AST formatter/pretty-printer

[jjcnn]

Describe your changes

A default formatter is added to ProgramAst and ModuleAst. The formatter acts as a pretty-printer for the AST, including indentation and procedure names rather than procedure indices/ids.

In order to perform indentation and to output legal assembly, a set of Formattable structs have been added. These keep track of the formatting context.

Call instructions are handled separately from other instructions, because the procedure indices and ids must be transformed into procedure names.

No tests have been added at this stage, because the formatter will be tested when connected to the compiler. It might also be worthwhile to add a -pp or -format option to the command-line assembler - comments regarding this feature would be appreciated.

No documentation has been added, since this PR is not user-facing.

Checklist before requesting a review

• Repo forked and branch created from next according to naming convention.
• Commit messages and codestyle follow conventions.
• Relevant issues are linked in the PR description.
• Tests added for new functionality.
• Documentation/comments updated according to changes.

[bobbinth]

Looks good! Thank you! I left a few small comments inline.

[bobbinth]

nit: Let's add a brief description (above the # Panics line) to say that this writs fully formatted MASM with correct indentation etc.

[bobbinth]

Let's update the comment to:

Writes this [ProgramAst] as formatted MASM code into the formatter.

The formatted code puts each instruction on a separate line and preserves correct indentation
for instruction blocks.

# Panics
Panics if import info is not associated with this program.

[bobbinth]

It might also be worthwhile to add a -pp or -format option to the command-line assembler.

Which command would this be relevant for? Or are you thinking about adding a new command - e.g., miden format? If the latter, I think this can be left for a future PR.

[jjcnn]

It might also be worthwhile to add a -pp or -format option to the command-line assembler.

Which command would this be relevant for? Or are you thinking about adding a new command - e.g., miden format? If the latter, I think this can be left for a future PR.

My plan was to add it as an option to an existing command, e.g., compile: miden compile -pp file.masm -o formatted.masm.

We could add it as a new command instead, if you think that's better.

I'm happy to leave that to a future PR.

[jjcnn]

Review comments addressed.

[bobbinth]

Looks good! Thank you! I left a few more comments inline. Once these are addressed, we can merge.

[bobbinth]

Let's update the comment to:

Writes this [ProgramAst] as formatted MASM code into the formatter.

The formatted code puts each instruction on a separate line and preserves correct indentation
for instruction blocks.

# Panics
Panics if import info is not associated with this program.

[bobbinth]

We could add it as a new command instead, if you think that's better.

I'm happy to leave that to a future PR.

Yes, let's hold off on this for now. One of the reasons is that we'd erase all internal comments from the input file - and I'm not sure if that's a good idea.

[jjcnn]

Review comments addressed, and PR rebased.