"""SCons.Tool.m4

Tool-specific initialization for m4.

There normally shouldn't be any need to import this module directly.
It will usually be imported through the generic SCons.Tool.Tool()
selection method.

"""

#
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__revision__ = "src/engine/SCons/Tool/m4.py 5134 2010/08/16 23:02:40 bdeegan"

import SCons.Action
import SCons.Builder
import SCons.Util

def generate(env):
    """Add Builders and construction variables for m4 to an Environment."""
    M4Action = SCons.Action.Action('$M4COM', '$M4COMSTR')
    bld = SCons.Builder.Builder(action = M4Action, src_suffix = '.m4')

    env['BUILDERS']['M4'] = bld

    # .m4 files might include other files, and it would be pretty hard
    # to write a scanner for it, so let's just cd to the dir of the m4
    # file and run from there.
    # The src_suffix setup is like so: file.c.m4 -> file.c,
    # file.cpp.m4 -> file.cpp etc.
    env['M4']      = 'm4'
    env['M4FLAGS'] = SCons.Util.CLVar('-E')
    env['M4COM']   = 'cd ${SOURCE.rsrcdir} && $M4 $M4FLAGS < ${SOURCE.file} > ${TARGET.abspath}'

def exists(env):
    return env.Detect('m4')

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