Re: [PATCH v6 6/9] docs: add doxygen preprocessor and related files

[Stefano Stabellini <sstabellini@kernel.org>]

On Mon, 10 May 2021, Luca Fancellu wrote:
> Add preprocessor called by doxygen before parsing headers,
> it will include in every header a doxygen_include.h file
> that provides missing defines and includes that are
> usually passed by the compiler.
> 
> Add doxy_input.list that is a text file containing the
> relative path to the source code file to be parsed by
> doxygen. The path sould be relative to the xen folder:
> E.g. xen/include/public/grant_table.h
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
> ---
>  docs/xen-doxygen/doxy-preprocessor.py | 110 ++++++++++++++++++++++++++
>  docs/xen-doxygen/doxy_input.list      |   0
>  docs/xen-doxygen/doxygen_include.h.in |  32 ++++++++
>  3 files changed, 142 insertions(+)
>  create mode 100755 docs/xen-doxygen/doxy-preprocessor.py
>  create mode 100644 docs/xen-doxygen/doxy_input.list
>  create mode 100644 docs/xen-doxygen/doxygen_include.h.in
> 
> diff --git a/docs/xen-doxygen/doxy-preprocessor.py b/docs/xen-doxygen/doxy-preprocessor.py
> new file mode 100755
> index 0000000000..496899d8e6
> --- /dev/null
> +++ b/docs/xen-doxygen/doxy-preprocessor.py
> @@ -0,0 +1,110 @@
> +#!/usr/bin/python3
> +#
> +# Copyright (c) 2021, Arm Limited.
> +#
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +
> +import os, sys, re
> +
> +
> +# Variables that holds the preprocessed header text
> +output_text = ""
> +header_file_name = ""
> +
> +# Variables to enumerate the anonymous structs/unions
> +anonymous_struct_count = 0
> +anonymous_union_count = 0
> +
> +
> +def error(text):
> +    sys.stderr.write("{}\n".format(text))
> +    sys.exit(1)
> +
> +
> +def write_to_output(text):
> +    sys.stdout.write(text)
> +
> +
> +def insert_doxygen_header(text):
> +    # Here the strategy is to insert the #include <doxygen_include.h> in the
> +    # first line of the header
> +    abspath = os.path.dirname(os.path.abspath(__file__))
> +    text += "#include \"{}/doxygen_include.h\"\n".format(abspath)
> +
> +    return text
> +
> +
> +def enumerate_anonymous(match):
> +    global anonymous_struct_count
> +    global anonymous_union_count
> +
> +    if "struct" in match.group(1):
> +        label = "anonymous_struct_%d" % anonymous_struct_count
> +        anonymous_struct_count += 1
> +    else:
> +        label = "anonymous_union_%d" % anonymous_union_count
> +        anonymous_union_count += 1
> +
> +    return match.group(1) + " " + label + " {"
> +
> +
> +def manage_anonymous_structs_unions(text):
> +    # Match anonymous unions/structs with this pattern:
> +    # struct/union {
> +    #     [...]
> +    #
> +    # and substitute it in this way:
> +    #
> +    # struct anonymous_struct_# {
> +    #     [...]
> +    # or
> +    # union anonymous_union_# {
> +    #     [...]
> +    # where # is a counter starting from zero, different between structs and
> +    # unions
> +    #
> +    # We don't count anonymous union/struct that are part of a typedef because
> +    # they don't create any issue for doxygen
> +    text = re.sub(
> +        "(?<!typedef\s)(struct|union)\s+?\{",
> +        enumerate_anonymous,
> +        text,
> +        flags=re.S
> +    )

My python is a bit rusty but I thought this is really clever!

One question: given that anonymous_struct_count is local per file being
processed, it always starts at 0 for each header. I think that is
actually better from a documentation readability point of view.

However, is it possible that Doxygen gets confused in a case where we
can multiple "struct anonymous_struct_0", e.g. one for grant_table.h,
one for event_channel.h, etc. ?