boost_1_45_0/tools/build/v2/tools/symlink.jam

# Copyright 2003 Dave Abrahams 
# Copyright 2002, 2003 Rene Rivera 
# Copyright 2002, 2003, 2004, 2005 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 the "symlink" special target. 'symlink' targets make symbolic links
# to the sources.

import targets modules path class os feature project property-set ;

.count = 0 ;

feature.feature symlink-location : project-relative build-relative : incidental ;

# The class representing "symlink" targets.
#
class symlink-targets : basic-target
{
    import numbers modules class property project path ;
    
    rule __init__ (
      project
        : targets *
        : sources *
    )
    {    
        # Generate a fake name for now. Need unnamed targets eventually.
        local c = [ modules.peek symlink : .count ] ;
        modules.poke symlink : .count : [ numbers.increment $(c) ] ;
        local fake-name = symlink#$(c) ;
    
          basic-target.__init__ $(fake-name) : $(project) : $(sources) ;
    
        # Remember the targets to map the sources onto. Pad or truncate
        # to fit the sources given.
        self.targets = ;
        for local source in $(sources)
        {
            if $(targets)
            {
                self.targets += $(targets[1]) ;
                targets = $(targets[2-]) ;
            }
            else
            {
                self.targets += $(source) ;
            }
        }
    
        # The virtual targets corresponding to the given targets.
        self.virtual-targets = ;
    }    
    
    rule construct ( name : source-targets * : property-set )
    {
        local i = 1 ;
        for local t in $(source-targets)
        {
            local s = $(self.targets[$(i)]) ;
            local a = [ class.new action  $(t) : symlink.ln : $(property-set) ] ;
            local vt = [ class.new file-target $(s:D=) 
              : [ $(t).type ] : $(self.project) : $(a) ] ;
            
            # Place the symlink in the directory relative to the project
            # location, instead of placing it in the build directory.
            if [ property.select <symlink-location> : [ $(property-set).raw ] ] = <symlink-location>project-relative
            {
                $(vt).set-path [ path.root $(s:D) [ $(self.project).get location ] ] ;
            }
            
            self.virtual-targets += $(vt) ;
            i = [ numbers.increment $(i) ] ;
        }
        return [ property-set.empty ] $(self.virtual-targets) ;
    }
}

# Creates a symbolic link from a set of targets to a set of sources.
# The targets and sources map one to one. The symlinks generated are
# limited to be the ones given as the sources. That is, the targets
# are either padded or trimmed to equate to the sources. The padding
# is done with the name of the corresponding source. For example::
#
#     symlink : one two ;
#
# Is equal to::
#
#     symlink one two : one two ;
#
# Names for symlink are relative to the project location. They cannot
# include ".." path components.
rule symlink (
    targets *
    : sources *
    )
{
    local project = [ project.current ] ;
    
    return [ targets.main-target-alternative
        [ class.new symlink-targets $(project) : $(targets) : 
          # Note: inline targets are not supported for symlink, intentionally,
          # since it's used to linking existing non-local targets.
          $(sources) ] ] ;
}

rule ln
{
    local os ;
    if [ modules.peek : UNIX ] { os = UNIX ; }
    else { os ?= [ os.name ] ; }
    # Remember the path to make the link relative to where the symlink is located.
    local path-to-source = [ path.relative-to
        [ path.make [ on $(<) return $(LOCATE) ] ]
        [ path.make [ on $(>) return $(LOCATE) ] ] ] ;
    if $(path-to-source) = .
    {
        PATH_TO_SOURCE on $(<) = "" ;
    }
    else
    {
        PATH_TO_SOURCE on $(<) = [ path.native $(path-to-source) ] ;
    }
    ln-$(os) $(<) : $(>) ;
}

actions ln-UNIX
{
    ln -f -s '$(>:D=:R=$(PATH_TO_SOURCE))' '$(<)'
}

# there is a way to do this; we fall back to a copy for now
actions ln-NT
{
    echo "NT symlinks not supported yet, making copy"
    del /f /q "$(<)" 2>nul >nul
    copy "$(>)" "$(<)" $(NULL_OUT)
}

IMPORT $(__name__) : symlink : : symlink ;