jinja2/filters.py

# -*- coding: utf-8 -*-
"""
    jinja.filters
    ~~~~~~~~~~~~~

    Bundled jinja filters.

    :copyright: 2008 by Armin Ronacher, Christoph Hack.
    :license: BSD, see LICENSE for more details.
"""
import re
from random import choice
try:
    from operator import itemgetter
except ImportError:
    itemgetter = lambda a: lambda b: b[a]
from urllib import urlencode, quote
from jinja2.utils import escape, pformat, urlize
from jinja2.runtime import Undefined



_striptags_re = re.compile(r'(<!--.*?-->|<[^>]*>)')


def contextfilter(f):
    """Decorator for marking context dependent filters. The current context
    argument will be passed as first argument.
    """
    f.contextfilter = True
    return f


def do_replace(s, old, new, count=None):
    """
    Return a copy of the value with all occurrences of a substring
    replaced with a new one. The first argument is the substring
    that should be replaced, the second is the replacement string.
    If the optional third argument ``count`` is given, only the first
    ``count`` occurrences are replaced:

    .. sourcecode:: jinja

        {{ "Hello World"|replace("Hello", "Goodbye") }}
            -> Goodbye World

        {{ "aaaaargh"|replace("a", "d'oh, ", 2) }}
            -> d'oh, d'oh, aaargh
    """
    if not isinstance(old, basestring) or \
       not isinstance(new, basestring):
        raise FilterArgumentError('the replace filter requires '
                                  'string replacement arguments')
    if count is None:
        return s.replace(old, new)
    if not isinstance(count, (int, long)):
        raise FilterArgumentError('the count parameter of the '
                                   'replace filter requires '
                                   'an integer')
    return s.replace(old, new, count)


def do_upper(s):
    """Convert a value to uppercase."""
    return unicode(s).upper()


def do_lower(s):
    """Convert a value to lowercase."""
    return unicode(s).lower()


def do_escape(s, attribute=False):
    """
    XML escape ``&``, ``<``, and ``>`` in a string of data. If the
    optional parameter is `true` this filter will also convert
    ``"`` to ``&quot;``. This filter is just used if the environment
    was configured with disabled `auto_escape`.

    This method will have no effect it the value is already escaped.
    """
    return escape(unicode(s), attribute)


def do_xmlattr(d, autospace=False):
    """
    Create an SGML/XML attribute string based on the items in a dict.
    All values that are neither `none` nor `undefined` are automatically
    escaped:

    .. sourcecode:: html+jinja

        <ul{{ {'class': 'my_list', 'missing': None,
                'id': 'list-%d'|format(variable)}|xmlattr }}>
        ...
        </ul>

    Results in something like this:

    .. sourcecode:: html

        <ul class="my_list" id="list-42">
        ...
        </ul>

    As you can see it automatically prepends a space in front of the item
    if the filter returned something. You can disable this by passing
    `false` as only argument to the filter.

    *New in Jinja 1.1*
    """
    if not hasattr(d, 'iteritems'):
        raise TypeError('a dict is required')
    result = []
    for key, value in d.iteritems():
        if value not in (None, env.undefined_singleton):
            result.append(u'%s="%s"' % (
                escape(env.to_unicode(key)),
                escape(env.to_unicode(value), True)
            ))
    rv = u' '.join(result)
    if autospace:
        rv = ' ' + rv
    return rv


def do_capitalize(s):
    """
    Capitalize a value. The first character will be uppercase, all others
    lowercase.
    """
    return unicode(s).capitalize()


def do_title(s):
    """
    Return a titlecased version of the value. I.e. words will start with
    uppercase letters, all remaining characters are lowercase.
    """
    return unicode(s).title()


def do_dictsort(value, case_sensitive=False, by='key'):
    """
    Sort a dict and yield (key, value) pairs. Because python dicts are
    unsorted you may want to use this function to order them by either
    key or value:

    .. sourcecode:: jinja

        {% for item in mydict|dictsort %}
            sort the dict by key, case insensitive

        {% for item in mydict|dicsort(true) %}
            sort the dict by key, case sensitive

