flatpandoc.py

"""
flask_flatpages_pandoc
~~~~~~~~~~~~~~~~~~~~~~

Flask-FlatPages-Pandoc is an HTML renderer for Flask-FlatPages that uses
pandoc as backend.

:copyright: (c) 2014 Fabian Hirschmann <fabian@hirschmann.email>
:license: MIT, see LICENSE.txt for more details.

With some changes by @apas:

  - Invoke pandoc via pypandoc instead subprocess
  - Indentation changes
  - Support of Pandoc 2.0 by @ThoseGrapefruits
  - Support of Python 3 by @frstp64

License: MIT
"""

import pkg_resources
import pypandoc

from flask import render_template_string, Markup

try:
  __version__ = pkg_resources.require("Flask-FlatPages-Pandoc")[0]
except pkg_resources.DistributionNotFound:
  __version__ = "0.0-dev"

class FlatPagesPandoc(object):
  """
  Class that, when applied to a :class:`flask.Flask` instance,
  sets up an HTML renderer using pandoc.
  """
  def __init__(self, source_format, app=None, pandoc_args=[],
   pre_render=False):
    """
    Initializes Flask-FlatPages-Pandoc.

    :param source_format: the source file format; directly passed
                          to pandoc.
    :type source_format: string
    :param app: your application. Can be omitted if you call
                :meth:`init_app` later.
    :type app: :class:`flask.Flask`
    :param pandoc_args: extra arguments passed to pandoc
    :type pandoc_args: sequence
    :param pre_render: pre-render the page as :class:`flask.Markup`
    :type pre_render: boolean
    """
    self.source_format = source_format
    self.pandoc_args = pandoc_args
    self.pre_render = pre_render

    if app:
      self.init_app(app)

  def init_app(self, app):
    """
    Used to initialize an application. This is useful when passing
    an app later.

    :param app: your application
    :type app: :class:`flask.Flask`
    """
    self.app = app

    # The following lambda expression works around Flask-FlatPage's
    # reflection magic.
    self.app.config["FLATPAGES_HTML_RENDERER"] = lambda t: self.renderer(t)

  def renderer(self, text):
    """
    Renders a flat page to HTML.

    :param text: the text of the flat page
    :type text: string
    """
    #if type(text) == str:
    #  text = str(text, self.app.config["FLATPAGES_ENCODING"])

    if self.pre_render:
      text = render_template_string(Markup(text))

    extra_args = [
      "--filter=pandoc-crossref",
      "--filter=pandoc-citeproc",
      "--filter=pandoc-sidenote",
      "--standalone",
      "--mathml",
      "--base-header-level=2",
      "--highlight-style", "pygments",
      "--bibliography=pages/all.bib",
      "--csl=pages/lncs.csl",
      "-Mreference-section-title=References",
      "-Mlink-citations=true"
    ]

    pandocver = int(pypandoc.get_pandoc_version()[0])

    if pandocver < 2:
      extra_args.append("-S")
      format_str = "markdown+raw_tex+yaml_metadata_block"
    else:
      format_str = "markdown+raw_tex+smart+yaml_metadata_block+header_attributes"

    output = pypandoc.convert_text(
      text.encode("utf8"),
      'html',
      format = format_str,
      extra_args=extra_args
    )

    return output