Re: Incremental compiling

[David Kastrup]

Vaughan McAlley <address@hidden> writes:

> Following one of the tangents from the “Sibelius Software UK office
> shuts down thread”, here’s a potential algorithm for incremental
> compiling. It’s only a suggestion: sorry if it’s flawed or you don’t
> like it!
>
> • when Lilypond is compiled, a temp file is created, containing the
> source file, and page-layout structure of the music. For example:
> Page 1 has two systems
>   System 1 contains measures 1-4
>   System 2 contains measures 5-7
> etc...
>
> Maybe also a database of which measure (if any) the beginning of each
> line of source is part of.
>
> • if Lilypond is invoked with the --incremental option, Lilypond
> compares its cached copy of the source file with the source file
> presented, and finds the first point of difference. Then it knows
> which measure it wants to be on the first page it’s actually
> publishing

No, it doesn't.  As opposed to TeX which makes its _vertical_ break
decisions sequentially and independently, LilyPond uses global
optimization.  One can still save the local decision tree, but it may
take a number of pages before it locally collapses to a single choice.

-- 
David Kastrup