Merge tag 'docs-6.19' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "This has been another busy cycle for documentation, with a lot of
  build-system thrashing. That work should slow down from here on out.

   - The various scripts and tools for documentation were spread out in
     several directories; now they are (almost) all coalesced under
     tools/docs/. The holdout is the kernel-doc script, which cannot be
     easily moved without some further thought.

   - As the amount of Python code increases, we are accumulating modules
     that are imported by multiple programs. These modules have been
     pulled together under tools/lib/python/ -- at least, for
     documentation-related programs. There is other Python code in the
     tree that might eventually want to move toward this organization.

   - The Perl kernel-doc.pl script has been removed. It is no longer
     used by default, and nobody has missed it, least of all anybody who
     actually had to look at it.

   - The docs build was controlled by a complex mess of makefilese that
     few dared to touch. Mauro has moved that logic into a new program
     (tools/docs/sphinx-build-wrapper) that, with any luck at all, will
     be far easier to understand and maintain.

   - The get_feat.pl program, used to access information under
     Documentation/features/, has been rewritten in Python, bringing an
     end to the use of Perl in the docs subsystem.

   - The top-level README file has been reorganized into a more
     reader-friendly presentation.

   - A lot of Chinese translation additions

   - Typo fixes and documentation updates as usual"

* tag 'docs-6.19' of git://git.lwn.net/linux: (164 commits)
  docs: makefile: move rustdoc check to the build wrapper
  README: restructure with role-based documentation and guidelines
  docs: kdoc: various fixes for grammar, spelling, punctuation
  docs: kdoc_parser: use '@' for Excess enum value
  docs: submitting-patches: Clarify that removal of Acks needs explanation too
  docs: kdoc_parser: add data/function attributes to ignore
  docs: MAINTAINERS: update Mauro's files/paths
  docs/zh_CN: Add wd719x.rst translation
  docs/zh_CN: Add libsas.rst translation
  get_feat.pl: remove it, as it got replaced by get_feat.py
  Documentation/sphinx/kernel_feat.py: use class directly
  tools/docs/get_feat.py: convert get_feat.pl to Python
  Documentation/admin-guide: fix typo and comment in cscope example
  docs/zh_CN: Add data-integrity.rst translation
  docs/zh_CN: Add blk-mq.rst translation
  docs/zh_CN: Add block/index.rst translation
  docs/zh_CN: Update the Chinese translation of kbuild.rst
  docs: bring some order to our Python module hierarchy
  docs: Move the python libraries to tools/lib/python
  Documentation/kernel-parameters: Move the kernel build options
  ...

