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