[PATCH] git-submodule: New subcommand 'summary' (3) - limit summary size

[Ping Yin <pkufranky@gmail.com>]

This patches teaches git-submodule an option '--summary-limit|-n <number>'
to limit number of commits for the summary. Number 0 will disable summary
and minus number will not limit the summary size.

For beauty and clarification, the last commit for each section (backward
and forward) will always be shown disregarding the given limit. So actual
summary size may be greater than the given limit.

In the same super project of these patch series, 'git submodule -n 2' and
'git submodule -n 3' will both show
    # Submodules modifiled: sm1 sm2 sm3
    #
    # * sm1 354cd45...3f751e5:
    #   <one line message for C
    #   <one line message for B
    #   >... (1 more)
    #   >one line message for E
    #
    # * sm2 5c8bfb5...000000:
    #   <one line message for F
    #
    # * sm3 354cd45...3f751e5:
    #   Warn: sm3 doesn't contain commit 354cd45
    #

Signed-off-by: Ping Yin <pkufranky@gmail.com>
---
 git-submodule.sh |   40 +++++++++++++++++++++++++++++++++++++---
 1 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/git-submodule.sh b/git-submodule.sh
index cccb539..58d0243 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -4,7 +4,8 @@
 #
 # Copyright (c) 2007 Lars Hjemli
 
-USAGE='[--quiet] [--cached] [add <repo> [-b branch]|status|init|update|summary <commit>] [--] [<path>...]'
+USAGE="[--quiet] [--cached] [-n|--summary-limit <number>] \
+[add <repo> [-b branch]|status|init|update|summary <commit>] [--] [<path>...]"
 OPTIONS_SPEC=
 . git-sh-setup
 require_work_tree
@@ -16,6 +17,7 @@ update=
 status=
 quiet=
 cached=
+summary_limit=
 
 #
 # print stuff on stdout unless -q was specified
@@ -265,6 +267,10 @@ set_name_rev () {
 #
 modules_summary()
 {
+	summary_limit=${summary_limit:-1000000}
+	summary_limit=$((summary_limit<0?1000000:summary_limit))
+	test $summary_limit = 0 && return
+
 	cache_option=${cached:+--cached}
 
 	if rev=$(git rev-parse --verify "$1^0" 2>/dev/null)
@@ -352,8 +358,29 @@ modules_summary()
 			then
 				echo "$errmsg"
 			else
-				test -n "$left" && echo "$left"
-				test -n "$right" && echo "$right"
+				lc0=0
+				rc0=0
+				test -n "$left" && lc0=$(echo "$left" | wc -l)
+				test -n "$right" && rc0=$(echo "$right" | wc -l)
+				lc=$((lc0<summary_limit?lc0:summary_limit))
+				rc=$((summary_limit>lc?summary_limit-lc:1))
+				rc=$((rc<rc0?rc:rc0))
+
+				if test -n "$left"
+				then
+					skip=$((lc0-lc))
+					echo "$left" | head -$((lc-1))
+					test $skip != 0 && echo "  <... ($skip more)"
+					echo "$left" | tail -1
+				fi
+
+				if test -n "$right"
+				then
+					skip=$((rc0-rc))
+					echo "$right" | head -$((rc-1))
+					test $skip != 0 && echo "  >... ($skip more)"
+					echo "$right" | tail -1
+				fi
 			fi
 			echo
 		) | sed 's/^/# /'
@@ -430,6 +457,13 @@ do
 	--cached)
 		cached=1
 		;;
+	-n|--summary-limit)
+		if [ -z "$2" ]; then
+			usage
+		fi
+		summary_limit="$2"
+		shift
+		;;
 	--)
 		break
 		;;
-- 
1.5.4.rc2.9.gf5146-dirty