node: Optimize completions for loading lazily on demand

Move `grunt` and `gulp` to separate completion definitions wrapping
`grunt --completion=zsh` and `gulp --completion=zsh` respectively.

Since the completions are loaded lazily on demand, they avoid the
performance overhead during Zsh initialization.

Additionally, remove `npm` completion since it is already bundled with
Zsh for quite a while.

modules/node/README.md

@@ -3,6 +3,9 @@
 Provides utility functions for [Node.js][1], loads the Node Version Manager, and
 enables [_npm_][2] completion.
 
+This module must be loaded _before_ the _`completion`_ module so that the
+provided completion definitions are loaded.
+
 ## nodenv
 
 [_nodenv_][5] does one thing well - it is concerned solely with switching

modules/node/functions/_grunt

@@ -0,0 +1,15 @@
+#compdef grunt
+#autoload
+
+#
+# Grunt completion, delegating to grunt to do all the completion work.
+#
+# Authors:
+#   Indrajit Raychaudhuri <irc@indrajit.com>
+#
+
+if (( $+commands[grunt] )); then
+  eval "$(grunt --completion=zsh)"
+
+  _grunt_completion "$@"
+fi

modules/node/functions/_gulp

@@ -0,0 +1,15 @@
+#compdef gulp
+#autoload
+
+#
+# Gulp completion, delegating to gulp to do all the completion work.
+#
+# Authors:
+#   Indrajit Raychaudhuri <irc@indrajit.com>
+#
+
+if (( $+commands[gulp] )); then
+  eval "$(gulp --completion=zsh)"
+
+  _gulp_completion "$@"
+fi

modules/node/init.zsh

@@ -5,6 +5,7 @@
 # Authors:
 #   Sorin Ionescu <sorin.ionescu@gmail.com>
 #   Zeh Rizzatti <zehrizzatti@gmail.com>
+#   Indrajit Raychaudhuri <irc@indrajit.com>
 #
 
 # Possible lookup locations.
@@ -36,30 +37,3 @@ elif (( $+commands[brew] )) \
 elif (( ! $+commands[node] )); then
   return 1
 fi
-
-# Load NPM and known helper completions.
-typeset -A _compl_commands=(
-  npm   'npm completion'
-  grunt 'grunt --completion=zsh'
-  gulp  'gulp --completion=zsh'
-)
-
-for _compl_command in "${(k)_compl_commands[@]}"; do
-  if (( $+commands[$_compl_command] )); then
-    cache_file="${XDG_CACHE_HOME:-$HOME/.cache}/prezto/${_compl_command}-cache.zsh"
-
-    # Completion commands are slow; cache their output if old or missing.
-    if [[ "$commands[$_compl_command]" -nt "$cache_file" \
-          || "${ZDOTDIR:-$HOME}/.zpreztorc" -nt "$cache_file" \
-          || ! -s "$cache_file" ]]; then
-      mkdir -p "$cache_file:h"
-      command ${=_compl_commands[$_compl_command]} >! "$cache_file" 2> /dev/null
-    fi
-
-    source "$cache_file"
-
-    unset cache_file
-  fi
-done
-
-unset _compl_command{s,}