New: search feature.

* cdlog.sh (cdlog.at2index, cdlog.at2path): New functions.
(cdlog.chdir, cdlog.rot, cdlog.mcd): Support searches
as way of specifying the target path or entry.

* README.md: Document searches.

2 files changed, 109 insertions, 27 deletions

diff --git a/README.md b/README.md
index d0b26b0..8af4d6c 100644
--- a/README.md
+++ b/README.md
@@ -82,6 +82,28 @@ 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.
 
+## Searches
+
+Search are arguments which begin with `@`. The rest
+of such an argument argument is interpreted as a pattern which is applied
+against the history to find the most recent path containing a match.
+
+In commands which accept a numeric argument denoting a reference
+to the `cdlog` history by position, the `@` prefix may be omitted
+from the search pattern. For instance `cs foo` will
+swap the current directory with the most recent history entry
+whose path contains a match for `foo`, and `cs @foo` will do
+exactly the same thing.
+
+When a pattern can is used in situations in which a path
+or alias is expected, namely as an argument to `cd`, the `@`
+is not optional, because without it, the argument would be
+interpreted as a path or alias.
+
+To include a leading `@` as part of the search pattern, write `@@`:
+the first `@` is recognized as the prefix, and removed; the
+second `@` remains as part of the pattern.
+
 ## Persistence
 
 Whenever the history changes, the current directory and the
diff --git a/cdlog.sh b/cdlog.sh
index e5a6aae..25118ff 100644
--- a/cdlog.sh
+++ b/cdlog.sh
@@ -152,6 +152,37 @@ cdlog.recover()
   fi
 }
 
+# Resolve @ search item to number
+cdlog.at2index()
+{
+  local i
+  local pat=${1#@}
+
+  for i in "${!cdlog_hist[@]}"; do
+    if [[ ${cdlog_hist[$i]} =~ $pat ]] ; then
+      echo $i
+      return 0
+    fi
+  done
+  return 1
+}
+
+# Resolve @ search item to path
+cdlog.at2path()
+{
+  local i
+  local pat=${1#@}
+
+  for i in "${!cdlog_hist[@]}"; do
+    local path=${cdlog_hist[$i]}
+    if [[ $path =~ $pat ]] ; then
+      echo $path
+      return 0
+    fi
+  done
+  return 1
+}
+
 # Change to directory: this is aliased to cd command.
 cdlog.chdir()
 {
@@ -162,6 +193,15 @@ cdlog.chdir()
 
   if [ $# -eq 2 -a "$1" = -P ] ; then
     case $2 in
+    ( @* )
+      if def=$(cdlog.at2path "$2"); then
+        set -- -P "$def"
+        print=y
+      else
+        printf "cdlog.chdir: no match for %s\n" "$2"
+        return 1
+      fi
+      ;;
     ( */* )
       ;;
     ( [1-9] )
@@ -218,6 +258,7 @@ cdlog.rot()
   local cur=$PWD
   local p=$cur
   local n=$cur
+  local i
   declare -n d=cdlog_hist
   local first=y
 
@@ -225,22 +266,30 @@ cdlog.rot()
 
   while [ $# -gt 0 ] ; do
     n=$1; shift
-    case $n in
-    ( [1-9] )
-      if [ $first ] ; then
-        command cd "${d[$n]}" || return
-        printf "%s\n" "$PWD"
-      else
-        d[$p]=${d[$n]}
-      fi
-      first=
-      p=$n
-      ;;
-    ( * )
-      printf "cdlog.rot: bad argument: %s\n" "$n"
-      return 1
-      ;;
-    esac
+    while true; do
+      case $n in
+      ( [1-9] )
+        if [ $first ] ; then
+          command cd "${d[$n]}" || return
+          printf "%s\n" "$PWD"
+        else
+          d[$p]=${d[$n]}
+        fi
+        first=
+        p=$n
+        ;;
+      ( * )
+        if i=$(cdlog.at2index "$n"); then
+          n=$i
+          continue
+        else
+          printf "cdlog.rot: no match for %s\n" "$n"
+          return 1
+        fi
+        ;;
+      esac
+      break
+    done
   done
 
   d[$p]=$cur
@@ -324,18 +373,29 @@ cdlog.mcd()
     printf "\e[A\e[K"
   done
 
-  case "$sel" in
-  ( [1-9] )
-    if [ $swap ] ; then
-      cdlog.rot $sel
-    else
-      if cdlog.chdir -P "${d[$sel]}" ; then
-        printf "%s\n" "$PWD"
+  while true; do
+    case "$sel" in
+    ( [1-9] )
+      if [ $swap ] ; then
+        cdlog.rot $sel
+      else
+        if cdlog.chdir -P "${d[$sel]}" ; then
+          printf "%s\n" "$PWD"
+        fi
       fi
-    fi
-    res=$?
-    ;;
-  esac
+      res=$?
+      ;;
+    ( * )
+      if i=$(cdlog.at2index "$sel"); then
+        sel=$i
+        continue
+      else
+        printf "cdlog.mcd: no match for %s\n" "$sel"
+        return 1
+      fi
+    esac
+    break
+  done
 
   return $res
 }