don't rewrite the header file if it hasn't changed; this reduces development build time
diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index 0b95aaa..d9d7662 100755
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -4,7 +4,9 @@
# TO DO
# handle fields that have a type but no name
-import os, sys
+import os
+import sys
+import StringIO
import subprocess
import asdl
@@ -1155,7 +1157,7 @@
sys.exit(1)
if INC_DIR:
p = "%s/%s-ast.h" % (INC_DIR, mod.name)
- f = open(p, "w")
+ f = StringIO.StringIO()
f.write(auto_gen_msg)
f.write('#include "asdl.h"\n\n')
c = ChainOfVisitors(TypeDefVisitor(f),
@@ -1166,7 +1168,12 @@
f.write("PyObject* PyAST_mod2obj(mod_ty t);\n")
f.write("mod_ty PyAST_obj2mod(PyObject* ast, PyArena* arena, int mode);\n")
f.write("int PyAST_Check(PyObject* obj);\n")
- f.close()
+ s = f.getvalue()
+ with open(p, "r") as fp:
+ write = fp.read() != s
+ if write:
+ with open(p, "w") as fp:
+ f.write(s)
if SRC_DIR:
p = os.path.join(SRC_DIR, str(mod.name) + "-ast.c")