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+;;  Copyright (c) Jeffrey Straszheim. All rights reserved.  The use and
+;;  distribution terms for this software are covered by the Eclipse Public
+;;  License 1.0 (http://opensource.org/licenses/eclipse-1.0.php) which can
+;;  be found in the file epl-v10.html at the root of this distribution.  By
+;;  using this software in any fashion, you are agreeing to be bound by the
+;;  terms of this license.  You must not remove this notice, or any other,
+;;  from this software.
+;;
+;;  magic.clj
+;;
+;;  A Clojure implementation of Datalog -- Magic Sets
+;;
+;;  straszheimjeffrey (gmail)
+;;  Created 18 Feburary 2009
+
+
+(ns clojure.contrib.datalog.magic
+  (:use clojure.contrib.datalog.util
+        clojure.contrib.datalog.literals
+        clojure.contrib.datalog.rules)
+  (:use [clojure.set :only (union intersection difference)]))
+
+
+;;; Adornment
+
+(defn adorn-query
+  "Adorn a query"
+  [q]
+  (adorned-literal q (get-self-bound-cs q)))
+
+(defn adorn-rules-set
+  "Adorns the given rules-set for the given query.  (rs) is a
+   rules-set, (q) is an adorned query."
+  [rs q]
+  (let [i-preds (all-predicates rs)
+        p-map (predicate-map rs)]
+    (loop [nrs empty-rules-set ; The rules set being built
+           needed #{(literal-predicate q)}]
+      (if (empty? needed)
+          nrs
+          (let [pred (first needed)
+                remaining (disj needed pred)
+                base-pred (get-base-predicate pred)
+                bindings (get-adorned-bindings pred)
+                new-rules (p-map base-pred)
+                new-adorned-rules (map (partial compute-sip bindings i-preds)
+                                       new-rules)
+                new-nrs (reduce conj nrs new-adorned-rules)
+                current-preds (all-predicates new-nrs)
+                not-needed? (fn [pred]
+                              (or (current-preds pred)
+                                  (-> pred get-base-predicate i-preds not)))
+                add-pred (fn [np pred]
+                           (if (not-needed? pred) np (conj np pred)))
+                add-preds (fn [np rule]
+                            (reduce add-pred np (map literal-predicate (:body rule))))
+                new-needed (reduce add-preds remaining new-adorned-rules)]
+            (recur new-nrs new-needed))))))
+
+;;; Magic !
+
+(defn seed-relation
+  "Given a magic form of a query, give back the literal form of its seed
+   relation"
+  [q]
+  (let [pred (-> q literal-predicate get-base-predicate)
+        bnds (-> q literal-predicate get-adorned-bindings)]
+    (with-meta (assoc q :predicate [pred :magic-seed bnds]) {})))
+
+(defn seed-rule
+  "Given an adorned query, give back its seed rule"
+  [q]
+  (let [mq (build-seed-bindings (magic-literal q))
+        sr (seed-relation mq)]
+    (build-rule mq [sr])))
+
+(defn seed-predicate-for-insertion
+  "Given a query, return the predicate to use for database insertion."
+  [q]
+  (let [seed (-> q seed-rule :body first)
+        columns (-> seed :term-bindings keys)
+        new-term-bindings (-> q :term-bindings (select-keys columns))]
+    (assoc seed :term-bindings new-term-bindings)))
+    
+(defn magic-transform
+  "Return a magic transformation of an adorned rules-set (rs).  The
+   (i-preds) are the predicates of the intension database.  These
+   default to the predicates within the rules-set."
+  ([rs]
+     (magic-transform rs (all-predicates rs)))
+  ([rs i-preds]
+     (let [not-duplicate? (fn [l mh bd]
+                            (or (not (empty? bd))
+                                (not (= (magic-literal l)
+                                        mh))))
+           xr (fn [rs rule]
+                (let [head (:head rule)
+                      body (:body rule)
+                      mh (magic-literal head)
+                      answer-rule (build-rule head
+                                              (concat [mh] body))
+                      step (fn [[rs bd] l]
+                             (if (and (i-preds (literal-predicate l))
+                                      (not-duplicate? l mh bd))
+                               (let [nr (build-rule (magic-literal l)
+                                                    (concat [mh] bd))]
+                                 [(conj rs nr) (conj bd l)])
+                               [rs (conj bd l)]))
+                      [nrs _] (reduce step [rs []] body)]
+                  (conj nrs answer-rule)))]
+     (reduce xr empty-rules-set rs))))
+             
+         
+
+;; End of file