[RFC/PATCH v2 5/8] completion: get rid of compgen

[Felipe Contreras <felipe.contreras@gmail.com>]

The functionality we use from compgen is not much, we can do the same
manually, with drastical improvements in speed, specially when dealing
with only a few rods.

This patch also has the sideffect that brekage reported by Jeroen Meijer
and SZEDER Gábor gets fixed because we no longer expand the resulting
words.

Other solutions with awk and sed are possible and more efficient when
dealing with tens of thousands of words. But is rarely the case. For the
common cases, this solution is faster.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
---
 contrib/completion/git-completion.bash | 15 ++++++++++-----
 t/t9902-completion.sh                  |  2 +-
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 19e18a8..0b72f24 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -227,11 +227,16 @@ fi
 
 __gitcompadd ()
 {
-	COMPREPLY=($(compgen -W "$1" -P "$2" -S "$4" -- "$3"))
+	local i=0
+	for x in $1; do
+		if [[ "$x" == "$3"* ]]; then
+			COMPREPLY[i++]="$2$x$4"
+		fi
+	done
 }
 
-# Generates completion reply with compgen, appending a space to possible
-# completion words, if necessary.
+# Generates completion reply, appending a space to possible completion words,
+# if necessary.
 # It accepts 1 to 4 arguments:
 # 1: List of possible completion words.
 # 2: A prefix to be added to each possible completion word (optional).
@@ -251,8 +256,8 @@ __gitcomp ()
 	esac
 }
 
-# Generates completion reply with compgen from newline-separated possible
-# completion words by appending a space to all of them.
+# Generates completion reply from newline-separated possible completion words
+# by appending a space to all of them.
 # It accepts 1 to 4 arguments:
 # 1: List of possible completion words, separated by a single newline.
 # 2: A prefix to be added to each possible completion word (optional).
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 35fc31b..7fb5b50 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -340,7 +340,7 @@ test_expect_success 'complete tree filename with spaces' '
 	EOF
 '
 
-test_expect_failure 'complete tree filename with metacharacters' '
+test_expect_success 'complete tree filename with metacharacters' '
 	echo content >"name with \${meta}" &&
 	git add . &&
 	git commit -m meta &&
-- 
1.8.0