build-system.jam

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    # Flags indicating that this build system run has been started in order to
    # clean existing instead of create new targets. Note that these are not the
    # final flag values as they may get changed later on due to some special
    # targets being specified on the command line.
    local clean    ; if "--clean"     in $(.argv) { clean    = true ; }
    local cleanall ; if "--clean-all" in $(.argv) { cleanall = true ; }


    # List of explicitly requested files to build. Any target references read
    # from the command line parameter not recognized as one of the targets
    # defined in the loaded Jamfiles will be interpreted as an explicitly
    # requested file to build. If any such files are explicitly requested then
    # only those files and the targets they depend on will be built and they
    # will be searched for among targets that would have been built had there
    # been no explicitly requested files.
    local explicitly-requested-files


    # List of Boost Build meta-targets, virtual-targets and actual Jam targets
    # constructed in this build system run.
    local targets ;
    local virtual-targets ;
    local actual-targets ;


    # Process each target specified on the command-line and convert it into
    # internal Boost Build target objects. Detect special clean target. If no
    # main Boost Build targets were explictly requested use the current project
    # as the target.
    for local id in $(target-ids)
    {
        if $(id) = clean
        {
            clean = true ;
        }
        else
        {
            local t ;
            if $(current-project)
            {
                t = [ $(current-project).find $(id) : no-error ] ;
            }
            else
            {
                t = [ find-target $(id) ] ;
            }

            if ! $(t)
            {
                ECHO "notice: could not find main target" $(id) ;
                ECHO "notice: assuming it is a name of file to create." ;
                explicitly-requested-files += $(id) ;
            }
            else
            {
                targets += $(t) ;
            }
        }
    }
    if ! $(targets)
    {
        targets += [ project.target [ project.module-name "." ] ] ;
    }


    # Now that we have a set of targets to build and a set of property sets to
    # build the targets with, we can start the main build process by using each
    # property set to generate virtual targets from all of our listed targets
    # and any of their dependants.
    for local p in $(expanded)
    {
        .command-line-free-features = [ property-set.create [ $(p).free ] ] ;
        for local t in $(targets)
        {
            local g = [ $(t).generate $(p) ] ;
            if ! [ class.is-a $(t) : project-target ]
            {
                .results-of-main-targets += $(g[2-]) ;
            }
            virtual-targets += $(g[2-]) ;
        }
    }


    # Convert collected virtual targets into actual raw Jam targets.
    for t in $(virtual-targets)
    {
        actual-targets += [ $(t).actualize ] ;
    }


    # If XML data output has been requested prepare additional rules and targets
    # so we can hook into Jam to collect build data while its building and have
    # it trigger the final XML report generation after all the planned targets
    # have been built.
    if $(.out-xml)
    {
        # Get a qualified virtual target name.
        rule full-target-name ( target )
        {
            local name = [ $(target).name ] ;
            local project = [ $(target).project ] ;
            local project-path = [ $(project).get location ] ;
            return $(project-path)//$(name) ;
        }

        # Generate an XML file containing build statistics for each constituent.
        #
        rule out-xml ( xml-file : constituents * )
        {
            # Prepare valid XML header and footer with some basic info.
            local nl = "
" ;
            local jam       = [ version.jam ] ;
            local os        = [ modules.peek : OS OSPLAT JAMUNAME ] "" ;
            local timestamp = [ modules.peek : JAMDATE ] ;
            local cwd       = [ PWD ] ;
            local command   = $(.argv) ;
            local bb-version = [ version.boost-build ] ;
            .header on $(xml-file) =
                "<?xml version=\"1.0\" encoding=\"utf-8\"?>"
                "$(nl)<build format=\"1.0\" version=\"$(bb-version)\">"
                "$(nl)  <jam version=\"$(jam:J=.)\" />"
                "$(nl)  <os name=\"$(os[1])\" platform=\"$(os[2])\"><![CDATA[$(os[3-]:J= )]]></os>"
                "$(nl)  <timestamp><![CDATA[$(timestamp)]]></timestamp>"
                "$(nl)  <directory><![CDATA[$(cwd)]]></directory>"
                "$(nl)  <command><![CDATA[\"$(command:J=\" \")\"]]></command>"
                ;
            .footer on $(xml-file) =
                "$(nl)</build>" ;

            # Generate the target dependency graph.
            .contents on $(xml-file) +=
                "$(nl)  <targets>" ;
            for local t in [ virtual-target.all-targets ]
            {
                local action = [ $(t).action ] ;
                if $(action)
                    # If a target has no action, it has no dependencies.
                {
                    local name = [ full-target-name $(t) ] ;
                    local sources = [ $(action).sources ] ;
                    local dependencies ;
                    for local s in $(sources)
                    {
                        dependencies += [ full-target-name $(s) ] ;
                    }

                    local path = [ $(t).path ] ;
                    local jam-target = [ $(t).actual-name ] ;

