util.py

"""
#
# File: util.py
# Description: Utility methods for use in AllIWant
#
# Copyright 2011-2015 Adam Meadows
#
#    Licensed under the Apache License, Version 2.0 (the "License");
#    you may not use this file except in compliance with the License.
#    You may obtain a copy of the License at
#
#        http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS,
#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#    See the License for the specific language governing permissions and
#    limitations under the License.
#
"""


def camelize(s, trailing=False):
    """Translate string into camel-case"""
    def should_cap(i):
        return not trailing or i > 0

    def cap_first(word, index):
        return word[0].upper() + word[1:] if should_cap(index) else word

    return ''.join(cap_first(w, i) for i, w in enumerate(s.split('_')))


def uncamelize(s):
    """Convert camel-case into underscore-separated"""
    news = s[0]
    for c in s[1:]:
        news += '_' + c if c.upper() == c else c
    return news.lower()


def pluralize(s):
    """Pluralize singular string"""
    if s[-1] == 'y':
        return s[:-1] + 'ies'
    return s + 's'


def extract_name(email):
    """
    Extracts a name from an email assuming the email is in the form:
        first.last@domain.com
    """
    username = email.split('@')[0]
    return ' '.join((w[0].upper() + w[1:] for w in username.split('.')))


def get_base_url(url):
    """Extract the base (root) URL from a complete URL"""
    from urlparse import urlparse  # Deferred

    parts = urlparse(url)
    return '%s://%s' % (parts.scheme, parts.netloc)


def prefetch_refprops(entities, *props):
    """
    Wonderful little method provided by Nick Johnson at
    http://blog.notdot.net/2010/01/ReferenceProperty-prefetching-in-App-Engine
    """
    from google.appengine.ext import db  # Deferred

    fields = [(entity, prop) for entity in entities for prop in props]
    ref_keys = [prop.get_value_for_datastore(x) for x, prop in fields]
    ref_entities = dict((x.key(), x) for x in db.get(set(ref_keys)))
    for (entity, prop), ref_key in zip(fields, ref_keys):
        prop.__set__(entity, ref_entities.get(ref_key, None))
    return entities