virtual-target.jam

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        # the sources of the target. For example to make unique names of object
        # files based on the source file.  --grafik
        ps = [ property-set.create [ $(ps).raw ] <target>$(__name__) ] ;

        local tag = [ $(ps).get <tag> ] ;

        if $(tag)
        {
            local rule-name = [ MATCH ^@(.*) : $(tag) ] ;
            if $(rule-name)
            {
                if $(tag[2])
                {
                    errors.error "<tag>@rulename is present but is not the only"
                        "<tag> feature" ;
                }

                self.name = [ indirect.call $(rule-name) $(specified-name)
                    : $(self.type) : $(ps) ] ;
            }
            else
            {
                errors.error
                    "The value of the <tag> feature must be '@rule-name'" ;
            }
        }

        # If there is no tag or the tag rule returned nothing.
        if ! $(tag) || ! $(self.name)
        {
            self.name = [ virtual-target.add-prefix-and-suffix $(specified-name)
                : $(self.type) : $(ps) ] ;
        }
    }

    rule actualize-no-scanner ( )
    {
        local name = [ actual-name ] ;

        # Do anything only on the first invocation.
        if ! $(self.made.$(name))
        {
            self.made.$(name) = true ;

            if $(self.action)
            {
                # For non-derived target, we do not care if there are several
                # virtual targets that refer to the same name. One case when
                # this is unavoidable is when the file name is main.cpp and two
                # targets have types CPP (for compiling) and MOCCABLE_CPP (for
                # conversion to H via Qt tools).
                virtual-target.register-actual-name $(name) : $(__name__) ;
            }

            for local i in $(self.dependencies)
            {
                DEPENDS $(name) : [ $(i).actualize ] ;
            }

            actualize-location $(name) ;
            actualize-action $(name) ;
        }
        return $(name) ;
    }
}


# Appends the suffix appropriate to 'type/property-set' combination to the
# specified name and returns the result.
#
rule add-prefix-and-suffix ( specified-name : type ? : property-set )
{
    local suffix = [ type.generated-target-suffix $(type) : $(property-set) ] ;

    # Handle suffixes for which no leading dot is desired. Those are specified
    # by enclosing them in <...>.  Needed by python so it can create "_d.so"
    # extensions, for example.
    if $(suffix:G)
    {
        suffix = [ utility.ungrist $(suffix) ] ;
    }
    else
    {
        suffix = .$(suffix) ;
    }

    local prefix = [ type.generated-target-prefix $(type) : $(property-set) ] ;

    if  [ MATCH ^($(prefix)) : $(specified-name) ]
    {
        prefix = ;
    }
    return $(prefix:E="")$(specified-name)$(suffix:E="") ;
}


# File targets with explicitly known location.
#
# The file path is determined as
#    * Value passed to the 'set-path' method, if any.
#    * For derived files, project's build dir, joined with components that
#      describe action properties. If free properties are not equal to the
#      project's reference properties an element with the name of the main
#      target is added.
#    * For source files, project's source dir.
#
# The file suffix is determined as:
#     * The value passed to the 'suffix' method, if any.
#     * The suffix corresponding to the target's type.
#
class file-target : abstract-file-target
{
    import "class" : new ;
    import common ;
    import errors ;

    rule __init__ (
        name exact ?
        : type ?  # Optional type for this target.
        : project
        : action ?
        : path ?
    )
    {
        abstract-file-target.__init__ $(name) $(exact) : $(type) : $(project) :
            $(action) ;

        self.path = $(path) ;
    }

    rule clone-with-different-type ( new-type )
    {
        return [ new file-target $(self.name) exact : $(new-type) :
            $(self.project) : $(self.action) : $(self.path) ] ;
    }

    rule actualize-location ( target )
    {
        if $(self.action)
        {
            # This is a derived file.
            local path = [ path ] ;
            LOCATE on $(target) = $(path) ;

            # Make sure the path exists.
            DEPENDS $(target) : $(path) ;
            common.MkDir $(path) ;

            # It is possible that the target name includes a directory too, for
            # example when installing headers. Create that directory.
            if $(target:D)
            {
                local d = $(target:D) ;
                d = $(d:R=$(path)) ;
                DEPENDS $(target) : $(d) ;
                common.MkDir $(d) ;
            }

            # For a real file target, we create a fake target depending on the
            # real target. This allows us to run
            #
            #    bjam hello.o
            #
            # without trying to guess the name of the real target. Note that the
            # target has no directory name and uses a special <e> grist.
            #
            # First, that means that "bjam hello.o" will build all known hello.o
            # targets. Second, the <e> grist makes sure this target will not be
            # confused with other targets, for example, if we have subdir 'test'
            # with target 'test' in it that includes a 'test.o' file, then the
            # target for directory will be just 'test' the target for test.o
            # will be <ptest/bin/gcc/debug>test.o and the target we create below
            # will be <e>test.o
            DEPENDS $(target:G=e) : $(target) ;
            # Allow bjam <path-to-file>/<file> to work. This will not catch all
            # possible ways to refer to the path (relative/absolute, extra ".",
            # various "..", but should help in obvious cases.
            DEPENDS $(target:G=e:R=$(path)) : $(target) ;
        }
        else
        {
            SEARCH on $(target) = [ path.native $(self.path) ] ;
        }
    }