1 files changed, 270 insertions, 0 deletions

diff --git a/tools/lib/python/kdoc/kdoc_re.py b/tools/lib/python/kdoc/kdoc_re.py
new file mode 100644
index 000000000000..2dfa1bf83d64
--- /dev/null
+++ b/tools/lib/python/kdoc/kdoc_re.py
@@ -0,0 +1,270 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+# Copyright(c) 2025: Mauro Carvalho Chehab <mchehab@kernel.org>.
+
+"""
+Regular expression ancillary classes.
+
+Those help caching regular expressions and do matching for kernel-doc.
+"""
+
+import re
+
+# Local cache for regular expressions
+re_cache = {}
+
+
+class KernRe:
+    """
+    Helper class to simplify regex declaration and usage.
+
+    It calls re.compile for a given pattern. It also allows adding
+    regular expressions and define sub at class init time.
+
+    Regular expressions can be cached via an argument, helping to speedup
+    searches.
+    """
+
+    def _add_regex(self, string, flags):
+        """
+        Adds a new regex or reuses it from the cache.
+        """
+        self.regex = re_cache.get(string, None)
+        if not self.regex:
+            self.regex = re.compile(string, flags=flags)
+            if self.cache:
+                re_cache[string] = self.regex
+
+    def __init__(self, string, cache=True, flags=0):
+        """
+        Compile a regular expression and initialize internal vars.
+        """
+
+        self.cache = cache
+        self.last_match = None
+
+        self._add_regex(string, flags)
+
+    def __str__(self):
+        """
+        Return the regular expression pattern.
+        """
+        return self.regex.pattern
+
+    def __add__(self, other):
+        """
+        Allows adding two regular expressions into one.
+        """
+
+        return KernRe(str(self) + str(other), cache=self.cache or other.cache,
+                  flags=self.regex.flags | other.regex.flags)
+
+    def match(self, string):
+        """
+        Handles a re.match storing its results
+        """
+
+        self.last_match = self.regex.match(string)
+        return self.last_match
+
+    def search(self, string):
+        """
+        Handles a re.search storing its results
+        """
+
+        self.last_match = self.regex.search(string)
+        return self.last_match
+
+    def findall(self, string):
+        """
+        Alias to re.findall
+        """
+
+        return self.regex.findall(string)
+
+    def split(self, string):
+        """
+        Alias to re.split
+        """
+
+        return self.regex.split(string)
+
+    def sub(self, sub, string, count=0):
+        """
+        Alias to re.sub
+        """
+
+        return self.regex.sub(sub, string, count=count)
+
+    def group(self, num):
+        """
+        Returns the group results of the last match
+        """
+
+        return self.last_match.group(num)
+
+
+class NestedMatch:
+    """
+    Finding nested delimiters is hard with regular expressions. It is
+    even harder on Python with its normal re module, as there are several
+    advanced regular expressions that are missing.
+
+    This is the case of this pattern:
+
+            '\\bSTRUCT_GROUP(\\(((?:(?>[^)(]+)|(?1))*)\\))[^;]*;'
+
+    which is used to properly match open/close parentheses of the
+    string search STRUCT_GROUP(),
+
+    Add a class that counts pairs of delimiters, using it to match and
+    replace nested expressions.
+
+    The original approach was suggested by:
+        https://stackoverflow.com/questions/5454322/python-how-to-match-nested-parentheses-with-regex
+
+    Although I re-implemented it to make it more generic and match 3 types
+    of delimiters. The logic checks if delimiters are paired. If not, it
+    will ignore the search string.
+    """
+
+    # TODO: make NestedMatch handle multiple match groups
+    #
+    # Right now, regular expressions to match it are defined only up to
+    #       the start delimiter, e.g.:
+    #
+    #       \bSTRUCT_GROUP\(
+    #
+    # is similar to: STRUCT_GROUP\((.*)\)
+    # except that the content inside the match group is delimiter-aligned.
+    #
+    # The content inside parentheses is converted into a single replace
+    # group (e.g. r`\1').
+    #
+    # It would be nice to change such definition to support multiple
+    # match groups, allowing a regex equivalent to:
+    #
+    #   FOO\((.*), (.*), (.*)\)
+    #
+    # it is probably easier to define it not as a regular expression, but
+    # with some lexical definition like:
+    #
+    #   FOO(arg1, arg2, arg3)
+
+    DELIMITER_PAIRS = {
+        '{': '}',
+        '(': ')',
+        '[': ']',
+    }
+
+    RE_DELIM = re.compile(r'[\{\}\[\]\(\)]')
+
+    def _search(self, regex, line):
+        """
+        Finds paired blocks for a regex that ends with a delimiter.
+
+        The suggestion of using finditer to match pairs came from:
+        https://stackoverflow.com/questions/5454322/python-how-to-match-nested-parentheses-with-regex
+        but I ended using a different implementation to align all three types
+        of delimiters and seek for an initial regular expression.
+
+        The algorithm seeks for open/close paired delimiters and places them
+        into a stack, yielding a start/stop position of each match when the
+        stack is zeroed.
+
+        The algorithm should work fine for properly paired lines, but will
+        silently ignore end delimiters that precede a start delimiter.
+        This should be OK for kernel-doc parser, as unaligned delimiters
+        would cause compilation errors. So, we don't need to raise exceptions
+        to cover such issues.
+        """
+
+        stack = []
+
+        for match_re in regex.finditer(line):
+            start = match_re.start()
+            offset = match_re.end()
+
+            d = line[offset - 1]
+            if d not in self.DELIMITER_PAIRS:
+                continue
+
+            end = self.DELIMITER_PAIRS[d]
+            stack.append(end)
+
+            for match in self.RE_DELIM.finditer(line[offset:]):
+                pos = match.start() + offset
+
+                d = line[pos]
+
+                if d in self.DELIMITER_PAIRS:
+                    end = self.DELIMITER_PAIRS[d]
+
+                    stack.append(end)
+                    continue
+
+                # Does the end delimiter match what is expected?
+                if stack and d == stack[-1]:
+                    stack.pop()
+
+                    if not stack:
+                        yield start, offset, pos + 1
+                        break
+
+    def search(self, regex, line):
+        """
+        This is similar to re.search:
+
+        It matches a regex that it is followed by a delimiter,
+        returning occurrences only if all delimiters are paired.
+        """
+
+        for t in self._search(regex, line):
+
+            yield line[t[0]:t[2]]
+
+    def sub(self, regex, sub, line, count=0):
+        """
+        This is similar to re.sub:
+
+        It matches a regex that it is followed by a delimiter,
+        replacing occurrences only if all delimiters are paired.
+
+        if r'\1' is used, it works just like re: it places there the
+        matched paired data with the delimiter stripped.
+
+        If count is different than zero, it will replace at most count
+        items.
+        """
+        out = ""
+
+        cur_pos = 0
+        n = 0
+
+        for start, end, pos in self._search(regex, line):
+            out += line[cur_pos:start]
+
+            # Value, ignoring start/end delimiters
+            value = line[end:pos - 1]
+
+            # replaces \1 at the sub string, if \1 is used there
+            new_sub = sub
+            new_sub = new_sub.replace(r'\1', value)
+
+            out += new_sub
+
+            # Drop end ';' if any
+            if line[pos] == ';':
+                pos += 1
+
+            cur_pos = pos
+            n += 1
+
+            if count and count >= n:
+                break
+
+        # Append the remaining string
+        l = len(line)
+        out += line[cur_pos:l]
+
+        return out