Merge branch 'feature/liquid-filter', closes #115

Currently, the following tags are ported:

- blockquote -- generate beautiful, semantic block quotes
- img -- easily post images with class names and titles
- youtube_ -- easy embedding of YouTube videos
- pullquote -- generate CSS only pull quotes — no duplicate data, no javascript
- tweet -- embed tweets using Twitter's oEmbed API

README.rst

@@ -69,10 +69,12 @@ other filters
 - TeX hyphenation
 - summarize ability
 - `acronym detection`_  that automatically replace acronyms and abbreviations
+- `liquid plugins`_ ported from `Octopress <http://octopress.org/>`_
 
 .. _typography: https://code.google.com/p/typogrify/
 .. _smartypants: http://daringfireball.net/projects/smartypants/
 .. _acronym detection: http://pyblosxom.github.com/1.5/plugins/acronyms.html
+.. _liquid plugins: http://octopress.org/docs/plugins/
 
 blogging features
 ~~~~~~~~~~~~~~~~~

acrylamid/filters/liquid.py

@@ -0,0 +1,212 @@
+# -*- encoding: utf-8 -*-
+#
+# Copyright 2013 Martin Zimmermann <info@posativ.org>. All rights reserved.
+# License: BSD Style, 2 clauses -- see LICENSE.
+
+import io
+import re
+import json
+
+from os.path import join
+from functools import partial
+
+from urllib import urlencode
+from urlparse import urlparse, parse_qs
+
+try:
+    import cPickle as pickle
+except ImportError:
+    import pickle  # NOQA
+
+from acrylamid import core, utils, lib
+
+from acrylamid.core import cache
+from acrylamid.utils import Struct
+from acrylamid.filters import Filter
+
+from acrylamid.lib import requests
+
+__img_re = r'(?P<class>\S.*\s+)?(?P<src>(?:https?:\/\/|\/|\S+\/)\S+)(?:\s+(?P<width>\d+))?(?:\s+(?P<height>\d+))?(?P<title>\s+.+)?'
+__img_re_title = r'(?:"|\')(?P<title>[^"\']+)?(?:"|\')\s+(?:"|\')(?P<alt>[^"\']+)?(?:"|\')'
+
+
+def blockquote(header, body):
+    """Mimic Octopress's blockquote plugin. See
+    http://octopress.org/docs/plugins/blockquote/ for examples."""
+
+    # TODO: use python-titlecase if available or use this implementation:
+    #       https://github.com/imathis/octopress/blob/master/plugins/titlecase.rb
+
+    def paragraphize(text):
+        return '<p>' + text.strip().replace('\n\n', '</p><p>').replace('\n', '<br/>') + '</p>'
+
+    by, source, title = None, None, None
+
+    m = re.match(r'(\S.*)\s+(https?:\/\/)(\S+)\s+(.+)', header, flags=re.I)
+    if m:
+        by = m.group(1)
+        source = m.group(2) + m.group(3)
+        title = m.group(4)  # titlecase
+    else:
+        m = re.match(r'(\S.*)\s+(https?:\/\/)(\S+)', header, re.I)
+        if m:
+            by = m.group(1)
+            source = m.group(2) + m.group(3)
+        else:
+            m = re.match(r'([^,]+),([^,]+)', header)
+            if m:
+                by = m.group(1)
+                title = m.group(2)  # titlecase
+            else:
+                m = re.match(r'(.+)', header)
+                if m:
+                    by = m.group(1)
+
+    quote = paragraphize(body)
+    author = '<strong>%s</strong>' % (by.strip() or '')
+
+    if source:
+        url = re.match(r'https?:\/\/(.+)', source).group(1)
+        parts = []
+        for part in url.split('/'):
+            if not part or len('/'.join(parts + [part])) >= 32:
+                break
+            parts.append(part)
+        else:
+            parts.append('&hellip;')
+
+        href = '/'.join(parts)
+
+    if source:
+        cite = ' <cite><a href="%s">%s</a></cite>' % (source, (title or href))
+    elif title:
+        cite = ' <cite>%s</cite>' % title
+
+    if not author:
+        blockquote = quote
+    elif cite:
+        blockquote = quote + "<footer>%s</footer>" % (author + cite)
+    else:
+        blockquote = quote + "<footer>%s</footer>" % author
+
+    return "<blockquote>%s</blockquote>" % blockquote
+
+
+def img(header, body=None):
+    """Alternate to Markdown's image tag. See
+    http://octopress.org/docs/plugins/image-tag/ for usage."""
