numenvs.py

#!/usr/bin/env python3

"""
Simple pandoc filter to create flexible environments in markdown. Style of
environments controlled via latex environment definitions or css for html.

Numbered theorem environment example:

  begin-Theorem

  $2+2=4$

  end-Theorem

Unnumered environment:

  begin+Example

  This.

  end+Example

The `begin` and `end` statements must be at the beginning of new paragraph.
"""

from pandocfilters import toJSONFilter, RawBlock


env_counts = {}


def html(string):
    """Return html block from string."""
    return RawBlock('html', string)


def latex(string):
    """Return latex block from string."""
    return RawBlock('latex', string)


def parse_env_latex(key, value):
    """Parse paragraph opening to extract environment name."""
    if key == 'Para':
        if len(value) >= 1:
            content = value[0]['c']
            if content[:6] == 'begin+' or content[:6] == 'begin-':
                return 'begin', content[6:]
            if content[:4] == 'end-' or content[:4] == 'end+':
                return 'end', content[4:]
    return '', ''


def parse_env_html(key, value):
    """Parse paragraph opening to extract environment name."""
    if key == 'Para':
        if len(value) >= 1:
            content = value[0]['c']
            if content[:6] == 'begin-':
                global env_counts
                name = content[6:]
                if name in env_counts:
                    env_counts[name] += 1
                else:
                    env_counts[name] = 1
                return 'begin', name, env_counts[name]
            if content[:6] == 'begin+':
                name = content[6:]
                return 'begin', name, None
            if content[:4] == 'end-' or content[:4] == 'end+':
                return 'end', content[4:], None
    return '', '', None


def num_envs_latex(key, value):
    """Create numbered divs environments."""
    instr, label = parse_env_latex(key, value)
    if instr == 'begin':
        return latex('\\begin{%s}\n' % label)
    if instr == 'end':
        return latex('\\end{%s}\n' % label)


def num_envs_html(key, value):
    """Create numbered divs environments."""
    instr, label, num = parse_env_html(key, value)
    if instr == 'begin':
        if num:
            title = label + ' ' + str(num)
        else:
            title = label
        return [html('<div class="numenv %s">' % label),
                html('<span class="numenv %s title">%s.</span>' % (label, title))]
    if instr == 'end':
        return html('</div>')


#pylint: disable=unused-argument
def num_envs(key, value, fmt, meta):
    """Select action based on format."""

    if fmt == 'html5':
        return num_envs_html(key, value)

    if fmt == 'latex':
        return num_envs_latex(key, value)

    return None


if __name__ == "__main__":
    toJSONFilter(num_envs)