From 1e3b1d67e46a687f35566315cf1d2fc927a0f857 Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Sat, 11 Apr 2015 17:28:23 -0500
Subject: [PATCH] Add mesh-to-code converter

---
 meshmode/mesh/__init__.py | 64 +++++++++++++++++++++++++++++++++++++++
 test/test_meshmode.py     | 22 ++++++++++++--
 2 files changed, 83 insertions(+), 3 deletions(-)

diff --git a/meshmode/mesh/__init__.py b/meshmode/mesh/__init__.py
index 299f9ef8..377f86c9 100644
--- a/meshmode/mesh/__init__.py
+++ b/meshmode/mesh/__init__.py
@@ -41,6 +41,8 @@ __doc__ = """
 
 .. autoclass:: ElementConnectivity
 
+.. autofunction:: as_python
+
 """
 
 
@@ -487,4 +489,66 @@ def _compute_connectivity_from_vertices(mesh):
 
 # }}}
 
+
+# {{{ as_python
+
+def _numpy_array_as_python(array):
+    return "np.array(%s, dtype=np.%s)" % (
+            repr(array.tolist()),
+            array.dtype.name)
+
+
+def as_python(mesh, function_name="make_mesh"):
+    """Return a snippet of Python code (as a string) that will
+    recreate the mesh given as an input parameter.
+    """
+
+    from pytools.py_codegen import PythonCodeGenerator, Indentation
+    cg = PythonCodeGenerator()
+    cg("# generated by meshmode.mesh.as_python")
+    cg("")
+    cg("import numpy as np")
+    cg("from meshmode.mesh import Mesh, MeshElementGroup")
+    cg("")
+
+    cg("def %s():" % function_name)
+    with Indentation(cg):
+        cg("vertices = " + _numpy_array_as_python(mesh.vertices))
+        cg("")
+        cg("groups = []")
+        cg("")
+        for group in mesh.groups:
+            cg("import %s" % type(group).__module__)
+            cg("groups.append(%s.%s(" % (
+                type(group).__module__,
+                type(group).__name__))
+            cg("    order=%s," % group.order)
+            cg("    vertex_indices=%s,"
+                    % _numpy_array_as_python(group.vertex_indices))
+            cg("    nodes=%s,"
+                    % _numpy_array_as_python(group.nodes))
+            cg("    unit_nodes=%s))"
+                    % _numpy_array_as_python(group.unit_nodes))
+
+        cg("return Mesh(vertices, groups, skip_tests=True,")
+        cg("    vertex_id_dtype=np.%s," % mesh.vertex_id_dtype.name)
+        cg("    element_id_dtype=np.%s," % mesh.element_id_dtype.name)
+
+        if isinstance(mesh._element_connectivity, ElementConnectivity):
+            el_con_str = "(%s, %s)" % (
+                    _numpy_array_as_python(
+                        mesh._element_connectivity.neighbors_starts),
+                    _numpy_array_as_python(
+                        mesh._element_connectivity.neighbors),
+                    )
+        else:
+            el_con_str = repr(mesh._element_connectivity)
+
+        cg("    element_connectivity=%s)" % el_con_str)
+
+    return cg.get()
+
+# }}}
+
+
 # vim: foldmethod=marker
diff --git a/test/test_meshmode.py b/test/test_meshmode.py
index 6047113c..25b26dab 100644
--- a/test/test_meshmode.py
+++ b/test/test_meshmode.py
@@ -1,6 +1,4 @@
-from __future__ import division
-from __future__ import absolute_import
-from __future__ import print_function
+from __future__ import division, absolute_import, print_function
 from six.moves import range
 
 __copyright__ = "Copyright (C) 2014 Andreas Kloeckner"
@@ -356,6 +354,24 @@ def test_rect_mesh(do_plot=False):
         pt.show()
 
 
+def test_as_python():
+    from meshmode.mesh.generation import make_curve_mesh, cloverleaf
+    mesh = make_curve_mesh(cloverleaf, np.linspace(0, 1, 100), order=3)
+
+    mesh.element_connectivity
+
+    from meshmode.mesh import as_python
+    code = as_python(mesh)
+
+    print(code)
+    exec_dict = {}
+    exec(compile(code, "gen_code.py", "exec"), exec_dict)
+
+    mesh_2 = exec_dict["make_mesh"]()
+
+    assert mesh == mesh_2
+
+
 if __name__ == "__main__":
     import sys
     if len(sys.argv) > 1:
-- 
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