enhance addition operator to concat lists, dicts

jaredstehler · jaredstehler · commit e138e30a687d · 2015-04-10T10:49:58.000-04:00
diff --git a/CHANGES.md b/CHANGES.md
@@ -3,6 +3,7 @@
 ### Version 2.0.1 ([Maven Central](http://search.maven.org/#search%7Cga%7C1%7Cg%3A%22com.hubspot.jinjava%22%20AND%20v%3A%222.0.1%22)) ###
 
 * Adding self-documenting feature to jinjava core
+* Updating addition expression operator ('+') to work with lists and dicts
 
 ### Version 2.0.0 ([Maven Central](http://search.maven.org/#search%7Cga%7C1%7Cg%3A%22com.hubspot.jinjava%22%20AND%20v%3A%222.0.0%22)) ###
 
diff --git a/src/main/java/com/hubspot/jinjava/el/ext/AdditionOperator.java b/src/main/java/com/hubspot/jinjava/el/ext/AdditionOperator.java
@@ -1,5 +1,10 @@
 package com.hubspot.jinjava.el.ext;
 
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 import java.util.Objects;
 
 import de.odysseus.el.misc.NumberOperations;
@@ -8,8 +13,28 @@
 
 public class AdditionOperator extends AstBinary.SimpleOperator {
 
+  @SuppressWarnings("unchecked")
   @Override
   protected Object apply(TypeConverter converter, Object o1, Object o2) {
+    if(o1 instanceof Collection) {
+      List<Object> result = new ArrayList<>((Collection<Object>) o1);
+      
+      if(o2 instanceof Collection) {
+        result.addAll((Collection<Object>) o2);
+      }
+      else {
+        result.add(o2);
+      }
+      
+      return result;
+    }
+    else if(o1 instanceof Map && o2 instanceof Map) {
+      Map<Object, Object> result = new HashMap<>((Map<Object, Object>) o1);
+      result.putAll((Map<Object, Object>) o2);
+
+      return result;
+    }
+    
     if(o1 instanceof String || o2 instanceof String) {
       return Objects.toString(o1).concat(Objects.toString(o2));
     }
diff --git a/src/test/java/com/hubspot/jinjava/el/ext/AdditionOperatorTest.java b/src/test/java/com/hubspot/jinjava/el/ext/AdditionOperatorTest.java
@@ -0,0 +1,64 @@
+package com.hubspot.jinjava.el.ext;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.entry;
+
+import java.util.Collection;
+import java.util.Map;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import com.hubspot.jinjava.Jinjava;
+import com.hubspot.jinjava.interpret.Context;
+import com.hubspot.jinjava.interpret.JinjavaInterpreter;
+
+
+@SuppressWarnings("unchecked")
+public class AdditionOperatorTest {
+
+
+  private JinjavaInterpreter interpreter;
+  private Context context;
+  
+  @Before
+  public void setup() {
+    Jinjava jinjava = new Jinjava();
+    context = new Context();
+    interpreter = new JinjavaInterpreter(jinjava, context, jinjava.getGlobalConfig());
+  }
+  
+  @Test
+  public void itConcatsStrings() {
+    assertThat(interpreter.resolveELExpression("'foo' + 'bar'", -1)).isEqualTo("foobar");
+  }
+  
+  @Test
+  public void itAddsNumbers() {
+    assertThat(interpreter.resolveELExpression("1 + 2", -1)).isEqualTo(3L);
+  }
+  
+  @Test
+  public void itConcatsNumberWithString() {
+    assertThat(interpreter.resolveELExpression("'1' + 2", -1)).isEqualTo("12");
+    assertThat(interpreter.resolveELExpression("1 + '2'", -1)).isEqualTo("12");
+  }
+  
+  @Test
+  public void itCombinesTwoLists() {
+    assertThat((Collection<Object>) interpreter.resolveELExpression("['foo', 'bar'] + ['other', 'one']", -1))
+      .containsExactly("foo", "bar", "other", "one");
+  }
+  
+  @Test
+  public void itAddsToList() {
+    assertThat((Collection<Object>) interpreter.resolveELExpression("['foo'] + 'bar'", -1)).containsExactly("foo", "bar");
+  }
+  
+  @Test
+  public void itCombinesTwoDicts() {
+    assertThat((Map<Object, Object>) interpreter.resolveELExpression("{'k1':'v1'} + {'k2':'v2'}", -1))
+      .containsOnly(entry("k1", "v1"), entry("k2", "v2"));
+  }
+  
+}
