# Copyright (c) 2005 Reece H. Dunn.
# Copyright 2006 Ilya Sokolov
#
# Use, modification and distribution is subject to the Boost Software
# License Version 1.0. (See accompanying file LICENSE_1_0.txt or
# http://www.boost.org/LICENSE_1_0.txt)
##### Using Precompiled Headers (Quick Guide) #####
#
# Make precompiled mypch.hpp:
#
# import pch ;
#
# cpp-pch mypch
# : # sources
# mypch.hpp
# : # requiremnts
# msvc:mypch.cpp
# ;
#
# Add cpp-pch to sources:
#
# exe hello
# : main.cpp hello.cpp mypch
# ;
import "class" : new ;
import type ;
import feature ;
import generators ;
type.register PCH : pch ;
type.register C_PCH : : PCH ;
type.register CPP_PCH : : PCH ;
# Control precompiled header (PCH) generation.
feature.feature pch :
on
off
: propagated ;
feature.feature pch-header : : free dependency ;
feature.feature pch-file : : free dependency ;
# Base PCH generator. The 'run' method has the logic to prevent this generator
# from being run unless it's being used for a top-level PCH target.
class pch-generator : generator
{
import property-set ;
rule action-class ( )
{
return compile-action ;
}
rule run ( project name ? : property-set : sources + )
{
if ! $(name)
{
# Unless this generator is invoked as the top-most generator for a
# main target, fail. This allows using 'H' type as input type for
# this generator, while preventing B2 to try this generator
# when not explicitly asked for.
#
# One bad example is msvc, where pch generator produces both PCH
# target and OBJ target, so if there's any header generated (like by
# bison, or by msidl), we'd try to use pch generator to get OBJ from
# that H, which is completely wrong. By restricting this generator
# only to pch main target, such problem is solved.
}
else
{
local r = [ run-pch $(project) $(name)
: [ $(property-set).add-raw BOOST_BUILD_PCH_ENABLED ]
: $(sources) ] ;
return [ generators.add-usage-requirements $(r)
: BOOST_BUILD_PCH_ENABLED ] ;
}
}
# This rule must be overridden by the derived classes.
rule run-pch ( project name ? : property-set : sources + )
{
}
}
# NOTE: requirements are empty, default pch generator can be applied when
# pch=off.
generators.register
[ new dummy-generator pch.default-c-pch-generator : : C_PCH ] ;
generators.register
[ new dummy-generator pch.default-cpp-pch-generator : : CPP_PCH ] ;