build/Jambase

# Minimal core Jambase for boost

# (C) Copyright David Abrahams 2001. Permission to copy, use,
# modify, sell and distribute this software is granted provided this
# copyright notice appears in all copies. This software is provided
# "as is" without express or implied warranty, and with no claim as
# to its suitability for any purpose.

#########################################
# User-settable Variable Documentation: #
#########################################

# Unless otherwise specified all variables will be picked up first from the
# command-line, next from the environment, then from Jamrules, and finally from
# the users' Jamfile

# JAMRULES
#       The name of the Jamrules file. By the time a Jamrules file is read it is
#       too late to affect the initial Jamrules file that's loaded, but you can
#       do it in a Jamfile.
#    Default = "Jamrules"

# JAMFILE
#       The name of the user file to load after the Jambase is read. Changing
#       JAMFILE in a Jamfile or Jamrules file will affect the name of the file
#       loaded for recursive dependencies or subincludes.
#    Default = "Jamfile"

# BOOST_BUILD_INSTALLATION
#       where to find the boost build jam code. Only the first setting of this
#       variable is used, in case multiple project Jamrules files should set it.
#    Default = project root of first project (boost Jamrules set this to tools/build).

# BOOST_JAMBASE
#       The name of the top-level build system source file. This file will be
#       loaded once from the directory BOOST_BUILD_INSTALLATION, after the first
#       project's Jamrules file is loaded. 
#    Default = boost-base.jam

#######################################################
# Useful variables that should NOT be set by the user #
#######################################################

# gPROJECT_ROOT
#       The path from the Jam invocation directory to the root of the current project.

#########################################
# Prepare utility globals               #
#########################################

# clear any settings for these that may have come from the environment
DOT = ;
DOTDOT = ;
SLASH = ;

# Customize for various OSes
if $(NT)
{
    SLASH = \\ ;
}
if $(VMS)
{
    DOT = [] ;
    DOTDOT = [-] ;
    SLASH = . ;
}
else if $(MAC)
{
    DOT = ":" ;
    DOTDOT = "::" ;
    SLASH = ":" ;
}
# Defaults for uncustomized values
DOT ?= . ;
DOTDOT ?= .. ;
JAMRULES ?= Jamrules ;
JAMFILE ?= Jamfile ;
SLASH ?= "/"  ;

#########################################
# Utility rules                         #
#########################################

rule report-argument-error # rule-name length argnum : $(1) : $(2) : $(3) : $(4)...
{
    # fancy footwork to get Jam to print $(x) where x is a number
    local dollar = "\$" ;
    local argname = $(dollar)($(<[3])) ;
    EXIT "rule '$(<[1])' expects $(<[2]) elements in $(argname),"
        "got arguments (" $(2)
        ": "$(3[1]) $(3[2-])
        ": "$(4[1]) $(4[2-])
        ": "$(5[1]) $(5[2-])
        ": "$(6[1]) $(6[2-])
        ": "$(7[1]) $(7[2-])
        ": "$(8[1]) $(8[2-])
        ": "$(9[1]) $(9[2-])
        ") instead." ;
}

# regex-match string pattern
#
# return "true" iff string matches pattern, empty otherwise.
rule regex-match
{
    check-arguments regex-match 2 : $(1) : $(2) : $(3) ;
    
    local source = $(<[1]) ;
    local pattern = $(<[2]) ;
    
    # SUBST rule is weird. When there's no match it returns the original string
    # for /all/ $n results. When there /is/ a match, only the $n results that
    # are set are matched
    local unmatched = [ SUBST $(source) ($(pattern)) $2 ] ;
    if ! $(unmatched)
    {
        return true ;
    }
}

# regex-split string pattern
#
# split a single string into a list of elements on the boundaries given by
# the regexp pattern.
rule regex-split 
{
    # grab arguments
    local source = $(<[1]) ;
    local divider = $(<[2]) ;

    # check for extra args
    check-arguments regex-split 2 : $(1) : $(2) : $(3) ;
    
    if ! [ regex-match $(source) ".*$(divider).*" ]
    {
        return $(source) ;
    }
    else
    {
        local pattern = "(.*)("$(divider)")(.*)" ;
        local head = [ SUBST $(source) $(pattern) $1 ] ;
        local tail = [ SUBST $(source) $(pattern) $3 ] ;
        return [ regex-split $(head) $(divider) ] $(tail) ;
    }
}

# split-path path
#
# split a path into its components. Always splits at forward-slashes, regardless
# of the OS.
rule split-path
{
    check-arguments split-path 1 : $(1) : $(2) : $(3) ;
    return [ regex-split $(<) "[/$(SLASH)]" ] ;
}

