Add insert! to frp

4 years ago · d780502a7c
parent f5aedcb510
commit d780502a7c
3 changed files with 109 additions and 17 deletions
--- a/src/com/owoga/frp/infrastructure.clj
+++ b/src/com/owoga/frp/infrastructure.clj
@ -1,8 +1,11 @@
-(ns com.owoga.frp.infrastructure)
+(ns com.owoga.frp.infrastructure
+  (:require [clojure.set :as set]))
 (defprotocol PRelations
  (load! [this relations])
-  (insert! [this relation])
-  (delete! [this relation])
+  (insert!
+    [this relation]
+    [this & relations])
+  (delete! [this & relations])
  (update! [this old-relation new-relation])
  (clear! [this]))

@ -17,12 +20,16 @@
  (divide [this relvar])
  (rename [this renames]))
 (declare project-)
+(declare restrict-)

 (deftype RelVar [relvar xf]
  PRelVar
  (project
   [this attributes]
   (project- this (map #(select-keys % attributes))))
+  (restrict
+   [this criteria]
+   (restrict- this (filter criteria)))

  clojure.lang.IDeref
  (deref [_] (into #{} xf @relvar)))
@ -32,9 +39,18 @@
  (project
   [this attributes]
   (project- this (map #(select-keys % attributes))))
+  (restrict
+   [this criteria]
+   (restrict- this (filter criteria)))

  PRelations
  (load! [this relations] (reset! store relations))
+  (insert!
+   [this relation]
+   (swap! store conj relation))
+  (insert!
+   [this & relations]
+   (swap! store set/union (into #{} relations)))

  clojure.lang.IDeref
  (deref [_] @store))
@ -42,5 +58,8 @@
 (defn project- [relvar xf]
  (->RelVar relvar xf))

+(defn restrict- [relvar xf]
+  (->RelVar relvar xf))
+
 (defmacro defrelvar
  [relvar-name & specs])
--- a/src/com/owoga/prhyme/tar_pit.org
+++ b/src/com/owoga/prhyme/tar_pit.org
@ -91,8 +91,10 @@ Let's start by imagining a nice syntax for this.
 #+BEGIN_SRC clojure :noweb no-export
 (defprotocol PRelations
  (load! [this relations])
-  (insert! [this relation])
-  (delete! [this relation])
+  (insert!
+    [this relation]
+    [this & relations])
+  (delete! [this & relations])
  (update! [this old-relation new-relation])
  (clear! [this]))

@ -110,9 +112,32 @@ Let's start by imagining a nice syntax for this.

 ** Relvar implementation

+The =project= function of a relvar will be returning another relvar. The
+implementation might look something like this:
+
+#+BEGIN_SRC clojure
+(deftype DerivedRelvar [relvar xf]
+  PRelVar
+  (project [this attributes] (->DerivedRelvar this (map #(select-keys % attributes)))))
+#+END_SRC
+
+I noticed though that an implementation can't refer to the type that it's
+defined in. =->DerivedRelvar= isn't yet defined when you try to use it inside
+that =project= function.
+
+A workaround I'm using is to declare a =project-= function before the =deftype=
+and use that declared function in the implementation. Then implement the
+aforementioned declared function after the deftype.
+
+Clojure is still fairly new to me. I'm curious if this "makes sense" as a way of
+implementing these types/functions.
+
+=RelVar= will implement =IDeref= which will be a way to access the relation associated with the =RelVar=.
+
 #+NAME: relvar implementations
 #+BEGIN_SRC clojure :noweb yes
 (declare project-)
+(declare restrict-)

 (deftype RelVar [relvar xf]
  PRelVar
@ -134,6 +159,9 @@ Let's start by imagining a nice syntax for this.
 (defn project- [relvar xf]
  (->RelVar relvar xf))

+(defn restrict- [relvar xf]
+  (->RelVar relvar xf))
+
 (defmacro defrelvar
  [relvar-name & specs])
 #+END_SRC
@ -143,6 +171,9 @@ Let's start by imagining a nice syntax for this.
 (project
 [this attributes]
 (project- this (map #(select-keys % attributes))))
+(restrict
+ [this criteria]
+ (restrict- this (filter criteria)))
 #+END_SRC

 #+NAME: relational algebra for base relvars
@ -150,22 +181,32 @@ Let's start by imagining a nice syntax for this.
 (project
 [this attributes]
 (project- this (map #(select-keys % attributes))))
+(restrict
+ [this criteria]
+ (restrict- this (filter criteria)))
 #+END_SRC

