git commit validator

git-commit-validator.py

#!/usr/bin/env python
from nltk.corpus import verbnet
import sys

class CommitException(Exception):

    def __init__(self, msg, line, start, end, fatal=False):
        Exception.__init__(self,msg)
        self._line = line
        self._start = start
        self._end = end
        self._fatal = fatal

    def formatError(self):
        return "%d:%d:%s" % (self._line, self._start, str(self))

    def isFatal(self):
        return self._fatal


class NoDescriptionException(CommitException):
    pass

class InvalidTitleException(CommitException):
    pass

class TrailingSpaceException(CommitException):
    pass

class LineTooLongException(CommitException):
    pass

class InvalidMessageException(CommitException):
    pass


class ContextInfo(object):

    def __init__(self, line):
        self.line = line


class Validator(object):
    def __init__(self, content, contextInfo=None):
        self._content = content
        self._context = contextInfo

    def context(self, lineNumber):
        if not self._context:
            return lineNumber
        return lineNumber + self._context.line

    def validate(self, *args, **kwargs):
        try:
            self.run(*args, **kwargs)
            return True
        except CommitException, e:
            print >>sys.stderr, e.formatError()
            if e.isFatal():
                raise e
            return False


class TrailingSpaceValidator(Validator):

    def run(self):
        for line, l in enumerate(self._content):
            if l.rstrip(' ') != l:
                raise TrailingSpaceException("Trailing space: [%s]" % l,
                        self.context(line+1),
                        len(l.rstrip(' '))+1,
                        len(l)+1)


class LineLengthValidator(Validator):

    def __init__(self, content, max_len, context=None):
        Validator.__init__(self, content, context)
        self._max_len = max_len

    def run(self):
        for line, l in enumerate(self._content):
            if len(l) > self._max_len:
                raise LineTooLongException("Line [%s] is too long (max=%d, length=%d)" % (l, self._max_len, len(l)),
                        self.context(line+1),
                        self._max_len,
                        len(l))


class TitleValidator(Validator):

    def run(self):
        TrailingSpaceValidator(self._content, self._context).validate()
        LineLengthValidator(self._content, 50, self._context).validate()

        firstWord = self._content[0].split(' ')[0]
        if not firstWord[0].isupper():
            raise InvalidTitleException("First title character must be a capital letter: [%s]" % self._content[0],
                    self.context(1),
                    1, 2)
        vclass = verbnet.classids(firstWord.lower())
        if not vclass:
            raise InvalidTitleException("Title must begin with an infinitive verb [%s]" % self._content[0],
                    self.context(1),
                    1, len(firstWord))



class EmptyLinesValidator(Validator):
    def run(self):
        if self._content and self._content[0]:
            if not self._content[0].strip(' ').strip('\t'):
                raise CommitException("Too many empty lines", self.context(1), 1, 2)


class DescriptionValidator(Validator):

    def run(self):
        EmptyLinesValidator(self._content, self._context).validate()
        TrailingSpaceValidator(self._content, self._context).validate()
        LineLengthValidator(self._content, 72, self._context).validate()


class CommitValidator(Validator):


    def __init__(self, msg):
        self._msg  = msg


    def run(self):
        lines = self._msg.splitlines()
        if len(lines) < 3:
            raise NoDescriptionException("Commit message does not contain a description", 0, 1,
                    len(lines[0]), fatal=True)

        if lines[1]:
            raise InvalidMessageException("Second commit line must be empty", 1, 1, 2, fatal=True)

        title, description = [lines[0]], lines[2:]
        self._validateTitle(title)
        self._validateDescription(description)

    def _validateTitle(self, title):
        TitleValidator(title).validate()

    def _validateDescription(self, description):
        DescriptionValidator(description, ContextInfo(2)).validate()



def validateFromFile(filename):

    with open(filename, 'r') as fd:
        msg = fd.read()
        CommitValidator(msg).validate()

if __name__ == "__main__":
    validateFromFile(sys.argv[1])