# rule subdirectory-to-root subdirectory
#
# Given a relative path from D1 to a subdirectory D2, return the relative path
# from D2 to D1 using ../../ etc. If subdirectory is empty it will be treated
# the same as $(DOT).
#
# CAVEATS: does not handle input paths containing ..
rule subdirectory-to-root
{
    local subdirectory = $(<[1]) ;
    
    # check arguments
    if $(subdirectory:R) || $(<[2-]) || $(2) || $(3)
    {
        EXIT subdirectory-to-root rule expects zero arguments or a single relative path
                "(" $(<) ": "$(2) ": "$(3) ")" ;
    }
    
    # split the path
    local tokens = [ split-path $(subdirectory) ] ;
    if $(DOTDOT) in $(tokens)
    {
        EXIT subdirectory-to-root rule can not handle paths
                        containing $(DOTDOT) "(" $(<) ")" ;
    }
    
    local token result = ;
    for token in $(tokens)
    {
        if $(token) != $(DOT)
        {
            # Will leave result unset the first time around
            result = $(result:R=$(DOTDOT)) ;
            result ?= $(DOTDOT) ; # correct that here
        }
    }

    # if the path is empty at this point, it should be $(DOT).
    result ?= $(DOT) ;
    return $(result) ;
}

# This rule named by this variable is used to find the path from the invocation
# directory to the subproject root when the subproject rule is invoked. The
# boost build system will redefine this variable to handle cross-project
# dependencies.
gFIND_SUBPROJECT_ROOT = subdirectory-to-root ;

# Any rules named by this variable will be called upon entry to any subproject
# Jamfile (after the project Jamrules file is read if the Jamfile is the first
# seen in the project). The arguments will be:
#   $(1) - the path from the invocation directory to the project root
#   $(2) - the path from the project root to the subproject directory
gSUBPROJECT_HOOKS = ;

# include-once file
rule include-once
{
    check-arguments include-once 1 : $(1) : $(2) : $(3) ;
    
    # include it if neccessary
    if ! $(gINCLUDED:$(<))
    {
        gINCLUDED:$(<) = true ;
        include $(<) ;
    }
}

# subproject path
#
# Introduces a Jamfile rooted at the given location wrt the top of the project
# tree. If the Jamrules file at the top of the project tree has not been loaded,
# it is included. The Jamrules file can be used to define rules, and to set
# global variables which change the behavior of the build system.
rule subproject
{
    local subproject_path = $(<) ;
    check-arguments subproject 1 : $(1) : $(2) : $(3) ;
    
    gPROJECT_ROOT = [ $(gFIND_SUBPROJECT_ROOT) $(subproject_path) ] ;

    if ( ! $(gPROJECT_ROOT[1]) ) || $(gPROJECT_ROOT[2])
    {
        EXIT  "subproject rule expects a scalar path from rule
                $(gFIND_SUBPROJECT_ROOT), but got ( $(gPROJECT_ROOT) )" ;
    }

    # locate the project Jamrules file for this subproject
    local jamrules = $(JAMRULES:R=$(gPROJECT_ROOT)) ;

    # include it if neccessary
    if ! $(gINCLUDED:$(jamrules))
    {
        gINCLUDED:$(jamrules) = true ;
        include $(jamrules) ;
    }

    # if the build system hasn't been loaded, do that.
    if ! $(gBOOST_BUILD_INSTALLATION)
    {
        # determine where toolset specifications and boost-base can be
        # found. The default is to find them in the project root directory
        BOOST_BUILD_INSTALLATION ?= $(gPROJECT_ROOT) ;

        # We ignore any further settings of BOOST_BUILD_INSTALLATION in other
        # Jamrules files. The value used from here on is in
        # gBOOST_BUILD_INSTALLATION. 
        gBOOST_BUILD_INSTALLATION = $(BOOST_BUILD_INSTALLATION) ;

        BOOST_JAMBASE ?= boost-base.jam ;
        include $(BOOST_JAMBASE:R=$(gBOOST_BUILD_INSTALLATION)) ;
    }

    # Call any subproject hooks
    local hook ;
    for hook in $(gSUBPROJECT_HOOKS)
    {
        local ignored = [ $(hook) $(gPROJECT_ROOT) $(subproject_path) ] ;
    }
}

# project-root
#
# Declares this directory to be the project root.
rule project-root
{
    subproject $(DOT) ;
}

# include the Jamfile
if $(JAMFILE)
{
    include $(JAMFILE) ;

    # Call any post-jamfile hooks
    local hook ;
    for hook in $(gPOST_JAMFILE_HOOKS)
    {
        local ignored = [ $(hook) ] ;
    }
}