Implement a fast reading mode.

[MicahGale]

Problem

A common use case of MontePy is model interrogation, where you are interested in just getting a few pieces of data from say one cell.
For large models this isn't very practical as loading the whole model can take upwards of a minute, and makes prototyping the code hard.

Solution

I proposed making a mode to read the input file in which only the objects the user cares about are loaded.

For instance montepy.fast_read(cells={1,2,3})

would only read cells 1,2,3 and their supporting surfaces, materials, transforms, modifiers, etc.

This does present opportunities for doing bad ideas like trying to modify a partially loaded model.

This would require significant work under the hood, and would need to really optimize the process of identifying relevant objects.

[tjlaboss]

A "fast-read, read-only" mode would be extremely useful.

[MicahGale]

What do you mean by read-only here?

[tjlaboss]

Because...

This does present opportunities for doing bad ideas like trying to modify a partially loaded model.

...then, having a partially loaded model that the user cannot modify makes sense. It might be too annoying to make read-only versions of objects, though. It might be better to just make it the user's responsibility not to do bad ideas.

[MicahGale]

Yeah... I think just a lot of warnings in the documentation is the way to go.

[tjlaboss]

Idea from our meeting with @dodu94: on-the-fly parsing

[MicahGale]

I'll open an issue about it