source: downloads/boost_1_33_1/tools/build/v2/kernel/bootstrap.jam @ 12

# (C) Copyright David Abrahams, 2001.
# (C) Copyright Rene Rivera, 2003.
#
# See accompanying license for terms and conditions of use.
#

# First of all, check the jam version

if $(JAM_VERSION:J="") < 030109
{
    ECHO "error: Boost.Jam version 3.1.9 or later required" ;
    EXIT ;
} 

local required-rules = GLOB-RECURSIVELY ;

for local r in $(required-rules)
{
    if ! $(r) in [ RULENAMES ]
    {
        ECHO "error: builtin rule '$(r)' is not present" ;
        ECHO "error: you version of bjam is likely out of date" ;
        ECHO "error: please get a fresh version from CVS." ;
        EXIT ;
    }    
}

# Check that the builtin .ENVIRON module is present. We don't have a
# builtin to check that a module is present, so we assume that the PATH
# environment variable is always set and verify that the .ENVIRON module
# has non-empty value of that variable.
module .ENVIRON 
{   
    local p = $(PATH) $(Path) $(path) ;
    if ! $(p)
    {
        ECHO "error: no builtin module .ENVIRON is found" ;
        ECHO "error: you version of bjam is likely out of date" ;
        ECHO "error: please get a fresh version from CVS." ;
        EXIT ;
    }
}



# Bootstrap the module system. Then bring the import rule into the global module.
#
SEARCH on <module@>modules.jam = $(.bootstrap-file:D) ;
module modules { include <module@>modules.jam ; }
IMPORT modules : import : : import ;

{
    # Add module subdirectories to the BOOST_BUILD_PATH, which allows
    # us to make an incremental refactoring step by moving modules to
    # the appropriate subdirectories, thereby achieving some physical
    # separation of different layers without changing all of our code
    # to specify subdirectories in import statements or use an extra
    # level of qualification on imported names.
    
    local subdirs = 
      kernel        # only the most-intrinsic modules: modules, errors
      util          # low-level substrate: string/number handling, etc.
      build         # essential elements of the build system architecture
      tools         # toolsets for handling specific build jobs and targets.
      
      new           # until we get everything sorted out, there is
                    # still some code here
      
      .             # build-system.jam lives here
      
      ;
    local whereami = [ NORMALIZE_PATH $(.bootstrap-file:DT) ] ;
    BOOST_BUILD_PATH += $(whereami:D)/$(subdirs) ;
    
    modules.poke .ENVIRON : BOOST_BUILD_PATH : $(BOOST_BUILD_PATH) ;    
}

# Reload the modules, to clean up things. The modules module can tolerate
# being included twice.
#
import modules ;

# Check command-line args as soon as possible.  For each option try
# to load module named after option. Is that succeeds, invoke 'process'
# rule in the module. The rule may return "true" to indicate that the
# regular built process should not be attempted.
#
# Options take the general form of: --<name>[=<value>] [<value>]
#
local dont-build ;
local args = $(ARGV) ;
while $(args)
{
    local arg = [ MATCH ^--(.*) : $(args[1]) ] ;
    while $(args[2-]) && ! $(arg)
    {
        args = $(args[2-]) ;
        arg = [ MATCH ^--(.*) : $(args[1]) ] ;
    }
    args = $(args[2-]) ;
    
    if $(arg)
    {
        local split = [ MATCH ^(([^-=]+)[^=]*)(=?)(.*)$ : $(arg) ] ;
        local full-name = $(split[1]) ;
        local prefix = $(split[2]) ;
        local values ;
        
        if $(split[3])
        {
            values = $(split[4]) ;
        }
        if $(args) && ! [ MATCH ^(--).* : $(args[1]) ]
        {
            values += $(args[1]) ;
            args = $(args[2-]) ;
        }
        
        # look in options subdirectories of BOOST_BUILD_PATH for modules
        # matching the full option name and then its prefix.
        local plugin-dir = options ;
        local option-files = [ 
            GLOB $(plugin-dir:D=$(BOOST_BUILD_PATH)) : $(full-name).jam $(prefix).jam 
            ] ;
        
        if $(option-files)
        {
            # load the file into a module named for the option
            local f = $(option-files[1]) ;
            local module-name = --$(f:D=:S=) ;
            modules.load $(module-name) : $(f:D=) : $(f:D) ;
            
            # if there's a process rule, call it with the full option name
            # and its value (if any).  If there was no "=" in the option,
            # the value will be empty.
            if process in [ RULENAMES $(module-name) ]
            {
                dont-build += 
                  [ modules.call-in $(module-name) : process --$(full-name) : $(values) ] ;
            }
        }
    }
}

if ! $(dont-build)
{   
    # Allow users to override the build system file from the
    # command-line (mostly for testing)
    local build-system = [ MATCH --build-system=(.*) : $(ARGV) ] ;
    build-system ?= build-system ;

    # Use last element in case of multiple command-line options
    import $(build-system[-1]) ;
}