emacs syntax lexer: bad mix of greediness & laziness

[sadielbartholomew]

#2784 provides correct highlighting by eyeball, as tested, however I have since discovered through dev use that it is occasionally slowed, & sometimes hangs, in practice. I have traced this back to the typing of the opening but not yet closing marker for specific syntactical expressions, namely:

• {# towards {# ... #}
• {% towards {% ... %}

... & in turn to a mix of greedy & lazy quantifiers in the associated regular expressions, which have identical format bar the #/% distinction. This PR replaces those instances at fault.

(This bug discovery will be another lesson to label on my steep learning curve in regular expressions.)

Also amend one other issue manifest with regular use; a task with plain-text name on the first line of a graph string is recognised as a key for a key = value pair from not considering the subsequent >, e.g:

graph = """
    plaintexttask => not_just_plain_text_task
    """

highlights plaintexttask in the same colour as graph & not not_just_plain_text_task as makes sense contextually.

[oliver-sanders]

Bugs all replicated, fixes all tested. Good!

[kinow]

Besides PyCharm and Eclipse, the only other editor I normally use is vim. I think I used emacs in the university to follow the assignments of a professor... but unfortunately I never had a chance to play with emacs again. So take my review with a pinch of salt 😬

Regexes look OK (I can normally parse/understand some regex-fu, but normally rely on IDE + Pythex to tell me if I messed it up).

Installed emacs25 on Ubuntu, followed instructions to set up the syntax highlighting (slightly broken I think, but sending a pull request for that), and can confirm that at least the task names are now matching before/after the => token.

Here's the screen shot of emacs with the change in this pull request.

And here's what it was looking before. Notice that the task on the left has a different colour.

+1 LGTM

[sadielbartholomew]

the only other editor I normally use is vim

Thanks @kinow. Sorry for having to assign you as second reviewer, a stand-in was needed for Hilary who reviewed the original PR, though being an emacs user is not strictly necessary as basic inspection & typing should suffice (in fact both he & Oliver also use vim).

[kinow]

It is actually good so I can learn some emacs too. Happy to review future issues like this and keep learning :-)