From e2e8fa091ed700d6c8b1b0c025bd2dbf1b7586d4 Mon Sep 17 00:00:00 2001
From: Nathan Marz <nathan@nathanmarz.com>
Date: Sat, 28 May 2016 13:57:30 -0400
Subject: [PATCH] Added continuous-subseqs navigator

---
 CHANGES.md                          |  2 ++
 src/clj/com/rpl/specter.cljx        | 18 ++++++++++++++++++
 src/clj/com/rpl/specter/impl.cljx   | 21 +++++++++++++++++++++
 test/com/rpl/specter/core_test.cljx | 22 ++++++++++++++++++++++
 4 files changed, 63 insertions(+)

diff --git a/CHANGES.md b/CHANGES.md
index d1d1860..99da7b4 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -7,9 +7,11 @@
 * BREAKING CHANGE: `path` renamed to `nav`
 * BREAKING CHANGE: `fixed-pathed-path` and `variable-pathed-path` renamed to `fixed-pathed-nav` and `variabled-pathed-nav`
 * Added `must` navigator to navigate to a key if and only if it exists in the structure
+* Added `continous-subseqs` navigator
 * Added `ATOM` navigator (thanks @rakeshp)
 * Added "navigator constructors" that can be defined via `defnavconstructor`. These allow defining a flexible function to parameterize a defnav, and the function integrates with inline caching for high performance.
 
+
 ## 0.10.0
 * Make codebase bootstrap cljs compatible
 * Remove usage of reducers in cljs version in favor of transducers (thanks @StephenRudolph)
diff --git a/src/clj/com/rpl/specter.cljx b/src/clj/com/rpl/specter.cljx
index 92425d1..efc476f 100644
--- a/src/clj/com/rpl/specter.cljx
+++ b/src/clj/com/rpl/specter.cljx
@@ -181,6 +181,24 @@
     (i/srange-transform structure start end next-fn)
     ))
 
+(defnav
+  ^{:doc "Navigates to every continuous subsequence of elements matching `pred`"}
+  continuous-subseqs
+  [pred]
+  (select* [this structure next-fn]
+    (doall
+      (mapcat
+        (fn [[s e]] (i/srange-select structure s e next-fn))
+        (i/matching-ranges structure pred)
+        )))
+  (transform* [this structure next-fn]
+    (reduce
+      (fn [structure [s e]]
+        (i/srange-transform structure s e next-fn))
+      structure
+      (reverse (i/matching-ranges structure pred))
+      )))
+
 (def BEGINNING (srange 0 0))
 
 (def END (srange-dynamic count count))
diff --git a/src/clj/com/rpl/specter/impl.cljx b/src/clj/com/rpl/specter/impl.cljx
index 65215d9..9da2099 100644
--- a/src/clj/com/rpl/specter/impl.cljx
+++ b/src/clj/com/rpl/specter/impl.cljx
@@ -575,6 +575,27 @@
       res
       )))
 
+(defn- matching-indices [aseq p]
+  (keep-indexed (fn [i e] (if (p e) i)) aseq))
+
+(defn matching-ranges [aseq p]
+  (first
+    (reduce
+      (fn [[ranges curr-start curr-last :as curr] i]
+        (cond
+          (nil? curr-start)
+          [ranges i i]
+
+          (= i (inc curr-last))
+          [ranges curr-start i]
+
+          :else
+          [(conj ranges [curr-start (inc curr-last)]) i i]
+          ))
+      [[] nil nil]
+      (concat (matching-indices aseq p) [-1])
+    )))
+
 (extend-protocol p/Navigator
   nil
   (select* [this structure next-fn]
diff --git a/test/com/rpl/specter/core_test.cljx b/test/com/rpl/specter/core_test.cljx
index 87f4f7f..054f723 100644
--- a/test/com/rpl/specter/core_test.cljx
+++ b/test/com/rpl/specter/core_test.cljx
@@ -969,3 +969,25 @@
              :a
              ))))
   )
+
+(defspec continuous-subseqs-filter-equivalence
+  (for-all+
+    [aseq (gen/vector (gen/elements [1 2 3 :a :b :c 4 5 :d :e]))
+     pred (gen/elements [keyword? number?])]
+    (= (setval (s/continuous-subseqs pred) nil aseq)
+       (filter (complement pred) aseq))
+    ))
+
+(deftest continuous-subseqs-test
+  (is (= [1 "ab" 2 3 "c" 4 "def"]
+         (transform
+           (s/continuous-subseqs string?)
+           (fn [s] [(apply str s)])
+           [1 "a" "b" 2 3 "c" 4 "d" "e" "f"]
+           )))
+  (is (= [[] [2] [4 6]]
+         (select
+           [(s/continuous-subseqs number?) (s/filterer even?)]
+           [1 "a" "b" 2 3 "c" 4 5 6 "d" "e" "f"]
+           )))
+  )