From c66ea58d5659257dd3fb41855e218a2458bfd45f Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Tue, 25 Dec 2012 13:30:31 -0800
Subject: [PATCH] Move transients to graph (fixes #285)

---
 js/id/graph/entity.js     | 44 +++++++++++++++++++--------------------
 js/id/graph/graph.js      | 13 ++++++++++++
 test/spec/graph/entity.js | 10 ---------
 3 files changed, 34 insertions(+), 33 deletions(-)

diff --git a/js/id/graph/entity.js b/js/id/graph/entity.js
index d0ed8b6e6..a7faee1b9 100644
--- a/js/id/graph/entity.js
+++ b/js/id/graph/entity.js
@@ -2,13 +2,12 @@ iD.Entity = function(a, b, c) {
     if (!(this instanceof iD.Entity)) return new iD.Entity(a, b, c);
 
     this.tags = {};
-    this.transients = {};
 
     var sources = [a, b, c], source;
     for (var i = 0; i < sources.length; ++i) {
         source = sources[i];
         for (var prop in source) {
-            if (prop !== 'transients' && Object.prototype.hasOwnProperty.call(source, prop)) {
+            if (Object.prototype.hasOwnProperty.call(source, prop)) {
                 this[prop] = source[prop];
             }
         }
@@ -59,35 +58,34 @@ iD.Entity.prototype = {
         return this._updated && this.osmId() > 0;
     },
 
-    intersects: function(extent, resolver) {
+    extent: function(resolver) {
         if (this.type === 'node') {
-            return this.loc[0] > extent[0][0] &&
-                   this.loc[0] < extent[1][0] &&
-                   this.loc[1] < extent[0][1] &&
-                   this.loc[1] > extent[1][1];
-        } else if (this.type === 'way') {
-            var _extent = this.transients.extent;
-
-            if (!_extent) {
-                _extent = this.transients.extent = [[-Infinity, Infinity], [Infinity, -Infinity]];
+            return [this.loc, this.loc];
+        } else if (this.type == 'way') {
+            return resolver.transient(this, 'extent', function() {
+                var extent = [[-Infinity, Infinity], [Infinity, -Infinity]];
                 for (var i = 0, l = this.nodes.length; i < l; i++) {
                     var node = resolver.entity(this.nodes[i]);
-                    if (node.loc[0] > _extent[0][0]) _extent[0][0] = node.loc[0];
-                    if (node.loc[0] < _extent[1][0]) _extent[1][0] = node.loc[0];
-                    if (node.loc[1] < _extent[0][1]) _extent[0][1] = node.loc[1];
-                    if (node.loc[1] > _extent[1][1]) _extent[1][1] = node.loc[1];
+                    if (node.loc[0] > extent[0][0]) extent[0][0] = node.loc[0];
+                    if (node.loc[0] < extent[1][0]) extent[1][0] = node.loc[0];
+                    if (node.loc[1] < extent[0][1]) extent[0][1] = node.loc[1];
+                    if (node.loc[1] > extent[1][1]) extent[1][1] = node.loc[1];
                 }
-            }
-
-            return _extent[0][0] > extent[0][0] &&
-                   _extent[1][0] < extent[1][0] &&
-                   _extent[0][1] < extent[0][1] &&
-                   _extent[1][1] > extent[1][1];
+                return extent;
+            });
         } else {
-            return false;
+            return [[NaN, NaN], [NaN, NaN]];
         }
     },
 
+    intersects: function(extent, resolver) {
+        var _extent = this.extent(resolver);
+        return _extent[0][0] > extent[0][0] &&
+               _extent[1][0] < extent[1][0] &&
+               _extent[0][1] < extent[0][1] &&
+               _extent[1][1] > extent[1][1];
+    },
+
     hasInterestingTags: function() {
         return _.keys(this.tags).some(function (key) {
             return key != "attribution" &&
diff --git a/js/id/graph/graph.js b/js/id/graph/graph.js
index 5d0a15631..6786e0f7e 100644
--- a/js/id/graph/graph.js
+++ b/js/id/graph/graph.js
@@ -10,6 +10,8 @@ iD.Graph = function(entities) {
         this.entities = entities || {};
     }
 
+    this.transients = {};
+
     if (iD.debug) {
         Object.freeze(this);
         Object.freeze(this.entities);
@@ -21,6 +23,17 @@ iD.Graph.prototype = {
         return this.entities[id];
     },
 
+    transient: function(entity, key, fn) {
+        var id = entity.id,
+            transients = this.transients[id] || (this.transients[id] = {});
+
+        if (transients[key]) {
+            return transients[key];
+        }
+
+        return transients[key] = fn.call(entity);
+    },
+
     parentStructure: function(ways) {
         var nodes = {};
         ways.forEach(function(w) {
diff --git a/test/spec/graph/entity.js b/test/spec/graph/entity.js
index ba0d6f05d..0010696fe 100644
--- a/test/spec/graph/entity.js
+++ b/test/spec/graph/entity.js
@@ -7,10 +7,6 @@ describe('iD.Entity', function () {
         it("freezes tags", function () {
             expect(Object.isFrozen(iD.Entity().tags)).to.be.true;
         });
-
-        it("does not freeze transients", function () {
-            expect(Object.isFrozen(iD.Entity().transients)).to.be.false;
-        });
     }
 
     describe(".id", function () {
@@ -57,12 +53,6 @@ describe('iD.Entity', function () {
             expect(attrs).to.eql({tags: {foo: 'bar'}});
         });
 
-        it("doesn't copy transients", function () {
-            var entity = iD.Entity();
-            entity.transients['foo'] = 'bar';
-            expect(entity.update({}).transients).not.to.have.property('foo');
-        });
-
         it("doesn't copy prototype properties", function () {
             expect(iD.Entity().update({})).not.to.have.ownProperty('update');
         });