my way of shorting path was way slower than the one originally implemented

redoing the dirtrim feature though

liquidprompt

@@ -398,7 +398,7 @@ _lp_proxy()
 # + keep some left part of the path if asked
 _lp_shorten_path()
 {
-    if [[ "$LP_ENABLE_SHORTEN_PATH" != 1 ]] ; then
+    if [[ "$LP_ENABLE_SHORTEN_PATH" != 1 || -n "$PROMPT_DIRTRIM" ]] ; then
         if [[ "$_LP_WORKING_SHELL" == "bash" ]]; then
             echo "\\w"
         else
@@ -490,6 +490,35 @@ _lp_shorten_path()
     fi
 }
 
+
+_lp_get_dirtrim() {
+    if [[ "$LP_ENABLE_SHORTEN_PATH" != 1 ]]; then
+        [[ -n "$PROMPT_DIRTRIM" ]] && echo "$PROMPT_DIRTRIM"
+        return
+    fi
+
+    local tot
+    [[ "$PWD" == *$HOME* ]] && tot="$((${#PWD}-${#HOME}+1))" || tot="${#PWD}"
+    local max_len=$((${COLUMNS:-80}*$LP_PATH_LENGTH/100))
+    local PROMPT_DIRTRIM=0
+
+    if [[ "$((tot))" -gt "$((max_len))" ]]; then
+        local i
+        local len=0
+        local p="$(echo $PWD | rev)"
+
+        local IFS="/"
+        for i in $p
+        do
+            len="$((len+${#i}))"
+            [[ "$((len))" -gt "$((max_len))" ]] && break
+            PROMPT_DIRTRIM=$((PROMPT_DIRTRIM+1))
+        done
+        [[ "$((PROMPT_DIRTRIM))" -eq 0 ]] && PROMPT_DIRTRIM=1
+    fi
+    echo "$PROMPT_DIRTRIM"
+}
+
 # Display a ":"
 # colored in green if user have write permission on the current directory
 # colored in red if it have not.
@@ -991,6 +1020,7 @@ _lp_set_prompt()
     # LP_HOST is a global set at load time
     LP_PERM=$(_lp_permissions_color)
     LP_PWD=$(_lp_shorten_path)
+    PROMPT_DIRTRIM=$(_lp_get_dirtrim)
     LP_PROXY="${LP_COLOR_PROXY}$(_lp_proxy)${NO_COL}"
 
     # right of main prompt: space at left