Re: Proposed extension of show-paren-mode: Highlight parens when point is in L or R margin.

[Andy Moreton <andrewjmoreton@gmail.com>]

On Wed 15 Oct 2014, Alan Mackenzie wrote:
> Sorry, I expressed myself really badly.  I'll try again.  Dividing a
> source file line into LH periphery, core, RH periphery:
>
>             foo = /* */ bar; /* comment */
> PPPPPPPPPPPP                PPPPPPPPPPPPPP
>             CCCCCCCCCCCCCCCC
>
> The periphery of a line does not extend outside that line.  An "internal
> comment" inside a line (a fairly rare thing) is not part of the
> periphery.  Comments before the core are vanishingly rare, hence not
> included in the definition.
>
> The candidates for a pertinent parenthesis are then:
> (i) A paren that point is immediately outside of.  A closing paren takes
> priority over an opening one.  (This is the existing implementation.)
> (ii) (Only when point is in the periphery) a paren at the beginning or
> end of the core.  The one nearest point takes priority.

So if understand correctly, LH periphery is leading whitespace/comments,
and RH periphery is trailing whitespace/comments ?

    AndyM