# Copyright 2002, 2003, 2004, 2005 Dave Abrahams
# Copyright 2002, 2005, 2006, 2007, 2010 Rene Rivera
# Copyright 2006 Juergen Hunold
# Copyright 2005 Toon Knapen
# Copyright 2002, 2003, 2004, 2005, 2006 Vladimir Prus
# Distributed under the Boost Software License, Version 1.0.
# (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)

# Defines standard features and rules.

import alias ;
import "class" : new ;
import errors ;
import feature ;
import generators ;
import numbers ;
import os ;
import path ;
import print ;
import project ;
import property ;
import regex ;
import scanner ;
import sequence ;
import stage ;
import symlink ;
import toolset ;
import type ;
import types/register ;
import utility ;
import virtual-target ;
import message ;
import convert ;

# FIXME: the following generate module import is not needed here but removing it
# too hastly will break using code (e.g. the main Boost library Jamroot file)
# that forgot to import the generate module before calling the generate rule.
import generate ;


.os-names = aix bsd cygwin darwin freebsd hpux iphone linux netbsd
    openbsd osf qnx qnxnto sgi solaris unix unixware windows 
    elf # Not actually an OS -- used for targeting bare metal where
        # object format is ELF.  This catches both -elf and -eabi gcc
        # targets and well as other compilers targeting ELF. It is not
        # clear how often do we need to key of ELF specifically as opposed
        # to other bare metal targets, but let's stick with gcc naming.
    ;

# Feature used to determine which OS we're on. New <target-os> and <host-os>
# features should be used instead.
local os = [ modules.peek : OS ] ;
feature.feature os : $(os) : propagated link-incompatible ;


# Translates from bjam current OS to the os tags used in host-os and target-os,
# i.e. returns the running host-os.
#
local rule default-host-os ( )
{
    local host-os ;
    if [ os.name ] in $(.os-names:U)
    {
        host-os = [ os.name ] ;
    }
    else
    {
        switch [ os.name ]
        {
            case NT           : host-os = windows ;
            case AS400        : host-os = unix    ;
            case MINGW        : host-os = windows ;
            case BSDI         : host-os = bsd     ;
            case COHERENT     : host-os = unix    ;
            case DRAGONFLYBSD : host-os = bsd     ;
            case IRIX         : host-os = sgi     ;
            case MACOSX       : host-os = darwin  ;
            case KFREEBSD     : host-os = freebsd ;
            case LINUX        : host-os = linux   ;
            case SUNOS        : 
              ECHO "SunOS is not a supported operating system." ;
              ECHO "We believe last version of SunOS was released in 1992, " ;
              ECHO "so if you get this message, something is very wrong with configuration logic. " ;
              ECHO "Please report this as a bug. " ;
              EXIT ;
            case *            : host-os = unix    ;
        }
    }
    return $(host-os:L) ;
}


# The two OS features define a known set of abstract OS names. The host-os is
# the OS under which bjam is running. Even though this should really be a fixed
# property we need to list all the values to prevent unknown value errors. Both
# set the default value to the current OS to account for the default use case of
# building on the target OS.
feature.feature host-os : $(.os-names) ;
feature.set-default host-os : [ default-host-os ] ;

feature.feature target-os : $(.os-names) : propagated link-incompatible ;
feature.set-default target-os : [ default-host-os ] ;


feature.feature toolset            :                 : implicit propagated symmetric ;
feature.feature stdlib             : native          : propagated composite ;
feature.feature link               : shared static   : propagated ;
feature.feature runtime-link       : shared static   : propagated ;
feature.feature runtime-debugging  : on off          : propagated ;
feature.feature optimization       : off speed space : propagated ;
feature.feature profiling          : off on          : propagated ;
feature.feature inlining           : off on full     : propagated ;
feature.feature threading          : single multi    : propagated ;
feature.feature rtti               : on off          : propagated ;
feature.feature exception-handling : on off          : propagated ;

# Whether there is support for asynchronous EH (e.g. catching SEGVs).
feature.feature asynch-exceptions  : off on          : propagated ;

