Add support for arrow functions to reduce filter.

Author: antoineveldhoven

src/twig.filters.js

@@ -869,6 +869,20 @@ module.exports = function (Twig) {
                 });
                 return newValue;
             }
+        },
+        reduce(value, params) {
+            if (is('Array', value)) {
+                const callBackParams = params.params.split(',');
+                return value.reduce((_carry, _v, _k) => {
+                    const data = {};
+                    data[callBackParams[0]] = _carry;
+                    data[callBackParams[1].trim()] = _v;
+                    data[callBackParams[2].trim()] = _k;
+
+                    const template = Twig.exports.twig({data: params.body});
+                    return template.render(data);
+                }, params.args || 0);
+            }
         }
     };
 

test/test.filters.js

@@ -887,6 +887,18 @@ describe('Twig.js Filters ->', function () {
         });
     });
 
+    describe('reduce ->', function () {
+        it('should reduce an array (with inital value)', function () {
+            let testTemplate = twig({data: '{{ [1,2,3]|reduce((carry, v, k) => carry + v * k) }}'});
+            testTemplate.render().should.equal('8');
+        });
+        
+        it('should reduce an array)', function () {
+            let testTemplate = twig({data: '{{ [1,2,3]|reduce((carry, v, k) => carry + v * k, 10) }}'});
+            testTemplate.render().should.equal('18');
+        });
+    });
+
     it('should chain', function () {
         const testTemplate = twig({data: '{{ ["a", "b", "c"]|keys|reverse }}'});
         testTemplate.render().should.equal('2,1,0');