Conditionally including lyrics

[Marc Hohl]

Hello list,

I have a lot of small music pieces with several stanzas which I store
like this

textA = \lyricmode {
  \set stanza = "1. "
  this is the first stan -- za.
}

textB = \lyricmode {
  \set stanza = "2. "
  and this one is the se -- cond.
}

textC = ...

together with the melody in files called data01.ily, data02.ily etc.

Now these files should be processed by some kind of generator file, 
which consists of something like this:

\include "data01.ily"
\score {
  \new Staff {
    \new Voice { \melody }
    \addlyrics { \textA }
    \addlyrics { \textB }
    \addlyrics { \textC }
  }
}

Now the data files contain different numbers of stanzas, and ideally, 
the generator file
should be intelligent enough to include all stanzas which are present. 
Has someone an idea
how to create a loop which scans for textA, textB, textC etc. and puts a 
command that acts like
\addlyrics for each hit?

I could do this with some shell scripting, but a lilypondish solution 
would be better to
maintain, I think.

Thanks in advance,

Marc