Allow cdalias by number or @ search.

* cdlog.sh (cdlog.alias): Remove unused local variable ali.
Check for a digit or argument starting with @ and
expand accordingly, checking for failure.

* README.md: Documented.

2 files changed, 30 insertions, 2 deletions

diff --git a/README.md b/README.md
index 8af4d6c..2a0fdc3 100644
--- a/README.md
+++ b/README.md
@@ -82,6 +82,14 @@ array.  The `cdlog.chdir` function recognizes an alias only if
 it is invoked as `cdlog.chdir -p <alias>`, which is the way
 `cd` invokes it.
 
+If the replacement (second argument) of `cdalias` is a digit
+from 1 to 9, then it refers to that entry in the `cdlog`.
+The path at that index will be retrieved and used as the alias value.
+
+If the replacement begins with `@` then it is a search. If
+the search succeeds, then the result will be used as the alias
+value.
+
 ## Searches
 
 Search are arguments which begin with `@`. The rest
diff --git a/cdlog.sh b/cdlog.sh
index 25118ff..869f708 100644
--- a/cdlog.sh
+++ b/cdlog.sh
@@ -402,7 +402,6 @@ cdlog.mcd()
 
 cdlog.alias()
 {
-  local ali=
   local def=
 
   if [ $# -ne 2 ] ; then
@@ -415,7 +414,28 @@ cdlog.alias()
     return 1
   fi
 
-  cdlog_alias[$1]=$2
+  def=$2
+
+  case "$def" in
+  ( @* )
+    if ! def=$(cdlog.at2path "$2"); then
+      printf "cdlog.alias: no match for %s\n" "$2"
+      return 1
+    fi
+    ;;
+  ( [1-9] )
+    def=${cdlog_hist[$2]}
+    if [ -z "$def" ] ; then
+      printf "cdlog.alias: %s position empty\n" "$2"
+      return 1
+    fi
+    ;;
+  ( * )
+    def=$2
+    ;;
+  esac
+
+  cdlog_alias[$1]=$def
   return 0
 }