Buffers are memoized on project by path

spec/app/buffer-spec.coffee

@@ -11,11 +11,11 @@ describe 'Buffer', ->
     buffer = new Buffer(filePath)
 
   afterEach ->
-    buffer?.destroy()
+    buffer?.release()
 
   describe 'constructor', ->
     beforeEach ->
-      buffer.destroy()
+      buffer.release()
 
     describe "when given a path", ->
       describe "when a file exists for the path", ->
@@ -56,8 +56,8 @@ describe 'Buffer', ->
     beforeEach ->
       path = "/tmp/tmp.txt"
       fs.write(path, "first")
-      buffer.destroy()
-      buffer = new Buffer(path)
+      buffer.release()
+      buffer = new Buffer(path).retain()
 
     afterEach ->
       fs.remove(path)
@@ -99,7 +99,7 @@ describe 'Buffer', ->
     it "returns false after modified buffer is saved", ->
       filePath = "/tmp/atom-tmp-file"
       fs.write(filePath, '')
-      buffer.destroy()
+      buffer.release()
       buffer = new Buffer(filePath)
       expect(buffer.isModified()).toBe false
 
@@ -243,7 +243,7 @@ describe 'Buffer', ->
 
   describe ".save()", ->
     beforeEach ->
-      buffer.destroy()
+      buffer.release()
 
     describe "when the buffer has a path", ->
       filePath = null
@@ -283,33 +283,34 @@ describe 'Buffer', ->
         expect(-> buffer.save()).toThrow()
 
   describe ".saveAs(path)", ->
-    filePath = null
+    [filePath, saveAsBuffer] = []
 
-    beforeEach ->
-      buffer.destroy()
+    afterEach ->
+      saveAsBuffer.release()
 
     it "saves the contents of the buffer to the path", ->
       filePath = '/tmp/temp.txt'
       fs.remove filePath if fs.exists(filePath)
 
-      buffer = new Buffer()
+      saveAsBuffer = new Buffer().retain()
       eventHandler = jasmine.createSpy('eventHandler')
-      buffer.on 'path-change', eventHandler
+      saveAsBuffer.on 'path-change', eventHandler
 
-      buffer.setText 'Buffer contents!'
-      buffer.saveAs(filePath)
+      saveAsBuffer.setText 'Buffer contents!'
+      saveAsBuffer.saveAs(filePath)
       expect(fs.read(filePath)).toEqual 'Buffer contents!'
 
-      expect(eventHandler).toHaveBeenCalledWith(buffer)
+      expect(eventHandler).toHaveBeenCalledWith(saveAsBuffer)
 
     it "stops listening to events on previous path and begins listening to events on new path", ->
       originalPath = "/tmp/original.txt"
       newPath = "/tmp/new.txt"
       fs.write(originalPath, "")
-      buffer = new Buffer(originalPath)
+
+      saveAsBuffer = new Buffer(originalPath).retain()
       changeHandler = jasmine.createSpy('changeHandler')
-      buffer.on 'change', changeHandler
-      buffer.saveAs(newPath)
+      saveAsBuffer.on 'change', changeHandler
+      saveAsBuffer.saveAs(newPath)
       expect(changeHandler).not.toHaveBeenCalled()
 
       fs.write(originalPath, "should not trigger buffer event")

spec/app/project-spec.coffee

@@ -13,18 +13,14 @@ describe "Project", ->
     it "removes edit session and calls destroy on buffer (if buffer is not referenced by other edit sessions)", ->
       editSession = project.buildEditSessionForPath("a")
       anotherEditSession = project.buildEditSessionForPath("a")
-      buffer = editSession.buffer
-      spyOn(buffer, 'destroy').andCallThrough()
 
       expect(project.editSessions.length).toBe 2
       expect(editSession.buffer).toBe anotherEditSession.buffer
 
       editSession.destroy()
-      expect(buffer.destroy).not.toHaveBeenCalled()
       expect(project.editSessions.length).toBe 1
 
       anotherEditSession.destroy()
-      expect(buffer.destroy).toHaveBeenCalled()
       expect(project.editSessions.length).toBe 0
 
   describe ".buildEditSessionForPath(path)", ->
@@ -66,6 +62,20 @@ describe "Project", ->
         expect(newBufferHandler).toHaveBeenCalledWith(editSession.buffer)
         expect(newEditSessionHandler).toHaveBeenCalledWith editSession
 
