Add some custom functions to input module

* ... -> ../.. expansion
 * sudo prefix
 * bind ^H to backward-kill-word

modules/input/init.zsh

@@ -95,3 +95,26 @@ zle-line-finish() {
 }
 zle -N zle-line-init
 zle -N zle-line-finish
+
+# Expands ... to ../..
+function expand-dot-to-parent-directory-path {
+  if [[ $LBUFFER = *.. ]]; then
+    LBUFFER+='/..'
+  else
+    LBUFFER+='.'
+  fi
+}
+zle -N expand-dot-to-parent-directory-path
+bindkey -M emacs "." expand-dot-to-parent-directory-path
+
+# Inserts 'sudo ' at the beginning of the line.
+function prepend-sudo() {
+  if [[ "$BUFFER" != su(do|)\ * ]]; then
+    BUFFER="sudo $BUFFER"
+    (( CURSOR += 5 ))
+  fi
+}
+zle -N prepend-sudo
+bindkey "^X^S" prepend-sudo
+
+bindkey '^H' backward-kill-word