53 add option to parsejava to print ast in json

[StoneyJackson]

feat: print AST in JSON format

To print an AST for a program in JSON format, do the following.

    plccmk --json_ast GRAMMAR_FILE
    parse --json_ast < PROGRAM_FILE

Adds a new dependency: the Jackson JSON library for java.
We distribute jars (in src/lib) from the following projects
under the Apache 2.0 license:

* https://github.com/FasterXML/jackson-core
* https://github.com/FasterXML/jackson-databind
* https://github.com/FasterXML/jackson-annotations

If manually compiling and running the generated Java code,
you'll need to add these jars to your classpath.

If you don't use the new --json_ast option,
these jars do not need to be in your classpath.

---

Closes #53 - Add option to print parsejava to print ast in json

Co-authored-by: Madison Mason <[email protected]>
Co-authored-by: Rarity Van Lone <[email protected]>
Co-authored-by: Stoney Jackson <[email protected]>

[StoneyJackson]

Review

Excellent! Now we need to get the design, the UI, and the documentation right. On the design side, it would be good if the new JSON generator is copied over to Java/ when it is needed. So this needs to be an extra option to plcc.py. This is important so existing systems, when updated do not need to update their classpaths. Also we need to update the installation documentation to explain how to add the 3rd party libraries, and when that is necessary. We also need docs on how to use this stuff. All docs are in the project's wiki. We should also update the docker images so they install the jackson libraries.

Here's a todo-list.

• Remove example grammar, program, and json ASTs from the repo.
• Tests need to pass.
• Need a test for the new system. Maybe build it out of the example grammar, program, and json AST that are currently in the root.
• Update wiki docs
  • Install
  • Use
• Write a commit message

[StoneyJackson]

plcc.py has a mechanism for handling command-line arguments. Unless there is a good reason, we should probably work within that framework.

Specifically, there is a loop in main() that walks through all the command line arguments and calls processFlag() to populate a global dict with flags. The rest of the system interrogates flags to decide what to do.

[StoneyJackson]

Let's use --json-ast for all of our options (e.g., plccmk --json-ast and plcc.py --json-ast). This better expresses what the new feature does. And allows for future features like --json-token.

The next phase of this project can add --python and make use of these --json-ast options.

[StoneyJackson]

Ideally, we should print the AST to stdout. Can we do that?

[StoneyJackson]

I've added a test that should pass when:

• --json-ast is used for plccmk and plcc.py
• parse prints the AST to stdout and not a file.

[StoneyJackson]

Great work on you recent commits!

I just overhauled the docs in main. Please synch this branch before updating docs.

[StoneyJackson]

• Do Windows Batch files need to be updated?

NOPE

[StoneyJackson]

I just overhauled the docs again! Now everything we either update the README.md in the root, or write a separate document about the new options. At the moment, the first sounds better.

[github-actions]

🎉 This PR is included in version 6.1.0 🎉

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