1 files changed, 173 insertions, 0 deletions
diff --git a/src/mistune/plugins/formatting.py b/src/mistune/plugins/formatting.py
new file mode 100644
index 0000000..57e5def
--- /dev/null
+++ b/src/mistune/plugins/formatting.py
@@ -0,0 +1,173 @@
+import re
+from ..helpers import PREVENT_BACKSLASH
+
+__all__ = ["strikethrough", "mark", "insert", "superscript", "subscript"]
+
+_STRIKE_END = re.compile(r'(?:' + PREVENT_BACKSLASH + r'\\~|[^\s~])~~(?!~)')
+_MARK_END = re.compile(r'(?:' + PREVENT_BACKSLASH + r'\\=|[^\s=])==(?!=)')
+_INSERT_END = re.compile(r'(?:' + PREVENT_BACKSLASH + r'\\\^|[^\s^])\^\^(?!\^)')
+
+SUPERSCRIPT_PATTERN = r'\^(?:' + PREVENT_BACKSLASH + r'\\\^|\S|\\ )+?\^'
+SUBSCRIPT_PATTERN = r'~(?:' + PREVENT_BACKSLASH + r'\\~|\S|\\ )+?~'
+
+
+def parse_strikethrough(inline, m, state):
+    return _parse_to_end(inline, m, state, 'strikethrough', _STRIKE_END)
+
+
+def render_strikethrough(renderer, text):
+    return '<del>' + text + '</del>'
+
+
+def parse_mark(inline, m, state):
+    return _parse_to_end(inline, m, state, 'mark', _MARK_END)
+
+
+def render_mark(renderer, text):
+    return '<mark>' + text + '</mark>'
+
+
+def parse_insert(inline, m, state):
+    return _parse_to_end(inline, m, state, 'insert', _INSERT_END)
+
+
+def render_insert(renderer, text):
+    return '<ins>' + text + '</ins>'
+
+
+def parse_superscript(inline, m, state):
+    return _parse_script(inline, m, state, 'superscript')
+
+
+def render_superscript(renderer, text):
+    return '<sup>' + text + '</sup>'
+
+
+def parse_subscript(inline, m, state):
+    return _parse_script(inline, m, state, 'subscript')
+
+
+def render_subscript(renderer, text):
+    return '<sub>' + text + '</sub>'
+
+
+def _parse_to_end(inline, m, state, tok_type, end_pattern):
+    pos = m.end()
+    m1 = end_pattern.search(state.src, pos)
+    if not m1:
+        return
+    end_pos = m1.end()
+    text = state.src[pos:end_pos-2]
+    new_state = state.copy()
+    new_state.src = text
+    children = inline.render(new_state)
+    state.append_token({'type': tok_type, 'children': children})
+    return end_pos
+
+
+def _parse_script(inline, m, state, tok_type):
+    text = m.group(0)
+    new_state = state.copy()
+    new_state.src = text[1:-1].replace('\\ ', ' ')
+    children = inline.render(new_state)
+    state.append_token({
+        'type': tok_type,
+        'children': children
+    })
+    return m.end()
+
+
+def strikethrough(md):
+    """A mistune plugin to support strikethrough. Spec defined by
+    GitHub flavored Markdown and commonly used by many parsers:
+
+    .. code-block:: text
+
+        ~~This was mistaken text~~
+
+    It will be converted into HTML:
+
+    .. code-block:: html
+
+        <del>This was mistaken text</del>
+
+    :param md: Markdown instance
+    """
+    md.inline.register(
+        'strikethrough',
+        r'~~(?=[^\s~])',
+        parse_strikethrough,
+        before='link',
+    )
+    if md.renderer and md.renderer.NAME == 'html':
+        md.renderer.register('strikethrough', render_strikethrough)
+
+
+def mark(md):
+    """A mistune plugin to add ``<mark>`` tag. Spec defined at
+    https://facelessuser.github.io/pymdown-extensions/extensions/mark/:
+
+    .. code-block:: text
+
+        ==mark me== ==mark \\=\\= equal==
+
+    :param md: Markdown instance
+    """
+    md.inline.register(
+        'mark',
+        r'==(?=[^\s=])',
+        parse_mark,
+        before='link',
+    )
+    if md.renderer and md.renderer.NAME == 'html':
+        md.renderer.register('mark', render_mark)
+
+
+def insert(md):
+    """A mistune plugin to add ``<ins>`` tag. Spec defined at
+    https://facelessuser.github.io/pymdown-extensions/extensions/caret/#insert:
+
+    .. code-block:: text
+
+        ^^insert me^^
+
+    :param md: Markdown instance
+    """
+    md.inline.register(
+        'insert',
+        r'\^\^(?=[^\s\^])',
+        parse_insert,
+        before='link',
+    )
+    if md.renderer and md.renderer.NAME == 'html':
+        md.renderer.register('insert', render_insert)
+
+
+def superscript(md):
+    """A mistune plugin to add ``<sup>`` tag. Spec defined at
+    https://pandoc.org/MANUAL.html#superscripts-and-subscripts:
+
+    .. code-block:: text
+
+        2^10^ is 1024.
+
+    :param md: Markdown instance
+    """
+    md.inline.register('superscript', SUPERSCRIPT_PATTERN, parse_superscript, before='linebreak')
+    if md.renderer and md.renderer.NAME == 'html':
+        md.renderer.register('superscript', render_superscript)
+
+
+def subscript(md):
+    """A mistune plugin to add ``<sub>`` tag. Spec defined at
+    https://pandoc.org/MANUAL.html#superscripts-and-subscripts:
+
+    .. code-block:: text
+
+        H~2~O is a liquid.
+
+    :param md: Markdown instance
+    """
+    md.inline.register('subscript', SUBSCRIPT_PATTERN, parse_subscript, before='linebreak')
+    if md.renderer and md.renderer.NAME == 'html':
+        md.renderer.register('subscript', render_subscript)