1 files changed, 76 insertions, 0 deletions
diff --git a/sx.el b/sx.el
new file mode 100644
index 0000000..cd8af95
--- /dev/null
+++ b/sx.el
@@ -0,0 +1,76 @@
+;;; sx.el --- core functions                         -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2014  Sean Allred
+
+;; Author: Sean Allred <code@seanallred.com>
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This file defines basic commands used by all other parts of
+;; StackMode.
+
+;;; Code:
+
+
+;;; Requirements
+(defun sx-message (format-string &rest args)
+  "Display a message"
+  (message "[stack] %s" (apply #'format format-string args)))
+
+(defun sx--thing-as-string (thing &optional sequence-sep)
+  "Return a string representation of THING.  If THING is already
+a string, just return it."
+  (cond
+   ((stringp thing) thing)
+   ((symbolp thing) (symbol-name thing))
+   ((numberp thing) (number-to-string thing))
+   ((sequencep thing)
+    (mapconcat #'sx--thing-as-string
+               thing (if sequence-sep sequence-sep ";")))))
+
+(defun sx--filter-data (data desired-tree)
+  "Filters DATA and returns the DESIRED-TREE"
+  (if (vectorp data)
+      (apply #'vector
+             (mapcar (lambda (entry)
+                       (sx--filter-data
+                        entry desired-tree))
+                     data))
+    (delq
+     nil
+     (mapcar (lambda (cons-cell)
+               ;; TODO the resolution of `f' is O(2n) in the worst
+               ;; case.  It may be faster to implement the same
+               ;; functionality as a `while' loop to stop looking the
+               ;; list once it has found a match.  Do speed tests.
+               ;; See edfab4443ec3d376c31a38bef12d305838d3fa2e.
+               (let ((f (or (memq (car cons-cell) desired-tree)
+                            (assoc (car cons-cell) desired-tree))))
+                 (when f
+                   (if (and (sequencep (cdr cons-cell))
+                            (sequencep (elt (cdr cons-cell) 0)))
+                       (cons (car cons-cell)
+                             (sx--filter-data
+                              (cdr cons-cell) (cdr f)))
+                     cons-cell))))
+             data))))
+
+(provide 'sx)
+;;; sx.el ends here
+
+;; Local Variables:
+;; indent-tabs-mode: nil
+;; End: