137 lines
2.9 KiB
Python
137 lines
2.9 KiB
Python
#! /usr/bin/env python
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# -*- coding: utf-8 -*-
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# vim:fenc=utf-8
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#
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# Copyright © 2017 lafrite <lafrite@Poivre>
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#
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# Distributed under terms of the MIT license.
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"""
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Expression
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"""
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from ..core import Tree, compute
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from .renders import renders
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class Expression(object):
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"""
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Expression class
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:example:
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>>> e = Expression.from_str("2+3*4")
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>>> e2 = e.simplify()
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>>> print(e2)
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14
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>>> for s in e2.explain():
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... print(s)
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2 + 3 * 4
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2 + 12
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14
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"""
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RENDER = 'txt'
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def __init__(self, tree, ancestor=None):
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"""
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"""
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self._tree = tree
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self._ancestor = ancestor
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@classmethod
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def from_str(cls, string):
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""" Initiate the expression from a string
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:param string: TODO
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:returns: TODO
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"""
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t = Tree.from_str(string)
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return cls(t)
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@classmethod
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def random(self, template, conditions = [], shuffle = False):
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""" Initiate randomly the expression
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:param template: the template of the expression
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:param conditions: conditions on randomly generate variable
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:param shuffle: allowing to shuffle the tree
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:returns: TODO
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"""
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pass
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@classmethod
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def set_render(cls, render):
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""" Define default render function
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:param render: render function Tree -> str
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:example:
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>>> Expression.RENDER
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'txt'
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>>> e = Expression.from_str("2+3*4")
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>>> print(e)
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2 + 3 * 4
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>>> Expression.set_render('tex')
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>>> Expression.RENDER
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'tex'
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>>> print(e)
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2 + 3 \\times 4
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"""
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cls.RENDER = render
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def __str__(self):
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return renders[self.RENDER](self._tree)
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def __repr__(self):
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return f"<Exp: {renders[self.RENDER](self._tree)}>"
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def simplify(self):
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""" Compute as much as possible the expression
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:return: an expression
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:example:
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>>> e = Expression.from_str("2+3*4")
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>>> e
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<Exp: 2 + 3 \\times 4>
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>>> f = e.simplify()
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>>> f
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<Exp: 14>
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>>> f._ancestor
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<Exp: 2 + 12>
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"""
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try:
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t = self._tree.apply_on_last_level(compute)
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except AttributeError:
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return self
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else:
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e = Expression(t, ancestor=self)
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return e.simplify()
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def explain(self):
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""" Yield every calculus step which have lead to self
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:example:
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>>> e = Expression.from_str("2+3*4")
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>>> f = e.simplify()
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>>> for s in f.explain():
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... print(s)
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2 + 3 * 4
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2 + 12
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14
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"""
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try:
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yield from self._ancestor.explain()
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except AttributeError:
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yield self
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else:
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yield self
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# -----------------------------
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# Reglages pour 'vim'
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# vim:set autoindent expandtab tabstop=4 shiftwidth=4:
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# cursor: 16 del
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