From 6941ecff2a1d1bcdeed74f2c83d0f93dcf3ea7ec Mon Sep 17 00:00:00 2001
From: Eric Schulte <schulte.eric@gmail.com>
Date: Mon, 24 Jan 2011 01:07:16 -0700
Subject: [PATCH] a simple spreadsheet application

---
 src/spreadsheet.clj | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 src/spreadsheet.clj

diff --git a/src/spreadsheet.clj b/src/spreadsheet.clj
new file mode 100644
index 0000000..0d374eb
--- /dev/null
+++ b/src/spreadsheet.clj
@@ -0,0 +1,44 @@
+(ns propagator.spreadsheet
+  (use propagator))
+
+(def xrange 10) (def yrange 10)
+
+(def spreadsheet
+  (map (fn [_] (map (fn [_]
+                     (let [c (gensym)] (eval `(defcell ~c nil)) c))
+                   (range xrange)))
+       (range yrange)))
+
+(defn spreadsheet-print []
+  (doseq [row spreadsheet]
+    (->> (map (comp deref eval) row)
+         (map #(if (nil? %) "[     ]" (format "[%5.2f]" (float %))))
+         (interpose " ")
+         (apply str)
+         (println))) (println))
+
+(defn parse [exp]
+  (let [refs (transient [])]
+    (letfn [(parse [exp]
+                   (cond
+                    (vector? exp)
+                    (let [[x y] exp
+                          c (-> spreadsheet (nth x) (nth y))]
+                      (conj! refs c) c)
+                    (seq? exp)
+                    (let [lst (map parse exp)] (dorun lst) lst)
+                    true exp))]
+      [(parse exp) (set (persistent! refs))])))
+
+(defn spreadsheet-set [[x y] v]
+  (if (seq? v)
+    (let [[e rs] (parse v)
+          out-cell (-> spreadsheet (nth y) (nth x))]
+      (eval `(defpropagator fm ~(vec rs) [~out-cell] ~e)))
+    (set-cell (eval (-> spreadsheet (nth y) (nth x))) v)))
+
+(comment                                   ; example usage
+  (spreadsheet-set [2 2] '(+ [1 1] [0 0])) ; a formula -- propagator
+  (spreadsheet-set [0 0] 2)                ; an integer -- cell
+  (spreadsheet-set [1 1] 45)               ; an integer -- cell
+  (spreadsheet-print))
-- 
2.11.4.GIT