examples/simple_menu/simple_menu.sh

   1 #!/usr/bin/env bash
   2
   3 # Variables
   4 # """""""""
   5 PROG=${0#*/}
   6
   7 typeset -a MENU_STACK # A stack of MENUS to store the previously visited menus
   8
   9 # Array of menu characteristics for caching purpose
  10 # '''''''''''''''''''''''''''''''''''''''''''''''''
  11 typeset -A MENU_ARRAY
  12 typeset -A COL_ARRAY
  13 typeset -A CENTERING_ARRAY
  14 typeset -A TITLE_ARRAY
  15 typeset -A ERASE_ARRAY
  16
  17 SEL=   # The selection
  18 SMENU= # The smenu path will be stored here
  19
  20 # ============================ #
  21 # Usage function, always fails #
  22 # ============================ #
  23 function usage
  24 {
  25   echo "Usage: $PROG menu_file[.mnu] user_program," >&2
  26   echo "       read the README for an example"      >&2
  27   exit 1
  28 }
  29
  30 # ==================== #
  31 # Fatal error function #
  32 # ==================== #
  33 function error
  34 {
  35   echo $* >&2
  36   exit 1
  37 }
  38
  39 # The script expects exactly one argument (the filename of the root menu).
  40 # """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
  41 (( $# != 2 )) && usage
  42
  43 USER_PROGRAM=$2
  44
  45 # ======================================================================= #
  46 # Parse a level in the menu hierarchy and call process with the selection #
  47 # (possibly empty).                                                       #
  48 # ======================================================================= #
  49 function process_menu
  50 {
  51   TITLE=$'\n'"[ENTER: select, q: abort]" # Untitled by default
  52   CENTERING="-M" # Is the menu centered in the screen ?, defaults to yes
  53   ERASE="-d"  # Destroy the selection window after use. Defaults to yes
  54
  55   MENU_FILE=$1
  56   MENU= # Make sure the working area is empty
  57
  58   # If the menu has already been seen, read its characteristics from the cache
  59   # else construct them.
  60   # """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
  61   if [[ -z ${MENU_ARRAY[$MENU_FILE]} ]]; then
  62     COL=1
  63
  64     # Parse the directives embedded in the menu file
  65     # """"""""""""""""""""""""""""""""""""""""""""""
  66     MENU_DIRECIVES=$(grep '^\.' $MENU_FILE)
  67
  68     while read DIRECTIVE VALUE; do
  69       case $DIRECTIVE in
  70         .columns) # Number of columns of the menu
  71            COL=$VALUE
  72            (( COL < 1 || COL > 15 )) && error "$DIRECTIVE, bad value"
  73            ;;
  74
  75         .centered) # Is the menu centered?
  76            [[ $VALUE == no ]] && CENTERING=""
  77            ;;
  78
  79         .eraseafter) # Will the space used by the menu be reclaimed?
  80            [[ $VALUE == no ]] && ERASE=""
  81            ;;
  82
  83         .title) # The menu title
  84            TITLE="$VALUE"$'\n'$TITLE
  85            ;;
  86
  87         *)
  88            error "bad directive $DIRECTIVE"
  89            ;;
  90       esac
  91     done <<< "$MENU_DIRECIVES"
  92
  93     # Build the menu entries in the working area
  94     # """"""""""""""""""""""""""""""""""""""""""
  95     MENU_LINES=$(grep -v -e '^\.' -e '^#' -e '^[ \t]*$' $MENU_FILE)
  96
  97     # The special tag "---" creates an empty entry (a hole in a column)
  98     # The special tag "===" create an empty line
  99     # The special tag "EXIT" permit to exit the menu
 100     # '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
 101
 102     while read TAG VALUE; do
 103       ITEMS_TO_ADD=1 # By default, only one iteration of the tag is taken
 104                      # into account
 105
 106       (( ${#TAG} > 30 )) \
 107         && error "Menu tag \"${TAG}\" too long (max 30 characters)."
