import re
from typing import Any, Callable, Dict, Optional
from markdown_it import MarkdownIt
from markdown_it.common.utils import escapeHtml, isWhiteSpace
from markdown_it.rules_block import StateBlock
from markdown_it.rules_inline import StateInline
[docs]def dollarmath_plugin(
md: MarkdownIt,
*,
allow_labels: bool = True,
allow_space: bool = True,
allow_digits: bool = True,
double_inline: bool = False,
label_normalizer: Optional[Callable[[str], str]] = None,
renderer: Optional[Callable[[str, Dict[str, Any]], str]] = None,
label_renderer: Optional[Callable[[str], str]] = None,
) -> None:
"""Plugin for parsing dollar enclosed math,
e.g. inline: ``$a=1$``, block: ``$$b=2$$``
This is an improved version of ``texmath``; it is more performant,
and handles ``\\`` escaping properly and allows for more configuration.
:param allow_labels: Capture math blocks with label suffix, e.g. ``$$a=1$$ (eq1)``
:param allow_space: Parse inline math when there is space
after/before the opening/closing ``$``, e.g. ``$ a $``
:param allow_digits: Parse inline math when there is a digit
before/after the opening/closing ``$``, e.g. ``1$`` or ``$2``.
This is useful when also using currency.
:param double_inline: Search for double-dollar math within inline contexts
:param label_normalizer: Function to normalize the label,
by default replaces whitespace with `-`
:param renderer: Function to render content: `(str, {"display_mode": bool}) -> str`,
by default escapes HTML
:param label_renderer: Function to render labels, by default creates anchor
"""
if label_normalizer is None:
label_normalizer = lambda label: re.sub(r"\s+", "-", label)
md.inline.ruler.before(
"escape",
"math_inline",
math_inline_dollar(allow_space, allow_digits, double_inline),
)
md.block.ruler.before(
"fence", "math_block", math_block_dollar(allow_labels, label_normalizer)
)
# TODO the current render rules are really just for testing
# would be good to allow "proper" math rendering,
# e.g. https://github.com/roniemartinez/latex2mathml
_renderer = (
(lambda content, _: escapeHtml(content)) if renderer is None else renderer
)
if label_renderer is None:
_label_renderer = (
lambda label: f'<a href="#{label}" class="mathlabel" title="Permalink to this equation">ΒΆ</a>' # noqa: E501
)
else:
_label_renderer = label_renderer
def render_math_inline(self, tokens, idx, options, env) -> str:
content = _renderer(str(tokens[idx].content).strip(), {"display_mode": False})
return f'<span class="math inline">{content}</span>'
def render_math_inline_double(self, tokens, idx, options, env) -> str:
content = _renderer(str(tokens[idx].content).strip(), {"display_mode": True})
return f'<div class="math inline">{content}</div>'
def render_math_block(self, tokens, idx, options, env) -> str:
content = _renderer(str(tokens[idx].content).strip(), {"display_mode": True})
return f'<div class="math block">\n{content}\n</div>\n'
def render_math_block_label(self, tokens, idx, options, env) -> str:
content = _renderer(str(tokens[idx].content).strip(), {"display_mode": True})
_id = tokens[idx].info
label = _label_renderer(tokens[idx].info)
return f'<div id="{_id}" class="math block">\n{label}\n{content}\n</div>\n'
md.add_render_rule("math_inline", render_math_inline)
md.add_render_rule("math_inline_double", render_math_inline_double)
md.add_render_rule("math_block", render_math_block)
md.add_render_rule("math_block_label", render_math_block_label)
def is_escaped(state: StateInline, back_pos: int, mod: int = 0) -> bool:
"""Test if dollar is escaped."""
# count how many \ are before the current position
backslashes = 0
while back_pos >= 0:
back_pos = back_pos - 1
if state.srcCharCode[back_pos] == 0x5C: # /* \ */
backslashes += 1
else:
break
if not backslashes:
return False
# if an odd number of \ then ignore
if (backslashes % 2) != mod:
return True
return False
def math_inline_dollar(
allow_space: bool = True, allow_digits: bool = True, allow_double: bool = False
) -> Callable[[StateInline, bool], bool]:
"""Generate inline dollar rule.
:param allow_space: Parse inline math when there is space
after/before the opening/closing ``$``, e.g. ``$ a $``
:param allow_digits: Parse inline math when there is a digit
before/after the opening/closing ``$``, e.g. ``1$`` or ``$2``.
This is useful when also using currency.
:param allow_double: Search for double-dollar math within inline contexts
"""
def _math_inline_dollar(state: StateInline, silent: bool) -> bool:
"""Inline dollar rule.
