yamlint

#!/usr/bin/python2.6
import yaml
from yaml.parser import ParserError
from yaml.scanner import ScannerError
import sys

ee = None

def usage():
    sys.stderr.write("{} FILENAME\n")
    sys.exit(1)


def find_line(filename, line_no):
    """
    Find a specific line by line number.
    """

    with open(filename) as f:
        for i, line in enumerate(f):
            if i + 1 == line_no:
                return line.strip()


def parse_yaml(filename):
    """
    Parses a yaml file and returns it's contents.
    """

    with open(filename) as f:
        return yaml.load(f)


def yaml_lint(filename):
    """
    Parses a yaml file and returns True if it can be parsed.
    Otherwise False is returned. Only parse errors are catched.
    """

    retval = False

    try:
        parse_yaml(filename)
        retval = True

    except IOError as err:
        print err

    except (ScannerError, ParserError) as err:
        line_no = err.problem_mark.line + 1
        column_no  = err.problem_mark.column + 1
        print err
        print
        print find_line(filename, line_no)
        print '^'.rjust(column_no, ' ')

    except Exception, e:
        print "Unkown error:"
        print type(e)
        print e
        global ee
        ee = e

    finally:
        return retval

if __name__ == '__main__':
    if len(sys.argv) <> 2:
        usage()
    filename = sys.argv[1]
    if yaml_lint(filename):
        sys.exit(0)
    else:
        sys.exit(1)