 108
 109       [[ $TAG == --- ]] && VALUE=@@@
 110       [[ $TAG == === ]] && VALUE=@@@ && ITEMS_TO_ADD=COL
 111
 112       [[ -z $VALUE ]] && error "Empty menu entry for $TAG"
 113       [[ $TAG == EXIT ]] && TAG="@EXIT@xxxxxxxxxxxxxxxxxxxxxxxx00"
 114       [[ $TAG == "<"* ]] && TAG="<xxxxxxxxxxxxxxxxxxxxxxxxxxxxx00"
 115
 116       # Protect quotes in VALUE
 117       # """""""""""""""""""""""
 118       FINAL_VALUE=$(echo "$VALUE" | sed -e 's/"/\\"/' -e "s/'/\\\\'/")
 119
 120       while (( ITEMS_TO_ADD-- > 0 )); do
 121         MENU+="'$TAG $FINAL_VALUE'"$'\n'
 122       done
 123     done <<< "$MENU_LINES"
 124
 125     # Feed the cache
 126     # """"""""""""""
 127     MENU_ARRAY[$MENU_FILE]="$MENU"
 128     COL_ARRAY[$MENU_FILE]=$COL
 129     CENTERING_ARRAY[$MENU_FILE]=$CENTERING
 130     TITLE_ARRAY[$MENU_FILE]=$TITLE
 131     ERASE_ARRAY[$MENU_FILE]=$ERASE
 132   else
 133     # Read from the cache
 134     # """""""""""""""""""
 135     MENU="${MENU_ARRAY[$MENU_FILE]}"
 136     COL=${COL_ARRAY[$MENU_FILE]}
 137     CENTERING=${CENTERING_ARRAY[$MENU_FILE]}
 138     TITLE=${TITLE_ARRAY[$MENU_FILE]}
 139     ERASE=${ERASE_ARRAY[$MENU_FILE]}
 140   fi
 141
 142   # Display the menu and get the selection
 143   # """"""""""""""""""""""""""""""""""""""
 144   SEL=$(echo "$MENU" | $SMENU               \
 145                          $CENTERING         \
 146                          $ERASE             \
 147                          -N                 \
 148                          -F -D o:30 i:0 n:2 \
 149                          -n                 \
 150                          -a m:0/6           \
 151                          -m "$TITLE"        \
 152                          -t $COL            \
 153                          -S'/@@@/ /'        \
 154                          -S'/^[^ ]+ //v'    \
 155                          -e @@@)
 156   SEL=${SEL%% *}
 157 }
 158
 159 # Check for the presence of smenu
 160 # """""""""""""""""""""""""""""""
 161 SMENU=$(which smenu 2>/dev/null)
 162 [[ -x "$SMENU" ]] || error "smenu is not in the PATH or not executable."
 163
 164 # Initialize the menu stack with the argument
 165 # """""""""""""""""""""""""""""""""""""""""""
 166 MENU_STACK+=(${1%.mnu}.mnu)
 167
 168 # And process the main menu
 169 # """""""""""""""""""""""""
 170 process_menu ${1%.mnu}.mnu
 171
 172 # According to the selection, navigate in the submenus or return
 173 # the tag associated with the selected menu entry.
 174 # """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
 175 while true; do
 176   if [[ $SEL == "<"* ]]; then
 177     # Back to the previous menu
 178     # '''''''''''''''''''''''''
 179     if (( ${#MENU_STACK[*]} == 1 )); then
 180       process_menu ${MENU_STACK[${#MENU_STACK[*]}-1]}
 181     else
 182       # Unstack the newly found submenu
 183       # '''''''''''''''''''''''''''''''
 184       unset MENU_STACK[${#MENU_STACK[*]}-1]
 185
 186       # And generate the previous menu
 187       # ''''''''''''''''''''''''''''''
 188       process_menu ${MENU_STACK[${#MENU_STACK[*]}-1]}
 189     fi
 190
 191   elif [[ $SEL == ">"* ]]; then
 192     # Enter the selected submenu
 193     # ''''''''''''''''''''''''''
 194     SMENU_FILE=${SEL#>}
 195     SMENU_FILE=${SMENU_FILE%.mnu}.mnu
 196     [[ -f $SMENU_FILE ]] || error "The file $SMENU_FILE was not found/readable."
 197
 198     # Stack the newly found submenu
 199     # '''''''''''''''''''''''''''''
 200     MENU_STACK+=($SMENU_FILE)
 201
 202     # And generate the submenu
 203     # ''''''''''''''''''''''''
 204     process_menu $SMENU_FILE
 205   else
 206     # An empty selection means than q or ^C has been hit
 207     # ''''''''''''''''''''''''''''''''''''''''''''''''''
 208     [[ -z $SEL ]] && exit 0
 209
 210     # Output the selected menu tag or exit the menu without outputting
 211     # anything.
 212     # ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
 213     [[ $SEL == @EXIT@* ]] && exit 0
 214
 215     # Launch the user action which has the responsibility to act according
 216     # to the tag passed as argument.
 217     # ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
 218     $USER_PROGRAM $SEL
 219
 220     # And re-generate the current menu
 221     # ''''''''''''''''''''''''''''''''
 222     process_menu ${MENU_STACK[-1]}
 223   fi
 224 done