From 89496642e526a2b8d1c50df6d366b538b4c603f3 Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Sat, 27 Aug 2011 15:23:09 +0200
Subject: [PATCH] cse() for vectors, plus make_sym_vector.

---
 pymbolic/__init__.py   |  2 ++
 pymbolic/primitives.py | 50 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/pymbolic/__init__.py b/pymbolic/__init__.py
index de5ad50..04a06f0 100644
--- a/pymbolic/__init__.py
+++ b/pymbolic/__init__.py
@@ -18,6 +18,8 @@ subscript = pymbolic.primitives.subscript
 flattened_product = pymbolic.primitives.flattened_product
 quotient = pymbolic.primitives.quotient
 linear_combination = pymbolic.primitives.linear_combination
+cse = pymbolic.primitives.make_common_subexpression
+make_sym_vector = pymbolic.primitives.make_sym_vector
 
 parse = pymbolic.parser.parse
 evaluate = pymbolic.mapper.evaluator.evaluate
diff --git a/pymbolic/primitives.py b/pymbolic/primitives.py
index bae27e3..825ebd1 100644
--- a/pymbolic/primitives.py
+++ b/pymbolic/primitives.py
@@ -826,3 +826,53 @@ def is_zero(value):
 
 
 
+
+def make_common_subexpression(field, prefix=None):
+    try:
+        from pytools.obj_array import log_shape
+    except ImportError:
+        have_obj_array = False
+    else:
+        have_obj_array = True
+
+    if have_obj_array:
+        ls = log_shape(field)
+
+    if have_obj_array and ls != ():
+        from pytools import indices_in_shape
+        result = numpy.zeros(ls, dtype=object)
+
+        for i in indices_in_shape(ls):
+            if prefix is not None:
+                component_prefix = prefix+"_".join(str(i_i) for i_i in i)
+            else:
+                component_prefix = None
+
+            if is_constant(field[i]):
+                result[i] = field[i]
+            else:
+                result[i] = CommonSubexpression(field[i], component_prefix)
+
+        return result
+    else:
+        if is_constant(field):
+            return field
+        else:
+            return CommonSubexpression(field, prefix)
+
+
+
+
+def make_sym_vector(name, components):
+    """Return an object array of *components* subscripted
+    :class:`Field` instances.
+
+    :param components: The number of components in the vector.
+    """
+    if isinstance(components, int):
+        components = range(components)
+
+    from hedge.tools import join_fields
+    vfld = Variable(name)
+    return join_fields(*[vfld[i] for i in components])
+
-- 
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