each closure_frame instance initiates a stack frame +// with a new set of closure local variables. Example: +// +// void foo() +// { +// closure_frame frame(clos); +// /* do something */ +// } +// +// where 'clos' is an instance of our closure 'my_closure' above. +// Take note that the usage above precludes locally declared +// classes. If my_closure is a locally declared type, we can still +// use its self_type as a paramater to closure_frame: +// +// closure_frame frame(clos); +// +// Upon instantiation, the closure_frame links the local variables +// to the closure. The previous link to another closure_frame +// instance created before is saved. Upon destruction, the +// closure_frame unlinks itself from the closure and relinks the +// preceding closure_frame prior to this instance. +// +// The local variables in the closure 'clos' above is default +// constructed in the stack inside function 'foo'. Once 'foo' is +// exited, all of these local variables are destructed. In some +// cases, default construction is not desirable and we need to +// initialize the local closure variables with some values. This +// can be done by passing in the initializers in a compatible +// tuple. A compatible tuple is one with the same number of +// elements as the destination and where each element from the +// destination can be constructed from each corresponding element +// in the source. Example: +// +// tuple init(123, "Hello", 1000); +// closure_frame frame(clos, init); +// +// Here now, our closure_frame's variables are initialized with +// int: 123, char const*: "Hello" and int: 1000. +// +/////////////////////////////////////////////////////////////////////////////// + + + +/////////////////////////////////////////////////////////////////////////////// +// +// closure_frame class +// +/////////////////////////////////////////////////////////////////////////////// +template +class closure_frame : public ClosureT::tuple_t { + +public: + + closure_frame(ClosureT& clos) + : ClosureT::tuple_t(), save(clos.frame), frame(clos.frame) + { clos.frame = this; } + + template + closure_frame(ClosureT& clos, TupleT const& init) + : ClosureT::tuple_t(init), save(clos.frame), frame(clos.frame) + { clos.frame = this; } + + ~closure_frame() + { frame = save; } + +private: + + closure_frame(closure_frame const&); // no copy + closure_frame& operator=(closure_frame const&); // no assign + + closure_frame* save; + closure_frame*& frame; +}; + +/////////////////////////////////////////////////////////////////////////////// +// +// closure_member class +// +/////////////////////////////////////////////////////////////////////////////// +template +class closure_member { + +public: + + typedef typename ClosureT::tuple_t tuple_t; + + closure_member() + : frame(ClosureT::closure_frame_ref()) {} + + template + struct sig { + + typedef typename detail::tuple_element_as_reference< + N, typename ClosureT::tuple_t + >::type type; + }; + + template + // typename detail::tuple_element_as_reference + // ::type + Ret + call(A&, B&, C&) const + { + assert(frame); + return boost::tuples::get(*frame); + } + + +private: + + typename ClosureT::closure_frame_t*& frame; +}; + +/////////////////////////////////////////////////////////////////////////////// +// +// closure class +// +/////////////////////////////////////////////////////////////////////////////// +template < + typename T0 = null_type, + typename T1 = null_type, + typename T2 = null_type, + typename T3 = null_type, + typename T4 = null_type +> +class closure { + +public: + + typedef tuple tuple_t; + typedef closure self_t; + typedef closure_frame closure_frame_t; + + closure() + : frame(0) { closure_frame_ref(&frame); } + closure_frame_t& context() { assert(frame); return frame; } + closure_frame_t const& context() const { assert(frame); return frame; } + + typedef lambda_functor > member1; + typedef lambda_functor > member2; + typedef lambda_functor > member3; + typedef lambda_functor > member4; + typedef lambda_functor > member5; + +private: + + closure(closure const&); // no copy + closure& operator=(closure const&); // no assign + + template + friend struct closure_member; + + template + friend class closure_frame; + + static closure_frame_t*& + closure_frame_ref(closure_frame_t** frame_ = 0) + { + static closure_frame_t** frame = 0; + if (frame_ != 0) + frame = frame_; + return *frame; + } + + closure_frame_t* frame; +}; + +}} + // namespace + +#endif