2 files changed, 154 insertions, 0 deletions
diff --git a/mdit_py_plugins/myst_blocks/__init__.py b/mdit_py_plugins/myst_blocks/__init__.py
new file mode 100644
index 0000000..434cad6
--- /dev/null
+++ b/mdit_py_plugins/myst_blocks/__init__.py
@@ -0,0 +1 @@
+from .index import myst_block_plugin  # noqa: F401
diff --git a/mdit_py_plugins/myst_blocks/index.py b/mdit_py_plugins/myst_blocks/index.py
new file mode 100644
index 0000000..d0e4cf6
--- /dev/null
+++ b/mdit_py_plugins/myst_blocks/index.py
@@ -0,0 +1,153 @@
+import itertools
+
+from markdown_it import MarkdownIt
+from markdown_it.common.utils import escapeHtml, isSpace
+from markdown_it.rules_block import StateBlock
+
+
+def myst_block_plugin(md: MarkdownIt):
+    """Parse MyST targets (``(name)=``), blockquotes (``% comment``) and block breaks (``+++``)."""
+    md.block.ruler.before(
+        "blockquote",
+        "myst_line_comment",
+        line_comment,
+        {"alt": ["paragraph", "reference", "blockquote", "list", "footnote_def"]},
+    )
+    md.block.ruler.before(
+        "hr",
+        "myst_block_break",
+        block_break,
+        {"alt": ["paragraph", "reference", "blockquote", "list", "footnote_def"]},
+    )
+    md.block.ruler.before(
+        "hr",
+        "myst_target",
+        target,
+        {"alt": ["paragraph", "reference", "blockquote", "list", "footnote_def"]},
+    )
+    md.add_render_rule("myst_target", render_myst_target)
+    md.add_render_rule("myst_line_comment", render_myst_line_comment)
+
+
+def line_comment(state: StateBlock, startLine: int, endLine: int, silent: bool):
+
+    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
+
+    if state.src[pos] != "%":
+        return False
+
+    if silent:
+        return True
+
+    token = state.push("myst_line_comment", "", 0)
+    token.attrSet("class", "myst-line-comment")
+    token.content = state.src[pos + 1 : maximum].rstrip()
+    token.markup = "%"
+
+    # search end of block while appending lines to `token.content`
+    for nextLine in itertools.count(startLine + 1):
+        if nextLine >= endLine:
+            break
+        pos = state.bMarks[nextLine] + state.tShift[nextLine]
+        maximum = state.eMarks[nextLine]
+
+        if state.src[pos] != "%":
+            break
+        token.content += "\n" + state.src[pos + 1 : maximum].rstrip()
+
+    state.line = nextLine
+    token.map = [startLine, nextLine]
+
+    return True
+
+
+def block_break(state: StateBlock, startLine: int, endLine: int, silent: bool):
+
+    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
+
+    marker = state.srcCharCode[pos]
+    pos += 1
+
+    # Check block marker /* + */
+    if marker != 0x2B:
+        return False
+
+    # markers can be mixed with spaces, but there should be at least 3 of them
+
+    cnt = 1
+    while pos < maximum:
+        ch = state.srcCharCode[pos]
+        if ch != marker and not isSpace(ch):
+            break
+        if ch == marker:
+            cnt += 1
+        pos += 1
+
+    if cnt < 3:
+        return False
+
+    if silent:
+        return True
+
+    state.line = startLine + 1
+
+    token = state.push("myst_block_break", "hr", 0)
+    token.attrSet("class", "myst-block")
+    token.content = state.src[pos:maximum].strip()
+    token.map = [startLine, state.line]
+    token.markup = chr(marker) * cnt
+
+    return True
+
+
+def target(state: StateBlock, startLine: int, endLine: int, silent: bool):
+
+    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
+
+    text = state.src[pos:maximum].strip()
+    if not text.startswith("("):
+        return False
+    if not text.endswith(")="):
+        return False
+    if not text[1:-2]:
+        return False
+
+    if silent:
+        return True
+
+    state.line = startLine + 1
+
+    token = state.push("myst_target", "", 0)
+    token.attrSet("class", "myst-target")
+    token.content = text[1:-2]
+    token.map = [startLine, state.line]
+
+    return True
+
+
+def render_myst_target(self, tokens, idx, options, env):
+    label = tokens[idx].content
+    class_name = "myst-target"
+    target = f'<a href="#{label}">({label})=</a>'
+    return f'<div class="{class_name}">{target}</div>'
+
+
+def render_myst_line_comment(self, tokens, idx, options, env):
+    # Strip leading whitespace from all lines
+    content = "\n".join(line.lstrip() for line in tokens[idx].content.split("\n"))
+    return f"<!-- {escapeHtml(content)} -->"