Re: Help getting started - lilypond structure

[Mats Bengtsson]

If you want to implement a new parser, I recommend that you
look at the parser in LilyPond, lily/parser.yy. There, you will
at least learn that the full syntax is a fairly complex creature.

Joe Neeman wrote:
> This is a follow-up on the question of lilypond structure. Here is how I 
> think a lilypond file is organised. It is fairly important that I get 
> this right, because I am trying to rewrite the lily parser in denemo. 
> Please correct me if I'm wrong.
>
> A Voice consists of a sequence of notes and various other objects (like 
> time signatures, etc). The notes are entirely sequential.
Time signatures and that like are handled by the Staff contexts, so you
could in principle have
\new Staff{ \time 3/4 \key a \minor \new Voice {...}}


> A \notes block consists of one or more Voice contexts. The Voices can be 
> arranged sequentially or in parallel or a combination of both.

\notes just tells the lexicographic part of the front end to switch
input syntax. You could actually say
\notes \score{
  \new Staff  ...
}
for example.

> A Staff consists of one or more \notes blocks. The blocks can be 
> arranged sequentially or in parallel or a combination of both.

No, a Staff context contains one or more Voice contexts. To learn the
full context hierarchy, you could browse up through the program
documentation at
http://lilypond.org/doc/v2.2/Documentation/user/out-www/lilypond-internals/Contexts.html#Contexts
However, it is possible to redefine this hierarchy and add or remove
context types so if you want a full parser, you shouldn't hard code
this context hierarchy. In fact, the different contexts don't really
belong to the syntax but to the semantics.

> A \score block consists of one or more Staves. The Staves can be 
> arranged seqentially or in parallel or a combination of both.
>
> Additionally, staves can be grouped (in parallel only) into Piano 
> Staves, Grand Staves, Choir Staves and several other group types. These 
> groups can be included in a \score block in the same way single staves are.

See above.

> TIA,
> Joe
>
> PS, if I have "\notes{a4 b << {c d} {e f} >> }", then the {c d} by 
> itself is a Voice context, right? And so is {e f}?

No, they will belong to the same Voice context, which you see if you
add a \stemUp in {c d}, for example. However, if you do
<< {c d} \\ {e f} >>
you will get two new Voice contexts.


    /Mats