From e24b22b518b35778c0e9344d6470bc0858637e9a Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Thu, 17 Jan 2013 09:57:22 -0800
Subject: [PATCH] Extract iD.svg.LineString

---
 js/id/svg.js             | 16 ++++++++++++++++
 js/id/svg/areas.js       | 12 +-----------
 js/id/svg/lines.js       | 10 +---------
 test/index.html          |  1 +
 test/index_packaged.html |  1 +
 test/spec/svg.js         | 10 ++++++++++
 6 files changed, 30 insertions(+), 20 deletions(-)
 create mode 100644 test/spec/svg.js

diff --git a/js/id/svg.js b/js/id/svg.js
index e1d26e058..bf73f32b8 100644
--- a/js/id/svg.js
+++ b/js/id/svg.js
@@ -9,5 +9,21 @@ iD.svg = {
         return function (entity) {
             return 'translate(' + projection(entity.loc) + ')';
         };
+    },
+
+    LineString: function (projection) {
+        var cache = {};
+        return function (entity) {
+            if (cache[entity.id] !== undefined) {
+                return cache[entity.id];
+            }
+
+            if (entity.nodes.length === 0) {
+                return (cache[entity.id] = '');
+            }
+
+            return (cache[entity.id] =
+                'M' + entity.nodes.map(function (n) { return projection(n.loc); }).join('L'));
+        }
     }
 };
diff --git a/js/id/svg/areas.js b/js/id/svg/areas.js
index 4fe06ba92..3862aca0c 100644
--- a/js/id/svg/areas.js
+++ b/js/id/svg/areas.js
@@ -38,17 +38,7 @@ iD.svg.Areas = function(projection) {
 
         areas.sort(areastack);
 
-        var lineStrings = {};
-
-        function lineString(entity) {
-            if (lineStrings[entity.id] !== undefined) {
-                return lineStrings[entity.id];
-            }
-            var nodes = _.pluck(entity.nodes, 'loc');
-            if (nodes.length === 0) return (lineStrings[entity.id] = '');
-            else return (lineStrings[entity.id] =
-                'M' + nodes.map(projection).join('L'));
-        }
+        var lineString = iD.svg.LineString(projection);
 
         function drawPaths(group, areas, filter, classes) {
             var paths = group.selectAll('path')
diff --git a/js/id/svg/lines.js b/js/id/svg/lines.js
index 4a2acfe38..167a9e75e 100644
--- a/js/id/svg/lines.js
+++ b/js/id/svg/lines.js
@@ -73,15 +73,7 @@ iD.svg.Lines = function(projection) {
 
         lines.sort(waystack);
 
-        function lineString(entity) {
-            if (lineStrings[entity.id] !== undefined) {
-                return lineStrings[entity.id];
-            }
-            var nodes = _.pluck(entity.nodes, 'loc');
-            if (nodes.length === 0) return (lineStrings[entity.id] = '');
-            else return (lineStrings[entity.id] =
-                'M' + nodes.map(projection).join('L'));
-        }
+        var lineString = iD.svg.LineString(projection);
 
         var casing = surface.select('.layer-casing'),
             stroke = surface.select('.layer-stroke'),
diff --git a/test/index.html b/test/index.html
index 195b459f6..96095a244 100644
--- a/test/index.html
+++ b/test/index.html
@@ -151,6 +151,7 @@
     <script src="spec/renderer/hash.js"></script>
     <script src="spec/renderer/map.js"></script>
 
+    <script src="spec/svg.js"></script>
     <script src="spec/svg/areas.js"></script>
     <script src="spec/svg/points.js"></script>
     <script src="spec/svg/vertices.js"></script>
diff --git a/test/index_packaged.html b/test/index_packaged.html
index 92c61df79..cf333b416 100644
--- a/test/index_packaged.html
+++ b/test/index_packaged.html
@@ -60,6 +60,7 @@
     <script src="spec/renderer/hash.js"></script>
     <script src="spec/renderer/map.js"></script>
 
+    <script src="spec/svg.js"></script>
     <script src="spec/svg/areas.js"></script>
     <script src="spec/svg/points.js"></script>
     <script src="spec/svg/vertices.js"></script>
diff --git a/test/spec/svg.js b/test/spec/svg.js
new file mode 100644
index 000000000..bbb78c990
--- /dev/null
+++ b/test/spec/svg.js
@@ -0,0 +1,10 @@
+describe("iD.svg.LineString", function () {
+    it("returns an SVG path description for the entity's nodes", function () {
+        var a = iD.Node({loc: [0, 0]}),
+            b = iD.Node({loc: [2, 3]}),
+            way = iD.Way({nodes: [a, b]}),
+            projection = Object;
+
+        expect(iD.svg.LineString(projection)(way)).to.equal("M0,0L2,3");
+    });
+});