Clojure reader pr/read support for DB and Datom

bobby · Jul 7, 2014 · 718dbb1 · 718dbb1
1 parent 091fb9d
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 0.1.6
+
+- Clojure reader support (pr/read) for DB and Datom
+
 # 0.1.5
 
 - `datoms` and `seek-datoms` API calls

diff --git a/src/data_readers.clj b/src/data_readers.clj
@@ -0,0 +1,2 @@
+{datascript/Datom datascript/datom-from-reader
+ datascript/DB    datascript/db-from-reader}
diff --git a/src/datascript.cljs b/src/datascript.cljs
@@ -75,8 +75,12 @@
     (cmp     (.-tx d1) (.-tx d2))))
 
 (defrecord DB [schema eavt aevt avet max-eid max-tx]
+  Object
+  (toString [this]
+    (pr-str* this))
+
   ISearch
-  (-search [db [e a v tx]]
+  (-search [_ [e a v tx]]
     (case-tree [e a (some? v) tx] [
       (slice eavt (Datom. e a v tx nil))                 ;; e a v tx
       (slice eavt (Datom. e a v nil nil))                ;; e a v _
@@ -529,3 +533,36 @@
 
 (defn seek-datoms [db index & cs]
   (slice (get db index) (components->pattern index cs) (Datom. nil nil nil nil nil)))
+
+;; printing and reading
+;; #datomic/DB {:schema <map>, :datoms <vector of [e a v tx]>}
+
+(extend-type Datom
+  IPrintWithWriter
+  (-pr-writer [d w opts]
+    (pr-sequential-writer w pr-writer "#datascript/Datom [" " " "]" opts [(.-e d) (.-a d) (.-v d) (.-tx d) (.-added d)])))
+
+(defn datom-from-reader [[e a v tx added]]
+  (Datom. e a v tx added))
+
+(extend-type DB
+  IPrintWithWriter
+  (-pr-writer [db w opts]
+    (-write w "#datascript/DB {")
+    (-write w ":schema ")
+    (pr-writer (.-schema db) w opts)
+    (-write w ", :datoms ")
+    (pr-sequential-writer w
+      (fn [d w opts]
+        (pr-sequential-writer w pr-writer "[" " " "]" opts [(.-e d) (.-a d) (.-v d) (.-tx d)]))
+      "[" " " "]" opts (.-eavt db))
+    (-write w "}")))
+
+(defn db-from-reader [{:keys [schema datoms]}]
+  (let [datoms (map (fn [[e a v tx]] (Datom. e a v tx true)) datoms)]
+    (DB. schema
+         (apply btset-by cmp-datoms-eavt datoms)
+         (apply btset-by cmp-datoms-aevt datoms)
+         (apply btset-by cmp-datoms-avet datoms)
+         (reduce max 0 (map :e datoms))
+         (reduce max tx0 (map :tx datoms)))))
diff --git a/test/test/datascript.cljs b/test/test/datascript.cljs
@@ -583,5 +583,22 @@
              [ [1 :name "Petr"]
                [3 :name "Sergey"] ])))))
 
+(deftest test-pr-read
+  (binding [cljs.reader/*tag-table* (atom {"datascript/Datom" d/datom-from-reader})]
+    (let [d (d/Datom. 1 :name 3 17 true)]
+      (is (= d (cljs.reader/read-string (pr-str d)))))
+    (let [d (d/Datom. 1 :name 3 nil nil)]
+      (is (= d (cljs.reader/read-string (pr-str d))))))
+
+  (let [db (-> (d/empty-db)
+               (d/with [[:db/add 1 :name "Petr"]
+                        [:db/add 1 :age 44]
+                        [:db/add 2 :name "Ivan"]
+                        [:db/add 2 :age 25]
+                        [:db/add 3 :name "Sergey"]
+                        [:db/add 3 :age 11]]))]
+    (binding [cljs.reader/*tag-table* (atom {"datascript/DB" d/db-from-reader})]
+      (is (= db (cljs.reader/read-string (pr-str db)))))))
+
 ;; (t/test-ns 'test.datascript)
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		{datascript/Datom datascript/datom-from-reader
		datascript/DB datascript/db-from-reader}