From c43d915625ce022a920cbbda7988a709c8551d22 Mon Sep 17 00:00:00 2001
From: Martijn van Exel <m@rtijn.org>
Date: Thu, 21 Nov 2013 10:58:29 -0700
Subject: [PATCH] Reverse cardinal directions for relation member roles

---
 js/id/actions/reverse.js     | 19 +++++++++++++++----
 test/spec/actions/reverse.js | 24 ++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/js/id/actions/reverse.js b/js/id/actions/reverse.js
index 587829d2b..7a1f74be7 100644
--- a/js/id/actions/reverse.js
+++ b/js/id/actions/reverse.js
@@ -14,6 +14,8 @@
 
     Relation members:
        role=forward ⟺ role=backward
+         role=north ⟺ role=south
+          role=east ⟺ role=west
 
    In addition, numeric-valued `incline` tags are negated.
 
@@ -29,9 +31,18 @@
  */
 iD.actions.Reverse = function(wayId) {
     var replacements = [
-        [/:right$/, ':left'], [/:left$/, ':right'],
-        [/:forward$/, ':backward'], [/:backward$/, ':forward']
-    ], numeric = /^([+\-]?)(?=[\d.])/;
+            [/:right$/, ':left'], [/:left$/, ':right'],
+            [/:forward$/, ':backward'], [/:backward$/, ':forward']
+        ],
+        numeric = /^([+\-]?)(?=[\d.])/,
+        roleReversals = {
+            forward: 'backward',
+            backward: 'forward',
+            north: 'south',
+            south: 'north',
+            east: 'west',
+            west: 'east'
+        };
 
     function reverseKey(key) {
         for (var i = 0; i < replacements.length; ++i) {
@@ -64,7 +75,7 @@ iD.actions.Reverse = function(wayId) {
 
         graph.parentRelations(way).forEach(function(relation) {
             relation.members.forEach(function(member, index) {
-                if (member.id === way.id && (role = {forward: 'backward', backward: 'forward'}[member.role])) {
+                if (member.id === way.id && (role = roleReversals[member.role])) {
                     relation = relation.updateMember({role: role}, index);
                     graph = graph.replace(relation);
                 }
diff --git a/test/spec/actions/reverse.js b/test/spec/actions/reverse.js
index 40d0f5500..9ddc29c7a 100644
--- a/test/spec/actions/reverse.js
+++ b/test/spec/actions/reverse.js
@@ -114,4 +114,28 @@ describe("iD.actions.Reverse", function () {
         graph = iD.actions.Reverse(way.id)(graph);
         expect(graph.entity(relation.id).members[0].role).to.eql('forward');
     });
+
+    it("transforms role=north ⟺ role=south in member relations", function () {
+        var way = iD.Way({tags: {highway: 'residential'}}),
+            relation = iD.Relation({members: [{type: 'way', id: way.id, role: 'north'}]}),
+            graph = iD.Graph([way, relation]);
+
+        graph = iD.actions.Reverse(way.id)(graph);
+        expect(graph.entity(relation.id).members[0].role).to.eql('south');
+
+        graph = iD.actions.Reverse(way.id)(graph);
+        expect(graph.entity(relation.id).members[0].role).to.eql('north');
+    });
+
+    it("transforms role=east ⟺ role=west in member relations", function () {
+        var way = iD.Way({tags: {highway: 'residential'}}),
+            relation = iD.Relation({members: [{type: 'way', id: way.id, role: 'east'}]}),
+            graph = iD.Graph([way, relation]);
+
+        graph = iD.actions.Reverse(way.id)(graph);
+        expect(graph.entity(relation.id).members[0].role).to.eql('west');
+
+        graph = iD.actions.Reverse(way.id)(graph);
+        expect(graph.entity(relation.id).members[0].role).to.eql('east');
+    });
 });