# Process front matter and pass to cb
from math import floor
from markdown_it import MarkdownIt
from markdown_it.common.utils import charCodeAt
from markdown_it.rules_block import StateBlock
[docs]def front_matter_plugin(md: MarkdownIt):
"""Plugin ported from
`markdown-it-front-matter <https://github.com/ParkSB/markdown-it-front-matter>`__.
It parses initial metadata, stored between opening/closing dashes:
.. code-block:: md
---
valid-front-matter: true
---
"""
frontMatter = make_front_matter_rule()
md.block.ruler.before(
"table",
"front_matter",
frontMatter,
{"alt": ["paragraph", "reference", "blockquote", "list"]},
)
def make_front_matter_rule():
min_markers = 3
marker_str = "-"
marker_char = charCodeAt(marker_str, 0)
marker_len = len(marker_str)
def frontMatter(state: StateBlock, startLine: int, endLine: int, silent: bool):
auto_closed = False
start = state.bMarks[startLine] + state.tShift[startLine]
maximum = state.eMarks[startLine]
src_len = len(state.src)
# Check out the first character of the first line quickly,
# this should filter out non-front matter
if startLine != 0 or marker_char != state.srcCharCode[0]:
return False
# Check out the rest of the marker string
# while pos <= 3
pos = start + 1
while pos <= maximum and pos < src_len:
if marker_str[(pos - start) % marker_len] != state.src[pos]:
break
pos += 1
marker_count = floor((pos - start) / marker_len)
if marker_count < min_markers:
return False
pos -= (pos - start) % marker_len
# Since start is found, we can report success here in validation mode
if silent:
return True
# Search for the end of the block
nextLine = startLine
while True:
nextLine += 1
if nextLine >= endLine:
# unclosed block should be autoclosed by end of document.
return False
if state.src[start:maximum] == "...":
break
start = state.bMarks[nextLine] + state.tShift[nextLine]
maximum = state.eMarks[nextLine]
if start < maximum and state.sCount[nextLine] < state.blkIndent:
# non-empty line with negative indent should stop the list:
# - ```
# test
break
if marker_char != state.srcCharCode[start]:
continue
if state.sCount[nextLine] - state.blkIndent >= 4:
# closing fence should be indented less than 4 spaces
continue
pos = start + 1
while pos < maximum:
if marker_str[(pos - start) % marker_len] != state.src[pos]:
break
pos += 1
# closing code fence must be at least as long as the opening one
if floor((pos - start) / marker_len) < marker_count:
continue
# make sure tail has spaces only
pos -= (pos - start) % marker_len
pos = state.skipSpaces(pos)
if pos < maximum:
continue
# found!
auto_closed = True
break
old_parent = state.parentType
old_line_max = state.lineMax
state.parentType = "container"
# this will prevent lazy continuations from ever going past our end marker
state.lineMax = nextLine
token = state.push("front_matter", "", 0)
token.hidden = True
token.markup = marker_str * min_markers
token.content = state.src[
state.bMarks[startLine + 1] : state.eMarks[nextLine - 1]
]
token.block = True
state.parentType = old_parent
state.lineMax = old_line_max
state.line = nextLine + (1 if auto_closed else 0)
token.map = [startLine, state.line]
return True
return frontMatter