👌 Remove hard-coded block indent limit

For CommonMark, the presence of indented code blocks prevent any other block element from having an indent of greater than 4 spaces.
Certain Markdown flavors and derivatives, such as mdx and djot, disable these code blocks though, since it is more common to use code fences and indenting is desirable.
Currently, disabling code blocks does not remove the indent limitation, since most block elements have the 3 space limitation hard-coded.
This commit therefore centralises the logic of applying this limitation, and only applies it when indented code blocks are enabled.
Note, this is a potential breaking change and divergence from upstream markdown-it, for this niche case, but I feel makes sense.

Author: chrisjsewell

markdown_it/rules_block/blockquote.py

@@ -18,8 +18,7 @@ def blockquote(state: StateBlock, startLine: int, endLine: int, silent: bool) ->
     pos = state.bMarks[startLine] + state.tShift[startLine]
     max = state.eMarks[startLine]
 
-    # if it's indented more than 3 spaces, it should be a code block
-    if (state.sCount[startLine] - state.blkIndent) >= 4:
+    if state.is_code_block(startLine):
         return False
 
     # check the block quote marker

markdown_it/rules_block/code.py

@@ -9,7 +9,7 @@
 def code(state: StateBlock, startLine: int, endLine: int, silent: bool) -> bool:
     LOGGER.debug("entering code: %s, %s, %s, %s", state, startLine, endLine, silent)
 
-    if state.sCount[startLine] - state.blkIndent < 4:
+    if not state.is_code_block(startLine):
         return False
 
     last = nextLine = startLine + 1
@@ -19,7 +19,7 @@ def code(state: StateBlock, startLine: int, endLine: int, silent: bool) -> bool:
             nextLine += 1
             continue
 
-        if state.sCount[nextLine] - state.blkIndent >= 4:
+        if state.is_code_block(nextLine):
             nextLine += 1
             last = nextLine
             continue

markdown_it/rules_block/fence.py

@@ -13,8 +13,7 @@ def fence(state: StateBlock, startLine: int, endLine: int, silent: bool) -> 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:
+    if state.is_code_block(startLine):
         return False
 
     if pos + 3 > maximum:
@@ -72,8 +71,7 @@ def fence(state: StateBlock, startLine: int, endLine: int, silent: bool) -> bool
         except IndexError:
             break
 
-        if state.sCount[nextLine] - state.blkIndent >= 4:
-            # closing fence should be indented less than 4 spaces
+        if state.is_code_block(nextLine):
             continue
 
         pos = state.skipChars(pos, marker)

markdown_it/rules_block/heading.py

@@ -15,8 +15,7 @@ def heading(state: StateBlock, startLine: int, endLine: int, silent: bool) -> bo
     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:
+    if state.is_code_block(startLine):
         return False
 
     ch: int | None = state.srcCharCode[pos]

markdown_it/rules_block/hr.py

@@ -16,8 +16,7 @@ def hr(state: StateBlock, startLine: int, endLine: int, silent: bool) -> 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:
+    if state.is_code_block(startLine):
         return False
 
     try:

markdown_it/rules_block/html_block.py

@@ -38,8 +38,7 @@ def html_block(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:
+    if state.is_code_block(startLine):
         return False
 
     if not state.md.options.get("html", None):

markdown_it/rules_block/lheading.py

@@ -15,8 +15,7 @@ def lheading(state: StateBlock, startLine: int, endLine: int, silent: bool) -> b
     ruler: Ruler = state.md.block.ruler
     terminatorRules = ruler.getRules("paragraph")
 
-    # if it's indented more than 3 spaces, it should be a code block
-    if state.sCount[startLine] - state.blkIndent >= 4:
+    if state.is_code_block(startLine):
         return False
 
     oldParentType = state.parentType

markdown_it/rules_block/list.py

@@ -102,8 +102,7 @@ def list_block(state: StateBlock, startLine: int, endLine: int, silent: bool) ->
     isTerminatingParagraph = False
     tight = True
 
-    # if it's indented more than 3 spaces, it should be a code block
-    if state.sCount[startLine] - state.blkIndent >= 4:
+    if state.is_code_block(startLine):
         return False
 
     # Special case:
@@ -295,8 +294,7 @@ def list_block(state: StateBlock, startLine: int, endLine: int, silent: bool) ->
         if state.sCount[nextLine] < state.blkIndent:
             break
 
-        # if it's indented more than 3 spaces, it should be a code block
-        if state.sCount[startLine] - state.blkIndent >= 4:
+        if state.is_code_block(startLine):
             break
 
