Support joining editor lines with ctrl-J

This can be used with or without a selection to join one
or more lines with the line below it separated by a space.

Refs #134

src/app/edit-session.coffee

@@ -778,6 +778,9 @@ class EditSession
   lowerCase: ->
     @replaceSelectedText selectWordIfEmpty:true, (text) => text.toLowerCase()
 
+  joinLine: ->
+    @mutateSelectedText (selection) -> selection.joinLine()
+
   expandLastSelectionOverLine: ->
     @getLastSelection().expandOverLine()
 

src/app/editor.coffee

@@ -155,6 +155,7 @@ class Editor extends View
         'editor:move-line-up': @moveLineUp
         'editor:move-line-down': @moveLineDown
         'editor:duplicate-line': @duplicateLine
+        'editor:join-line': @joinLine
         'editor:toggle-indent-guide': => config.set('editor.showIndentGuide', !config.get('editor.showIndentGuide'))
         'editor:save-debug-snapshot': @saveDebugSnapshot
         'editor:toggle-line-numbers': =>  config.set('editor.showLineNumbers', !config.get('editor.showLineNumbers'))
@@ -183,6 +184,7 @@ class Editor extends View
   moveLineDown: -> @activeEditSession.moveLineDown()
   setCursorScreenPosition: (position, options) -> @activeEditSession.setCursorScreenPosition(position, options)
   duplicateLine: -> @activeEditSession.duplicateLine()
+  joinLine: -> @activeEditSession.joinLine()
   getCursorScreenPosition: -> @activeEditSession.getCursorScreenPosition()
   getCursorScreenRow: -> @activeEditSession.getCursorScreenRow()
   setCursorBufferPosition: (position, options) -> @activeEditSession.setCursorBufferPosition(position, options)

src/app/keymaps/editor.cson

@@ -24,6 +24,7 @@
   'ctrl-meta-up': 'editor:move-line-up'
   'ctrl-meta-down': 'editor:move-line-down'
   'meta-D': 'editor:duplicate-line'
+  'ctrl-J': 'editor:join-line'
 
 '.editor.mini':
   'enter': 'core:confirm',

src/app/selection.coffee

@@ -286,6 +286,31 @@ class Selection
         end--
       @editSession.buffer.deleteRows(start, end)
 
+  joinLine: ->
+    selectedRange = @getBufferRange()
+    if selectedRange.isEmpty()
+      return if selectedRange.start.row is @editSession.buffer.getLastRow()
+    else
+      joinMarker = @editSession.markBufferRange(selectedRange, invalidationStrategy: 'never')
+
+    rowCount = Math.max(1, selectedRange.getRowCount() - 1)
+    for row in [0...rowCount]
+      @cursor.setBufferPosition([selectedRange.start.row])
+      @cursor.moveToEndOfLine()
+      nextRow = selectedRange.start.row + 1
+      if nextRow <= @editSession.buffer.getLastRow() and @editSession.buffer.lineLengthForRow(nextRow) > 0
+        @insertText(' ')
+        @cursor.moveToEndOfLine()
+      @modifySelection =>
+        @cursor.moveRight()
+        @cursor.moveToFirstCharacterOfLine()
+      @deleteSelectedText()
+
+    if joinMarker?
+      newSelectedRange = @editSession.getMarkerBufferRange(joinMarker)
+      @setBufferRange(newSelectedRange)
+      @editSession.destroyMarker(joinMarker)
+
   outdentSelectedRows: ->
     [start, end] = @getBufferRowRange()
     buffer = @editSession.buffer