How far can CTFE go?

[H. S. Teoh]

I'm experimenting with pluggable expression parser modules, and I'm
wondering if I can use CTFE to build parser tables and such. What are
the current limitations of CTFE? Are dynamic arrays of structs
supported? Associative arrays?  What about compile-time cross-module
initialization?

The idea is to have a library of modules that parse different kinds of
expressions, and depending on which subset of modules are actually
imported into the main program, the capability of the generated parser
will vary. E.g., the basic parser understands only scalar expressions;
import the vector module and it gets extended to handle vector
expressions; import another module and it understands other kinds of
expressions (matrices, etc.).  The parser will be fully specified at
compile-time (I'm not planning to support dynamically loading parsing
modules), so ideally this should be possible to handle using CTFE.

Or is this just a fool's errand?

On another level, how far are we expecting CTFE to go eventually? In my
mind, the ideal situation would be that CTFE can replace writing an
arbitrarily complex helper program that generates D code (either
functions or data, etc.) which then gets incorporated into the main
program.


T

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