git-completion.bash: add support for path completion

The git-completion.bash script did not implemented full, git aware,
support to complete paths, for git commands that operate on files within
the current working directory or the index.

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.

Support path completion, for git commands where the non-option arguments
always refer to paths within the current working directory or the index,
as follows:

* the path completion for the "git rm" and "git ls-files"
  commands will suggest all cached files.

* 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 mv" command will suggest all cached
  files when expanding the first argument, and all untracked and cached
  files for subsequent arguments.  In the latter case, empty directories
  are included and ignored files are excluded.

* the path completion for the "git commit" command will suggest all
  files that have been modified from the HEAD, if HEAD exists, otherwise
  it will suggest all cached files.

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.

When using a recent Bash version, Git path completion will be the same
as builtin file completion, e.g.

	git add contrib/

will suggest relative file names.

Signed-off-by: Manlio Perillo <manlio.perillo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

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 +234,118 @@ __gitcomp_nl ()
 	COMPREPLY=($(compgen -P "${2-}" -S "${4- }" -W "$1" -- "${3-$cur}"))
 }
 
+# Generates completion reply with compgen from newline-separated possible
+# completion filenames.
+# It accepts 1 to 3 arguments:
+# 1: List of possible completion filenames, separated by a single newline.
+# 2: A directory prefix to be added to each possible completion filename
+#    (optional).
+# 3: Generate possible completion matches for this word (optional).
+__gitcomp_file ()
+{
+	local IFS=$'\n'
+
+	# XXX does not work when the directory prefix contains a tilde,
+	# since tilde expansion is not applied.
+	# This means that COMPREPLY will be empty and Bash default
+	# completion will be used.
+	COMPREPLY=($(compgen -P "${2-}" -W "$1" -- "${3-$cur}"))
+
+	# Tell Bash that compspec generates filenames.
+	compopt -o filenames 2>/dev/null
+}
+
+__git_index_file_list_filter_compat ()
+{
+	local path
+
+	while read -r path; do
+		case "$path" in
+		?*/*) echo "${path%%/*}/" ;;
+		*) echo "$path" ;;
+		esac
+	done
+}
+
+__git_index_file_list_filter_bash ()
+{
+	local path
+
+	while read -r path; do
+		case "$path" in
+		?*/*)
+			# XXX if we append a slash to directory names when using
+			# `compopt -o filenames`, Bash will append another slash.
+			# This is pretty stupid, and this the reason why we have to
+			# define a compatible version for this function.
+			echo "${path%%/*}" ;;
+		*)
+			echo "$path" ;;
+		esac
+	done
+}
+
+# Process path list returned by "ls-files" and "diff-index --name-only"
+# commands, in order to list only file names relative to a specified
+# directory, and append a slash to directory names.
+__git_index_file_list_filter ()
+{
+	# Default to Bash >= 4.x
+	__git_index_file_list_filter_bash
+}
+
+# Execute git ls-files, returning paths relative to the directory
+# specified in the first argument, and using the options specified in
+# the second argument.
+__git_ls_files_helper ()
+{
+	# NOTE: $2 is not quoted in order to support multiple options
+	cd "$1" && git ls-files --exclude-standard $2
+} 2>/dev/null
+
+
+# Execute git diff-index, returning paths relative to the directory
+# specified in the first argument, and using the tree object id
+# specified in the second argument.
+__git_diff_index_helper ()
+{
+	cd "$1" && git diff-index --name-only --relative "$2"
+} 2>/dev/null
+
+# __git_index_files accepts 1 or 2 arguments:
+# 1: Options to pass to ls-files (required).
+#    Supported options are --cached, --modified, --deleted, --others,
+#    and --directory.
+# 2: A directory path (optional).
+#    If provided, only files within the specified directory are listed.
+#    Sub directories are never recursed.  Path must have a trailing
+#    slash.
+__git_index_files ()
+{
+	local dir="$(__gitdir)" root="${2-.}"
+
+	if [ -d "$dir" ]; then
+		__git_ls_files_helper "$root" "$1" | __git_index_file_list_filter |
+			sort | uniq
+	fi
+}
+
+# __git_diff_index_files accepts 1 or 2 arguments:
+# 1) The id of a tree object.
+# 2) A directory path (optional).
+#    If provided, only files within the specified directory are listed.
+#    Sub directories are never recursed.  Path must have a trailing
+#    slash.
+__git_diff_index_files ()
+{
+	local dir="$(__gitdir)" root="${2-.}"
+
+	if [ -d "$dir" ]; then
+		__git_diff_index_helper "$root" "$1" | __git_index_file_list_filter |
+			sort | uniq
+	fi
+}
+
 __git_heads ()
 {
 	local dir="$(__gitdir)"
@@ -430,6 +543,46 @@ __git_complete_revlist_file ()
 }
 
 
+# __git_complete_index_file requires 1 argument: the options to pass to
+# ls-file
+__git_complete_index_file ()
+{
+	local pfx cur_="$cur"
+
+	case "$cur_" in
+	?*/*)
+		pfx="${cur_%/*}"
+		cur_="${cur_##*/}"
+		pfx="${pfx}/"
+
+		__gitcomp_file "$(__git_index_files "$1" "$pfx")" "$pfx" "$cur_"
+		;;
+	*)
+		__gitcomp_file "$(__git_index_files "$1")" "" "$cur_"
+		;;
+	esac
+}
+
+# __git_complete_diff_index_file requires 1 argument: the id of a tree
+# object
+__git_complete_diff_index_file ()
+{
+	local pfx cur_="$cur"
+
+	case "$cur_" in
+	?*/*)
+		pfx="${cur_%/*}"
+		cur_="${cur_##*/}"
+		pfx="${pfx}/"
+
+		__gitcomp_file "$(__git_diff_index_files "$1" "$pfx")" "$pfx" "$cur_"
+		;;
+	*)
+		__gitcomp_file "$(__git_diff_index_files "$1")" "" "$cur_"
+		;;
+	esac
+}
+
 __git_complete_file ()
 {
 	__git_complete_revlist_file
@@ -722,6 +875,43 @@ __git_has_doubledash ()
 	return 1
 }
 
