gistfile1.py

#In r2/config/routing.py

def make_map(global_conf={}, app_conf={}):

    #Some other routing location

    mc('/submit',   controller='front', action='submit')


#So I need to go to /r2/controllers/front.py and find the GET_submit method (by Pylons naming convention)
from r2.lib.utils import query_string, UrlParser, link_from_url, link_duplicates
#tons of stuff
def GET_submit(self, url, title, then):
        """Submit form."""
        if url and not request.get.get('resubmit'):
            links = link_from_url(url)


#So I need to go to /r2/lib/utils/utils.py and find the link_from_url method.
def link_from_url(path, filter_spam = False, multiple = True):
    from pylons import c
    from r2.models import IDBuilder, Link, Subreddit, NotFound

    if not path:
        return

    try:
        links = Link._by_url(path, c.site)


#So I need to go to /r2/models/link.py and find the _by_url method...
@classmethod
def _by_url(cls, url, sr):
    from subreddit import FakeSubreddit
    if isinstance(sr, FakeSubreddit):
        sr = None

    try:
        lbu = LinksByUrl._byID(LinksByUrl._key_from_url(url))

#Which leads me to the method _key_from_url in the class LinksByUrl in r2/models/link.py
class LinksByUrl(tdb_cassandra.View):
    _use_db = True

    @classmethod
    def _key_from_url(cls, url):
        if not utils.domain(url) in g.case_sensitive_domains:
            keyurl = _force_utf8(UrlParser.base_url(url.lower()))
        else:
            # Convert only hostname to lowercase
            up = UrlParser(url)
            up.hostname = up.hostname.lower()
            keyurl = _force_utf8(UrlParser.base_url(up.unparse()))
        return keyurl

#Which calles a method from UrlParser.