add LastGroup component

component.json

@@ -27,6 +27,7 @@
     "components/CollectObject.coffee",
     "components/CollectTree.coffee",
     "components/FirstGroup.coffee",
+    "components/LastGroup.coffee",
     "components/MapGroup.coffee",
     "components/MergeGroups.coffee",
     "components/GroupByObjectKey.coffee",
@@ -51,6 +52,7 @@
       "CollectObject": "components/CollectObject.coffee",
       "CollectTree": "components/CollectTree.coffee",
       "FirstGroup": "components/FirstGroup.coffee",
+      "LastGroup": "components/LastGroup.coffee",
       "MapGroup": "components/MapGroup.coffee",
       "MergeGroups": "components/MergeGroups.coffee",
       "GroupByObjectKey": "components/GroupByObjectKey.coffee"

components/LastGroup.coffee

@@ -0,0 +1,41 @@
+noflo = require 'noflo'
+
+class LastGroup extends noflo.Component
+  constructor: ->
+    @inPorts =
+      in: new noflo.Port
+    @outPorts =
+      out: new noflo.Port
+
+    @groups = []
+    @groupSent = 0
+
+    @inPorts.in.on 'begingroup', (group) =>
+      @storeGroup group
+    @inPorts.in.on 'data', (data) =>
+      @sendBeginGroup()
+      @outPorts.out.send data if @outPorts.out.isAttached()
+    @inPorts.in.on 'endgroup', (group) =>
+      @sendEndGroup()
+    @inPorts.in.on 'disconnect', =>
+      @outPorts.out.disconnect() if @outPorts.out.isConnected()
+
+  storeGroup: (group) ->
+    @groups.push { name: group, emitted: false }
+
+  sendBeginGroup: () ->
+    return unless @groups.length > 0
+    group = @groups[@groups.length - 1]
+    return if group.emitted
+    group.emitted = true
+    @outPorts.out.beginGroup group.name if @outPorts.out.isAttached()
+
+  sendEndGroup: () ->
+    group = @groups.pop()
+    return unless group.emitted
+    @outPorts.out.endGroup() if @outPorts.out.isAttached()
+
+  clearGroups: () ->
+    @groups = []
+
+exports.getComponent = -> new LastGroup

package.json

@@ -65,6 +65,7 @@
       "CollectObject": "components/CollectObject.coffee",
       "CollectTree": "components/CollectTree.coffee",
       "FirstGroup": "./components/FirstGroup.coffee",
+      "LastGroup": "./components/LastGroup.coffee",
       "MapGroup": "./components/MapGroup.coffee",
       "MergeGroups": "./components/MergeGroups.coffee",
       "GroupByObjectKey": "./components/GroupByObjectKey.coffee"

test/LastGroup.coffee

@@ -0,0 +1,43 @@
+test = require "noflo-test"
+
+test.component("groups/LastGroup").
+  discuss("pass no group").
+    send.connect("in").
+      send.data("in", "data").
+    send.disconnect("in").
+  discuss("no group is sent").
+    receive.connect("out").
+      receive.data("out", "data").
+    receive.disconnect("out").
+
+  next().
+  discuss("pass one group & data").
+    send.connect("in").
+      send.beginGroup("in", "group").
+        send.data("in", "data").
+      send.endGroup("in").
+    send.disconnect("in").
+  discuss("one group is sent").
+    receive.connect("out").
+      receive.beginGroup("out", "group").
+        receive.data("out", "data").
+      receive.endGroup("out").
+    receive.disconnect("out").
+
+  next().
+  discuss("pass 2 groups & data").
+    send.connect("in").
+      send.beginGroup("in", "group1").
+        send.beginGroup("in", "group2").
+          send.data("in", "data").
+        send.endGroup("in").
+      send.endGroup("in").
+    send.disconnect("in").
+  discuss("one group is sent").
+    receive.connect("out").
+      receive.beginGroup("out", "group2").
+        receive.data("out", "data").
+      receive.endGroup("out").
+    receive.disconnect("out").
+
+export module