Add invoke (pyinvoke.org) completions

completion/available/invoke.completion.bash

@@ -0,0 +1,30 @@
+# Invoke (pyinvoke.org) tab-completion script to be sourced with Bash shell.
+
+_complete_invoke() {
+    local candidates
+
+    # COMP_WORDS contains the entire command string up til now (including
+    # program name).
+    # We hand it to Invoke so it can figure out the current context: spit back
+    # core options, task names, the current task's options, or some combo.
+    candidates=`invoke --complete -- ${COMP_WORDS[*]}`
+
+    # `compgen -W` takes list of valid options & a partial word & spits back
+    # possible matches. Necessary for any partial word completions (vs
+    # completions performed when no partial words are present).
+    #
+    # $2 is the current word or token being tabbed on, either empty string or a
+    # partial word, and thus wants to be compgen'd to arrive at some subset of
+    # our candidate list which actually matches.
+    #
+    # COMPREPLY is the list of valid completions handed back to `complete`.
+    COMPREPLY=( $(compgen -W "${candidates}" -- $2) )
+}
+
+
+# Tell shell builtin to use the above for completing 'inv'/'invoke':
+# * -F: use given function name to generate completions.
+# * -o default: when function generates no results, use filenames.
+# * positional args: program names to complete for.
+complete -F _complete_invoke -o default invoke inv
+