+  describe ".bufferForPath(path)", ->
+    describe "when opening a previously opened path", ->
+      it "does not create a new buffer", ->
+        buffer = project.bufferForPath("a").retain()
+        expect(project.bufferForPath("a")).toBe buffer
+
+        alternativeBuffer = project.bufferForPath("b").retain().release()
+        expect(alternativeBuffer).not.toBe buffer
+        buffer.release()
+
+      it "creates a new buffer if the previous buffer was destroyed", ->
+        buffer = project.bufferForPath("a").retain().release()
+        expect(project.bufferForPath("a").retain().release()).not.toBe buffer
+
   describe ".resolve(path)", ->
     it "returns an absolute path based on the project's root", ->
       absolutePath = require.resolve('fixtures/dir/a')

spec/spec-helper.coffee

@@ -26,6 +26,7 @@ afterEach ->
   $('#jasmine-content').empty()
   document.title = defaultTitle
   ensureNoPathSubscriptions()
+  window.fixturesProject.destroy()
 
 window.keymap.bindKeys '*', 'meta-w': 'close'
 $(document).on 'close', -> window.close()

src/app/buffer.coffee

@@ -20,7 +20,7 @@ class Buffer
   anchorRanges: null
   refcount: 0
 
-  constructor: (path) ->
+  constructor: (path, @project) ->
     @id = @constructor.idCounter++
     @anchors = []
     @anchorRanges = []
@@ -38,8 +38,9 @@ class Buffer
 
   destroy: ->
     throw new Error("Destroying buffer twice with path '#{@getPath()}'") if @destroyed
-    @destroyed = true
     @file?.off()
+    @destroyed = true
+    @project?.removeBuffer(this)
 
   retain: ->
     @refcount++
@@ -50,6 +51,12 @@ class Buffer
     @destroy() if @refcount <= 0
     this
 
+  subscribeToFile: ->
+    @file?.on "contents-change", =>
+      unless @isModified()
+        @setText(fs.read(@file.getPath()))
+        @modified = false
+
   getPath: ->
     @file?.getPath()
 
@@ -58,10 +65,7 @@ class Buffer
 
     @file?.off()
     @file = new File(path)
-    @file.on "contents-change", =>
-      unless @isModified()
-        @setText(fs.read(@file.getPath()))
-        @modified = false
+    @subscribeToFile()
     @trigger "path-change", this
 
   getExtension: ->

src/app/project.coffee

@@ -21,7 +21,7 @@ class Project
   constructor: (path) ->
     @setPath(path)
     @editSessions = []
-    @buffer = []
+    @buffers = []
     @setTabText('  ')
     @setAutoIndent(true)
     @setSoftTabs(true)
@@ -30,6 +30,9 @@ class Project
       /(^|\/)\.git(\/|$)/
     ]
 
+  destroy: ->
+    editSession.destroy() for editSession in @getEditSessions()
+
   getPath: ->
     @rootDirectory?.path
 
@@ -106,9 +109,6 @@ class Project
   getEditSessions: ->
     new Array(@editSessions...)
 
-  destroy: ->
-    editSession.destroy() for editSession in @getEditSessions()
-
   removeEditSession: (editSession) ->
     _.remove(@editSessions, editSession)
 
@@ -122,16 +122,20 @@ class Project
   bufferForPath: (filePath) ->
     if filePath?
       filePath = @resolve(filePath)
-      return editSession.buffer for editSession in @editSessions when editSession.buffer.getPath() == filePath
-      @buildBuffer(filePath)
+      buffer = _.find @buffers, (buffer) -> buffer.getPath() == filePath
+      buffer or @buildBuffer(filePath)
     else
       @buildBuffer()
 
   buildBuffer: (filePath) ->
-    buffer = new Buffer(filePath)
+    buffer = new Buffer(filePath, this)
+    @buffers.push buffer
     @trigger 'new-buffer', buffer
     buffer
 
+  removeBuffer: (buffer) ->
+    _.remove(@buffers, buffer)
+
   scan: (regex, iterator) ->
     regex = new RegExp(regex.source, 'g')
     commands = [