        {% for item in mydict|dictsort(false, 'value') %}
            sort the dict by key, case insensitive, sorted
            normally and ordered by value.
    """
    if by == 'key':
        pos = 0
    elif by == 'value':
        pos = 1
    else:
        raise FilterArgumentError('You can only sort by either '
                                  '"key" or "value"')
    def sort_func(value):
        if isinstance(value, basestring):
            value = unicode(value)
            if not case_sensitive:
                value = value.lower()
        return value

    items = value.items()
    items.sort(lambda a, b: cmp(sort_func(a[pos]), sort_func(b[pos])))
    return items


def do_default(value, default_value=u'', boolean=False):
    """
    If the value is undefined it will return the passed default value,
    otherwise the value of the variable:

    .. sourcecode:: jinja

        {{ my_variable|default('my_variable is not defined') }}

    This will output the value of ``my_variable`` if the variable was
    defined, otherwise ``'my_variable is not defined'``. If you want
    to use default with variables that evaluate to false you have to
    set the second parameter to `true`:

    .. sourcecode:: jinja

        {{ ''|default('the string was empty', true) }}
    """
    if (boolean and not value) or isinstance(value, Undefined):
        return default_value
    return value


def do_join(value, d=u''):
    """
    Return a string which is the concatenation of the strings in the
    sequence. The separator between elements is an empty string per
    default, you can define ith with the optional parameter:

    .. sourcecode:: jinja

        {{ [1, 2, 3]|join('|') }}
            -> 1|2|3

        {{ [1, 2, 3]|join }}
            -> 123
    """
    return unicode(d).join([unicode(x) for x in value])


def do_count(value):
    """
    Return the length of the value. In case if getting an integer or float
    it will convert it into a string an return the length of the new
    string. If the object has no length it will of corse return 0.
    """
    try:
        if type(value) in (int, float, long):
            return len(str(value))
        return len(value)
    except TypeError:
        return 0


def do_reverse(value):
    """
    Return a reversed list of the sequence filtered. You can use this
    for example for reverse iteration:

    .. sourcecode:: jinja

        {% for item in seq|reverse %}
            {{ item|e }}
        {% endfor %}
    """
    try:
        return value[::-1]
    except:
        l = list(value)
        l.reverse()
        return l


def do_center(value, width=80):
    """
    Centers the value in a field of a given width.
    """
    return unicode(value).center(width)


def do_first(seq):
    """
    Return the frist item of a sequence.
    """
    try:
        return iter(seq).next()
    except StopIteration:
        return env.undefined_singleton


def do_last(seq):
    """
    Return the last item of a sequence.
    """
    try:
        return iter(reversed(seq)).next()
    except StopIteration:
        return env.undefined_singleton


def do_random(seq):
    """
    Return a random item from the sequence.
    """
    try:
        return choice(seq)
    except IndexError:
        return env.undefined_singleton


def do_jsonencode(value):
    """
    JSON dump a variable. just works if simplejson is installed.

    .. sourcecode:: jinja

        {{ 'Hello World'|jsonencode }}
            -> "Hello World"
    """
    global simplejson
    try:
        simplejson
    except NameError:
        import simplejson
    return simplejson.dumps(value)


def do_filesizeformat(value):
    """
    Format the value like a 'human-readable' file size (i.e. 13 KB, 4.1 MB, 102
    bytes, etc).
    """
    # fail silently
    try:
        bytes = float(value)
    except TypeError:
        bytes = 0

    if bytes < 1024:
        return "%d Byte%s" % (bytes, bytes != 1 and 's' or '')
    elif bytes < 1024 * 1024:
        return "%.1f KB" % (bytes / 1024)
    elif bytes < 1024 * 1024 * 1024:
        return "%.1f MB" % (bytes / (1024 * 1024))
    return "%.1f GB" % (bytes / (1024 * 1024 * 1024))


def do_pprint(value, verbose=False):
    """
    Pretty print a variable. Useful for debugging.

    With Jinja 1.2 onwards you can pass it a parameter.  If this parameter
    is truthy the output will be more verbose (this requires `pretty`)
    """
    return pformat(value, verbose=verbose)


def do_urlize(value, trim_url_limit=None, nofollow=False):
    """
    Converts URLs in plain text into clickable links.

