fix(#72): differentiate math and escaped brackets

mdformat_mkdocs/mdit_plugins/_pymd_arithmatex.py

@@ -17,14 +17,19 @@
 
 from __future__ import annotations
 
+import re
+from textwrap import dedent
 from typing import TYPE_CHECKING
 
 from mdit_py_plugins.amsmath import amsmath_plugin
 from mdit_py_plugins.dollarmath import dollarmath_plugin
 from mdit_py_plugins.texmath import texmath_plugin
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+
     from markdown_it import MarkdownIt
+    from markdown_it.rules_block import StateBlock
 
 # Token types from the plugins
 # Note: dollarmath and texmath share the same token types for inline/block math:
@@ -36,14 +41,39 @@
 TEXMATH_BLOCK_EQNO = "math_block_eqno"  # For \[...\] (label) syntax
 AMSMATH_BLOCK = "amsmath"
 
+_ESCAPED_BRACKET_RE = re.compile(r"^\\\[([^\n\r]*?)\\\](\S)")
+r"""Pattern to detect single-line \[...\] with content after closing bracket.
+
+This identifies escaped brackets like \[test\]: value (not math)"""
+
+_EXPECTED_WRAPPED_RULES = 2
+
+
+def _is_escaped_bracket(state: StateBlock, start_line: int) -> bool:
+    r"""Check if \[...\] on this line is escaped brackets, not math.
+
+    Returns True if line starts with \[ and \] are on same line with non-whitespace after \].
+    Only checks lines starting with \[ to avoid interfering with dollar math.
+    """
+    pos = state.bMarks[start_line] + state.tShift[start_line]
+    if pos + 2 > len(state.src):
+        return False
+    line_start = state.src[pos : pos + 2]
+    if line_start != r"\[":
+        return False
+    return bool(_ESCAPED_BRACKET_RE.match(state.src[pos:]))
+
 
 def pymd_arithmatex_plugin(md: MarkdownIt) -> None:
     r"""Register Arithmatex support using existing mdit-py-plugins.
 
     This is a convenience wrapper that configures three existing plugins:
     - dollarmath_plugin: for $...$ and $$...$$
-    - texmath_plugin: for \\(...\\) and \\[...\\]
+    - texmath_plugin: for \\(...\\) and \\[...\\] (with fix for issue #72)
     - amsmath_plugin: for \\begin{env}...\\end{env}
+
+    Raises:
+        RuntimeError: If texmath rules cannot be found and wrapped.
     """
     # Dollar syntax: $...$ and $$...$$
     # Defaults provide smart dollar mode (no digits/space adjacent to $)
@@ -52,5 +82,40 @@ def pymd_arithmatex_plugin(md: MarkdownIt) -> None:
     # Bracket syntax: \(...\) and \[...\]
     md.use(texmath_plugin, delimiters="brackets")
 
+    # Fix for issue #72: Wrap texmath block rules to reject \[test\]: value
+    # Find the texmath rules (inserted after dollarmath's math_block)
+    def make_wrapper(
+        original_fn: Callable[[StateBlock, int, int, bool], bool],
+    ) -> Callable[[StateBlock, int, int, bool], bool]:
+        def wrapped(state: StateBlock, start: int, end: int, silent: bool) -> bool:
+            if _is_escaped_bracket(state, start):
+                return False
+            return original_fn(state, start, end, silent)
+
+        return wrapped
+
+    # Wrap math_block_eqno and the second math_block (both from texmath)
+    # Find them by name, skipping the first math_block (from dollarmath)
+    found_first_math_block = False
+    wrapped_count = 0
+    for idx, rule in enumerate(md.block.ruler.__rules__):
+        if rule.name == "math_block":
+            if found_first_math_block:
+                # This is the second math_block (from texmath)
+                md.block.ruler.__rules__[idx].fn = make_wrapper(rule.fn)
+                wrapped_count += 1
+            else:
+                found_first_math_block = True
+        elif rule.name == "math_block_eqno":
+            # This is from texmath
+            md.block.ruler.__rules__[idx].fn = make_wrapper(rule.fn)
+            wrapped_count += 1
+
+    if wrapped_count != _EXPECTED_WRAPPED_RULES:
+        msg = dedent(f"""\
+            Expected to wrap {_EXPECTED_WRAPPED_RULES} texmath rules (math_block and math_block_eqno), but wrapped {wrapped_count}.
+            Plugin configuration may have changed.""")
+        raise RuntimeError(msg)
+
     # LaTeX environments: \begin{env}...\end{env}
     md.use(amsmath_plugin)

tests/format/fixtures/pymd_arithmatex_edge_cases.md

@@ -9,6 +9,62 @@ This is not math: $escaped$ and \\(also escaped\\).
 Literal dollar: I paid $5.00 for $3.00 worth.
 .
 
+Escaped Bracket Notation (Issue #72)
+.
+- \[test\]: value
+- \[label\]:content
+.
+- \[test\]: value
+- \[label\]:content
+.
+
+Escaped Brackets vs Math Brackets
+.
+Single-line escaped bracket: \[test\]: value
+
+Multi-line math block:
+
+\[
+a^2 + b^2 = c^2
+\]
+
+Math with label (space before parenthesis):
+
+\[
+E = mc^2
+\] (eq:einstein)
+
+Escaped bracket with letter: \[test\]x
+
+Math at end of line:
+
+\[
+x = y
+\]
+.
+Single-line escaped bracket: \[test\]: value
+
+Multi-line math block:
+
+\[
+a^2 + b^2 = c^2
+\]
+
+Math with label (space before parenthesis):
+
+\[
+E = mc^2
+\] (eq:einstein)
+
+Escaped bracket with letter: [test]x
+
+Math at end of line:
+
+\[
+x = y
+\]
+.
+
 Math in Lists
 .
 1. First item with math $x = y$