Sublime Text 3 - End key toggles end of line and start of comment - sublimetext3

Question

If I remember correctly, in Eclipse IDE you can press the End key and go to the end of a line, then again to go to the end of your code line, before the beginning of a comment. Here's an example with | as the cursor:
var str = 'press end to move the cursor here:'| // then here:|
It's very similar to how when you press Home it goes to the very start of the line, then another press moves the cursor to the beginning of your code, like this:
| |var str = 'press home to toggle cursor position';
Anyone know how to acheive this functionality in Sublime Text 3?

Answer 1

Sublime Text's native move and move_to commands don't support scopes or comments as an argument, therefore it is necessary to create a plugin in Python to achieve this behavior, and bind the End key to it.
From the Tools menu in Sublime Text, click New Plugin.
Replace the contents with the following:
import sublime, sublime_plugin
class MoveToEndOfLineOrStartOfCommentCommand(sublime_plugin.TextCommand):
def run(self, edit):
new_cursors = []
for cursor in self.view.sel():
cursor_end_pos = cursor.end()
line_end_pos = self.view.line(cursor_end_pos).end()
if line_end_pos == cursor_end_pos and self.view.match_selector(line_end_pos, 'comment'): # if the cursor is already at the end of the line and there is a comment at the end of the line
# move the cursor to the start of the comment
new_cursors.append(sublime.Region(self.view.extract_scope(line_end_pos).begin()))
else:
new_cursors.append(sublime.Region(line_end_pos)) # use default end of line behavior
self.view.sel().clear()
self.view.sel().add_all(new_cursors)
self.view.show(new_cursors[0]) # scroll to show the first cursor, if it is not already visible
Save it in the folder ST suggests, the name is unimportant as long as the extension is .py. (The command name for reference by the keybinding is based on the Python code/class name, not the file name.)
Goto Preferences menu -> Key Bindings - User and insert the following:
{ "keys": ["end"], "command": "move_to_end_of_line_or_start_of_comment" }
When pressing the End key, it will move to the end of the line as usual, unless it is already at the end of the line, and there is a comment, in which case it will move to the start of the comment.
Note that this is a tiny bit different to your example of:
var str = 'press end to move the cursor here:'| // then here:|
because it will move the cursor to after the whitespace at the end of the code like this:
var str = 'press end to move the cursor here:' |// then here:|
but it should give you a framework to work from. You can use the substr method of the view to get the characters in a certain region, so you can check for spaces using this quite easily.
EDIT: Note that since this answer was written, I have created a package for this functionality with some extra considerations, customization and use case support, as mentioned in another answer to this question.

Answer 2

Years later, I’ve stumbled onto this package: https://github.com/SublimeText/GoToEndOfLineOrScope
Sublime's scope documentation isn’t super easy to understand so it took a bit of digging and trial and error, but here’s a key binding that makes it work pretty well:
{
"keys": ["end"],
"command": "move_to_end_of_line_or_before_specified_scope",
"args": {
"scope": "comment.line",
"before_whitespace": true,
"eol_first": false
}
},
This makes the End key toggle between the end of the line and to the left of the comment delimiter, before any white space that trails code. It will also move to end of code first, then end of the line, saving a key press where that’s the intended behavior. It’s very easy to tweak though obviously.
The comment scope (as used above in Keith Hall’s answer) works too, but I don’t like the toggling behavior in block/multiline comments, so comment.line was a nice find.