+# Mechanism for registering a command to be executed when we come
+# across a particular commit. To handle the case when only the
+# prefix of the commit is known, the commitinterest array is now
+# indexed by the first 4 characters of the ID. Each element is a
+# list of id, cmd pairs.
+proc interestedin {id cmd} {
+ global commitinterest
+
+ lappend commitinterest([string range $id 0 3]) $id $cmd
+}
+
+proc check_interest {id scripts} {
+ global commitinterest
+
+ set prefix [string range $id 0 3]
+ if {[info exists commitinterest($prefix)]} {
+ set newlist {}
+ foreach {i script} $commitinterest($prefix) {
+ if {[string match "$i*" $id]} {
+ lappend scripts [string map [list "%I" $id "%P" $i] $script]
+ } else {
+ lappend newlist $i $script
+ }
+ }
+ if {$newlist ne {}} {
+ set commitinterest($prefix) $newlist
+ } else {
+ unset commitinterest($prefix)
+ }
+ }
+ return $scripts
+}
+