Re: [PATCH v3 2/5] buildtools: script to generate cmdline boilerplate

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Oct 13, 2023 at 02:23:13PM +0200, Robin Jarry wrote:
> Bruce Richardson, Oct 11, 2023 at 15:33:
> > Provide a "dpdk-cmdline-gen.py" script for application developers to
> > quickly generate the boilerplate code necessary for using the cmdline
> > library.
> > 
> > Example of use:
> > The script takes an input file with a list of commands the user wants in
> > the app, where the parameter variables are tagged with the type.
> > For example:
> > 
> > 	$ cat commands.list
> > 	list
> > 	add <UINT16>x <UINT16>y
> > 	echo <STRING>message
> > 	add socket <STRING>path
> > 	quit
> > 
> > When run through the script as "./dpdk-cmdline-gen.py commands.list",
> > the output will be the contents of a header file with all the
> > boilerplate necessary for a commandline instance with those commands.
> > 
> > If the flag --stubs is passed, an output header filename must also be
> > passed, in which case both a header file with the definitions and a C
> > file with function stubs in it is written to disk. The separation is so
> > that the header file can be rewritten at any future point to add more
> > commands, while the C file can be kept as-is and extended by the user
> > with any additional functions needed.
> > 
> > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > ---
> 
> Hi Bruce,
> 
> this is a nice addition, I have a few python style remarks below.
> 
> In general, I would advise formatting your code with black[1] to avoid
> debates over coding style. It makes all code homogeneous and lets you focus
> on more important things :)
> 

Thanks for the feedback. I'll look into black.

> >  buildtools/dpdk-cmdline-gen.py    | 167 ++++++++++++++++++++++++++++++
> >  buildtools/meson.build            |   7 ++
> >  doc/guides/prog_guide/cmdline.rst | 131 ++++++++++++++++++++++-
> >  3 files changed, 304 insertions(+), 1 deletion(-)
> >  create mode 100755 buildtools/dpdk-cmdline-gen.py
> > 
> > diff --git a/buildtools/dpdk-cmdline-gen.py b/buildtools/dpdk-cmdline-gen.py
> > new file mode 100755
> > index 0000000000..3b41fb0493
> > --- /dev/null
> > +++ b/buildtools/dpdk-cmdline-gen.py
> > @@ -0,0 +1,167 @@
> > +#!/usr/bin/env python3
> > +# SPDX-License-Identifier: BSD-3-Clause
> > +# Copyright(c) 2023 Intel Corporation
> > +#
> > +"""Script to automatically generate boilerplate for using DPDK cmdline library."""
> 
> Multi line (or single line) doc strings are usually formatted as follows:
> 
> """
> Script to automatically generate boilerplate for using DPDK cmdline library.
> """
> 
> It makes adding new lines more readable and saves a bit of characters per
> line.
> 

Sure.

> > +
> > +import argparse
> > +import sys
> > +
> > +PARSE_FN_PARAMS = 'void *parsed_result, struct cmdline *cl, void *data'
> > +PARSE_FN_BODY = """
> > +    /* TODO: command action */
> > +    RTE_SET_USED(parsed_result);
> > +    RTE_SET_USED(cl);
> > +    RTE_SET_USED(data);
> > +"""
> > +
> > +
> > +def process_command(tokens, cfile, comment):
> > +    """Generate the structures and definitions for a single command."""
> > +    name = []
> > +
> > +    if tokens[0].startswith('<'):
> > +        print('Error: each command must start with at least one literal string', file=sys.stderr)
> > +        sys.exit(1)
> 
> It would be better to raise an exception here and handle it in main() for
> error reporting.
> 

I'll look into that. I probably should include the offending line/token in
the error report too.