# Whether all extern "C" functions are considered nothrow by default.
feature.feature extern-c-nothrow   : off on          : propagated ;

feature.feature debug-symbols      : on off          : propagated ;
# Controls whether the binary should be stripped -- that is have
# everything not necessary to running removed. This option should
# not be very often needed. Also, this feature will show up in
# target paths of everything, not just binaries. Should fix that
# when impelementing feature relevance.
feature.feature strip              : off on          : propagated ;
feature.feature define             :                 : free ;
feature.feature undef              :                 : free ;
feature.feature "include"          :                 : free path ; #order-sensitive ;
feature.feature cflags             :                 : free ;
feature.feature cxxflags           :                 : free ;
feature.feature fflags             :                 : free ;
feature.feature asmflags           :                 : free ;
feature.feature linkflags          :                 : free ;
feature.feature archiveflags       :                 : free ;
feature.feature version            :                 : free ;

# Generic, i.e. non-language specific, flags for tools.
feature.feature flags           : : free ;
feature.feature location-prefix : : free ;


# The following features are incidental since they have no effect on built
# products. Not making them incidental will result in problems in corner cases,
# e.g.:
#
#    unit-test a : a.cpp : <use>b ;
#    lib b : a.cpp b ;
#
# Here, if <use> is not incidental, we would decide we have two targets for
# a.obj with different properties and complain about it.
#
# Note that making a feature incidental does not mean it is ignored. It may be
# ignored when creating a virtual target, but the rest of build process will use
# them.
feature.feature use                 : : free dependency incidental ;
feature.feature dependency          : : free dependency incidental ;
feature.feature implicit-dependency : : free dependency incidental ;

feature.feature warnings :
    on         # Enable default/"reasonable" warning level for the tool.
    all        # Enable all possible warnings issued by the tool.
    off        # Disable all warnings issued by the tool.
  : incidental propagated ;

feature.feature warnings-as-errors :
    off        # Do not fail the compilation if there are warnings.
    on         # Fail the compilation if there are warnings.
  : incidental propagated ;

# Feature that allows us to configure the maximal template instantiation depth
# level allowed by a C++ compiler. Applies only to C++ toolsets whose compilers
# actually support this configuration setting.
#
# Note that Boost Build currently does not allow defining features that take any
# positive integral value as a parameter, which is what we need here, so we just
# define some of the values here and leave it up to the user to extend this set
# as he needs using the feature.extend rule.
#
# TODO: This should be upgraded as soon as Boost Build adds support for custom
# validated feature values or at least features allowing any positive integral
# value. See related Boost Build related trac ticket #194.
#
feature.feature c++-template-depth
    :
        [ numbers.range 64 1024 : 64 ]
        [ numbers.range 20 1000 : 10 ]
        #   Maximum template instantiation depth guaranteed for ANSI/ISO C++
        # conforming programs.
        17
    :
        incidental optional propagated ;

feature.feature source              :            : free dependency incidental ;
feature.feature library             :            : free dependency incidental ;
feature.feature file                :            : free dependency incidental ;
feature.feature find-shared-library :            : free ; #order-sensitive ;
feature.feature find-static-library :            : free ; #order-sensitive ;
feature.feature library-path        :            : free path ; #order-sensitive ;

# Internal feature.
feature.feature library-file        :            : free dependency ;

feature.feature name                :            : free ;
feature.feature tag                 :            : free ;
feature.feature search              :            : free path ; #order-sensitive ;
feature.feature location            :            : free path ;
feature.feature dll-path            :            : free path ;
feature.feature hardcode-dll-paths  : true false : incidental ;


# An internal feature that holds the paths of all dependency shared libraries.
# On Windows, it is needed so that we can add all those paths to PATH when
# running applications. On Linux, it is needed to add proper -rpath-link command
# line options.
feature.feature xdll-path : : free path ;

# Provides means to specify def-file for windows DLLs.
feature.feature def-file : : free dependency ;

feature.feature suppress-import-lib : false true : incidental ;

# Internal feature used to store the name of a bjam action to call when building
# a target.
feature.feature action : : free ;

