Re: [PATCH v3] git-completion.bash: add support for path completion

[Junio C Hamano <gitster@pobox.com>]

[jch: cc'ed git-completion experts to review implementation details]

Manlio Perillo <manlio.perillo@gmail.com> writes:

> The git-completion.bash script did not implemented full, git aware,
> support for completion, for git commands that operate on files within
> the current working directory or the index.
>
> For these commands, only long options completion was available.

I find the "long options completion" is a misleading phrase.  It
sounds as if you changed the current completion that does not
complete "git commit -<TAB>" but does "git commit --<TAB>" to
complete the short options (e.g. "git commit -c"), but I do not
think that is the topic of this patch.

> As an example:
>
> 	git add <TAB>
>
> will suggest all files in the current working directory, including
> ignored files and files that have not been modified.
>
> Full support for completion is now implemented, for git commands where

s/Full.*implemented/Support more comprehensive completion/; or
something, talking in the imperative mood (i.e. as if you are giving
the order to the codebase to do something).

> the non-option arguments always refer to paths within the current
> working directory or the index, as the follow:
>
> * the path completion for the "git mv", "git rm" and "git ls-tree"
>   commands will suggest all cached files.

I thought you dropped "git mv" in this round.

> * the path completion for the "git add" command will suggest all
>   untracked and modified files.  Ignored files are excluded.
>
> * the path completion for the "git clean" command will suggest all
>   untracked files.  Ignored files are excluded.
>
> * the path completion for the "git commit" command will suggest all
>   files that have been modified from the HEAD.
>
> For all affected commands, completion will always stop at directory
> boundary.  Only standard ignored files are excluded, using the
> --exclude-standard option of the ls-files command.

I read "always stop at directory boundary" to mean that

	git cmd t<TAB>

will give us "t/ tag.c" (assuming there is a new or modified file in
t/ and tag.c is the only modified file at the root level that begins
with "t") and then

	git cmd t/<TAB>

will likewise show the files and top-level subdirectories within t/
directory.  That would be great.

> Signed-off-by: Manlio Perillo <manlio.perillo@gmail.com>
> ---
>  contrib/completion/git-completion.bash | 112 ++++++++++++++++++++++++++++-----
>  1 file changed, 97 insertions(+), 15 deletions(-)
>
> diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
> index 0b77eb1..923ef37 100644
> --- a/contrib/completion/git-completion.bash
> +++ b/contrib/completion/git-completion.bash
> @@ -13,6 +13,7 @@
>  #    *) .git/remotes file names
>  #    *) git 'subcommands'
>  #    *) tree paths within 'ref:path/to/file' expressions
> +#    *) file paths within current working directory and index
>  #    *) common --long-options
>  #
>  # To use these routines:
> @@ -233,6 +234,59 @@ __gitcomp_nl ()
>  	COMPREPLY=($(compgen -P "${2-}" -S "${4- }" -W "$1" -- "${3-$cur}"))
>  }
>  
> +# Perl filter used to process path list returned by ls-files and
> +# diff-index --name-only commands, in order to list file names
> +# relative to a specified directory, and append a slash to directory
> +# names.
> +# The script expects the prefix path in the "pfx" environ variable.
> +# The output must be processed with the uniq filter, to remove
> +# duplicate directories.
> +# XXX remove duplicates in the Perl script ?

Surely, that will remove one fork/exec with pipeline.  I am not sure
what the performance implication of using Perl here, but because we
do not have to stick to POSIX shell in this file, the completion
experts would be able to help rewriting this logic as a pure bash
script.

> +__git_index_file_list_filter='$pfx = $ENV{"pfx"};
> +			$idx = index($_, $pfx);
> +			if ($idx == 0) {
> +				$_ = substr $_, length($pfx);
> +				@segments = split("/", $_);
> +				if ($segments[1]) {
> +					print $segments[0], "/\n"
> +				} else {
> +					print $segments[0], "\n"
> +				}
> +			}'
> +
> +# __git_files accepts 1 or 2 arguments:
> +# 1: A string for file index status mode ("c", "m", "d", "o"), as
> +#    supported by git ls-files command.  This is required.
> +# 2: An optional directory path.  If provided, only files within the
> +#    specified directory are listed.  Sub directories are never recursed.
> +#    Path must have a trailing slash.
> +__git_files ()
> +{
> +	local dir="$(__gitdir)" flags="-${1}"
> +
> +	if [ -d "$dir" ]; then
> +		git --git-dir="$dir" ls-files --exclude-standard ${flags} ${pfx} \
> +			| pfx=$2 perl -ne "${__git_index_file_list_filter}" \
> +			| uniq

This is purely a style thing (note that style suggestions are not
optional), but

        the data source command |
        a filter command |
        another filter command

is easier to read and can be spelled without the backslash.  The
same comment applies to git-commit-files as well.

Thanks.