+# Returns 1 if a is on an earlier row than b, otherwise 0
+proc comes_before {a b} {
+ global varcid varctok curview
+
+ set v $curview
+ if {$a eq $b || ![info exists varcid($v,$a)] || \
+ ![info exists varcid($v,$b)]} {
+ return 0
+ }
+ if {$varcid($v,$a) != $varcid($v,$b)} {
+ return [expr {[string compare [lindex $varctok($v) $varcid($v,$a)] \
+ [lindex $varctok($v) $varcid($v,$b)]] < 0}]
+ }
+ return [expr {[rowofcommit $a] < [rowofcommit $b]}]
+}
+