From ea8671c2eccbae23d0e92cc20a1571b0b323286e Mon Sep 17 00:00:00 2001
From: Dag Sverre Seljebotn <d.s.seljebotn@astro.uio.no>
Date: Wed, 22 Apr 2015 14:23:39 +0200
Subject: [PATCH] Prevent invoking Jinja templating unecessarily

---
 Makefile                     | 6 +++---
 libsharp/sharp_legendre.c    | 4 +++-
 libsharp/sharp_legendre.c.in | 1 -
 runjinja.py                  | 5 ++++-
 4 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index f44ecfd..a621948 100644
--- a/Makefile
+++ b/Makefile
@@ -54,10 +54,10 @@ perftest: compile_all
 	$(BINDIR)/sharp_testsuite test gauss 4095 -1 -1 8192 0 1 && \
 	$(BINDIR)/sharp_testsuite test gauss 8191 -1 -1 16384 0 1
 
-# Jinja templates
-
 %.c: %.c.in
-	./runjinja.py < $< > $@
+# Only do this if the md5sum changed, in order to avoid Python and Jinja
+# dependency when not modifying the c.in file
+	grep `md5sum $< | cut -d ' ' -f 1` $@ || ./runjinja.py < $< > $@
 
 genclean:
 	rm libsharp/sharp_legendre.c || exit 0
diff --git a/libsharp/sharp_legendre.c b/libsharp/sharp_legendre.c
index 75518d6..8b4fe4b 100644
--- a/libsharp/sharp_legendre.c
+++ b/libsharp/sharp_legendre.c
@@ -1,4 +1,4 @@
-/*
+/* DO NOT EDIT. md5sum of source: 88eec944ab6fbfdc7f391fbb58df3bf1 *//*
 
     NOTE NOTE NOTE
 
@@ -1303,3 +1303,5 @@ void sharp_legendre_transform_s(float *bl,
     }
 }
 
+
+
diff --git a/libsharp/sharp_legendre.c.in b/libsharp/sharp_legendre.c.in
index 9862127..e30f787 100644
--- a/libsharp/sharp_legendre.c.in
+++ b/libsharp/sharp_legendre.c.in
@@ -160,4 +160,3 @@ void sharp_legendre_transform{{T}}({{scalar}} *bl,
     }
 }
 /*{ endfor }*/
-
diff --git a/runjinja.py b/runjinja.py
index 5269c1a..fd659fa 100755
--- a/runjinja.py
+++ b/runjinja.py
@@ -5,6 +5,7 @@ Preprocesses foo.c.in to foo.c. Reads STDIN and writes STDOUT.
 """
 
 import sys
+import hashlib
 from jinja2 import Template, Environment
 
 env = Environment(block_start_string='/*{',
@@ -13,4 +14,6 @@ env = Environment(block_start_string='/*{',
                   variable_end_string='}}')
 
 extra_vars = dict(len=len)
-sys.stdout.write(env.from_string(sys.stdin.read()).render(**extra_vars))
+input = sys.stdin.read()
+sys.stdout.write('/* DO NOT EDIT. md5sum of source: %s */' % hashlib.md5(input).hexdigest())
+sys.stdout.write(env.from_string(input).render(**extra_vars))