                    .contents on $(xml-file) +=
                        "$(nl)    <target>"
                        "$(nl)      <name><![CDATA[$(name)]]></name>"
                        "$(nl)      <dependencies>"
                        "$(nl)        <dependency><![CDATA[$(dependencies)]]></dependency>"
                        "$(nl)      </dependencies>"
                        "$(nl)      <path><![CDATA[$(path)]]></path>"
                        "$(nl)      <jam-target><![CDATA[$(jam-target)]]></jam-target>"
                        "$(nl)    </target>"
                        ;
                }
            }
            .contents on $(xml-file) +=
                "$(nl)  </targets>" ;

            # Build $(xml-file) after $(constituents). Do so even if a
            # constituent action fails and regenerate the xml on every bjam run.
            INCLUDES $(xml-file) : $(constituents) ;
            ALWAYS $(xml-file) ;
            __ACTION_RULE__ on $(xml-file) = build-system.out-xml.generate-action ;
            out-xml.generate $(xml-file) ;
        }

        # The actual build actions are here; if we did this work in the actions
        # clause we would have to form a valid command line containing the
        # result of @(...) below (the name of the XML file).
        #
        rule out-xml.generate-action ( args * : xml-file
            : command status start end user system : output ? )
        {
            local contents =
                [ on $(xml-file) return $(.header) $(.contents) $(.footer) ] ;
            local f = @($(xml-file):E=$(contents)) ;
        }

        # Nothing to do here; the *real* actions happen in
        # out-xml.generate-action.
        actions quietly out-xml.generate { }

        # Define the out-xml file target, which depends on all the targets so
        # that it runs the collection after the targets have run.
        out-xml $(.out-xml) : $(actual-targets) ;

        # Set up a global __ACTION_RULE__ that records all the available
        # statistics about each actual target in a variable "on" the --out-xml
        # target.
        #
        rule out-xml.collect ( xml-file : target : command status start end user
            system : output ? )
        {
            local nl = "
" ;
            # Open the action with some basic info.
            .contents on $(xml-file) +=
                "$(nl)  <action status=\"$(status)\" start=\"$(start)\" end=\"$(end)\" user=\"$(user)\" system=\"$(system)\">" ;

            # If we have an action object we can print out more detailed info.
            local action = [ on $(target) return $(.action) ] ;
            if $(action)
            {
                local action-name    = [ $(action).action-name ] ;
                local action-sources = [ $(action).sources     ] ;
                local action-props   = [ $(action).properties  ] ;

                # The qualified name of the action which we created the target.
                .contents on $(xml-file) +=
                    "$(nl)    <name><![CDATA[$(action-name)]]></name>" ;

                # The sources that made up the target.
                .contents on $(xml-file) +=
                    "$(nl)    <sources>" ;
                for local source in $(action-sources)
                {
                    local source-actual = [ $(source).actual-name ] ;
                    .contents on $(xml-file) +=
                        "$(nl)      <source><![CDATA[$(source-actual)]]></source>" ;
                }
                .contents on $(xml-file) +=
                    "$(nl)    </sources>" ;

                # The properties that define the conditions under which the
                # target was built.
                .contents on $(xml-file) +=
                    "$(nl)    <properties>" ;
                for local prop in [ $(action-props).raw ]
                {
                    local prop-name = [ MATCH ^<(.*)>$ : $(prop:G) ] ;
                    .contents on $(xml-file) +=
                        "$(nl)      <property name=\"$(prop-name)\"><![CDATA[$(prop:G=)]]></property>" ;
                }
                .contents on $(xml-file) +=
                    "$(nl)    </properties>" ;
            }

            local locate = [ on $(target) return $(LOCATE) ] ;
            locate ?= "" ;
            .contents on $(xml-file) +=
                "$(nl)    <jam-target><![CDATA[$(target)]]></jam-target>"
                "$(nl)    <path><![CDATA[$(target:G=:R=$(locate))]]></path>"
                "$(nl)    <command><![CDATA[$(command)]]></command>"
                "$(nl)    <output><![CDATA[$(output)]]></output>" ;
            .contents on $(xml-file) +=
                "$(nl)  </action>" ;
        }

        # When no __ACTION_RULE__ is set "on" a target, the search falls back to
        # the global module.
        module
        {
            __ACTION_RULE__ = build-system.out-xml.collect
                [ modules.peek build-system : .out-xml ] ;
        }
    }


    # The 'all' pseudo target is not strictly needed expect in the case when we
    # use it below but people often assume they always have this target
    # available and do not declare it themselves before use which may cause
    # build failures with an error message about not being able to build the
    # 'all' target.
    NOTFILE all ;


    # And now that all the actual raw Jam targets and all the dependencies
    # between them have been prepared all that is left is to tell Jam to update
    # those targets.
    if $(explicitly-requested-files)
    {
        # Note that this case can not be joined with the regular one when only
        # exact Boost Build targets are requested as here we do not build those
        # requested targets but only use them to construct the dependency tree
        # needed to build the explicitly requested files.
        UPDATE $(explicitly-requested-files:G=e) $(.out-xml) ;
    }
    else if $(cleanall)
    {
        UPDATE clean-all ;
    }
    else if $(clean)
    {
        common.Clean clean : [ actual-clean-targets ] ;
        UPDATE clean ;
    }
    else
    {
        DEPENDS all : $(actual-targets) ;
        UPDATE all $(.out-xml) ;
    }
}