# This feature is used to allow specific generators to run. For example, QT
# tools can only be invoked when QT library is used. In that case, <allow>qt
# will be in usage requirement of the library.
feature.feature allow : : free ;

# The addressing model to generate code for. Currently a limited set only
# specifying the bit size of pointers.
feature.feature address-model : 16 32 64 32_64 : propagated optional ;

# Type of CPU architecture to compile for.
feature.feature architecture :
    # x86 and x86-64
    x86

    # ia64
    ia64

    # Sparc
    sparc

    # RS/6000 & PowerPC
    power

    # MIPS/SGI
    mips1 mips2 mips3 mips4 mips32 mips32r2 mips64

    # HP/PA-RISC
    parisc

    # Advanced RISC Machines
    arm

    # Combined architectures for platforms/toolsets that support building for
    # multiple architectures at once. "combined" would be the default multi-arch
    # for the toolset.
    combined
    combined-x86-power

    : propagated optional ;

# The specific instruction set in an architecture to compile.
feature.feature instruction-set :
    # x86 and x86-64
    native i386 i486 i586 i686 pentium pentium-mmx pentiumpro pentium2 pentium3
    pentium3m pentium-m pentium4 pentium4m prescott nocona core2 conroe conroe-xe
    conroe-l allendale mermon mermon-xe kentsfield kentsfield-xe penryn wolfdale
    yorksfield nehalem k6 k6-2 k6-3 athlon athlon-tbird athlon-4 athlon-xp
    athlon-mp k8 opteron athlon64 athlon-fx winchip-c6 winchip2 c3 c3-2

    # ia64
    itanium itanium1 merced itanium2 mckinley

    # Sparc
    v7 cypress v8 supersparc sparclite hypersparc sparclite86x f930 f934
    sparclet tsc701 v9 ultrasparc ultrasparc3

    # RS/6000 & PowerPC
    401 403 405 405fp 440 440fp 505 601 602 603 603e 604 604e 620 630 740 7400
    7450 750 801 821 823 860 970 8540 power-common ec603e g3 g4 g5 power power2
    power3 power4 power5 powerpc powerpc64 rios rios1 rsc rios2 rs64a

    # MIPS
    4kc 4kp 5kc 20kc m4k r2000 r3000 r3900 r4000 r4100 r4300 r4400 r4600 r4650
    r6000 r8000 rm7000 rm9000 orion sb1 vr4100 vr4111 vr4120 vr4130 vr4300
    vr5000 vr5400 vr5500

    # HP/PA-RISC
    700 7100 7100lc 7200 7300 8000

    # Advanced RISC Machines
    armv2 armv2a armv3 armv3m armv4 armv4t armv5 armv5t armv5te armv6 armv6j iwmmxt ep9312

    : propagated optional ;

# Used to select a specific variant of C++ ABI if the compiler supports several.
feature.feature c++abi : : propagated optional ;

feature.feature conditional : : incidental free ;

# The value of 'no' prevents building of a target.
feature.feature build : yes no : optional ;

# Windows-specific features

feature.feature user-interface : console gui wince native auto ;

feature.feature variant : : implicit composite propagated symmetric ;


# Declares a new variant.
#
# First determines explicit properties for this variant, by refining parents'
# explicit properties with the passed explicit properties. The result is
# remembered and will be used if this variant is used as parent.
#
# Second, determines the full property set for this variant by adding to the
# explicit properties default values for all missing non-symmetric properties.
#
# Lastly, makes appropriate value of 'variant' property expand to the full
# property set.
#
rule variant ( name            # Name of the variant
    : parents-or-properties *  # Specifies parent variants, if
                               # 'explicit-properties' are given, and
                               # explicit-properties or parents otherwise.
    : explicit-properties *    # Explicit properties.
    )
{
    local parents ;
    if ! $(explicit-properties)
    {
        if $(parents-or-properties[1]:G)
        {
            explicit-properties = $(parents-or-properties) ;
        }
        else
        {
            parents = $(parents-or-properties) ;
        }
    }
    else
    {
        parents = $(parents-or-properties) ;
    }