    If you pass the filter an additional integer it will shorten the urls
    to that number. Also a third argument exists that makes the urls
    "nofollow":

    .. sourcecode:: jinja

        {{ mytext|urlize(40, True) }}
            links are shortened to 40 chars and defined with rel="nofollow"
    """
    return urlize(unicode(value), trim_url_limit, nofollow)


def do_indent(s, width=4, indentfirst=False):
    """
    {{ s|indent[ width[ indentfirst[ usetab]]] }}

    Return a copy of the passed string, each line indented by
    4 spaces. The first line is not indented. If you want to
    change the number of spaces or indent the first line too
    you can pass additional parameters to the filter:

    .. sourcecode:: jinja

        {{ mytext|indent(2, True) }}
            indent by two spaces and indent the first line too.
    """
    indention = ' ' * width
    if indentfirst:
        return u'\n'.join([indention + line for line in s.splitlines()])
    return s.replace('\n', '\n' + indention)


def do_truncate(s, length=255, killwords=False, end='...'):
    """
    Return a truncated copy of the string. The length is specified
    with the first parameter which defaults to ``255``. If the second
    parameter is ``true`` the filter will cut the text at length. Otherwise
    it will try to save the last word. If the text was in fact
    truncated it will append an ellipsis sign (``"..."``). If you want a
    different ellipsis sign than ``"..."`` you can specify it using the
    third parameter.

    .. sourcecode jinja::

        {{ mytext|truncate(300, false, '&raquo;') }}
            truncate mytext to 300 chars, don't split up words, use a
            right pointing double arrow as ellipsis sign.
    """
    if len(s) <= length:
        return s
    elif killwords:
        return s[:length] + end
    words = s.split(' ')
    result = []
    m = 0
    for word in words:
        m += len(word) + 1
        if m > length:
            break
        result.append(word)
    result.append(end)
    return u' '.join(result)


def do_wordwrap(s, pos=79, hard=False):
    """
    Return a copy of the string passed to the filter wrapped after
    ``79`` characters. You can override this default using the first
    parameter. If you set the second parameter to `true` Jinja will
    also split words apart (usually a bad idea because it makes
    reading hard).
    """
    if len(s) < pos:
        return s
    if hard:
        return u'\n'.join([s[idx:idx + pos] for idx in
                          xrange(0, len(s), pos)])
    # code from http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/148061
    return reduce(lambda line, word, pos=pos: u'%s%s%s' %
                  (line, u' \n'[(len(line)-line.rfind('\n') - 1 +
                                len(word.split('\n', 1)[0]) >= pos)],
                   word), s.split(' '))


def do_wordcount(s):
    """
    Count the words in that string.
    """
    return len([x for x in s.split() if x])


def do_textile(s):
    """
    Prase the string using textile.

    requires the `PyTextile`_ library.

    .. _PyTextile: http://dealmeida.net/projects/textile/
    """
    from textile import textile
    return textile(s.encode('utf-8')).decode('utf-8')


def do_markdown(s):
    """
    Parse the string using markdown.

    requires the `Python-markdown`_ library.

    .. _Python-markdown: http://www.freewisdom.org/projects/python-markdown/
    """
    from markdown import markdown
    return markdown(s.encode('utf-8')).decode('utf-8')


def do_rst(s):
    """
    Parse the string using the reStructuredText parser from the
    docutils package.

    requires `docutils`_.

    .. _docutils: http://docutils.sourceforge.net/
    """
    from docutils.core import publish_parts
    parts = publish_parts(source=s, writer_name='html4css1')
    return parts['fragment']


def do_int(value, default=0):
    """
    Convert the value into an integer. If the
    conversion doesn't work it will return ``0``. You can
    override this default using the first parameter.
    """
    try:
        return int(value)
    except (TypeError, ValueError):
        try:
            return int(float(value))
        except (TypeError, ValueError):
            return default


def do_float(value, default=0.0):
    """
    Convert the value into a floating point number. If the
    conversion doesn't work it will return ``0.0``. You can
    override this default using the first parameter.
    """
    try:
        return float(value)
    except (TypeError, ValueError):
        return default


def do_string(value):
    """
    Convert the value into an string.
    """
    return unicode(value)


def do_format(value, *args):
    """
    Apply python string formatting on an object:

    .. sourcecode:: jinja

        {{ "%s - %s"|format("Hello?", "Foo!") }}
            -> Hello? - Foo!