> > +    for t in tokens:
> > +        if t.startswith('<'):
> > +            break
> > +        name.append(t)
> > +    name = '_'.join(name)
> > +
> > +    result_struct = []
> > +    initializers = []
> > +    token_list = []
> > +    for t in tokens:
> > +        if t.startswith('<'):
> > +            t_type, t_name = t[1:].split('>')
> > +            t_val = 'NULL'
> > +        else:
> > +            t_type = 'STRING'
> > +            t_name = t
> > +            t_val = f'"{t}"'
> > +
> > +        if t_type == 'STRING':
> > +            result_struct.append(f'\tcmdline_fixed_string_t {t_name};')
> > +            initializers.append(
> > +                    f'static cmdline_parse_token_string_t cmd_{name}_{t_name}_tok =\n' +
> > +                    f'\tTOKEN_STRING_INITIALIZER(struct cmd_{name}_result, {t_name}, {t_val});')
> > +        elif t_type in ['UINT8', 'UINT16', 'UINT32', 'UINT64', 'INT8', 'INT16', 'INT32', 'INT64']:
> > +            result_struct.append(f'\t{t_type.lower()}_t {t_name};')
> > +            initializers.append(
> > +                    f'static cmdline_parse_token_num_t cmd_{name}_{t_name}_tok =\n' +
> > +                    f'\tTOKEN_NUM_INITIALIZER(struct cmd_{name}_result, {t_name}, RTE_{t_type});')
> > +        elif t_type in ['IP', 'IP_ADDR', 'IPADDR']:
> > +            result_struct.append(f'\tcmdline_ipaddr_t {t_name};')
> > +            initializers.append(
> > +                    f'cmdline_parse_token_ipaddr_t cmd_{name}_{t_name}_tok =\n' +
> > +                    f'\tTOKEN_IPV4_INITIALIZER(struct cmd_{name}_result, {t_name});')
> > +        else:
> > +            print(f'Error: unknown token-type {t}', file=sys.stderr)
> > +            sys.exit(1)
> > +        token_list.append(f'cmd_{name}_{t_name}_tok')
> > +
> > +    print(f'/* Auto-generated handling for command "{" ".join(tokens)}" */')
> > +    # output function prototype
> > +    func_sig = f'void\ncmd_{name}_parsed({PARSE_FN_PARAMS})'
> > +    print(f'extern {func_sig};\n')
> > +    # output function template if C file being written
> > +    if (cfile):
> > +        print(f'{func_sig}\n{{{PARSE_FN_BODY}}}\n', file=cfile)
> > +    # output result data structure
> > +    print(
> > +            f'struct cmd_{name}_result {{\n' +
> > +            '\n'.join(result_struct) +
> > +            '\n};\n')
> > +    # output the initializer tokens
> > +    print('\n'.join(initializers) + '\n')
> > +    # output the instance structure
> > +    print(
> > +            f'static cmdline_parse_inst_t cmd_{name} = {{\n' +
> > +            f'\t.f = cmd_{name}_parsed,\n' +
> > +            '\t.data = NULL,\n' +
> > +            f'\t.help_str = "{comment}",\n' +
> > +            '\t.tokens = {')
> > +    for t in token_list:
> > +        print(f'\t\t(void *)&{t},')
> > +    print('\t\tNULL\n' + '\t}\n' + '};\n')
> > +
> > +    # return the instance structure name
> > +    return f'cmd_{name}'
> > +
> > +
> > +def process_commands(infile, hfile, cfile, ctxname):
> > +    """Generate boilerplate output for a list of commands from infile."""
> > +    instances = []
> > +
> > +    # redirect stdout to output the header, to save passing file= each print
> > +    old_sys_stdout = sys.stdout
> > +    sys.stdout = hfile
> 
> Why not use hfile.write()?
> 
> I think the main issue here is to use print() in process_commands(). It
> would probably be cleaner to have process_command() return a list of lines
> and print them in this function.
> 

Good idea, let me look into that. Just using print was shorter than
hfile.write, and I felt it would save me some line-breaking.