- Initial check:
- check if first character is a $
- check if the first character is escaped
- check if the next character is a space (if not allow_space)
- check if the next character is a digit (if not allow_digits)
- Advance one, if allow_double
- Find closing (advance one, if allow_double)
- Check closing:
- check if the previous character is a space (if not allow_space)
- check if the next character is a digit (if not allow_digits)
- Check empty content
"""
# TODO options:
# even/odd backslash escaping
if state.srcCharCode[state.pos] != 0x24: # /* $ */
return False
if not allow_space:
# whitespace not allowed straight after opening $
try:
if isWhiteSpace(state.srcCharCode[state.pos + 1]):
return False
except IndexError:
return False
if not allow_digits:
# digit not allowed straight before opening $
try:
if state.src[state.pos - 1].isdigit():
return False
except IndexError:
pass
if is_escaped(state, state.pos):
return False
try:
is_double = allow_double and state.srcCharCode[state.pos + 1] == 0x24
except IndexError:
return False
# find closing $
pos = state.pos + 1 + (1 if is_double else 0)
found_closing = False
while not found_closing:
try:
end = state.srcCharCode.index(0x24, pos)
except ValueError:
return False
if is_escaped(state, end):
pos = end + 1
continue
try:
if is_double and state.srcCharCode[end + 1] != 0x24:
pos = end + 1
continue
except IndexError:
return False
if is_double:
end += 1
found_closing = True
if not found_closing:
return False
if not allow_space:
# whitespace not allowed straight before closing $
try:
if isWhiteSpace(state.srcCharCode[end - 1]):
return False
except IndexError:
return False
if not allow_digits:
# digit not allowed straight after closing $
try:
if state.src[end + 1].isdigit():
return False
except IndexError:
pass
text = (
state.src[state.pos + 2 : end - 1]
if is_double
else state.src[state.pos + 1 : end]
)
# ignore empty
if not text:
return False
if not silent:
token = state.push(
"math_inline_double" if is_double else "math_inline", "math", 0
)
token.content = text
token.markup = "$$" if is_double else "$"
state.pos = end + 1
return True
return _math_inline_dollar
# reversed end of block dollar equation, with equation label
DOLLAR_EQNO_REV = re.compile(r"^\s*\)([^)$\r\n]+?)\(\s*\${2}")
def math_block_dollar(
allow_labels: bool = True,
label_normalizer: Optional[Callable[[str], str]] = None,
) -> Callable[[StateBlock, int, int, bool], bool]:
"""Generate block dollar rule."""
def _math_block_dollar(
state: StateBlock, startLine: int, endLine: int, silent: bool
) -> bool:
# TODO internal backslash escaping
haveEndMarker = False
startPos = state.bMarks[startLine] + state.tShift[startLine]
end = state.eMarks[startLine]
# if it's indented more than 3 spaces, it should be a code block
if state.sCount[startLine] - state.blkIndent >= 4:
return False
if startPos + 2 > end:
return False
if (
state.srcCharCode[startPos] != 0x24
or state.srcCharCode[startPos + 1] != 0x24
): # /* $ */
return False
# search for end of block
nextLine = startLine
label = None
# search for end of block on same line
lineText = state.src[startPos:end]
if len(lineText.strip()) > 3:
if lineText.strip().endswith("$$"):
haveEndMarker = True
end = end - 2 - (len(lineText) - len(lineText.strip()))
elif allow_labels:
# reverse the line and match
eqnoMatch = DOLLAR_EQNO_REV.match(lineText[::-1])
if eqnoMatch:
haveEndMarker = True
label = eqnoMatch.group(1)[::-1]
end = end - eqnoMatch.end()
# search for end of block on subsequent line
if not haveEndMarker:
while True:
nextLine += 1
if nextLine >= endLine:
break
start = state.bMarks[nextLine] + state.tShift[nextLine]
end = state.eMarks[nextLine]
if end - start < 2:
continue
lineText = state.src[start:end]
if lineText.strip().endswith("$$"):
haveEndMarker = True
end = end - 2 - (len(lineText) - len(lineText.strip()))
break
# reverse the line and match
if allow_labels:
eqnoMatch = DOLLAR_EQNO_REV.match(lineText[::-1])
if eqnoMatch:
haveEndMarker = True
label = eqnoMatch.group(1)[::-1]
end = end - eqnoMatch.end()
break
if not haveEndMarker:
return False
state.line = nextLine + (1 if haveEndMarker else 0)
token = state.push("math_block_label" if label else "math_block", "math", 0)
token.block = True
token.content = state.src[startPos + 2 : end]
token.markup = "$$"
token.map = [startLine, state.line]
if label:
token.info = label if label_normalizer is None else label_normalizer(label)
return True
return _math_block_dollar