[RFC/PATCH 2/1] bash: eliminate dependency on bash_completion lib

[Jonathan Nieder <jrnieder@gmail.com>]

Add a minimal implementation of _get_comp_words_by_ref,
the routine used to work around bash 4.0's COMP_WORDS semantics.

Based on bash-completion 2.x (commit bf763033, 2010-10-26) but
tweaked for simplicity and to allow zsh to at least parse the
code.

Based-on-patch-by: Peter van der Does <peter@avirtualhome.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
Peter van der Does wrote:
> Jonathan Nieder <jrnieder@gmail.com> wrote:

>>  2. Import the definition of _get_comp_words_by_ref from the
>>     bash-completion lib and use it if ZSH_VERSION is unset.
>> 
>>  3. Further refinements, if needed.
>> 
>> What do you think?
>
> I like the idea and we should go with this solution.
> 
> If by importing you mean using :
> [CODE]. /git_bash_completion-functions[/CODE] in the
> contrib/completion/git-completion.bash script, which would be the best
> solution imho. The question is where to place that the function file.
[...]
> It would have to include copying the functions file somewhere as well.
> 
> Or we could use the method used now and include the functions in the
> git-completion.bash script.

Sorry for the lack of clarity.  Here's what I meant.

 contrib/completion/git-completion.bash |  125 ++++++++++++++++++++++++++++++++
 1 files changed, 125 insertions(+), 0 deletions(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 0b0eb45..1743319 100755
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -327,7 +327,102 @@ __gitcomp_1 ()
 	done
 }
 
+# The following function is based on code from:
+#
+#   bash_completion - programmable completion functions for bash 3.2+
+#
+#   Copyright © 2006-2008, Ian Macdonald <ian@caliban.org>
+#             © 2009-2010, Bash Completion Maintainers
+#                     <bash-completion-devel@lists.alioth.debian.org>
+#
+#   This program is free software; you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation; either version 2, or (at your option)
+#   any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program; if not, write to the Free Software Foundation,
+#   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+#
+#   The latest version of this software can be obtained here:
+#
+#   http://bash-completion.alioth.debian.org/
+#
+#   RELEASE: 2.x
+
+# This function can be used to access a tokenized list of words
+# on the command line:
+#
+#	__reassemble_comp_words_by_ref '=:'
+#	if test "${words_[cword_-1]}" = -w
+#	then
+#		...
+#	fi
+#
+# The argument should be a collection of characters from the list of
+# word completion separators (COMP_WORDBREAKS) to treat as ordinary
+# characters.
+#
+# This is roughly equivalent to locally setting COMP_WORDBREAKS to
+# exclude those characters, but it does not clobber COMP_WORDBREAKS.
+# The intent is for it to be used by commands like ssh that want to
+# treat host:path as one token.
+#
+# Output: words_, cword_, cur_.
+
+__git_reassemble_comp_words_by_ref()
+{
+	local exclude i j first
+	# Which word separators to exclude?
+	exclude="${1//[^$COMP_WORDBREAKS]}"
+	cword_=$COMP_CWORD
+	if [ -z "$exclude" ]; then
+		words_=("${COMP_WORDS[@]}")
+		return
+	fi
+	# List of word completion separators has shrunk;
+	# re-assemble words to complete.
+	for ((i=0, j=0; i < ${#COMP_WORDS[@]}; i++, j++)); do
+		# Append each nonempty word consisting of just
+		# word separator characters to the current word.
+		first=t
+		while
+			[ $i -gt 0 ] &&
+			[ -n "${COMP_WORDS[$i]}" ] &&
+			# word consists of excluded word separators
+			[ "${COMP_WORDS[$i]//[^$exclude]}" = "${COMP_WORDS[$i]}" ]
+		do
+			# Attach to the previous token,
+			# unless the previous token is the command name.
+			if [ $j -ge 2 ] && [ -n "$first" ]; then
+				((j--))
+			fi
+			first=
+			words_[$j]=${words_[j]}${COMP_WORDS[i]}
+			if [ $i = $COMP_CWORD ]; then
+				cword_=$j
+			fi
+			if (($i < ${#COMP_WORDS[@]} - 1)); then
+				((i++))
+			else
+				# Done.
+				return
+			fi
+		done
+		words_[$j]=${words_[j]}${COMP_WORDS[i]}
+		if [ $i = $COMP_CWORD ]; then
+			cword_=$j
+		fi
+	done
+}
+
 if ! type _get_comp_words_by_ref >/dev/null 2>&1; then
+if [[ -n $ZSH_VERSION ]]; then
 _get_comp_words_by_ref ()
 {
 	while [ $# -gt 0 ]; do
@@ -352,6 +447,36 @@ _get_comp_words_by_ref ()
 		shift
 	done
 }
+else
+_get_comp_words_by_ref ()
+{
+	local exclude cur_ cword_
+	local words_=()
+	if [ "$1" = "-n" ]; then
+		exclude=$2
+		shift 2
+	fi
+	__git_reassemble_comp_words_by_ref "$exclude"
+	cur_=${words_[cword_]}
+	while [ $# -gt 0 ]; do
+		case "$1" in
+		cur)
+			cur=$cur_
+			;;
+		prev)
+			prev=${words_[$cword_-1]}
+			;;
+		words)
+			words=("${words_[@]}")
+			;;
+		cword)
+			cword=$cword_
+			;;
+		esac
+		shift
+	done
+}
+fi
 fi
 
 # __gitcomp accepts 1, 2, 3, or 4 arguments
-- 
1.7.2.3