text: from __future__ import division, absolute_import
  
  __copyright__ = "Copyright (C) 2009-2013 Andreas Kloeckner"
  
  __license__ = """
  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.
  """
  
  import pymbolic.primitives as prim
  from pymbolic.mapper.evaluator import EvaluationMapper
  from functools import partial
  
  
  class SympyLikeMapperBase(object):
  
      def __call__(self, expr, *args, **kwargs):
          return self.rec(expr, *args, **kwargs)
  
      def rec(self, expr, *args, **kwargs):
          mro = list(type(expr).__mro__)
          dispatch_class = kwargs.pop("dispatch_class", type(self))
  
          while mro:
              method_name = "map_"+mro.pop(0).__name__
  
              try:
                  method = getattr(dispatch_class, method_name)
              except AttributeError:
                  pass
              else:
                  return method(self, expr, *args, **kwargs)
  
          return self.not_supported(expr)
  
      def not_supported(self, expr):
          print(expr, expr.__class__.__mro__)
          raise NotImplementedError(
                  "%s does not know how to map type '%s'"
                  % (type(self).__name__,
                      type(expr).__name__))
  
  
  # {{{ sympy like -> pymbolic
  
  class SympyLikeToPymbolicMapper(SympyLikeMapperBase):
  
      # {{{ utils
  
      def to_float(self, expr):
          return float(expr)
  
      def function_name(self, expr):
          # Given a symbolic function application f(x), return the name of f as a
          # string
          raise NotImplementedError()
  
      # }}}
  
      def map_Symbol(self, expr):  # noqa
          return prim.Variable(str(expr.name))
  
      def map_Rational(self, expr):  # noqa
          p, q = expr.p, expr.q
  
          num = self.rec(p)
          denom = self.rec(q)
  
          if prim.is_zero(denom-1):
              return num
          return prim.Quotient(num, denom)
  
      def map_Integer(self, expr):  # noqa
          return int(expr)
  
      def map_Add(self, expr):  # noqa
          return prim.Sum(tuple(self.rec(arg) for arg in expr.args))
  
      def map_Mul(self, expr):  # noqa
          return prim.Product(tuple(self.rec(arg) for arg in expr.args))
  
      def map_Pow(self, expr):  # noqa
          base, exp = expr.args
          return prim.Power(self.rec(base), self.rec(exp))
  
      def map_Subs(self, expr):  # noqa
          return prim.Substitution(self.rec(expr.expr),
                  tuple(v.name for v in expr.variables),
                  tuple(self.rec(v) for v in expr.point),
                  )
  
      def map_Derivative(self, expr):  # noqa
          return prim.Derivative(self.rec(expr.expr),
                  tuple(v.name for v in expr.variables))
  
      def map_UnevaluatedExpr(self, expr):  # noqa
          return self.rec(expr.args[0])
  
      def not_supported(self, expr):  # noqa
          if isinstance(expr, int):
              return expr
          elif getattr(expr, "is_Function", False):
              return prim.Variable(self.function_name(expr))(
                      *tuple(self.rec(arg) for arg in expr.args))
          else:
              return SympyLikeMapperBase.not_supported(self, expr)
  
      def map_Piecewise(self, expr):  # noqa
          # We only handle piecewises with 2 arguments!
          assert len(expr.args) == 2
          # We only handle if/else cases
          assert expr.args[1][1].is_Boolean and bool(expr.args[1][1]) is True
          then = self.rec(expr.args[0][0])
          else_ = self.rec(expr.args[1][0])
          cond = self.rec(expr.args[0][1])
          return prim.If(cond, then, else_)
  
      def _comparison_operator(self, expr, operator=None):
          left = self.rec(expr.args[0])
          right = self.rec(expr.args[1])
          return prim.Comparison(left, operator, right)
  
      map_Equality = partial(_comparison_operator, operator="==")  # noqa: N815
      map_Unequality = partial(_comparison_operator, operator="!=")  # noqa: N815
      map_GreaterThan = partial(_comparison_operator, operator=">=")  # noqa: N815
      map_LessThan = partial(_comparison_operator, operator="<=")  # noqa: N815
      map_StrictGreaterThan = partial(_comparison_operator, operator=">")  # noqa: N815
      map_StrictLessThan = partial(_comparison_operator, operator="<")  # noqa: N815
  
  # }}}
  
  
  # {{{ pymbolic -> sympy like
  
  class PymbolicToSympyLikeMapper(EvaluationMapper):
  
      @property
      def sym(self):
          raise NotImplementedError
  
      def raise_conversion_error(self, message):
          raise NotImplementedError
  
      def map_variable(self, expr):
          return self.sym.Symbol(expr.name)
  
      def map_constant(self, expr):
          return self.sym.sympify(expr)
  
      def map_call(self, expr):
          if isinstance(expr.function, prim.Variable):
              func_name = expr.function.name
              try:
                  func = getattr(self.sym.functions, func_name)
              except AttributeError:
                  func = self.sym.Function(func_name)
              return func(*[self.rec(par) for par in expr.parameters])
          else:
              self.raise_conversion_error(expr)
  
      def map_subscript(self, expr):
          if isinstance(expr.aggregate, prim.Variable) and isinstance(expr.index, int):
              return self.sym.Symbol("%s_%d" % (expr.aggregate.name, expr.index))
          else:
              self.raise_conversion_error(expr)
  
      def map_substitution(self, expr):
          return self.sym.Subs(self.rec(expr.child),
                  tuple(self.sym.Symbol(v) for v in expr.variables),
                  tuple(self.rec(v) for v in expr.values),
                  )
  
      def map_if(self, expr):
          cond = self.rec(expr.condition)
          return self.sym.Piecewise((self.rec(expr.then), cond),
                                    (self.rec(expr.else_), True)
                                    )
  
      def map_comparison(self, expr):
          left = self.rec(expr.left)
          right = self.rec(expr.right)
          if expr.operator == "==":
              return self.sym.Equality(left, right)
          elif expr.operator == "!=":
              return self.sym.Unequality(left, right)
          elif expr.operator == "<":
              return self.sym.StrictLessThan(left, right)
          elif expr.operator == ">":
              return self.sym.StrictGreaterThan(left, right)
          elif expr.operator == "<=":
              return self.sym.LessThan(left, right)
          elif expr.operator == ">=":
              return self.sym.GreaterThan(left, right)
          else:
              raise NotImplementedError("Unknown operator '%s'" % expr.operator)
  
      def map_derivative(self, expr):
          return self.sym.Derivative(self.rec(expr.child),
                  *[self.sym.Symbol(v) for v in expr.variables])
  
  # }}}
  
  # vim: fdm=marker
  