import sys

def patch_for_specialized_compiler():
    """
    Patch functions in distutils.msvc9compiler to use the standalone compiler
    build for Python (Windows only). Fall back to original behavior when the
    standalone compiler is not available.
    """
    try:
        distutils = __import__('distutils.msvc9compiler')
    except ImportError:
        # The module isn't available to be patched
        return

    VC_BASE = r'Software\%sMicrosoft\DevDiv\VCForPython\%0.1f'
    find_vcvarsall = distutils.msvc9compiler.find_vcvarsall
    query_vcvarsall = distutils.msvc9compiler.query_vcvarsall
    if find_vcvarsall and find_vcvarsall.__module__.startswith('setuptools.'):
        # Already patched
        return

    def _find_vcvarsall(version):
        Reg = distutils.msvc9compiler.Reg
        try:
            # Per-user installs register the compiler path here
            productdir = Reg.get_value(VC_BASE % ('', version), "installdir")
        except KeyError:
            try:
                # All-user installs on a 64-bit system register here
                productdir = Reg.get_value(VC_BASE % ('Wow6432Node\\', version), "installdir")
            except KeyError:
                productdir = None

        if productdir:
            import os
            vcvarsall = os.path.join(productdir, "vcvarsall.bat")
            if os.path.isfile(vcvarsall):
                return vcvarsall

        return find_vcvarsall(version)

    def _query_vcvarsall(version, *args, **kwargs):
        try:
            return query_vcvarsall(version, *args, **kwargs)
        except distutils.errors.DistutilsPlatformError:
            exc = sys.exc_info()[1]
            if exc and "vcvarsall.bat" in exc.args[0]:
                message = 'Microsoft Visual C++ %0.1f is required (%s).' % (version, exc.args[0])
                if int(version) == 9:
                    # This redirection link is maintained by Microsoft.
                    # Contact vspython@microsoft.com if it needs updating.
                    raise distutils.errors.DistutilsPlatformError(
                        message + ' Get it from http://aka.ms/vcpython27'
                    )
                raise distutils.errors.DistutilsPlatformError(message)
            raise

    distutils.msvc9compiler.find_vcvarsall = _find_vcvarsall
    distutils.msvc9compiler.query_vcvarsall = _query_vcvarsall