Give TextBuffer an object-oriented marker interface

The previous API revolved around methods on TextBuffer for querying
and manipulating markers based on their id. Now marker creation
methods return marker objects. These are still retrievable by id so
they can be dealt with across serialization boundaries in the future,
but you deal with them directly as objects.

src/app/buffer-marker.coffee

@@ -162,6 +162,12 @@ class BufferMarker
   unobserve: (callback) ->
     @off 'changed', callback
 
+  destroy: ->
+    @buffer.destroyMarker(@id)
+
+  isValid: ->
+    @buffer.getMarker(@id)?
+
   ###
   # Internal #
   ###

src/app/text-buffer.coffee

@@ -427,6 +427,9 @@ class Buffer
   getMarkers: ->
     _.values(@validMarkers)
 
+  getMarker: (id) ->
+    @validMarkers[id]
+
   # Public: Finds the first marker satisfying the given attributes
   #
   # Returns a {String} marker-identifier
@@ -440,11 +443,10 @@ class Buffer
   #   startRow - The row at which the marker starts
   #   endRow - The row at which the marker ends
   #
-  # Returns an {Array} of {String} marker-identifiers
+  # Returns an {Array} of {BufferMarker}s
   findMarkers: (attributes) ->
     markers = @getMarkers().filter (marker) -> marker.matchesAttributes(attributes)
     markers.sort (a, b) -> a.getRange().compare(b.getRange())
-    _.pluck(markers, 'id')
 
   # Public: Retrieves the quantity of markers in a buffer.
   #
@@ -474,7 +476,6 @@ class Buffer
       attributes
     }, options))
     @validMarkers[marker.id] = marker
-    marker.id
 
   # Public: Constructs a new marker at a given position.
   #
@@ -485,129 +486,14 @@ class Buffer
   markPosition: (position, options) ->
     @markRange([position, position], _.defaults({noTail: true}, options))
 
-  # Public: Removes the marker with the given id.
-  #
-  # id - The {Number} of the ID to remove
-  destroyMarker: (id) ->
-    delete @validMarkers[id]
-    delete @invalidMarkers[id]
-
-  getMarkerPosition: (args...) ->
-    @getMarkerHeadPosition(args...)
-
-  setMarkerPosition: (args...) ->
-    @setMarkerHeadPosition(args...)
-
-  # Public: Retrieves the position of the marker's head.
-  #
-  # id - A {Number} representing the marker to check
-  #
-  # Returns a {Point}, or `null` if the marker does not exist.
-  getMarkerHeadPosition: (id) ->
-    @validMarkers[id]?.getHeadPosition()
-
-  # Public: Sets the position of the marker's head.
-  #
-  # id - A {Number} representing the marker to change
-  # position - The new {Point} to place the head
-  # options - A hash with the following keys:
-  #         :clip - if `true`, the point is [clipped]{Buffer.clipPosition}
-  #         :bufferChanged - if `true`, indicates that the {Buffer} should trigger an event that it's changed
-  #
-  # Returns a {Point} representing the new head position.
-  setMarkerHeadPosition: (id, position, options) ->
-    @validMarkers[id]?.setHeadPosition(position)
-
-  # Public: Retrieves the position of the marker's tail.
-  #
-  # id - A {Number} representing the marker to check
-  #
-  # Returns a {Point}, or `null` if the marker does not exist.
-  getMarkerTailPosition: (id) ->
-    @validMarkers[id]?.getTailPosition()
-
-  # Public: Sets the position of the marker's tail.
-  #
-  # id - A {Number} representing the marker to change
-  # position - The new {Point} to place the tail
-  # options - A hash with the following keys:
-  #         :clip - if `true`, the point is [clipped]{Buffer.clipPosition}
-  #         :bufferChanged - if `true`, indicates that the {Buffer} should trigger an event that it's changed
-  #
-  # Returns a {Point} representing the new tail position.
-  setMarkerTailPosition: (id, position, options) ->
-    @validMarkers[id]?.setTailPosition(position)
-
-  # Public: Retrieves the {Range} between a marker's head and its tail.
-  #
-  # id - A {Number} representing the marker to check
-  #
-  # Returns a {Range}.
-  getMarkerRange: (id) ->
-    @validMarkers[id]?.getRange()
-
-  # Public: Sets the marker's range, potentialy modifying both its head and tail.
-  #
-  # id - A {Number} representing the marker to change
-  # range - The new {Range} the marker should cover
-  # options - A hash of options with the following keys:
-  #           :reverse - if `true`, the marker is reversed; that is, its tail is "above" the head
-  #           :noTail - if `true`, the marker doesn't have a tail
-  setMarkerRange: (id, range, options) ->
-    @validMarkers[id]?.setRange(range, options)
-
-  # Public: Sets the marker's tail to the same position as the marker's head.
-  #
-  # This only works if there isn't already a tail position.
-  #
-  # id - A {Number} representing the marker to change
-  #
-  # Returns a {Point} representing the new tail position.
-  placeMarkerTail: (id) ->
-    @validMarkers[id]?.placeTail()
-
-  # Public: Removes the tail from the marker.
-  #
-  # id - A {Number} representing the marker to change
-  clearMarkerTail: (id) ->
-    @validMarkers[id]?.clearTail()
-
-  # Public: Identifies if the ending position of a marker is greater than the starting position.
-  #
-  # This can happen when, for example, you highlight text "up" in a {Buffer}.
-  #
-  # id - A {Number} representing the marker to check
-  #
-  # Returns a {Boolean}.
-  isMarkerReversed: (id) ->
-    @validMarkers[id]?.isReversed()
-
-  # Public: Identifies if the marker's head position is equal to its tail.
-  #
-  # id - A {Number} representing the marker to check
-  #
-  # Returns a {Boolean}.
-  isMarkerRangeEmpty: (id) ->
-    @validMarkers[id]?.isRangeEmpty()
-
-  # Public: Sets a callback to be fired whenever a marker is changed.
-  #
-  # id - A {Number} representing the marker to watch
-  # callback - A {Function} to execute
-  observeMarker: (id, callback) ->
-    @validMarkers[id]?.observe(callback)
-
   # Public: Given a buffer position, this finds all markers that contain the position.
   #
   # bufferPosition - A {Point} to check
   #
   # Returns an {Array} of {Numbers}, representing marker IDs containing `bufferPosition`.
-  markersForPosition: (bufferPosition) ->
-    bufferPosition = Point.fromObject(bufferPosition)
-    ids = []
-    for id, marker of @validMarkers
-      ids.push(id) if marker.containsPoint(bufferPosition)
-    ids
+  markersForPosition: (position) ->
+    position = Point.fromObject(position)
+    @getMarkers().filter (marker) -> marker.containsPoint(position)
 
   # Public: Identifies if a character sequence is within a certain range.
   #
@@ -758,6 +644,10 @@ class Buffer
   # Internal #
   ###
 
+  destroyMarker: (id) ->
+    delete @validMarkers[id]
+    delete @invalidMarkers[id]
+
   scheduleModifiedEvents: ->
     clearTimeout(@stoppedChangingTimeout) if @stoppedChangingTimeout
     stoppedChangingCallback = =>