    # The problem is that we have to check for conflicts between base variants.
    if $(parents[2])
    {
        errors.error "multiple base variants are not yet supported" ;
    }

    local inherited ;
    # Add explicitly specified properties for parents.
    for local p in $(parents)
    {
        # TODO: This check may be made stricter.
        if ! [ feature.is-implicit-value $(p) ]
        {
            errors.error "Invalid base variant" $(p)  ;
        }

        inherited += $(.explicit-properties.$(p)) ;
    }
    property.validate $(explicit-properties) ;
    explicit-properties = [ property.refine $(inherited)
        : $(explicit-properties) ] ;

    # Record explicitly specified properties for this variant. We do this after
    # inheriting parents' properties so they affect other variants derived from
    # this one.
    .explicit-properties.$(name) = $(explicit-properties) ;

    feature.extend variant : $(name) ;
    feature.compose <variant>$(name) : $(explicit-properties) ;
}
IMPORT $(__name__) : variant : : variant ;


variant debug   : <optimization>off <debug-symbols>on <inlining>off
                  <runtime-debugging>on ;
variant release : <optimization>speed <debug-symbols>off <inlining>full
                  <runtime-debugging>off <define>NDEBUG ;
variant profile : release : <profiling>on <debug-symbols>on ;


class searched-lib-target : abstract-file-target
{
    rule __init__ ( name
        : project
        : shared ?
        : search *
        : action
    )
    {
        abstract-file-target.__init__ $(name) : SEARCHED_LIB : $(project)
          : $(action) : ;

        self.shared = $(shared) ;
        self.search = $(search) ;
    }

    rule shared ( )
    {
        return $(self.shared) ;
    }

    rule search ( )
    {
        return $(self.search) ;
    }

    rule actualize-location ( target )
    {
        NOTFILE $(target) ;
    }

    rule path ( )
    {
    }
}


# The generator class for libraries (target type LIB). Depending on properties
# it will request building of the appropriate specific library type --
# -- SHARED_LIB, STATIC_LIB or SHARED_LIB.
#
class lib-generator : generator
{
    rule __init__ ( * : * )
    {
        generator.__init__ $(1) : $(2) : $(3) : $(4) : $(5) : $(6) : $(7) : $(8) : $(9) ;
    }

    rule run ( project name ? : property-set : sources * )
    {
        # The lib generator is composing, and can be only invoked with an
        # explicit name. This check is present in generator.run (and so in
        # builtin.linking-generator) but duplicated here to avoid doing extra
        # work.
        if $(name)
        {
            local properties = [ $(property-set).raw ] ;
            # Determine the needed target type.
            local actual-type ;
                # <source>files can be generated by <conditional>@rule feature
                # in which case we do not consider it a SEARCHED_LIB type.
            if ! <source> in $(properties:G) &&
               ( <search> in $(properties:G) || <name> in $(properties:G) )
            {
                actual-type = SEARCHED_LIB ;
            }
            else if <file> in $(properties:G)
            {
                actual-type = LIB ;
            }
            else if <link>shared in $(properties)
            {
                actual-type = SHARED_LIB ;
            }
            else
            {
                actual-type = STATIC_LIB ;
            }
            property-set = [ $(property-set).add-raw <main-target-type>LIB ] ;
            # Construct the target.
            return [ generators.construct $(project) $(name) : $(actual-type)
                : $(property-set) : $(sources) ] ;
        }
    }

    rule viable-source-types ( )
    {
        return * ;
    }
}


generators.register [ new lib-generator builtin.lib-generator :  : LIB ] ;


# The implementation of the 'lib' rule. Beyond standard syntax that rule allows
# simplified: "lib a b c ;".
#
rule lib ( names + : sources * : requirements * : default-build * :
    usage-requirements * )
{
    if $(names[2])
    {
        if <name> in $(requirements:G)
        {
            errors.user-error "When several names are given to the 'lib' rule" :
                "it is not allowed to specify the <name> feature." ;
        }
        if $(sources)
        {
            errors.user-error "When several names are given to the 'lib' rule" :
                "it is not allowed to specify sources." ;
        }
    }