 #+NAME: relations manipulations
 #+BEGIN_SRC clojure
 (load! [this relations] (reset! store relations))
+(insert!
+ [this relation]
+ (swap! store conj relation))
+(insert!
+ [this & relations]
+ (swap! store set/union (into #{} relations)))
 #+END_SRC

 ** Relvar infrastructure

 #+BEGIN_SRC clojure :noweb no-export :tangle ../frp/infrastructure.clj
-(ns com.owoga.frp.infrastructure)
+(ns com.owoga.frp.infrastructure
+  (:require [clojure.set :as set]))
 <<relvar protocols>>
 <<relvar implementations>>
 #+END_SRC

-#+BEGIN_SRC clojure
+#+BEGIN_SRC clojure :results pp
 (ns example
  (:require [com.owoga.frp.infrastructure :refer [->BaseRelVar project load!]]))

@ -173,15 +214,13 @@ Let's start by imagining a nice syntax for this.
 (def OfferPrices (project Offer [:price]))

 (load! Offer #{{:address "123 Fake St." :price 2e5}})
-(println @OfferPrices)
+(assert (= #{{:price 2e5}} @OfferPrices))
+(print @OfferPrices)
 #+END_SRC

 #+RESULTS:
-| class java.lang.IllegalAccessError            |
-| class clojure.lang.Compiler$CompilerException |
-| class clojure.lang.Compiler$CompilerException |
-| class clojure.lang.Compiler$CompilerException |
-| class java.lang.ClassCastException            |
+: #{{:price 200000.0}}
+:

 ** Derived Relvar implementation

@ -194,9 +233,6 @@ every time the relations of its base relvar are updated.

 #+NAME: essential state infrastructure
 #+BEGIN_SRC clojure :noweb no-export
-(defprotocol PRelVar
-  (relset! [this relations]))
-
 (def constraints (atom {}))

 (defmacro candidate-key [relvar tuple]
@ -328,7 +364,6 @@ A specification of the required interfaces to the outside world.
 <<interface (feeders and observers)>>
 #+END_SRC

-
 * Essential Logic

 Derived relvar names and definitions.
@ -403,3 +438,24 @@ Despite this the intention is not for observers to be used as a substitute for t
 (fn [key ref old-state new-state]
   (pprint new-state)))
 #+END_SRC
+
+* Tests
+
+#+BEGIN_SRC clojure :tangle ../../../../test/com/owoga/frp/infrastructure-test.clj
+(ns com.owoga.frp.infrastructure-test
+  (:require [com.owoga.frp.infrastructure :as frp]
+            [clojure.test :refer [deftest is testing]]))
+
+(deftest test-project
+  (testing "projection"
+    (let [Offer (frp/->BaseRelVar 'Offer nil (atom #{}))
+          OfferPrices (frp/project Offer [:price])]
+      (frp/load! Offer #{{:address "123 Fake St." :price 2e5}})
+      (is (= @OfferPrices #{{:price 2e5}})))))
+
+(deftest test-insert!
+  (testing "insert!"
+    (let [Offer (frp/->BaseRelVar 'Offer nil (atom #{}))]
+      (frp/insert! Offer {:address "123 Fake St." :price 1.5e5})
+      (is (= @Offer #{{:address "123 Fake St." :price 1.5e5}})))))
+#+END_SRC
--- a/test/com/owoga/frp/infrastructure-test.clj
+++ b/test/com/owoga/frp/infrastructure-test.clj
@ -0,0 +1,17 @@
+(ns com.owoga.frp.infrastructure-test
+  (:require [com.owoga.frp.infrastructure :as frp]
+            [clojure.test :refer [deftest is testing]]))
+
+(deftest test-insert!
+  (testing "insert!"
+    (let [Offer (frp/->BaseRelVar 'Offer nil (atom #{}))]
+      (frp/insert! Offer {:address "123 Fake St." :price 1.5e5})
+      (is (= @Offer #{{:address "123 Fake St." :price 1.5e5}})))))
+
+(deftest test-project
+  (testing "projection"
+    (let [Offer (frp/->BaseRelVar 'Offer nil (atom #{}))
+          OfferPrices (frp/project Offer [:price])]
+      (frp/load! Offer #{{:address "123 Fake St." :price 2e5}})
+      (is (= @OfferPrices #{{:price 2e5}})))))
+