add sxp script

docs/example.Xresources

@@ -224,7 +224,7 @@ speedwm.layout.monocle.count:          0 ! Enable focused client and number of t
 speedwm.layout.monocle.format:         [%d/%d]
 
 !! Custom layout
-speedwm.layout.custom.cmd:             printf '' | spmenu -i -l 10 -p 'Enter S expression:'
+speedwm.layout.custom.cmd:             speedwm-sxp
 
 !! mfact options
 speedwm.mfact:                         0.50 ! Default mfact (0-1)

options.h

@@ -153,7 +153,7 @@ static int deckcount						  = 0; /* Display deck count in the deck layout */
 static char deckformat[]                      = "[%d]"; /* Format of the deck count. deckcount must be set to 1 for this to be used. */
 
 /* Custom layout */
-static char *custom_cmd                       = "printf '' | spmenu -i -l 10 -p 'Enter S expression:'"; /* Command to run when setting S expression */
+static char *custom_cmd                       = "speedwm-sxp"; /* Command to run when setting S expression */
 
 /* Resetting */
 static int resetlayout                        = 0; /* Reset layout when there is only one client visible */

scripts/speedwm-sxp

@@ -0,0 +1,24 @@
+#!/bin/sh
+# speedwm-sxp
+
+# function which returns history
+MENU_DATA() { cat "$CUSTOM_HISTFILE"; printf "%s\nClear\nExit\n" "------"; }
+
+# basic variables
+[ -z "$CUSTOM_HISTFILE" ] && CUSTOM_HISTFILE="$HOME/.config/speedwm/.custom_history"
+[ -z "$RUNLAUNCHER" ] && RUNLAUNCHER="spmenu"
+
+# make sure $CUSTOM_HISTFILE exists
+mkdir -p "$(dirname "$CUSTOM_HISTFILE")"; touch "$CUSTOM_HISTFILE"
+
+# prompt the user
+OP="$(MENU_DATA | "$RUNLAUNCHER" -g 1 -l 40 -p 'Enter an S expression:')"
+
+# parse current expression
+[ "$OP" = "Clear" ] && printf "" > "$CUSTOM_HISTFILE" && exit
+[ "$OP" = "Exit" ] && exit 0
+[ "$OP" = "------" ] && exit 0
+[ -z "$OP" ] && exit 0
+
+# write expression
+printf "%s\n" "$OP" >> "$CUSTOM_HISTFILE"