    # This is a circular module dependency so it must be imported here.
    import targets ;

    local project = [ project.current ] ;
    local result ;

    for local name in $(names)
    {
        local r = $(requirements) ;
        # Support " lib a ; " and " lib a b c ; " syntax.
        if ! $(sources) && ! <name> in $(requirements:G)
                        && ! <file> in $(requirements:G)
        {
            r += <name>$(name) ;
        }
        result += [ targets.main-target-alternative
            [ new typed-target $(name) : $(project) : LIB
                : [ targets.main-target-sources $(sources) : $(name) ]
                : [ targets.main-target-requirements $(r) : $(project) ]
                : [ targets.main-target-default-build $(default-build) : $(project) ]
                : [ targets.main-target-usage-requirements $(usage-requirements) : $(project) ]
            ] ] ;
    }
    return $(result) ;
}
IMPORT $(__name__) : lib : : lib ;


class searched-lib-generator : generator
{
    import property-set ;

    rule __init__ ( )
    {
        # The requirements cause the generators to be tried *only* when we're
        # building a lib target with a 'search' feature. This seems ugly --- all
        # we want is to make sure searched-lib-generator is not invoked deep
        # inside transformation search to produce intermediate targets.
        generator.__init__ searched-lib-generator : : SEARCHED_LIB ;
    }

    rule run ( project name ? : property-set : sources * )
    {
        if $(name)
        {
            # If 'name' is empty, it means we have not been called to build a
            # top-level target. In this case, we just fail immediately, because
            # searched-lib-generator cannot be used to produce intermediate
            # targets.

            local properties = [ $(property-set).raw ] ;
            local shared ;
            if <link>shared in $(properties)
            {
                shared = true ;
            }

            local search = [ feature.get-values <search> : $(properties) ] ;

            local a = [ new null-action $(property-set) ] ;
            local lib-name = [ feature.get-values <name> : $(properties) ] ;
            lib-name ?= $(name) ;
            local t = [ new searched-lib-target $(lib-name) : $(project)
                : $(shared) : $(search) : $(a) ] ;
            # We return sources for a simple reason. If there is
            #    lib png : z : <name>png ;
            # the 'z' target should be returned, so that apps linking to 'png'
            # will link to 'z', too.
            return [ property-set.create <xdll-path>$(search) ]
                   [ virtual-target.register $(t) ] $(sources) ;
        }
    }
}

generators.register [ new searched-lib-generator ] ;


class prebuilt-lib-generator : generator
{
    rule __init__ ( * : * )
    {
        generator.__init__ $(1) : $(2) : $(3) : $(4) : $(5) : $(6) : $(7) : $(8) : $(9) ;
    }

    rule run ( project name ? : property-set : sources * )
    {
        local f = [ $(property-set).get <file> ] ;
        return $(f) $(sources) ;
    }
}

generators.register
  [ new prebuilt-lib-generator builtin.prebuilt : : LIB : <file> ] ;

generators.override builtin.prebuilt : builtin.lib-generator ;


class compile-action : action
{
    import sequence ;

    rule __init__ ( targets * : sources * : action-name : properties * )
    {
        action.__init__ $(targets) : $(sources) : $(action-name) : $(properties) ;
    }

    # For all virtual targets for the same dependency graph as self, i.e. which
    # belong to the same main target, add their directories to the include path.
    #
    rule adjust-properties ( property-set )
    {
        local s = [ $(self.targets[1]).creating-subvariant ] ;
        return [ $(property-set).add-raw
          [ $(s).implicit-includes "include" : H ] ] ;
    }
}


# Declare a special compiler generator. The only thing it does is changing the
# type used to represent 'action' in the constructed dependency graph to
# 'compile-action'. That class in turn adds additional include paths to handle
# cases when a source file includes headers which are generated themselves.
#
class C-compiling-generator : generator
{
    rule __init__ ( id : source-types + : target-types + : requirements *
        : optional-properties * )
    {
        generator.__init__ $(id) : $(source-types) : $(target-types) :
            $(requirements) : $(optional-properties) ;
    }

    rule action-class ( )
    {
        return compile-action ;
    }
}


rule register-c-compiler ( id : source-types + : target-types + : requirements *
    : optional-properties * )
{
    generators.register [ new C-compiling-generator $(id) : $(source-types) :
        $(target-types) : $(requirements) : $(optional-properties) ] ;
}

