Re: [dpdk-dev] [RFC PATCH] devtools: script to check meson indentation of lists

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 22-Apr-21 10:58 AM, Bruce Richardson wrote:
> On Thu, Apr 22, 2021 at 10:40:37AM +0100, Burakov, Anatoly wrote:
>> On 22-Apr-21 10:02 AM, Bruce Richardson wrote:
>>> This is a draft script developed when I was working on the whitespace rework
>>> changes, since extended a little to attempt to fix some trailing comma issues.
>>>
>>> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
>>> ---
>>>    devtools/dpdk_meson_check.py | 106 +++++++++++++++++++++++++++++++++++
>>>    1 file changed, 106 insertions(+)
>>>    create mode 100755 devtools/dpdk_meson_check.py
>>>
>>> diff --git a/devtools/dpdk_meson_check.py b/devtools/dpdk_meson_check.py
>>> new file mode 100755
>>> index 000000000..dc4c714ad
>>> --- /dev/null
>>> +++ b/devtools/dpdk_meson_check.py
>>> @@ -0,0 +1,106 @@
>>> +#!/usr/bin/env python3
>>> +# SPDX-License-Identifier: BSD-3-Clause
>>> +# Copyright(c) 2021 Intel Corporation
>>> +
>>> +'''
>>> +A Python script to run some checks on meson.build files in DPDK
>>> +'''
>>> +
>>> +import sys
>>> +import os
>>> +from os.path import relpath, join
>>> +from argparse import ArgumentParser
>>> +
>>> +VERBOSE = False
>>> +FIX = False
>>> +
>>> +def scan_dir(path):
>>> +    '''return meson.build files found in path'''
>>> +    for root, dirs, files in os.walk(path):
>>> +        if 'meson.build' in files:
>>> +            yield(relpath(join(root, 'meson.build')))
>>> +
>>> +
>>> +def check_indentation(filename, contents):
>>> +    '''check that a list or files() is correctly indented'''
>>> +    infiles = False
>>> +    inlist = False
>>> +    edit_count = 0
>>> +    for lineno in range(len(contents)):
>>
>> for lineno, line in enumerate(contents)
>>
> Yep, that's a good idea. Wasn't aware of enumerate. [Learn something new
> every day, eh? :-)]
> 
>> ?
>>
>>> +        line = contents[lineno].rstrip()
>>> +        if not line:
>>> +            continue
>>> +        if line.endswith('files('):
>>> +            if infiles:
>>> +                raise(f'Error parsing {filename}:{lineno}, got "files(" when already parsing files list')
>>> +            if inlist:
>>> +                print(f'Error parsing {filename}:{lineno}, got "files(" when already parsing array list')
>>> +            infiles = True
>>> +            indent = 0
>>> +            while line[indent] == ' ':
>>> +                indent += 1
>>
>> Here and in other places, if this is measuring length of indent, maybe do
>> something like:
>>
>> indent = len(line) - len(line.lstrip(' '))
>>
> Yep, that is cleaner
> 
>> ?
>>
>>> +            indent += 8  # double indent required
>>> +        elif line.endswith('= ['):
>>> +            if infiles:
>>> +                raise(f'Error parsing {filename}:{lineno}, got start of array when already parsing files list')
>>> +            if inlist:
>>> +                print(f'Error parsing {filename}:{lineno}, got start of array when already parsing array list')
>>> +            inlist = True
>>> +            indent = 0
>>> +            while line[indent] == ' ':
>>> +                indent += 1
>>> +            indent += 8  # double indent required
>>> +        elif infiles and (line.endswith(')') or line.strip().startswith(')')):
>>
>> It's kinda hard to read with all the endswith/startswith, maybe extract
>> those into a function? e.g. 'elif infiles and is_file_start(line)'
>>
> It is all a bit of a mess, yes, and needs cleaning up - which is why I
> didn't previously send it with the patchset. Splitting into functions is
> something I'll look at.
> 
>>> +            infiles = False
>>> +            continue
>>> +        elif inlist and line.endswith(']') or line.strip().startswith(']'):
>>> +            inlist = False
>>> +            continue
>>> +        elif inlist or infiles:
>>> +            # skip further subarrays or lists
>>> +            if '[' in line  or ']' in line:
>>> +                continue
>>
>> I guess you could make it recursive instead of giving up? Does this happen
>> with any kind of regularity?
>>
> No, not that much, which is why I haven't explicitly tried to deal with it.
> It would be good to support in future.
> 
>>> +            if not line.startswith(' ' * indent) or line[indent] == ' ':
>>> +                print(f'Error: Incorrect indent at {filename}:{lineno + 1}')
>>> +                contents[lineno] = (' ' * indent) + line.strip() + '\n'
>>> +                line = contents[lineno].rstrip()
>>> +                edit_count += 1
>>> +            if not line.endswith(',') and '#' not in line:
>>> +                # TODO: support stripping comment and adding ','
>>> +                print(f'Error: Missing trailing "," in list at {filename}:{lineno + 1}')
>>> +                contents[lineno] = line + ',\n'
>>> +                line = contents[lineno].rstrip()
>>
>> What is the point of setting `line` here?
>>
> Because it allows us to make further checks using "line" as we add them
> later.
> The one question is whether it's worth using line as a shortcut for
> contents[lineno] or not. I'd tend to keep it, as it also allows us not to
> worry about the '\n' at the end. Then again, other rework might just change
> the whole script to strip off all the '\n' post-read and add them back
> again pre-write.
> 
> Again, further cleanup work.

