scripts/kernel-doc.py: properly handle struct_group macros

    def group(self, num):

        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 parenthesis 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:

    # 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's aligned.

    #

    # The content inside parenthesis are 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 place them

        into a stack, yielding a start/stop position of each match  when the

        stack is zeroed.

        The algorithm shoud work fine for properly paired lines, but will

        silently ignore end delimiters that preceeds an start delimiter.

        This should be OK for kernel-doc parser, as unaligned delimiters

        would cause compilation errors. So, we don't need to rise 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 it 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

        found = False

        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

#

# Regular expressions used to parse kernel-doc markups at KernelDoc class.

#

            (Re(r'\s*____cacheline_aligned_in_smp', re.S),  ' '),

            (Re(r'\s*____cacheline_aligned', re.S),  ' '),

            # Unwrap struct_group() based on this definition:

            # Unwrap struct_group macros based on this definition:

            # __struct_group(TAG, NAME, ATTRS, MEMBERS...)

            # which has variants like: struct_group(NAME, MEMBERS...)

            # Only MEMBERS arguments require documentation.

            #

            # Parsing them happens on two steps:

            #

            # 1. drop struct group arguments that aren't at MEMBERS,

            #    storing them as STRUCT_GROUP(MEMBERS)

            #

            # 2. remove STRUCT_GROUP() ancillary macro.

            #

            # The original logic used to remove STRUCT_GROUP() using an

            # advanced regex:

            #

            #   \bSTRUCT_GROUP(\(((?:(?>[^)(]+)|(?1))*)\))[^;]*;

            #

            # with two patterns that are incompatible with

            # Python re module, as it has:

            #

            #   - a recursive pattern: (?1)

            #   - an atomic grouping: (?>...)

            #

            # I tried a simpler version: but it didn't work either:

            #   \bSTRUCT_GROUP\(([^\)]+)\)[^;]*;

            #

            # As it doesn't properly match the end parenthesis on some cases.

            #

            # So, a better solution was crafted: there's now a NestedMatch

            # class that ensures that delimiters after a search are properly

            # matched. So, the implementation to drop STRUCT_GROUP() will be

            # handled in separate.

            (Re(r'\bstruct_group\s*\(([^,]*,)', re.S),  r'STRUCT_GROUP('),

            (Re(r'\bstruct_group_attr\s*\(([^,]*,){2}', re.S),  r'STRUCT_GROUP('),

            (Re(r'\bstruct_group_tagged\s*\(([^,]*),([^,]*),', re.S),  r'struct \1 \2; STRUCT_GROUP('),

            (Re(r'\b__struct_group\s*\(([^,]*,){3}', re.S),  r'STRUCT_GROUP('),

            # This is incompatible with Python re, as it uses:

            #  recursive patterns ((?1)) and atomic grouping ((?>...)):

            #   '\bSTRUCT_GROUP(\(((?:(?>[^)(]+)|(?1))*)\))[^;]*;'

            # Let's see if this works instead:

            (Re(r'\bSTRUCT_GROUP\(([^\)]+)\)[^;]*;', re.S),  r'\1'),

            # Replace macros

            #

            # TODO: it is better to also move those to the NestedMatch logic,

            # to ensure that parenthesis will be properly matched.

            (Re(r'__ETHTOOL_DECLARE_LINK_MODE_MASK\s*\(([^\)]+)\)', re.S),  r'DECLARE_BITMAP(\1, __ETHTOOL_LINK_MODE_MASK_NBITS)'),

            (Re(r'DECLARE_PHY_INTERFACE_MASK\s*\(([^\)]+)\)', re.S),  r'DECLARE_BITMAP(\1, PHY_INTERFACE_MODE_MAX)'),

            (Re(r'DECLARE_BITMAP\s*\(' + args_pattern + r',\s*' + args_pattern + r'\)', re.S),  r'unsigned long \1[BITS_TO_LONGS(\2)]'),

            (Re(r'DEFINE_DMA_UNMAP_LEN\s*\(' + args_pattern + r'\)', re.S),  r'__u32 \1'),

        ]

        # Regexes here are guaranteed to have the end limiter matching

        # the start delimiter. Yet, right now, only one replace group

        # is allowed.

        sub_nested_prefixes = [

            (re.compile(r'\bSTRUCT_GROUP\('),  r'\1'),

        ]

        for search, sub in sub_prefixes:

            members = search.sub(sub, members)

        nested = NestedMatch()

        for search, sub in sub_nested_prefixes:

            members = nested.sub(search, sub, members)

        # Keeps the original declaration as-is

        declaration = members