hy/hy/macros.py
Kodi Arfer 14fddbe6c3 Give require the same features as import (#1142)
Give `require` the same features as `import`

You can now do (require foo), (require [foo [a b c]]), (require [foo [*]]), and (require [foo :as bar]). The first and last forms get you macros named foo.a, foo.b, etc. or bar.a, bar.b, etc., respectively. The second form only gets the macros in the list.

Implements #1118 and perhaps partly addresses #277.

N.B. The new meaning of (require foo) will cause all existing code that uses macros to break. Simply replace these forms with (require [foo [*]]) to get your code working again.

There's a bit of a hack involved in the forms (require foo) or (require [foo :as bar]). When you call (foo.a ...) or (bar.a ...), Hy doesn't actually look inside modules. Instead, these (require ...) forms give the macros names that have periods in them, which happens to work fine with the way Hy finds and interprets macro calls.

* Make `require` syntax stricter and add tests

* Update documentation for `require`

* Documentation wording improvements

* Allow :as in `require` name lists
2016-11-03 09:35:58 +02:00

228 lines
7.1 KiB
Python

# Copyright (c) 2013 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 inspect import getargspec, formatargspec
from hy.models import replace_hy_obj, wrap_value
from hy.models.expression import HyExpression
from hy.models.string import HyString
from hy.errors import HyTypeError, HyMacroExpansionError
from collections import defaultdict
CORE_MACROS = [
"hy.core.bootstrap",
]
EXTRA_MACROS = [
"hy.core.macros",
]
_hy_macros = defaultdict(dict)
_hy_reader = defaultdict(dict)
def macro(name):
"""Decorator to define a macro called `name`.
This stores the macro `name` in the namespace for the module where it is
defined.
If the module where it is defined is in `hy.core`, then the macro is stored
in the default `None` namespace.
This function is called from the `defmacro` special form in the compiler.
"""
def _(fn):
argspec = getargspec(fn)
fn._hy_macro_pass_compiler = argspec.keywords is not None
module_name = fn.__module__
if module_name.startswith("hy.core"):
module_name = None
_hy_macros[module_name][name] = fn
return fn
return _
def reader(name):
"""Decorator to define a reader macro called `name`.
This stores the macro `name` in the namespace for the module where it is
defined.
If the module where it is defined is in `hy.core`, then the macro is stored
in the default `None` namespace.
This function is called from the `defreader` special form in the compiler.
"""
def _(fn):
module_name = fn.__module__
if module_name.startswith("hy.core"):
module_name = None
_hy_reader[module_name][name] = fn
return fn
return _
def require(source_module, target_module,
all_macros=False, assignments={}, prefix=""):
"""Load macros from `source_module` in the namespace of
`target_module`. `assignments` maps old names to new names, but is
ignored if `all_macros` is true. If `prefix` is nonempty, it is
prepended to the name of each imported macro. (This means you get
macros named things like "mymacromodule.mymacro", which looks like
an attribute of a module, although it's actually just a symbol
with a period in its name.)
This function is called from the `require` special form in the compiler.
"""
seen_names = set()
if prefix:
prefix += "."
for d in _hy_macros, _hy_reader:
for name, macro in d[source_module].items():
seen_names.add(name)
if all_macros:
d[target_module][prefix + name] = macro
elif name in assignments:
d[target_module][prefix + assignments[name]] = macro
if not all_macros:
unseen = frozenset(assignments.keys()).difference(seen_names)
if unseen:
raise ImportError("cannot require names: " + repr(list(unseen)))
def load_macros(module_name):
"""Load the hy builtin macros for module `module_name`.
Modules from `hy.core` can only use the macros from CORE_MACROS.
Other modules get the macros from CORE_MACROS and EXTRA_MACROS.
"""
def _import(module, module_name=module_name):
"__import__ a module, avoiding recursions"
if module != module_name:
__import__(module)
for module in CORE_MACROS:
_import(module)
if module_name.startswith("hy.core"):
return
for module in EXTRA_MACROS:
_import(module)
def make_empty_fn_copy(fn):
argspec = getargspec(fn)
formatted_args = formatargspec(*argspec)
fn_str = 'lambda {}: None'.format(
formatted_args.lstrip('(').rstrip(')'))
empty_fn = eval(fn_str)
return empty_fn
def macroexpand(tree, compiler):
"""Expand the toplevel macros for the `tree`.
Load the macros from the given `module_name`, then expand the (top-level)
macros in `tree` until it stops changing.
"""
load_macros(compiler.module_name)
old = None
while old != tree:
old = tree
tree = macroexpand_1(tree, compiler)
return tree
def macroexpand_1(tree, compiler):
"""Expand the toplevel macro from `tree` once, in the context of
`module_name`."""
if isinstance(tree, HyExpression):
if tree == []:
return tree
fn = tree[0]
if fn in ("quote", "quasiquote"):
return tree
ntree = HyExpression(tree[:])
ntree.replace(tree)
opts = {}
if isinstance(fn, HyString):
m = _hy_macros[compiler.module_name].get(fn)
if m is None:
m = _hy_macros[None].get(fn)
if m is not None:
if m._hy_macro_pass_compiler:
opts['compiler'] = compiler
try:
m_copy = make_empty_fn_copy(m)
m_copy(*ntree[1:], **opts)
except TypeError as e:
msg = "expanding `" + str(tree[0]) + "': "
msg += str(e).replace("<lambda>()", "", 1).strip()
raise HyMacroExpansionError(tree, msg)
try:
obj = wrap_value(m(*ntree[1:], **opts))
except HyTypeError as e:
if e.expression is None:
e.expression = tree
raise
except Exception as e:
msg = "expanding `" + str(tree[0]) + "': " + repr(e)
raise HyMacroExpansionError(tree, msg)
replace_hy_obj(obj, tree)
return obj
return ntree
return tree
def reader_macroexpand(char, tree, compiler):
"""Expand the reader macro "char" with argument `tree`."""
load_macros(compiler.module_name)
reader_macro = _hy_reader[compiler.module_name].get(char)
if reader_macro is None:
try:
reader_macro = _hy_reader[None][char]
except KeyError:
raise HyTypeError(
char,
"`{0}' is not a defined reader macro.".format(char)
)
expr = reader_macro(tree)
return replace_hy_obj(wrap_value(expr), tree)