Add sequential UUID support.

src/hasch/core.cljc

@@ -9,7 +9,10 @@
 (def hash->str platform/hash->str)
 
 (defn edn-hash
-  "Hash an edn value with SHA-512 by default or a compatible hash function of choice."
+  "Hash an edn value with SHA-512 by default or a compatible hash function of choice.
+
+  Please use the write-handlers only in legacy cases and rather extend the PHashCoercion
+  protocol to your own types."
   ([val] (edn-hash val {}))
   ([val write-handlers] (edn-hash val hasch.platform/sha512-message-digest write-handlers))
   ([val md-create-fn write-handlers]
@@ -24,3 +27,21 @@
   structures."
   ([] (uuid4))
   ([val & {:keys [write-handlers]}] (-> val (edn-hash write-handlers) uuid5)))
+
+
+(defn squuid
+  "Calculates a sequential UUID as described in
+  https://github.com/clojure-cookbook/clojure-cookbook/blob/master/01_primitive-data/1-24_uuids.asciidoc"
+  ([] (squuid (java.util.UUID/randomUUID)))
+  ([uuid]
+   (let [time (System/currentTimeMillis)
+         secs (quot time 1000)
+         lsb (.getLeastSignificantBits uuid)
+         msb (.getMostSignificantBits uuid)
+         timed-msb (bit-or (bit-shift-left secs 32)
+                           (bit-and 0x00000000ffffffff msb))]
+     (java.util.UUID. timed-msb lsb))))
+
+
+
+

test/hasch/test.cljc

@@ -1,5 +1,5 @@
 (ns hasch.test
-  (:require [hasch.core :refer [edn-hash uuid]]
+  (:require [hasch.core :refer [edn-hash uuid squuid]]
             [hasch.benc :refer [xor-hashes]]
             [hasch.platform :refer [uuid5 sha512-message-digest hash->str]]
             [incognito.base :as ic]
@@ -100,6 +100,10 @@
     (is (= (hash->str (range 256))
            "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff"))))
 
+(deftest squuid-test
+  (testing "Sequential UUID functionality."
+    (is (= (squuid (uuid [1 2 3]))
+           #uuid "5914da46-5c15-555e-a1c8-6166a78fc808"))))
 
 
 #_(run-tests)