138 lines
4.3 KiB
Python
138 lines
4.3 KiB
Python
# Copyright (c) 2013 Paul Tagliamonte <paultag@debian.org>
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#
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# Permission is hereby granted, free of charge, to any person obtaining a
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# copy of this software and associated documentation files (the "Software"),
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# to deal in the Software without restriction, including without limitation
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# the rights to use, copy, modify, merge, publish, distribute, sublicense,
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# and/or sell copies of the Software, and to permit persons to whom the
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# Software is furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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# DEALINGS IN THE SOFTWARE.
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import abc
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from hy.models.expression import HyExpression
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# from hy.models.list import HyList
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MANGLES = []
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class Mangle(object):
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"""
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Mangle (n.)
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1. To mutilate or disfigure by battering, hacking, cutting,
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or tearing. See Synonyms at batter1.
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(but mostly hacking)
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"""
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__metaclass___ = abc.ABCMeta
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class TreeChanged(Exception):
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"""
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This exception gets raised whenver any code alters the tree. This is
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to let the handling code re-normalize parents, etc, and make sure we
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re-enter the current position in order.
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"""
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pass
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@abc.abstractmethod
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def visit(self, element):
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raise NotImplementedError
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def _mangle(self, tree):
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"""
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Main function of self.mangle, which is called over and over. This
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is used to beat the tree until it stops moving.
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"""
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scoped = False
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self.push_stack(tree)
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if isinstance(tree, HyExpression):
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# If it's an expression, let's make sure we reset the "scope"
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# (code branch) if it's a scopable object.
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what = tree[0]
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if what in ["fn", "if"]:
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self.push_scope(tree)
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scoped = True
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if isinstance(tree, list):
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# If it's a list, let's mangle all the elements of the list.
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for i, element in enumerate(tree):
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nel = self.visit(element)
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if nel:
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# if the subclass returned an object, we replace the
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# current node.
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tree[i] = nel
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self.tree_changed() # auto-raise a changed notice.
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self._mangle(element) # recurse down, unwind on change.
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if scoped:
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self.pop_scope()
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self.pop_stack()
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def hoist(self, what):
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"""
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Take a thing (what), and move it before whichever ancestor is in the
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"scope" (code branch). This will hoist it *all* the way out of a deeply
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nested statement in one pass. If it's still "invalid" (which it
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shouldn't be), it'll just hoist again anyway.
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"""
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scope = self.scope
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for point, el in enumerate(scope):
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if el in self.stack:
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break
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self.scope.insert(point, what)
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def get_scope(self):
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return self.scopes[0]
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def tree_changed(self):
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""" Invoke this if you alter the tree in any way """
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raise self.TreeChanged()
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@property
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def scope(self):
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return self.get_scope()
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def push_scope(self, tree):
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self.scopes.insert(0, tree)
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def push_stack(self, tree):
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self.stack.insert(0, tree)
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def pop_scope(self):
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return self.scopes.pop(0)
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def pop_stack(self):
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return self.stack.pop(0)
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def mangle(self, tree):
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"""Magic external entry point.
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We mangle until the tree stops moving, i.e. until we don't get a
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TreeChanged Exception during mangle.
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"""
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while True:
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self.root = tree
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self.scopes = []
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self.stack = []
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self.push_scope(tree)
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try:
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self._mangle(tree)
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break
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except self.TreeChanged:
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pass
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