+
+    attrs = re.match(__img_re, header).groupdict()
+    m = re.match(__img_re_title, attrs['title'])
+
+    if m:
+        attrs['title'] = m.groupdict()['title']
+        attrs['alt'] = m.groupdict()['alt']
+    elif 'title' in attrs:
+        attrs['alt'] = attrs['title'].replace('"', '&#34')
+
+    if 'class' in attrs:
+        attrs['class'] = attrs['class'].replace('"', '')
+
+    if attrs:
+        return '<img ' + ' '.join('%s="%s"' % (k, v) for k, v in attrs.items() if v) + ' />'
+    return ("Error processing input, expected syntax: "
+            "{% img [class name(s)] [http[s]:/]/path/to/image [width [height]] "
+            "[title text | \"title text\" [\"alt text\"]] %}")
+
+
+def youtube(header, body=None):
+
+    # TODO add options similar to rstx_youtube directive
+
+    if header.startswith(('http://', 'https://')):
+        header = parse_qs(urlparse(header).query)['v'][0]
+
+    return '<div class="video">' + \
+                '<iframe src="http://www.youtube.com/embed/%s"></iframe>' % header + \
+           '</div>'
+
+
+def pullquote(header, body):
+    """Semantic pullquote using CSS only. Defaults to right alignment. See
+    http://octopress.org/docs/plugins/pullquote/ for details."""
+
+    # TODO support a markup language somehow
+
+    align = 'left' if 'left' in header.lower() else 'right'
+    m = re.search(r'{"\s*(.+?)\s*"}', body, re.MULTILINE | re.DOTALL)
+
+    if m:
+        return '<span class="pullquote-{0}" data-pullquote="{1}">{2}</span>'.format(
+            align, m.group(1), re.sub(r'\{"\s*|\s*"\}', '', body))
+    return "Surround your pullquote like this {\" text to be quoted \"}"
+
+
+def tweet(header, body=None):
+    """Easy embedding of Tweets. The Twitter oEmbed API is rate-limited,
+    hence we are caching the response per configuration to `.cache/`."""
+
+    oembed = 'https://api.twitter.com/1/statuses/oembed.json'
+    args = map(unicode.strip, re.split(r'\s+', header))
+
+    params = Struct(url=args.pop(0))
+    for arg in args:
+        k, v = map(unicode.strip, arg.split('='))
+        if k and v:
+            v = v.strip('\'')
+        params[k] = v
+
+    try:
+        with io.open(join(core.cache.cache_dir, 'tweets'), 'rb') as fp:
+            cache = pickle.load(fp)
+    except (IOError, pickle.PickleError):
+        cache = {}
+
+    if params in cache:
+        body = cache[params]
+    else:
+        try:
+            body = json.loads(requests.get(oembed + '?' + urlencode(params)).read())['html']
+        except (requests.HTTPError, requests.URLError):
+            log.exception('unable to fetch tweet')
+            body = "Tweet could not be fetched"
+        except (ValueError, KeyError):
+            log.exception('could not parse response')
+            body = "Tweet could not be processed"
+        else:
+            cache[params] = body
+
+    try:
+        with io.open(join(core.cache.cache_dir, 'tweets'), 'wb') as fp:
+            pickle.dump(cache, fp, pickle.HIGHEST_PROTOCOL)
+    except (IOError, pickle.PickleError):
+        log.exception('uncaught exception during pickle.dump')
+
+    return "<div class='embed tweet'>%s</div>" % body
+
+
+class Liquid(Filter):
+
+    match = [re.compile('^(liquid|octopress)$', re.I)]
+    priority = 80.0
+
+    directives = {
+        'blockquote': blockquote, 'pullquote': pullquote,
+        'img': img, 'tweet': tweet,
+        'youtube': youtube
+    }
+
+    def block(self, tag):
+        return re.compile(''.join([
+            r'{%% %s (.*?) ?%%}' % tag,
+            '(?:',
+                '\n(.+?)\n',
+                r'{%% end%s %%}' % tag,
+            ')?']), re.MULTILINE | re.DOTALL)
+
+    def transform(self, text, entry, *args):
+
+        for tag, func in self.directives.iteritems():
+            text = re.sub(self.block(tag), lambda m: func(*m.groups()), text)
+
+        return text

