From ccabd46c2b6553c91c1e40c00ccb8f96b2eb8d60 Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Tue, 27 Mar 2012 00:42:07 -0400
Subject: [PATCH] Add facility for conversion from sympy.

---
 pymbolic/sympy_conv.py | 80 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 pymbolic/sympy_conv.py

diff --git a/pymbolic/sympy_conv.py b/pymbolic/sympy_conv.py
new file mode 100644
index 0000000..f656676
--- /dev/null
+++ b/pymbolic/sympy_conv.py
@@ -0,0 +1,80 @@
+from __future__ import division
+import pymbolic.primitives as prim
+import sympy as sp
+
+
+
+
+class _SympyMapper(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):
+        raise NotImplementedError(
+                "%s does not know how to map type '%s'"
+                % (type(self).__name__,
+                    type(expr).__name__))
+
+
+
+
+class ToPymbolicMapper(_SympyMapper):
+    def map_Symbol(self, expr):
+        return prim.Variable(expr.name)
+
+    def map_ImaginaryUnit(self, expr):
+        return 1j
+
+    def map_Add(self, expr):
+        return prim.Sum(tuple(self.rec(arg) for arg in expr.args))
+
+    def map_Mul(self, expr):
+        return prim.Product(tuple(self.rec(arg) for arg in expr.args))
+
+    def map_Rational(self, expr):
+        num = self.rec(expr.p)
+        denom = self.rec(expr.q)
+
+        if prim.is_zero(denom-1):
+            return num
+        if isinstance(num, int) and isinstance(denom, int):
+            return int(num) / int(denom)
+        return prim.Quotient(num, denom)
+
+    def map_Pow(self, expr):
+        return prim.Power(self.rec(expr.base), self.rec(expr.exp))
+
+    def map_Subs(self, expr):
+        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):
+        return prim.Derivative(self.rec(expr.expr),
+                tuple(v.name for v in expr.variables))
+
+    def not_supported(self, expr):
+        if isinstance(expr, int):
+            return expr
+        elif getattr(expr, "is_Function", False):
+            return prim.Variable(type(expr).__name__)(
+                    *tuple(self.rec(arg) for arg in expr.args))
+        else:
+            return _SympyMapper.not_supported(self, expr)
-- 
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