    Note that you cannot use the mapping syntax (``%(name)s``)
    like in python. Use `|dformat` for that.
    """
    return unicode(value) % args


def do_dformat(d):
    """
    Apply python mapping string formatting on an object:

    .. sourcecode:: jinja

        {{ "Hello %(username)s!"|dformat({'username': 'John Doe'}) }}
            -> Hello John Doe!

    This is useful when adding variables to translateable
    string expressions.

    *New in Jinja 1.1*
    """
    if not isinstance(d, dict):
        raise FilterArgumentError('dict required')
    def wrapped(env, context, value):
        return env.to_unicode(value) % d
    return wrapped


def do_trim(value):
    """
    Strip leading and trailing whitespace.
    """
    return value.strip()


def do_striptags(value):
    """
    Strip SGML/XML tags and replace adjacent whitespace by one space.

    *new in Jinja 1.1*
    """
    return ' '.join(_striptags_re.sub('', value).split())


def do_slice(value, slices, fill_with=None):
    """
    Slice an iterator and return a list of lists containing
    those items. Useful if you want to create a div containing
    three div tags that represent columns:

    .. sourcecode:: html+jinja

        <div class="columwrapper">
          {%- for column in items|slice(3) %}
            <ul class="column-{{ loop.index }}">
            {%- for item in column %}
              <li>{{ item }}</li>
            {%- endfor %}
            </ul>
          {%- endfor %}
        </div>

    If you pass it a second argument it's used to fill missing
    values on the last iteration.

    *new in Jinja 1.1*
    """
    result = []
    seq = list(value)
    length = len(seq)
    items_per_slice = length // slices
    slices_with_extra = length % slices
    offset = 0
    for slice_number in xrange(slices):
        start = offset + slice_number * items_per_slice
        if slice_number < slices_with_extra:
            offset += 1
        end = offset + (slice_number + 1) * items_per_slice
        tmp = seq[start:end]
        if fill_with is not None and slice_number >= slices_with_extra:
            tmp.append(fill_with)
        result.append(tmp)
    return result


def do_batch(value, linecount, fill_with=None):
    """
    A filter that batches items. It works pretty much like `slice`
    just the other way round. It returns a list of lists with the
    given number of items. If you provide a second parameter this
    is used to fill missing items. See this example:

    .. sourcecode:: html+jinja

        <table>
        {%- for row in items|batch(3, '&nbsp;') %}
          <tr>
          {%- for column in row %}
            <tr>{{ column }}</td>
          {%- endfor %}
          </tr>
        {%- endfor %}
        </table>

    *new in Jinja 1.1*
    """
    result = []
    tmp = []
    for item in value:
        if len(tmp) == linecount:
            result.append(tmp)
            tmp = []
        tmp.append(item)
    if tmp:
        if fill_with is not None and len(tmp) < linecount:
            tmp += [fill_with] * (linecount - len(tmp))
        result.append(tmp)
    return result


def do_sum():
    """
    Sum up the given sequence of numbers.

    *new in Jinja 1.1*
    """
    def wrapped(env, context, value):
        return sum(value)
    return wrapped


def do_abs():
    """
    Return the absolute value of a number.

    *new in Jinja 1.1*
    """
    def wrapped(env, context, value):
        return abs(value)
    return wrapped


def do_round(precision=0, method='common'):
    """
    Round the number to a given precision. The first
    parameter specifies the precision (default is ``0``), the
    second the rounding method:

    - ``'common'`` rounds either up or down
    - ``'ceil'`` always rounds up
    - ``'floor'`` always rounds down

    If you don't specify a method ``'common'`` is used.

    .. sourcecode:: jinja

        {{ 42.55|round }}
            -> 43
        {{ 42.55|round(1, 'floor') }}
            -> 42.5

    *new in Jinja 1.1*
    """
    if not method in ('common', 'ceil', 'floor'):
        raise FilterArgumentError('method must be common, ceil or floor')
    if precision < 0:
        raise FilterArgumentError('precision must be a postive integer '
                                  'or zero.')
    def wrapped(env, context, value):
        if method == 'common':
            return round(value, precision)
        import math
        func = getattr(math, method)
        if precision:
            return func(value * 10 * precision) / (10 * precision)
        else:
            return func(value)
    return wrapped


def do_sort(reverse=False):
    """
    Sort a sequence. Per default it sorts ascending, if you pass it
    `True` as first argument it will reverse the sorting.

