Added requirements.txt hook
diff --git a/pre_commit_hooks/requirements_txt_fixer.py b/pre_commit_hooks/requirements_txt_fixer.py
new file mode 100644
index 0000000..22fdb52
--- /dev/null
+++ b/pre_commit_hooks/requirements_txt_fixer.py
@@ -0,0 +1,82 @@
+from __future__ import print_function
+
+import argparse
+
+from pre_commit_hooks.util import entry
+
+
+class Requirement(object):
+
+ def __init__(self):
+ super(Requirement, self).__init__()
+ self.value = None
+ self.comments = []
+
+ def __lt__(self, requirement):
+ # \n means top of file comment, so always return True,
+ # otherwise just do a string comparison with value.
+ if self.value == b'\n':
+ return True
+ elif requirement.value == b'\n':
+ return False
+ else:
+ return self.value < requirement.value
+
+
+def fix_requirements(f):
+ requirements = []
+ before = []
+ after = []
+
+ for line in f:
+ before.append(line)
+
+ # If the most recent requirement object has a value, then it's time to
+ # start building the next requirement object.
+ if not len(requirements) or requirements[-1].value is not None:
+ requirements.append(Requirement())
+
+ requirement = requirements[-1]
+
+ # If we see a newline before any requirements, then this is a top of
+ # file comment.
+ if len(requirements) == 1 and line.strip() == b'':
+ if len(requirement.comments) and requirement.comments[0].startswith(b'#'):
+ requirement.value = b'\n'
+ else:
+ requirement.comments.append(line)
+ elif line.startswith(b'#') or line.strip() == b'':
+ requirement.comments.append(line)
+ else:
+ requirement.value = line
+
+ for requirement in sorted(requirements):
+ for comment in requirement.comments:
+ after.append(comment)
+ after.append(requirement.value)
+
+ before_string = b''.join(before)
+ after_string = b''.join(after)
+
+ if before_string == after_string:
+ return 0
+ else:
+ f.seek(0)
+ f.write(after_string)
+ f.truncate()
+ return 1
+
+
+@entry
+def fix_requirements_txt(argv):
+ parser = argparse.ArgumentParser()
+ parser.add_argument('filenames', nargs='*', help='Filenames to fix')
+ args = parser.parse_args(argv)
+
+ retv = 0
+
+ for arg in args.filenames:
+ with open(arg, 'rb+') as f:
+ retv |= fix_requirements(f)
+
+ return retv
