Add encoding pragma hook. Resolves pre-commit/pre-commit#15
diff --git a/pre_commit_hooks/fix_encoding_pragma.py b/pre_commit_hooks/fix_encoding_pragma.py
new file mode 100644
index 0000000..48fc9c7
--- /dev/null
+++ b/pre_commit_hooks/fix_encoding_pragma.py
@@ -0,0 +1,75 @@
+from __future__ import absolute_import
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import argparse
+import io
+
+expected_pragma = b'# -*- coding: utf-8 -*-\n'
+
+
+def has_coding(line):
+ if not line.strip():
+ return False
+ return (
+ line.lstrip()[0:1] == b'#' and (
+ b'unicode' in line or
+ b'encoding' in line or
+ b'coding:' in line or
+ b'coding=' in line
+ )
+ )
+
+
+def fix_encoding_pragma(f):
+ first_line = f.readline()
+ second_line = f.readline()
+ old = f.read()
+ f.seek(0)
+
+ # Ok case: the file is empty
+ if not (first_line + second_line + old).strip():
+ return 0
+
+ # Ok case: we specify pragma as the first line
+ if first_line == expected_pragma:
+ return 0
+
+ # OK case: we have a shebang as first line and pragma on second line
+ if first_line.startswith(b'#!') and second_line == expected_pragma:
+ return 0
+
+ # Otherwise we need to rewrite stuff!
+ if first_line.startswith(b'#!'):
+ if has_coding(second_line):
+ f.write(first_line + expected_pragma + old)
+ else:
+ f.write(first_line + expected_pragma + second_line + old)
+ elif has_coding(first_line):
+ f.write(expected_pragma + second_line + old)
+ else:
+ f.write(expected_pragma + first_line + second_line + old)
+
+ return 1
+
+
+def main(argv=None):
+ parser = argparse.ArgumentParser('Fixes the encoding pragma of python files')
+ parser.add_argument('filenames', nargs='*', help='Filenames to fix')
+ args = parser.parse_args(argv)
+
+ retv = 0
+
+ for filename in args.filenames:
+ with io.open(filename, 'r+b') as f:
+ file_ret = fix_encoding_pragma(f)
+ retv |= file_ret
+ if file_ret:
+ print('Added `{0}` to {1}'.format(
+ expected_pragma.strip(), filename,
+ ))
+
+ return retv
+
+if __name__ == "__main__":
+ exit(main())
