"non-blocking" read in VHDL?

[Edward L. Hepler]

Is there any VHDL equivalent to a "non-blocking" read in C?

I want to be able to read from a file only when a line exists,
otherwise wait until some "future" time when I can try again
and a line does exist... Effectively a "FIFO" type mechanism from
another process...

I know that I can do this via the FLI in Modelsim by writing C code,
but would like to do this via native VHDL if possible...

Thanks,

Ed Hepler