    *new in Jinja 1.1*
    """
    def wrapped(env, context, value):
        return sorted(value, reverse=reverse)
    return wrapped


def do_groupby(attribute):
    """
    Group a sequence of objects by a common attribute.

    If you for example have a list of dicts or objects that represent persons
    with `gender`, `first_name` and `last_name` attributes and you want to
    group all users by genders you can do something like the following
    snippet:

    .. sourcecode:: html+jinja

        <ul>
        {% for group in persons|groupby('gender') %}
            <li>{{ group.grouper }}<ul>
            {% for person in group.list %}
                <li>{{ person.first_name }} {{ person.last_name }}</li>
            {% endfor %}</ul></li>
        {% endfor %}
        </ul>

    As you can see the item we're grouping by is stored in the `grouper`
    attribute and the `list` contains all the objects that have this grouper
    in common.

    *New in Jinja 1.2*
    """
    def wrapped(env, context, value):
        expr = lambda x: env.get_attribute(x, attribute)
        return sorted([{
            'grouper':  a,
            'list':     list(b)
        } for a, b in groupby(sorted(value, key=expr), expr)],
            key=itemgetter('grouper'))
    return wrapped


def do_getattribute(attribute):
    """
    Get one attribute from an object. Normally you don't have to use this
    filter because the attribute and subscript expressions try to either
    get an attribute of an object or an item. In some situations it could
    be that there is an item *and* an attribute with the same name. In that
    situation only the item is returned, never the attribute.

    .. sourcecode:: jinja

        {{ foo.bar }} -> {{ foo|getattribute('bar') }}

    *New in Jinja 1.2*
    """
    def wrapped(env, context, value):
        try:
            return get_attribute(value, attribute)
        except (SecurityException, AttributeError):
            return env.undefined_singleton
    return wrapped


def do_getitem(key):
    """
    This filter basically works like the normal subscript expression but
    it doesn't fall back to attribute lookup. If an item does not exist for
    an object undefined is returned.

    .. sourcecode:: jinja

        {{ foo.bar }} -> {{ foo|getitem('bar') }}

    *New in Jinja 1.2*
    """
    def wrapped(env, context, value):
        try:
            return value[key]
        except (TypeError, KeyError, IndexError, AttributeError):
            return env.undefined_singleton
    return wrapped


FILTERS = {
    'replace':              do_replace,
    'upper':                do_upper,
    'lower':                do_lower,
    'escape':               do_escape,
    'e':                    do_escape,
    'xmlattr':              do_xmlattr,
    'capitalize':           do_capitalize,
    'title':                do_title,
    'default':              do_default,
    'join':                 do_join,
    'count':                do_count,
    'dictsort':             do_dictsort,
    'length':               do_count,
    'reverse':              do_reverse,
    'center':               do_center,
    'title':                do_title,
    'capitalize':           do_capitalize,
    'first':                do_first,
    'last':                 do_last,
    'random':               do_random,
    'jsonencode':           do_jsonencode,
    'filesizeformat':       do_filesizeformat,
    'pprint':               do_pprint,
    'indent':               do_indent,
    'truncate':             do_truncate,
    'wordwrap':             do_wordwrap,
    'wordcount':            do_wordcount,
    'textile':              do_textile,
    'markdown':             do_markdown,
    'rst':                  do_rst,
    'int':                  do_int,
    'float':                do_float,
    'string':               do_string,
    'urlize':               do_urlize,
    'format':               do_format,
    'dformat':              do_dformat,
    'trim':                 do_trim,
    'striptags':            do_striptags,
    'slice':                do_slice,
    'batch':                do_batch,
    'sum':                  do_sum,
    'abs':                  do_abs,
    'round':                do_round,
    'sort':                 do_sort,
    'groupby':              do_groupby,
    'getattribute':         do_getattribute,
    'getitem':              do_getitem
}