feat: add joinAnd function

docs/Functions.md

@@ -19,6 +19,7 @@ This is a short description of the functions implemented in Stencil:
 - [html](#html)
 - [integer](#integer)
 - [join](#join)
+- [joinAnd](#joinAnd)
 - [length](#length)
 - [list](#list)
 - [lowercase](#lowercase)
@@ -102,6 +103,13 @@ Joins a list of items with an optional separator.
 
 **Example:** call join(xs) to just concatenate the items.
 
+### JoinAnd
+
+Joins a list of items using two separators. The first separator is used to join the items except for the last item. The second separator is used to join the last item. When two items are supplied, then
+only the second separator is used.
+
+**Example:** call <code>join(xs, ", ", " and ")</code> to get <code>"1, 2, 3 and 4"</code>.
+
 ### Date
 
 Formats a date value according to a given [format string](https://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html).

src/stencil/functions.clj

@@ -1,6 +1,7 @@
 (ns stencil.functions
   "Function definitions"
-  (:require [stencil.types :refer [->HideTableColumnMarker ->HideTableRowMarker]]
+  (:require [clojure.string]
+            [stencil.types :refer [->HideTableColumnMarker ->HideTableRowMarker]]
             [stencil.util :refer [fail find-first]]))
 
 (set! *warn-on-reflection* true)
@@ -20,7 +21,7 @@
 (defmethod call-fn "decimal" [_ f] (some-> f bigdec))
 
 ;; The format() function calls java.lang.String.format()
-;; but it predicts the argumet types from the format string and
+;; but it predicts the argument types from the format string and
 ;; converts the argument values to the correct types to prevent runtime errors.
 (let [fs-pattern #"%(?:(\d+)\$)?([-#+ 0,(\<]*)?(\d+)?(\.\d+)?([tT])?([a-zA-Z%])"
       get-types  (fn [pattern-str]
@@ -101,3 +102,9 @@
                   (keep (partial lookup p) elems))))
           data
           (.split column "\\.")))
+
+(defmethod call-fn "joinAnd" [_ elements ^String separator1 ^String separator2]
+  (case (count elements)
+     0 ""
+     1 (str (first elements))
+     (str (clojure.string/join separator1 (butlast elements)) separator2 (last elements))))

test/stencil/functions_test.clj

@@ -104,6 +104,14 @@
     (is (thrown? ExceptionInfo (call-fn "map" "x" {:x 1 :y 2})))
     (is (thrown? ExceptionInfo (call-fn "map" 1 [])))))
 
+(deftest test-join-and
+  (are [expect param] (= expect (call-fn "joinAnd" param ", " " and "))
+    ""           nil
+    ""           []
+    "1"          [1]
+    "1 and 2"    [1 2]
+    "1, 2 and 3" [1 2 3]))
+
 (import '[stencil.types ReplaceImage])
 (def data-uri "data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==")