Columnize session_list when its too long

Fixes #9

Author: Bruno Sutic

CHANGELOG.md

@@ -5,6 +5,10 @@
   has dimensions 80x25. This is the default `new-session -d` win size. Fixing
   this by first switching to a new session (so the window is resized), then
   pulling target pane over.
+- 'goto-session' feature - when session list does not fit on the screen, show it
+  in columns
+- 'goto-session' - when all the sessions don't fit on the screen, the last
+  displayed element is '...' indicating there's more sessions
 
 ### v2.1.0, 2015-01-11
 - add a `@` key binding for "promoting" current pane into a new session

scripts/tmux_goto_session.sh

@@ -9,27 +9,8 @@ CURRENT_SCRIPT="$CURRENT_DIR/$FILE_NAME"
 LOOP="$1"
 SESSION_NAME="$2"
 
-# Programming Tmux is great!
-#
-# For example, take a look at the below line. It's by far the biggest hack of
-# my life. Essentially this should be just:
-# `tmux list-sessions -F "#{session_name}"`
-#
-# But that only shows the session list in the current shell, and we want a nice
-# display across the whole screen.
-# To achieve this, we wrap the above command in `tmux run-shell` like this:
-# `tmux run-shell 'tmux list-sessions -F "#{session_name}"'`
-#
-# This does produce the "whole screen display" effect, but it also introduces a
-# bug: `#{session_name}` is only expanded to the current session name, so you
-# get a session list where only the name of the current session is displayed.
-#
-# So we hack what is already hacked. `#{session_name}` interpolation is split
-# with the help of of `interpolation` variable.
-# Wrapper command (`tmux run-shell`) won't perform interpolation and the inner
-# `tmux list-sessions` command will.
 display_session_list() {
-	tmux run-shell 'interpolation={session_name}; tmux list-sessions -F "#$interpolation"'
+	tmux run-shell $CURRENT_DIR/tmux_list_sessions.sh
 }
 
 # Starts a loop: the command is invoked until correct session name is typed,

scripts/tmux_list_sessions.sh

@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+
+session_list() {
+	tmux list-sessions -F "#{session_name}"
+}
+
+output_height() {
+	local list="$1"
+	echo "$list" |
+		wc -l |
+		tr -d ' '
+}
+
+# calculates required number of columns for the multi-column output
+get_column_number() {
+	local output_height="$1"
+	local pane_height="$2"
+	local columns="$(expr $output_height / $pane_height )"
+	if [ $(expr $output_height % $pane_height ) -gt 0 ]; then
+		columns=$(expr $columns + 1)
+	fi
+	echo "$columns"
+}
+
+get_column_width() {
+	declare -a array=("${!1}")
+	local width=0
+	# searching for the longest session name
+	for session_name in "${array[@]}"; do
+		if [ ${#session_name} -gt $width ]; then
+			width="${#session_name}"
+		fi
+	done
+	# add some padding to the right
+	echo $((width + 2))
+}
+
+print_multi_column_output() {
+	local output_height="$1"
+	local pane_height="$2"
+	local pane_width="$3"
+	local columns="$(get_column_number "$output_height" "$pane_height")"
+	eval session_array=( $(tmux list-sessions -F "'#{session_name}'") )
+	local width="$(get_column_width session_array[@])"
+
+	# limit number of displayed columns
+	local max_columns=$(( $((pane_width + 2)) / $width))
+	if [ $columns -gt $max_columns ]; then
+		# there's more columns than it fits on the display
+		columns="$max_columns"
+		# last displayed element indicates there's more
+		session_array[$((pane_height * columns - 1))]="..."
+	fi
+
+	# Composing a string that prints variable number of columns.
+	# Example print_string for 2 columns:
+	# printf "%-17s  %s\n" "${session_array[$index]}" "${session_array[$((index + 54 ))]}"
+	local first_arg=''
+	local arg_list=''
+	local i=1
+	while [ $i -lt $columns ]; do
+		first_arg+="%-${width}s"
+		arg_list+=" \"\${session_array[\$((index + $((i * $pane_height)) ))]}\""
+		i=$((i + 1))
+	done
+
+	local print_string=''
+	print_string+='printf "'
+	print_string+=$first_arg
+	print_string+='%s\n" "${session_array[$index]}"'
+	print_string+=$arg_list
+
+	local index=0
+	while [ $index -lt $pane_height ]; do
+		eval "$print_string"
+		index=$((index + 1))
+	done
+}
+
+main() {
+	local pane_height=$(tmux display-message -p -F "#{pane_height}")
+	local pane_width=$(tmux display-message -p -F "#{pane_width}")
+	local session_list="$(session_list)"
+	local output_height=$(output_height "$session_list")
+	if [ $output_height -gt $pane_height ]; then
+		print_multi_column_output "$output_height" "$pane_height" "$pane_width"
+	else
+		echo "$session_list"
+	fi
+}
+main