         # fail if terminating block found

markdown_it/rules_block/reference.py

@@ -16,8 +16,7 @@ def reference(state: StateBlock, startLine: int, _endLine: int, silent: bool) ->
     maximum = state.eMarks[startLine]
     nextLine = startLine + 1
 
-    # if it's indented more than 3 spaces, it should be a code block
-    if state.sCount[startLine] - state.blkIndent >= 4:
+    if state.is_code_block(startLine):
         return False
 
     if state.srcCharCode[pos] != 0x5B:  # /* [ */

markdown_it/rules_block/state_block.py

@@ -116,6 +116,9 @@ def __init__(
 
         self.lineMax = len(self.bMarks) - 1  # don't count last fake line
 
+        # pre-check if code blocks are enabled, to speed up is_code_block method
+        self._code_enabled = "code" in self.md["block"].ruler.get_active_rules()
+
     def __repr__(self) -> str:
         return (
             f"{self.__class__.__name__}"
@@ -228,3 +231,9 @@ def getLines(self, begin: int, end: int, indent: int, keepLastLF: bool) -> str:
             i += 1
 
         return "".join(queue)
+
+    def is_code_block(self, line: int) -> bool:
+        """Check if line is a code block,
+        i.e. the code block rule is enabled and text is indented by more than 3 spaces.
+        """
+        return self._code_enabled and (self.sCount[line] - self.blkIndent) >= 4

markdown_it/rules_block/table.py

@@ -61,8 +61,7 @@ def table(state: StateBlock, startLine: int, endLine: int, silent: bool) -> bool
     if state.sCount[nextLine] < state.blkIndent:
         return False
 
-    # if it's indented more than 3 spaces, it should be a code block
-    if state.sCount[nextLine] - state.blkIndent >= 4:
+    if state.is_code_block(nextLine):
         return False
 
     # first character of the second line should be '|', '-', ':',
@@ -126,7 +125,7 @@ def table(state: StateBlock, startLine: int, endLine: int, silent: bool) -> bool
     lineText = getLine(state, startLine).strip()
     if "|" not in lineText:
         return False
-    if state.sCount[startLine] - state.blkIndent >= 4:
+    if state.is_code_block(startLine):
         return False
     columns = escapedSplit(lineText)
     if columns and columns[0] == "":
@@ -192,7 +191,7 @@ def table(state: StateBlock, startLine: int, endLine: int, silent: bool) -> bool
         lineText = getLine(state, nextLine).strip()
         if not lineText:
             break
-        if state.sCount[nextLine] - state.blkIndent >= 4:
+        if state.is_code_block(nextLine):
             break
         columns = escapedSplit(lineText)
         if columns and columns[0] == "":

tests/test_port/fixtures/disable_code_block.md

@@ -0,0 +1,69 @@
+indent paragraph
+.
+    This is a paragraph,
+    with multiple lines.
+
+    This paragraph
+has variable indents,
+      like this.
+.
+<p>This is a paragraph,
+with multiple lines.</p>
+<p>This paragraph
+has variable indents,
+like this.</p>
+.
+
+indent in HTML
+.
+<div>
+
+    Paragraph
+
+</div>
+.
+<div>
+<p>Paragraph</p>
+</div>
+.
+
+indent fence
+.
+        ```python
+        def foo():
+            pass
+        ```
+.
+<pre><code class="language-python">def foo():
+    pass
+</code></pre>
+.
+
+indent heading
+.
+     # Heading
+.
+<h1>Heading</h1>
+.
+
+indent table
+.
+     | foo | bar |
+     | --- | --- |
+     | baz | bim |
+.
+<table>
+<thead>
+<tr>
+<th>foo</th>
+<th>bar</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td>baz</td>
+<td>bim</td>
+</tr>
+</tbody>
+</table>
+.

tests/test_port/test_fixtures.py

@@ -104,6 +104,17 @@ def test_strikethrough(line, title, input, expected):
     assert text.rstrip() == expected.rstrip()
 
 
+@pytest.mark.parametrize(
+    "line,title,input,expected",
+    read_fixture_file(FIXTURE_PATH.joinpath("disable_code_block.md")),
+)
+def test_disable_code_block(line, title, input, expected):
+    md = MarkdownIt().enable("table").disable("code")
+    text = md.render(input)
+    print(text.rstrip())
+    assert text.rstrip() == expected.rstrip()
+
+
 @pytest.mark.parametrize(
     "line,title,input,expected",
     read_fixture_file(FIXTURE_PATH.joinpath("issue-fixes.md")),