Add Javadoc on generated Psi interfaces

[oowekyala]

Many thanks for the great work on this plugin!

Something irks me slightly though: I find I constantly have to refer directly to the BNF file to find out the structure of a node. Maybe there's another way to do that I'm not aware of (?), but for me what would really help is to add a javadoc comment on the generated psi interfaces.

The generated parser already has a doc comment on every method, which describes the form of the production, eg. here:

https://github.com/JetBrains/intellij-sdk-docs/blob/69edc8f403b1ab4d7a7b7a7c8155f3567228b76d/code_samples/simple_language_plugin/gen/com/simpleplugin/parser/SimpleParser.java#L93-L94

Having a javadoc comment featuring the same kind of info would be nice. Token references would link to the IElementType constant if it's generated too, production references would link to the relevant Psi interface.

I imagine if it was on a public production (eg if simpleFile was public), the comment // (property|COMMENT)* would be rendered as the following Javadoc:

/**
 * <pre>
 *   simpleFile ::= ({@linkplain SimpleProperty property} | {@linkplain SimpleTypes.COMMENT COMMENT})*
 * </pre>
 */
public interface SimpleFile { // ... 

(modulo imports). Maybe even adding an attribute to add a header line to the javadoc could be helpful too.

I'm not aware of an existing way to do this. If this is already possible then sorry for the noise.

[gregsh]

Thanks for a good suggestion. I'll try to find some time for that in the new update.