# FIXME: this is ugly, should find a better way (we would like client code to
# register all generators as "generators.some-rule" instead of
# "some-module.some-rule".)
#
IMPORT $(__name__) : register-c-compiler : : generators.register-c-compiler ;


# The generator class for handling EXE and SHARED_LIB creation.
#
class linking-generator : generator
{
    import path ;
    import project ;
    import property-set ;
    import type ;

    rule __init__ ( id
        composing ?    :  # The generator will be composing if a non-empty
                          # string is passed or the parameter is not given. To
                          # make the generator non-composing, pass an empty
                          # string ("").
        source-types + :
        target-types + :
        requirements * )
    {
        composing ?= true ;
        generator.__init__ $(id) $(composing) : $(source-types)
            : $(target-types) : $(requirements) ;
    }

    rule run ( project name ? : property-set : sources + )
    {
        sources += [ $(property-set).get <library>  ] ;

        # Add <library-path> properties for all searched libraries.
        local extra ;
        for local s in $(sources)
        {
            if [ $(s).type ] = SEARCHED_LIB
            {
                local search = [ $(s).search ] ;
                extra += <library-path>$(search) ;
            }
        }

        # It is possible that sources include shared libraries that did not came
        # from 'lib' targets, e.g. .so files specified as sources. In this case
        # we have to add extra dll-path properties and propagate extra xdll-path
        # properties so that application linking to us will get xdll-path to
        # those libraries.
        local extra-xdll-paths ;
        for local s in $(sources)
        {
            if [ type.is-derived [ $(s).type ] SHARED_LIB ] && ! [ $(s).action ]
            {
                # Unfortunately, we do not have a good way to find the path to a
                # file, so use this nasty approach.
                #
                # TODO: This needs to be done better. One thing that is really
                # broken with this is that it does not work correctly with
                # projects having multiple source locations.
                local p = [ $(s).project ] ;
                local location = [ path.root [ $(s).name ]
                    [ $(p).get source-location ] ] ;
                extra-xdll-paths += [ path.parent $(location) ] ;
            }
        }

        # Hardcode DLL paths only when linking executables.
        # Pros: do not need to relink libraries when installing.
        # Cons: "standalone" libraries (plugins, python extensions) can not
        # hardcode paths to dependent libraries.
        if [ $(property-set).get <hardcode-dll-paths> ] = true
            && [ type.is-derived $(self.target-types[1]) EXE ]
        {
            local xdll-path = [ $(property-set).get <xdll-path> ] ;
            extra += <dll-path>$(xdll-path) <dll-path>$(extra-xdll-paths) ;
        }

        if $(extra)
        {
            property-set = [ $(property-set).add-raw $(extra) ] ;
        }

        local result = [ generator.run $(project) $(name) : $(property-set)
            : $(sources) ] ;

        local ur ;
        if $(result)
        {
            ur = [ extra-usage-requirements $(result) : $(property-set) ] ;
            ur = [ $(ur).add
              [ property-set.create <xdll-path>$(extra-xdll-paths) ] ] ;
        }
        return $(ur) $(result) ;
    }

    rule extra-usage-requirements ( created-targets * : property-set )
    {
        local result = [ property-set.empty ] ;
        local extra ;

        # Add appropricate <xdll-path> usage requirements.
        local raw = [ $(property-set).raw ] ;
        if <link>shared in $(raw)
        {
            local paths ;
            local pwd = [ path.pwd ] ;
            for local t in $(created-targets)
            {
                if [ type.is-derived [ $(t).type ] SHARED_LIB ]
                {
                    paths += [ path.root [ path.make [ $(t).path ] ] $(pwd) ] ;
                }
            }
            extra += $(paths:G=<xdll-path>) ;
        }

        # We need to pass <xdll-path> features that we've got from sources,
        # because if a shared library is built, exe using it needs to know paths
        # to other shared libraries this one depends on in order to be able to
        # find them all at runtime.

