hy/hy/macros.py

# Copyright (c) 2012 Paul Tagliamonte <paultag@debian.org>
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.

from hy.models.expression import HyExpression
from hy.models.list import HyList

_hy_macros = {}


def macro(name):
    def _(fn):
        _hy_macros[name] = fn

        def __(*args, **kwargs):
            return fn(*args, **kwargs)
        return __
    return _


def process(tree):
    if isinstance(tree, HyExpression):
        it = iter(tree)
        fn = next(it)

        body = [process(x) for x in it]

        if fn in _hy_macros:
            m = _hy_macros[fn]
            return m(HyExpression([fn] + body))

        return [fn] + body

    if isinstance(tree, HyList):
        return HyList([process(x) for x in tree])

    return tree