94 lines
3.3 KiB
Python
94 lines
3.3 KiB
Python
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import keyword as kw
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import sympy
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from .repr import ReprPrinter
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from .str import StrPrinter
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# A list of classes that should be printed using StrPrinter
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STRPRINT = ("Add", "Infinity", "Integer", "Mul", "NegativeInfinity",
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"Pow", "Zero")
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class PythonPrinter(ReprPrinter, StrPrinter):
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"""A printer which converts an expression into its Python interpretation."""
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def __init__(self, settings=None):
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super().__init__(settings)
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self.symbols = []
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self.functions = []
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# Create print methods for classes that should use StrPrinter instead
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# of ReprPrinter.
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for name in STRPRINT:
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f_name = "_print_%s" % name
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f = getattr(StrPrinter, f_name)
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setattr(PythonPrinter, f_name, f)
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def _print_Function(self, expr):
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func = expr.func.__name__
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if not hasattr(sympy, func) and func not in self.functions:
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self.functions.append(func)
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return StrPrinter._print_Function(self, expr)
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# procedure (!) for defining symbols which have be defined in print_python()
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def _print_Symbol(self, expr):
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symbol = self._str(expr)
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if symbol not in self.symbols:
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self.symbols.append(symbol)
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return StrPrinter._print_Symbol(self, expr)
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def _print_module(self, expr):
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raise ValueError('Modules in the expression are unacceptable')
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def python(expr, **settings):
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"""Return Python interpretation of passed expression
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(can be passed to the exec() function without any modifications)"""
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printer = PythonPrinter(settings)
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exprp = printer.doprint(expr)
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result = ''
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# Returning found symbols and functions
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renamings = {}
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for symbolname in printer.symbols:
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# Remove curly braces from subscripted variables
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if '{' in symbolname:
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newsymbolname = symbolname.replace('{', '').replace('}', '')
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renamings[sympy.Symbol(symbolname)] = newsymbolname
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else:
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newsymbolname = symbolname
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# Escape symbol names that are reserved Python keywords
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if kw.iskeyword(newsymbolname):
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while True:
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newsymbolname += "_"
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if (newsymbolname not in printer.symbols and
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newsymbolname not in printer.functions):
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renamings[sympy.Symbol(
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symbolname)] = sympy.Symbol(newsymbolname)
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break
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result += newsymbolname + ' = Symbol(\'' + symbolname + '\')\n'
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for functionname in printer.functions:
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newfunctionname = functionname
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# Escape function names that are reserved Python keywords
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if kw.iskeyword(newfunctionname):
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while True:
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newfunctionname += "_"
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if (newfunctionname not in printer.symbols and
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newfunctionname not in printer.functions):
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renamings[sympy.Function(
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functionname)] = sympy.Function(newfunctionname)
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break
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result += newfunctionname + ' = Function(\'' + functionname + '\')\n'
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if renamings:
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exprp = expr.subs(renamings)
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result += 'e = ' + printer._str(exprp)
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return result
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def print_python(expr, **settings):
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"""Print output of python() function"""
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print(python(expr, **settings))
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