Generalize swap to rotate.

* cdlog.sh (cdlog.swap): Function removed.
(cdlog.rot): New function.
(cs): Alias now points to cdlog.rot.

* README.md: Updated.

2 files changed, 33 insertions, 19 deletions

diff --git a/README.md b/README.md
index a98c6e5..28236fd 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,11 @@ The first four entries are also copied into the variables `x`, `y`,
 the current directory with a selected `cslog` entry selected
 by a numeric argument, which defaults to 1. The current directory
 overwrites that entry in the log, and then the shell changes to the directory
-which was previously in that entry.
+which was previously in that entry. If `cs` is given two or more
+arguments, it rotates among those. The directory is changed to the
+`cdlog` item indicated by the first argument. That item is overwritten
+by the second item, the second by the third and so on. The last item
+receives the previously current directory.
 
 * `pd` (pop dir) is an alias for a command which changes to the most recent
 directory in the log, and removes that entry from the log. The second
diff --git a/cdlog.sh b/cdlog.sh
index 645c483..a617b4b 100644
--- a/cdlog.sh
+++ b/cdlog.sh
@@ -50,40 +50,50 @@ cdlog.chdir()
   fi
 }
 
-# Swap current directory with specified directory
-cdlog.swap()
+# Rotate through specified directories.
+cdlog.rot()
 {
   local cur=$PWD
-  local n=1
+  local p=$cur
+  local n=$cur
   local d=("" "$c1" "$c2" "$c3" "$c4" "$c5" "$c6" "$c7" "$c8" "$c9")
 
   unset d[0]
 
-  if [ $# -eq 1 ]; then
-    n=$1
-  fi
-
-  case $n in
-  ( x ) n = 1 ;;
-  ( y ) n = 2 ;;
-  ( z ) n = 3 ;;
-  ( w ) n = 4 ;;
-  esac
+  [ $# -gt 0 ] || set 1
 
+  n=$1; shift
   case $n in
   ( [1-9] )
-    if command cd "${d[$n]}" ; then
-      d[$n]=$cur
-    fi
+    command cd "${d[$n]}" || return
+    p=$n
     ;;
   ( * )
-    printf "cdlog.swap: bad argument: %s\n" "$n"
+    printf "cdlog.rot: bad argument: %s\n" "$n"
+    return 1
     ;;
   esac
 
+  while [ $# -gt 0 ] ; do
+    n=$1; shift
+    case $n in
+    ( [1-9] )
+      d[$p]=${d[$n]}
+      p=$n
+      ;;
+    ( * )
+      printf "cdlog.rot: bad argument: %s\n" "$n"
+      return 1
+      ;;
+    esac
+  done
+
+  d[$p]=$cur
+
   cdlog.args "${d[@]}"
 }
 
+
 # Change to most recent diretory in cdlog and remove it
 # from the log.
 cdlog.pop()
@@ -112,7 +122,7 @@ cdlog()
 # Aliases.
 alias cd='cdlog.chdir -P'
 alias pd='cdlog.pop'
-alias cs='cdlog.swap'
+alias cs='cdlog.rot'
 
 # Better completion for $x[Tab]
 shopt -s direxpand