#236 - Generalize continuous-subseqs

DEVELOPER.md

@@ -7,6 +7,5 @@ lein do clean, test
 # Running ClojureScript tests
 
 ```
-lein javac
-lein doo node test-build once
+lein do clean, javac, test-cljs
 ```

project.clj

@@ -40,4 +40,5 @@
          [["clojars" {:url "https://repo.clojars.org"
                       :sign-releases false}]]
 
-  :aliases {"deploy" ["do" "clean," "deploy" "clojars"]})
+  :aliases {"deploy" ["do" "clean," "deploy" "clojars"]
+            "test-cljs" ["do" "doo" "node" "test-build" "once"]})

src/clj/com/rpl/specter.cljc

@@ -507,6 +507,11 @@
     (defmacro end-fn [& args]
       `(n/->SrangeEndFunction (fn ~@args)))
 
+    (defmacro subseq-pred-fn
+      "Used in conjunction with `continuous-subseqs`.  See [[continuous-subseqs]]."
+      [get-truthy-fn & args]
+      `(i/->SubseqsDynamicPredFn ~get-truthy-fn (i/wrap-pred-with-index (fn ~@args))))
+
     ))
 
 
@@ -800,7 +805,14 @@
 
 
 (defnav
-  ^{:doc "Navigates to every continuous subsequence of elements matching `pred`"}
+  ^{:doc "Navigates to every continuous subsequence of elements matching `pred`. `pred` can be specified one of two
+          forms. If a regular function (e.g. defined with `fn`), it takes in only the current element as input.  If
+          defined using the special `subseq-pred-fn` macro, it takes in a `get-truthy-fn` as its first parameter,
+          followed by arguments to a predicate function [`elem` `prev`], followed by the predicate function body.  The
+          `elem` argument to the predicate function is the current element, and the `pred` argument is the value
+          returned by your predicate on the previous element, so it can be in any structure you choose.  `get-truthy-fn`
+          is a function that should return true from your predicate's return structure if that element should be
+          included in a subsequence."}
   continuous-subseqs
   [pred]
   (select* [this structure next-fn]

src/clj/com/rpl/specter/impl.cljc

@@ -546,8 +546,38 @@
         res
         ))))
 
+(defn wrap-pred-with-index [pred]
+  (fn [i elem prev]
+    [(pred elem (first prev)), i]))
+
+;; adapted from clojure.core$keep_indexed
+(defn- subseq-pred-fn-transducer
+  ([pred-fn]
+    (fn [rf]
+      (let [last-val (volatile! nil) idx (volatile! -1)]
+        (fn
+          ([] (rf))               ;; init arity
+          ([result] (rf result))  ;; completion arity
+          ([result input]         ;; reduction arity
+            (let [last @last-val
+                  i (vswap! idx inc)
+                  curr ((:pred-fn pred-fn) i input last)]
+              (vreset! last-val curr)
+              (if (nil? curr)
+                result
+                (rf result curr)))))))))
+
+;; see com.rpl.specter.navs.SrangeEndFunction
+(defrecord SubseqsDynamicPredFn [get-truthy-fn pred-fn])
+
 (defn- matching-indices [aseq p]
-  (keep-indexed (fn [i e] (if (p e) i)) aseq))
+  (if (instance? SubseqsDynamicPredFn p)
+  ;;  use new subseq predicate form (taking current and previous vals)
+    (let [index-results (into [] (subseq-pred-fn-transducer p) aseq)]
+      ;; apply the get-truthy-fn to extract the truthy (i.e. include) result
+      (map last (filter (comp true? (:get-truthy-fn p) first) index-results)))
+    ;; else use the previous 1-arity predicate
+    (keep-indexed (fn [i e] (if (p e) i)) aseq)))
 
 (defn matching-ranges [aseq p]
   (first

test/com/rpl/specter/core_test.cljc

@@ -11,7 +11,7 @@
                       select-any selected-any? collected? traverse
                       multi-transform path dynamicnav recursive-path
                       defdynamicnav traverse-all satisfies-protpath? end-fn
-                      vtransform]]))
+                      subseq-pred-fn vtransform]]))
   (:use
     #?(:clj [clojure.test :only [deftest is]])
     #?(:clj [clojure.test.check.clojure-test :only [defspec]])
@@ -23,7 +23,7 @@
                     select-any selected-any? collected? traverse
                     multi-transform path dynamicnav recursive-path
                     defdynamicnav traverse-all satisfies-protpath? end-fn
-                    vtransform]]))
+                    subseq-pred-fn vtransform]]))
 
 
 
@@ -949,6 +949,23 @@
     (= (setval (s/continuous-subseqs pred) nil aseq)
        (filter (complement pred) aseq))))
 
+(defn- make-bounds-pred-fn-vecs [start end]
+  (s/subseq-pred-fn first [elem prev]
+                    (let [[included last] prev]
+                    (cond
+                      (= start elem) [false start]
+                      (= end elem) [false end]
+                      (= end last) [false elem]
+                      :else [(or (= start last) included) elem]))))
+
+(defn- make-bounds-pred-fn-maps [start end]
+  (s/subseq-pred-fn :include [elem prev]
+                    (let [{include :include last :last} prev]
+                      (cond
+                        (= start elem) {:include false :last start}
+                        (= end elem) {:include false :last end}
+                        (= end last) {:include false :last elem}
+                        :else {:include (or (= start last) include) :last elem}))))
 
 (deftest continuous-subseqs-test
   (is (= [1 "ab" 2 3 "c" 4 "def"]
@@ -960,7 +977,19 @@
   (is (= [[] [2] [4 6]]
          (select
            [(s/continuous-subseqs number?) (s/filterer even?)]
-           [1 "a" "b" 2 3 "c" 4 5 6 "d" "e" "f"]))))
+           [1 "a" "b" 2 3 "c" 4 5 6 "d" "e" "f"])))
+  (is (= [[1 2 3] [8 9]]
+         (select
+           [(s/continuous-subseqs (make-bounds-pred-fn-vecs :START :END))]
+           [:START 1 2 3 :END 5 6 7 :START 8 9 :END])))
+
+  (is (= [1 2 3 :START-SUM 15 :END-SUM 7 8 9 :START-SUM 21 :END-SUM 12 :START-SUM 27 :END-SUM]
+         (transform
+           (s/continuous-subseqs (make-bounds-pred-fn-maps :START-SUM :END-SUM))
+           (fn [vals] [(apply + vals)])
+           [1 2 3 :START-SUM 4 5 6 :END-SUM 7 8 9 :START-SUM 10 11 :END-SUM 12 :START-SUM 13 14 :END-SUM])))
+  )
+
 
 
 
@@ -1589,7 +1618,7 @@
   (s/comp-paths
     (s/srange-dynamic
       (fn [aseq] (long (/ (count aseq) 2)))
-      (end-fn [aseq s] (if (empty? aseq) 0 (inc s))))
+      (s/end-fn [aseq s] (if (empty? aseq) 0 (inc s))))
     s/FIRST
     ))