> > +
> > +    print(f'/* File autogenerated by {sys.argv[0]} */')
> > +    print('#ifndef GENERATED_COMMANDS_H')
> > +    print('#define GENERATED_COMMANDS_H')
> > +    print('#include <rte_common.h>')
> > +    print('#include <cmdline.h>')
> > +    print('#include <cmdline_parse_string.h>')
> > +    print('#include <cmdline_parse_num.h>')
> > +    print('#include <cmdline_parse_ipaddr.h>')
> > +    print('')
> 
> You can use a multi-line f-string here with a single print/write.
> 
>    hfile.write(f"""/* File autogenerated by {sys.argv[0]} */
> #ifndef GENERATED_COMMANDS_H
> #define GENERATED_COMMANDS_H
> 
> #include <rte_common.h>
> #include <cmdline.h>
> #include <cmdline_parse_string.h>
> #include <cmdline_parse_num.h>
> #include <cmdline_parse_ipaddr.h>
> 
> """)
> 

Yes, I was aware of that.  However, I deliberately didn't use it, because
the indentation looks completely wrong with it (at least to my eyes). I
really don't like having each line start at column zero in the middle of a
block of code.

> > +
> > +    for line in infile.readlines():
> > +        if line.lstrip().startswith('#'):
> > +            continue
> > +        if '#' not in line:
> > +            line = line + '#'  # ensure split always works, even if no help text
> > +        tokens, comment = line.split('#', 1)
> > +        instances.append(process_command(tokens.strip().split(), cfile, comment.strip()))
> 
> If process_command returns a name and a list of lines, that could be
> transformed as:
> 
>           name, lines = process_command(tokens.strip().split(), cfile, comment.strip())
>           instances.append(name)
>           hfile.write("\n".join(lines) + "\n")
>

Will investigate
 
> > +
> > +    print(f'static __rte_used cmdline_parse_ctx_t {ctxname}[] = {{')
> > +    for inst in instances:
> > +        print(f'\t&{inst},')
> > +    print('\tNULL')
> > +    print('};\n')
> > +    print('#endif /* GENERATED_COMMANDS_H */')
> 
> also multi line print here:
> 
> hfile.write("""\tNULL
> };
> #endif /* GENERATED_COMMANDS_H */
> """)
> 

As above, I didn't like the non-indented nature of it.

> > +
> > +    sys.stdout = old_sys_stdout
> > +
> > +
> > +def main():
> > +    """Application main entry point."""
> > +    ap = argparse.ArgumentParser()
> 
> Nit to have a nice description of the command with --help:
> 
>       ap = argparse.ArgumentParser(description=__doc__)
> 
> > +    ap.add_argument(
> > +            '--stubs', action='store_true',
> > +            help='Produce C file with empty function stubs for each command')
> > +    ap.add_argument(
> > +            '--output-file', '-o', default='-',
> > +            help='Output header filename [default to stdout]')
> > +    ap.add_argument(
> > +            '--context-name', default='ctx',
> > +            help='Name given to the cmdline context variable in the output header [default=ctx]')
> > +    ap.add_argument(
> > +            'infile', type=argparse.FileType('r'),
> > +            help='File with list of commands')
> > +    args = ap.parse_args()
> > +
> > +    if not args.stubs:
> > +        if args.output_file == '-':
> > +            process_commands(args.infile, sys.stdout, None, args.context_name)
> > +        else:
> > +            with open(args.output_file, 'w') as hfile:
> > +                process_commands(args.infile, hfile, None, args.context_name)
> > +    else:
> > +        if not args.output_file.endswith('.h'):
> > +            print(
> > +                    'Error: output filename must end with ".h" extension when creating stubs',
> > +                    file=sys.stderr)
> > +            sys.exit(1)
> 
> You can replace print to stderr + exit with:
> 
> ap.error("-o/--output-file: must end with .h extension when creating stubs")
> 

Ack.

> > +
> > +        cfilename = args.output_file[:-2] + '.c'
> > +        with open(args.output_file, 'w') as hfile:
> > +            with open(cfilename, 'w') as cfile:
> > +                print(f'#include "{args.output_file}"\n', file=cfile)
> > +                process_commands(args.infile, hfile, cfile, args.context_name)
> > +
> > +
> > +if __name__ == '__main__':
> > +    main()
> 
> I'll stop here ;) Thanks!
>