Re: Syntax tables for multiple modes [was: bug#22983: syntax-ppss returns wrong result.]

[Dmitry Gutov <dgutov@yandex.ru>]

On 03/21/2016 04:42 PM, Vitalie Spinu wrote:

>> """
>> Instead, if you want to know what indentation an inner mode would return if
>> STRING-BEFORE was before it, insert that string into the buffer (while
>> inhibiting undo history). Call the indentation function, then remove the string.
>> """
>
> Inner mode might decide to operate on string directly, or put stuff in a temp
> buffer, work on last line only, or simply ignore it.

Yes, each major mode would have to make all of these choices.

Why burden them with that concern? Wouldn't that become a part of the 
same problem that you yourself mentioned, "teaching modes about 
multi-modes"?

> Why to hard-wire the usage
> of STRING-BEFORE so badly?

What hard-wiring?

STRING-BEFORE is not a tangible part of my proposal. There's no API 
change tied to it.

> My gut feeling is to avoid modifying buffer context in indentation engine at all
> costs.

Why? That's worked out okay for me.

Alternatively, you can create a temp buffer each time, compose pieces of 
inner mode text in it, and call the indentation function. Again, in 
multi-mode code.

> In the future, if performance with temp buffers will be a real issue, we
> can add more low level functions for fast operation on string to do some common
> parsing tasks. We can even extend parse-ppss to deal with BEFORE-STRING.

Performance is a distant concern, complexity is the immediate one. If 
modifying buffers turns out to be a problem, then we can do all the 
stuff you mention above.