1 files changed, 72 insertions, 0 deletions
diff --git a/markdown_it/rules_block/heading.py b/markdown_it/rules_block/heading.py
new file mode 100644
index 0000000..8d4ef3e
--- /dev/null
+++ b/markdown_it/rules_block/heading.py
@@ -0,0 +1,72 @@
+""" Atex heading (#, ##, ...) """
+from __future__ import annotations
+
+import logging
+
+from ..common.utils import isSpace
+from .state_block import StateBlock
+
+LOGGER = logging.getLogger(__name__)
+
+
+def heading(state: StateBlock, startLine: int, endLine: int, silent: bool):
+
+    LOGGER.debug("entering heading: %s, %s, %s, %s", state, startLine, endLine, silent)
+
+    pos = state.bMarks[startLine] + state.tShift[startLine]
+    maximum = 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
+
+    ch: int | None = state.srcCharCode[pos]
+
+    # /* # */
+    if ch != 0x23 or pos >= maximum:
+        return False
+
+    # count heading level
+    level = 1
+    pos += 1
+    try:
+        ch = state.srcCharCode[pos]
+    except IndexError:
+        ch = None
+    # /* # */
+    while ch == 0x23 and pos < maximum and level <= 6:
+        level += 1
+        pos += 1
+        try:
+            ch = state.srcCharCode[pos]
+        except IndexError:
+            ch = None
+
+    if level > 6 or (pos < maximum and not isSpace(ch)):
+        return False
+
+    if silent:
+        return True
+
+    # Let's cut tails like '    ###  ' from the end of string
+
+    maximum = state.skipSpacesBack(maximum, pos)
+    tmp = state.skipCharsBack(maximum, 0x23, pos)  # #
+    if tmp > pos and isSpace(state.srcCharCode[tmp - 1]):
+        maximum = tmp
+
+    state.line = startLine + 1
+
+    token = state.push("heading_open", "h" + str(level), 1)
+    token.markup = "########"[:level]
+    token.map = [startLine, state.line]
+
+    token = state.push("inline", "", 0)
+    token.content = state.src[pos:maximum].strip()
+    token.map = [startLine, state.line]
+    token.children = []
+
+    token = state.push("heading_close", "h" + str(level), -1)
+    token.markup = "########"[:level]
+
+    return True