+# Try to count non option arguments passed on the command line for the
+# specified git command.
+# When options are used, it is necessary to use the special -- option to
+# tell the implementation were non option arguments begin.
+# XXX this can not be improved, since options can appear everywhere, as
+# an example:
+#	git mv x -n y
+#
+# __git_count_arguments requires 1 argument: the git command executed.
+__git_count_arguments ()
+{
+	local word i c=0
+
+	# Skip "git" (first argument)
+	for ((i=1; i < ${#words[@]}; i++)); do
+		word="${words[i]}"
+
+		case "$word" in
+			--)
+				# Good; we can assume that the following are only non
+				# option arguments.
+				((c = 0))
+				;;
+			"$1")
+				# Skip the specified git command and discard git
+				# main options
+				((c = 0))
+				;;
+			?*)
+				((c++))
+				;;
+		esac
+	done
+
+	printf "%d" $c
+}
+
 __git_whitespacelist="nowarn warn error error-all fix"
 
 _git_am ()
@@ -770,8 +960,6 @@ _git_apply ()
 
 _git_add ()
 {
-	__git_has_doubledash && return
-
 	case "$cur" in
 	--*)
 		__gitcomp "
@@ -780,7 +968,9 @@ _git_add ()
 			"
 		return
 	esac
-	COMPREPLY=()
+
+	# XXX should we check for --update and --all options ?
+	__git_complete_index_file "--others --modified"
 }
 
 _git_archive ()
@@ -930,15 +1120,15 @@ _git_cherry_pick ()
 
 _git_clean ()
 {
-	__git_has_doubledash && return
-
 	case "$cur" in
 	--*)
 		__gitcomp "--dry-run --quiet"
 		return
 		;;
 	esac
-	COMPREPLY=()
+
+	# XXX should we check for -x option ?
+	__git_complete_index_file "--others"
 }
 
 _git_clone ()
@@ -969,7 +1159,12 @@ _git_clone ()
 
 _git_commit ()
 {
-	__git_has_doubledash && return
+	case "$prev" in
+	-c|-C)
+		__gitcomp_nl "$(__git_refs)" "" "${cur}"
+		return
+		;;
+	esac
 
 	case "$cur" in
 	--cleanup=*)
@@ -998,7 +1193,13 @@ _git_commit ()
 			"
 		return
 	esac
-	COMPREPLY=()
+
+	if git rev-parse --verify --quiet HEAD >/dev/null; then
+		__git_complete_diff_index_file "HEAD"
+	else
+		# This is the first commit
+		__git_complete_index_file "--cached"
+	fi
 }
 
 _git_describe ()
@@ -1216,8 +1417,6 @@ _git_init ()
 
 _git_ls_files ()
 {
-	__git_has_doubledash && return
-
 	case "$cur" in
 	--*)
 		__gitcomp "--cached --deleted --modified --others --ignored
@@ -1230,7 +1429,10 @@ _git_ls_files ()
 		return
 		;;
 	esac
-	COMPREPLY=()
+
+	# XXX ignore options like --modified and always suggest all cached
+	# files.
+	__git_complete_index_file "--cached"
 }
 
 _git_ls_remote ()
@@ -1362,7 +1564,14 @@ _git_mv ()
 		return
 		;;
 	esac
-	COMPREPLY=()
+
+	if [ $(__git_count_arguments "mv") -gt 0 ]; then
+		# We need to show both cached and untracked files (including
+		# empty directories) since this may not be the last argument.
+		__git_complete_index_file "--cached --others --directory"
+	else
+		__git_complete_index_file "--cached"
+	fi
 }
 
 _git_name_rev ()
@@ -2068,15 +2277,14 @@ _git_revert ()
 
 _git_rm ()
 {
-	__git_has_doubledash && return
-
 	case "$cur" in
 	--*)
 		__gitcomp "--cached --dry-run --ignore-unmatch --quiet"
 		return
 		;;
 	esac
-	COMPREPLY=()
+
+	__git_complete_index_file "--cached"
 }
 
 _git_shortlog ()
@@ -2441,6 +2649,15 @@ if [[ -n ${ZSH_VERSION-} ]]; then
 		compadd -Q -S "${4- }" -p "${2-}" -- ${=1} && _ret=0
 	}
 
+	__gitcomp_file ()
+	{
+		emulate -L zsh
+
+		local IFS=$'\n'
+		compset -P '*[=:]'
+		compadd -Q -p "${2-}" -f -- ${=1} && _ret=0
+	}
+
 	__git_zsh_helper ()
 	{
 		emulate -L ksh
@@ -2462,6 +2679,14 @@ if [[ -n ${ZSH_VERSION-} ]]; then
 
 	compdef _git git gitk
 	return
+elif [[ -n ${BASH_VERSION-} ]]; then
+	if ((${BASH_VERSINFO[0]} < 4)); then
+		# compopt is not supported
+		__git_index_file_list_filter ()
+		{
+			__git_index_file_list_filter_compat
+		}
+	fi
 fi
 
 __git_func_wrap ()