release 0.2.7: added join() string function

docs/Functions.md

@@ -35,6 +35,14 @@ of an array or hide the whole paragraph when the array is empty.
 
 These functions deal with textual data.
 
+## Join
+
+Joins a list of items with an optional separator.
+
+**Example:** call join(xs, ",") to join them with a comma.
+
+**Example:** call join(xs) to just concatenate the items.
+
 ## Format
 
 Calls [String.format](https://docs.oracle.com/javase/7/docs/api/java/util/Formatter.html) function.

java-src/io/github/erdos/stencil/functions/StringFunctions.java

@@ -1,7 +1,9 @@
 package io.github.erdos.stencil.functions;
 
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.IllegalFormatException;
+import java.util.Objects;
 import java.util.stream.Collectors;
 
 /**
@@ -32,6 +34,42 @@ public Object call(Object... arguments) {
         }
     },
 
+    JOIN {
+        @SuppressWarnings("unchecked")
+        @Override
+        public Object call(Object... arguments) {
+            if (arguments.length == 0) {
+                throw new IllegalArgumentException("At least one arg is expected!");
+            } else if (arguments.length == 1 || (arguments.length == 2 && arguments[1] == null)) {
+                if (arguments[0] == null) {
+                    return "";
+                } else if (arguments[0] instanceof Collection) {
+                    final Collection<Object> items = (Collection<Object>) arguments[0];
+                    return items.stream()
+                            .filter(Objects::nonNull)
+                            .map(Objects::toString)
+                            .collect(Collectors.joining());
+                } else {
+                    throw new IllegalArgumentException("First parameter must be a Collection!");
+                }
+            } else if (arguments.length == 2) {
+                if (!(arguments[0] instanceof Collection)) {
+                    throw new IllegalArgumentException("First parameter must be a Collection!");
+                } else if (!(arguments[1] instanceof String)) {
+                    throw new IllegalArgumentException("Second parameter must be a String!");
+                } else {
+                    final Collection<Object> items = (Collection<Object>) arguments[0];
+                    return items.stream()
+                            .filter(Objects::nonNull)
+                            .map(Objects::toString)
+                            .collect(Collectors.joining((String) (arguments[1])));
+                }
+            } else {
+                throw new IllegalArgumentException("Join function expects 1 or 2 arguments!");
+            }
+        }
+    },
+
     /**
      * Converts parameters to strings and concatenates the result.
      * Returns empty string on empty or null arguments.

java-test/io/github/erdos/stencil/functions/StringFunctionsTest.java

@@ -3,7 +3,12 @@
 import org.junit.Assert;
 import org.junit.Test;
 
+import java.util.Collections;
+
 import static io.github.erdos.stencil.functions.StringFunctions.FORMAT;
+import static io.github.erdos.stencil.functions.StringFunctions.JOIN;
+import static java.util.Arrays.asList;
+import static java.util.Collections.emptyList;
 import static org.junit.Assert.assertEquals;
 
 public class StringFunctionsTest {
@@ -27,4 +32,16 @@ public void testFormat() {
             // direkt ures!
         }
     }
+
+    @Test
+    public void testJoin() {
+        assertEquals("", JOIN.call(emptyList()));
+
+        assertEquals("123", JOIN.call(asList(1, 2, 3)));
+        assertEquals("123", JOIN.call(asList(1, 2, 3), null));
+        assertEquals("1,2,3", JOIN.call(asList(1, 2, 3), ","));
+
+        assertEquals("", JOIN.call(emptyList(), null));
+        assertEquals("", JOIN.call(emptyList(), ","));
+    }
 }

project.clj

@@ -1,4 +1,4 @@
-(defproject io.github.erdos/stencil-core "0.2.6"
+(defproject io.github.erdos/stencil-core "0.2.7"
   :url "https://github.com/erdos/stencil"
   :description       "Templating engine for office documents."
   :license {:name "Eclipse Public License - v 2.0"