Re: Make an editor for a language

  "Davide Marino" <dfsgm@tin.it> writes:
> I need make an editor for a programming language. It would be capable
> of color tokens according their lexical value. ...


One idea for dealing with this for an FSA-based scanner is to remember
the state between any two characters. After a change, you start
running the FSA from the first changed character, and then continue
until the state synchronizes with the stored state. You can defer
this operation for off-screen stuff until it becomes on-screen.


If your lexical analysis requires something like lex' lookahead
feature, things become complicated, though. And I have no idea how to
coerce lex/flex to support this scheme.


> My idea is to mantain in
> memory all the text in this form:
>
> - there is a double linked list with one element for each line of text
> with a link to the line after and before.


I tried that and failed. A much better representation in my
experience is the plain character array with a hole at the cursor.
AFAIK emacs uses this data structure; I have also seen it described in
several places, but don't remember where.


- anton
--
M. Anton Ertl Some things have to be seen to be believed
anton@mips.complang.tuwien.ac.at Most things have to be believed to be seen
http://www.complang.tuwien.ac.at/anton/home.html

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