acrylamid/specs/filters_builtin.py

@@ -175,3 +175,49 @@ def strip():
 
     assert strip.transform('<pre>...</pre>', Entry(), 'pre') == ''
     assert strip.transform('<pre>&lt;</pre>', Entry(), 'pre') == ''
+
+
+@tt.test
+def liquid():
+
+    liquid = get_filters()['liquid'](conf, env, 'liquid')
+
+    # liquid block recognition
+    text = '\n'.join([
+        "{% tag %}", "", "Foo Bar.", "", "{% endtag %}"
+    ])
+
+    rv = liquid.block("tag").match(text)
+    assert rv.group(1) == ""
+    assert rv.group(2) == "\nFoo Bar.\n"
+
+    # multiple, not nested blocks
+    text = '\n'.join([
+        "{% block %}", "", "Foo Bar.", "", "{% endblock %}",
+        "",
+        "{% block %}", "", "Baz.", "", "{% endblock %}"
+    ])
+
+    rv = tuple(liquid.block("block").finditer(text))
+    assert len(rv) == 2
+
+    x, y = rv
+    assert x.group(2).strip() == "Foo Bar."
+    assert y.group(2).strip() == "Baz."
+
+    # self-closing block
+    text = '{% block a few args %}'
+    rv = liquid.block("block").match(text)
+
+    assert rv is not None
+    assert rv.group(1) == 'a few args'
+    assert rv.group(2) is None
+
+    # blockquote
+    examples = [
+        ('{% blockquote Author, Source http://example.org/ Title %}\nFoo Bar\n{% endblockquote %}',
+         '<blockquote><p>Foo Bar</p><footer><strong>Author, Source</strong> <cite><a href="http://example.org/">Title</a></cite></footer></blockquote>'),
+    ]
+
+    for text, result in examples:
+        assert liquid.transform(text, Entry()) == result

docs/filters.rst

@@ -312,6 +312,46 @@ Conflicts     reStructuredText, Markdown, Pandoc
 ============  ==================================================
 
 
+Liquid
+------
+
+Implementation of most plugins of the Jekyll/Octopress project. This filter
+(unfortunately) can not be used with reST or any other markup language, that
+can not handle inline HTML.
+
+The liquid filters are useful of you are migrating from Jekyll/Octopress or
+look for an inofficial standard (rather than custom Markdown extensions) that
+is used by Jekyll_/Octopress_, Hexo_.
+
+.. _Jekyll: https://github.com/mojombo/jekyll/wiki/Liquid-Extensions#tags
+.. _Octopress: http://octopress.org/docs/plugins/
+.. _Hexo: http://zespia.tw/hexo/docs/tag-plugins.html
+
+Currently, the following tags are ported (I reference the Octopress plugin
+documentation for usage details):
+
+- blockquote__ -- generate beautiful, semantic block quotes
+- img__ -- easily post images with class names and titles
+- youtube__ -- easy embedding of YouTube videos
+- pullquote__ -- generate CSS only pull quotes — no duplicate data, no javascript
+- tweet__ -- embed tweets using Twitter's oEmbed API
+
+__ http://octopress.org/docs/plugins/blockquote/
+__ http://octopress.org/docs/plugins/image-tag/
+__ http://www.portwaypoint.co.uk/jekyll-youtube-liquid-template-tag-gist/
+__ http://octopress.org/docs/plugins/pullquote/
+__ https://github.com/scottwb/jekyll-tweet-tag
+
+If you need another plugin, just ask on `GitHub:Issues
+<https://github.com/posativ/acrylamid/issues>`_ (plugins that will not
+implemented in near future: Include Array, Render Partial, Code Block).
+
+============  ==================================================
+Requires      <built-in>
+Aliases       liquid, octopress
+============  ==================================================
+
+
 h, head_offset
 --------------
 

docs/index.rst

@@ -89,10 +89,12 @@ other filters
 - TeX hyphenation
 - summarize ability
 - `acronym detection`_  that automatically replace acronyms and abbreviations
+- `liquid plugins`_ ported from `Octopress <http://octopress.org/>`_
 
 .. _typography: https://code.google.com/p/typogrify/
 .. _smartypants: http://daringfireball.net/projects/smartypants/
 .. _acronym detection: http://pyblosxom.github.com/1.5/plugins/acronyms.html
+.. _liquid plugins: http://octopress.org/docs/plugins/
 
 blogging features
 ~~~~~~~~~~~~~~~~~