Support Map for iteration and nested paths

lib/handlebars/helpers/each.js

@@ -33,7 +33,7 @@ export default function(instance) {
       data = createFrame(options.data);
     }
 
-    function execIteration(field, index, last) {
+    function execIteration(field, value, index, last) {
       if (data) {
         data.key = field;
         data.index = index;
@@ -47,22 +47,25 @@ export default function(instance) {
 
       ret =
         ret +
-        fn(context[field], {
+        fn(value, {
           data: data,
-          blockParams: blockParams(
-            [context[field], field],
-            [contextPath + field, null]
-          )
+          blockParams: blockParams([value, field], [contextPath + field, null])
         });
     }
 
     if (context && typeof context === 'object') {
       if (isArray(context)) {
         for (let j = context.length; i < j; i++) {
           if (i in context) {
-            execIteration(i, i, i === context.length - 1);
+            execIteration(i, context[i], i, i === context.length - 1);
           }
         }
+      } else if (context instanceof Map) {
+        const j = context.size - 1;
+        for (const [key, value] of context) {
+          execIteration(key, value, i, i === j);
+          i++;
+        }
       } else if (global.Symbol && context[global.Symbol.iterator]) {
         const newContext = [];
         const iterator = context[global.Symbol.iterator]();
@@ -71,7 +74,7 @@ export default function(instance) {
         }
         context = newContext;
         for (let j = context.length; i < j; i++) {
-          execIteration(i, i, i === context.length - 1);
+          execIteration(i, context[i], i, i === context.length - 1);
         }
       } else {
         let priorKey;
@@ -81,13 +84,13 @@ export default function(instance) {
           // the last iteration without have to scan the object twice and create
           // an itermediate keys array.
           if (priorKey !== undefined) {
-            execIteration(priorKey, i - 1);
+            execIteration(priorKey, context[priorKey], i - 1);
           }
           priorKey = key;
           i++;
         });
         if (priorKey !== undefined) {
-          execIteration(priorKey, i - 1, true);
+          execIteration(priorKey, context[priorKey], i - 1, true);
         }
       }
     }

lib/handlebars/runtime.js

@@ -127,6 +127,9 @@ export function template(templateSpec, env) {
       return obj[name];
     },
     lookupProperty: function(parent, propertyName) {
+      if (parent instanceof Map) {
+        return parent.get(propertyName);
+      }
       let result = parent[propertyName];
       if (result == null) {
         return result;

spec/basic.js

@@ -394,6 +394,17 @@ describe('basic context', function() {
     );
   });
 
+  it('nested paths with Map', function() {
+    var map = new Map();
+    map.set('expression', 'beautiful');
+    shouldCompileTo(
+      'Goodbye {{foo/expression}} world!',
+      { foo: map },
+      'Goodbye beautiful world!',
+      'Nested paths access nested objects'
+    );
+  });
+
   it('nested paths with empty string value', function() {
     shouldCompileTo(
       'Goodbye {{alan/expression}} world!',

spec/builtins.js

@@ -551,6 +551,29 @@ describe('builtin helpers', function() {
         );
       });
     }
+
+    it('each on Map and @key', function() {
+      var goodbyes = new Map();
+      goodbyes.set('first', 'goodbye');
+      goodbyes.set('second', 'Goodbye');
+      goodbyes.set('last', 'GOODBYE');
+      var goodbyesEmpty = new Map();
+      var string =
+        '{{#each goodbyes}}{{@key}}. {{.}}! {{/each}}cruel {{world}}!';
+      var hash = { goodbyes: goodbyes, world: 'world' };
+      shouldCompileTo(
+        string,
+        hash,
+        'first. goodbye! second. Goodbye! last. GOODBYE! cruel world!',
+        'each with map argument iterates over entries when not empty'
+      );
+      shouldCompileTo(
+        string,
+        { goodbyes: goodbyesEmpty, world: 'world' },
+        'cruel world!',
+        'each with map argument ignores the contents when empty'
+      );
+    });
   });
 
   describe('#log', function() {