merge, update, and tap

lib/hash.js

@@ -1,8 +1,18 @@
 module.exports = Hash;
 var Traverse = require('traverse');
 
-function Hash (ref) {
-    var hash = Traverse.clone(ref);
+function Hash (hash, extra) {
+    if (extra == 'clone') { // deep copy
+        hash = Traverse.clone(hash);
+    }
+    else if (extra == 'copy') {
+        var acc = { __proto__ : hash.__proto__ };
+        Object.keys(hash).forEach(function (key) {
+            acc[key] = hash[key];
+        });
+        hash = acc;
+    }
+
     var self = {
         map : function (f) {
             var acc = { __proto__ : hash.__proto__ };
@@ -12,11 +22,10 @@ function Hash (ref) {
             return Hash(acc);
         },
         forEach : function (f) {
-            var acc = { __proto__ : hash.__proto__ };
             Object.keys(hash).forEach(function (key) {
                 f.call(hash, hash[key], key);
             });
-            return Hash(hash);
+            return self;
         },
         filter : function (f) {
             var acc = { __proto__ : hash.__proto__ };
@@ -35,6 +44,24 @@ function Hash (ref) {
             });
             return acc;
         },
+        update : function (h) {
+            Object.keys(h).forEach(function (key) {
+                hash[key] = h[key];
+            });
+            return self;
+        },
+        merge : function (h) {
+            var acc = {};
+            Object.keys(hash).forEach(function (key) {
+                acc[key] = hash[key];
+            });
+            Object.keys(h).forEach(function (key) {
+                acc[key] = h[key];
+            });
+            hash = acc;
+            return self;
+        },
+        tap : function (f) { f.call(self, hash) },
         end : hash,
         items : hash
     };
@@ -52,14 +79,20 @@ function Hash (ref) {
 };
 
 Hash.map = function (ref, f) {
-    return Hash(ref).map(f).end;
+    return Hash(ref).map(f).items;
 };
 
 Hash.filter = function (ref, f) {
-    return Hash(ref).filter(f).end;
+    return Hash(ref).filter(f).items;
 };
 
 Hash.reduce = function (ref, f, acc) {
     return Hash(ref).reduce(f, acc);
 };
 
+Hash.concat = function (xs) {
+    var hash = Hash({});
+    xs.forEach(function (x) { hash.update(x) });
+    return hash;
+};
+

test/hash.js

@@ -33,5 +33,7 @@ exports['hash traversal'] = function (assert) {
 
     assert.equal(Hash(ref3).keys.sort().join(' '), '1337 a b c');
     assert.equal(Hash(ref3).values.sort().join(' '), '2 5 7 leet');
+
+    assert.equal(Hash(ref3).length, 4);
 };