    # Returns the directory for this target.
    #
    rule path ( )
    {
        if ! $(self.path)
        {
            if $(self.action)
            {
                local p = [ $(self.action).properties ] ;
                local path,relative-to-build-dir = [ $(p).target-path ] ;
                local path = $(path,relative-to-build-dir[1]) ;
                local relative-to-build-dir = $(path,relative-to-build-dir[2]) ;

                if $(relative-to-build-dir)
                {
                    path = [ path.join [ $(self.project).build-dir ] $(path) ] ;
                }

                self.path = [ path.native $(path) ] ;
            }
        }
        return $(self.path) ;
     }
}


class notfile-target : abstract-file-target
{
    rule __init__ ( name : project : action ? )
    {
        abstract-file-target.__init__ $(name) : : $(project) : $(action) ;
    }

    # Returns nothing to indicate that the target's path is not known.
    #
    rule path ( )
    {
        return ;
    }

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


# Class representing an action. Both 'targets' and 'sources' should list
# instances of 'virtual-target'. Action name should name a rule with this
# prototype:
#     rule action-name ( targets + : sources * : properties * )
# Targets and sources are passed as actual Jam targets. The rule may not
# establish additional dependency relationships.
#
class action
{
    import "class" ;
    import errors ;
    import type ;
    import toolset ;
    import property-set ;
    import indirect ;
    import path ;

    rule __init__ ( sources * : action-name + : property-set ? )
    {
        self.sources = $(sources) ;

        self.action-name = [ indirect.make-qualified $(action-name) ] ;

        if ! $(property-set)
        {
            property-set = [ property-set.empty ] ;
        }

        if ! [ class.is-instance $(property-set) ]
        {
            errors.error "Property set instance required" ;
        }

        self.properties = $(property-set) ;
    }

    rule add-targets ( targets * )
    {
        self.targets += $(targets) ;
    }

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

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

    rule action-name ( )
    {
        return $(self.action-name) ;
    }

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

    # Generates actual build instructions.
    #
    rule actualize ( )
    {
        if ! $(self.actualized)
        {
            self.actualized = true ;

            local ps = [ properties ] ;
            local properties = [ adjust-properties $(ps) ] ;

            local actual-targets ;
            for local i in [ targets ]
            {
                actual-targets += [ $(i).actualize ] ;
            }

            actualize-sources [ sources ] : $(properties) ;

            DEPENDS $(actual-targets) : $(self.actual-sources)
                $(self.dependency-only-sources) ;

            # Action name can include additional argument to rule, which should
            # not be passed to 'set-target-variables'
            toolset.set-target-variables
                [ indirect.get-rule $(self.action-name[1]) ] $(actual-targets)
                : $(properties) ;

            # Reflect ourselves in a variable for the target. This allows
            # looking up additional info for the action given the raw target.
            # For example to debug or output action information from action
            # rules.
            .action on $(actual-targets) = $(__name__) ;

            indirect.call $(self.action-name) $(actual-targets)
                : $(self.actual-sources) : [ $(properties).raw ] ;

            # Since we set up the creating action here, we set up the action for
            # cleaning up as well.
            common.Clean clean-all : $(actual-targets) ;
        }
    }

    # Helper for 'actualize-sources'. For each passed source, actualizes it with
    # the appropriate scanner. Returns the actualized virtual targets.
    #
    rule actualize-source-type ( sources * : property-set )
    {
        local result = ;
        for local i in $(sources)
        {
            local scanner ;
            if [ $(i).type ]
            {
                scanner = [ type.get-scanner [ $(i).type ] : $(property-set) ] ;
            }
            result += [ $(i).actualize $(scanner) ] ;
        }
        return $(result) ;
    }

    # Creates actual Jam targets for sources. Initializes the following member
    # variables:
    #   'self.actual-sources'          -- sources passed to the updating action.
    #   'self.dependency-only-sources' -- sources marked as dependencies, but
    #                                     are not used otherwise.
    #
    # New values will be *appended* to the variables. They may be non-empty if
    # caller wants it.
    #
    rule actualize-sources ( sources * : property-set )
    {
        local dependencies = [ $(self.properties).get <dependency> ] ;

        self.dependency-only-sources +=
            [ actualize-source-type $(dependencies) : $(property-set) ] ;
        self.actual-sources +=
            [ actualize-source-type $(sources) : $(property-set) ] ;

        # This is used to help bjam find dependencies in generated headers and
        # other main targets, e.g. in:
        #
        #   make a.h : ....... ;
        #   exe hello : hello.cpp : <implicit-dependency>a.h ;
        #
        # For bjam to find the dependency the generated target must be
        # actualized (i.e. have its Jam target constructed). In the above case,
        # if we are building just hello ("bjam hello"), 'a.h' will not be
        # actualized unless we do it here.
        local implicit = [ $(self.properties).get <implicit-dependency> ] ;
        for local i in $(implicit)
        {
            $(i:G=).actualize ;
        }
    }

    # Determines real properties when trying to build with 'properties'. This is
    # the last chance to fix properties, for example to adjust includes to get
    # generated headers correctly. Default implementation simply returns its
    # argument.
    #
    rule adjust-properties ( property-set )
    {
        return $(property-set) ;
    }
}


# Action class which does nothing --- it produces the targets with specific
# properties out of nowhere. It is needed to distinguish virtual targets with
# different properties that are known to exist and have no actions which create
# them.
#
class null-action : action
{
    rule __init__ ( property-set ? )
    {
        action.__init__ : .no-action : $(property-set) ;
    }

    rule actualize ( )
    {
        if ! $(self.actualized)
        {
            self.actualized = true ;
            for local i in [ targets ]
            {
                $(i).actualize ;
            }
        }
    }
}