        # Just pass all features in property-set, it is theorically possible
        # that we will propagate <xdll-path> features explicitly specified by
        # the user, but then the user is to blaim for using an internal feature.
        local values = [ $(property-set).get <xdll-path> ] ;
        extra += $(values:G=<xdll-path>) ;

        if $(extra)
        {
            result = [ property-set.create $(extra) ] ;
        }
        return $(result) ;
    }

    rule generated-targets ( sources + : property-set : project name ? )
    {
        local sources2 ;     # Sources to pass to inherited rule.
        local properties2 ;  # Properties to pass to inherited rule.
        local libraries ;    # Library sources.

        # Searched libraries are not passed as arguments to the linker but via
        # some option. So, we pass them to the action using a property.
        properties2 = [ $(property-set).raw ] ;
        local fsa ;
        local fst ;
        for local s in $(sources)
        {
            if [ type.is-derived [ $(s).type ] SEARCHED_LIB ]
            {
                local name = [ $(s).name ] ;
                if [ $(s).shared ]
                {
                    fsa += $(name) ;
                }
                else
                {
                    fst += $(name) ;
                }
            }
            else
            {
                sources2 += $(s) ;
            }
        }
        properties2 += <find-shared-library>$(fsa:J=&&)
                       <find-static-library>$(fst:J=&&) ;

        return [ generator.generated-targets $(sources2)
            : [ property-set.create $(properties2) ] : $(project) $(name) ] ;
    }
}


rule register-linker ( id composing ? : source-types + : target-types +
    : requirements * )
{
    generators.register [ new linking-generator $(id) $(composing)
        : $(source-types) : $(target-types) : $(requirements) ] ;
}


# The generator class for handling STATIC_LIB creation.
#
class archive-generator : generator
{
    import property-set ;

    rule __init__ ( id composing ? : source-types + : target-types +
        : requirements * )
    {
        composing ?= true ;
        generator.__init__ $(id) $(composing) : $(source-types)
            : $(target-types) : $(requirements) ;
    }

    rule run ( project name ? : property-set : sources + )
    {
        sources += [ $(property-set).get <library>  ] ;

        local result = [ generator.run $(project) $(name) : $(property-set)
            : $(sources) ] ;

        # For static linking, if we get a library in source, we can not directly
        # link to it so we need to cause our dependencies to link to that
        # library. There are two approaches:
        # - adding the library to the list of returned targets.
        # - using the <library> usage requirements.
        # The problem with the first is:
        #
        #     lib a1 : : <file>liba1.a ;
        #     lib a2 : a2.cpp a1 : <link>static ;
        #     install dist : a2 ;
        #
        # here we will try to install 'a1', even though it is not necessary in
        # the general case. With the second approach, even indirect dependants
        # will link to the library, but it should not cause any harm. So, return
        # all LIB sources together with created targets, so that dependants link
        # to them.
        local usage-requirements ;
        if [ $(property-set).get <link> ] = static
        {
            for local t in $(sources)
            {
                if [ type.is-derived [ $(t).type ] LIB ]
                {
                    usage-requirements += <library>$(t) ;
                }
            }
        }

        usage-requirements = [ property-set.create $(usage-requirements) ] ;

        return $(usage-requirements) $(result) ;
    }
}


rule register-archiver ( id composing ? : source-types + : target-types +
    : requirements * )
{
    generators.register [ new archive-generator $(id) $(composing)
        : $(source-types) : $(target-types) : $(requirements) ] ;
}


# Generator that accepts everything and produces nothing. Useful as a general
# fallback for toolset-specific actions like PCH generation.
#
class dummy-generator : generator
{
    import property-set ;

    rule run ( project name ? : property-set : sources + )
    {
        return [ property-set.empty ] ;
    }
}

IMPORT $(__name__) : register-linker register-archiver
    : : generators.register-linker generators.register-archiver ;