Well, yes, i got that, it's just that as far as i can tell, the last 
"line = ..." is at the end of the iteration, so there's no point in 
setting it. Maybe i'm missing something :)

> 
>>> +                edit_count += 1
>>> +    return edit_count
>>> +
>>> +
>>> +def process_file(filename):
>>> +    '''run checks on file "filename"'''
>>> +    if VERBOSE:
>>> +        print(f'Processing {filename}')
>>> +    with open(filename) as f:
>>> +        contents = f.readlines()
>>
>> I guess meson build files don't get too big so it's OK to read the entire
>> file in memory and then work on it, rather than go line by line...
>>
> This was a deliberate choice when starting the script. For now the script
> only checks indentation and formatting of lists, but ideally in future it
> should check other things, e.g. alphabetical order of lists, or formatting
> of other parts. Rather than checking it all in one go, the script is
> structured so that we can call multiple functions with "contents" each of
> which does the processing without constantly re-reading and rewriting the
> file. Something like sorting a list alphabetically also requires changing
> multiple lines at a time, which is easier to do with lists that when
> streaming input.

Right, gotcha.

> 
>>> +
>>> +    if check_indentation(filename, contents) > 0 and FIX:
>>> +        print(f"Fixing {filename}")
>>> +        with open(filename, 'w') as f:
>>> +            f.writelines(contents)
>>> +
>>> +
>>> +def main():
>>> +    '''parse arguments and then call other functions to do work'''
>>> +    global VERBOSE
>>> +    global FIX
>>
>> Seems like globals are unnecessary here when you can just pass them into
>> process_file?
>>
> Yes, they can just be passed, but I actually prefer to have those as
> globals rather than having larger parameter lists. It's also possible that
> e.g. verbose, should need to be passed through multiple levels of functions.
> Personal preference, though really.

Static analyzers (e.g. pylint) will complain about it, which is why i 
usually avoid those unless really necessary :) For something like 
"verbose", sure, one could argue that it's OK to have it as a global, 
but FIX is definitely something that could be a parameter, as you don't 
seem to use it anywhere other than in process_file(), nor would it seem 
likely that it will be used in the future.

> 
>>> +    parser = ArgumentParser(description='Run syntax checks on DPDK meson.build files')
>>> +    parser.add_argument('-d', metavar='directory', default='.', help='Directory to process')
>>> +    parser.add_argument('--fix', action='store_true', help='Attempt to fix errors')
>>> +    parser.add_argument('-v', action='store_true', help='Verbose output')
>>> +    args = parser.parse_args()
>>> +
>>> +    VERBOSE = args.v
>>> +    FIX = args.fix
>>> +    for f in scan_dir(args.d):
>>> +        process_file(f)
>>> +
>>> +if __name__ == "__main__":
>>> +    main()
>>> --
>>> 2.27.0
>>>
>>
>>
>> -- 
>> Thanks,
> 
> Thanks for the review Anatoly.
> 
> /Bruce
> 


-- 
Thanks,
Anatoly