[FLINK-10170] [table] Support string representation for map and array types in descriptor-based Table API

[jerryjzhang]

What is the purpose of the change

Since 1.6 the recommended way of creating source/sink table is using connector/format/schema/ descriptors. However, when declaring map types in the schema descriptor, the following exception would be thrown:

org.apache.flink.table.api.TableException: A string representation for map types is not supported yet.

This pull request is to add string representation support for map types.

Brief change log

• Add new Keyword and PackratParser for map types in TypeStringUtils
• Add normalization logic for map types in TypeStringUtils.writeTypeInfo()
• Update relevant unit tests in TypeStringUtilsTest and TableDescriptorTest

Verifying this change

This change can be verified covered by updated unit tests, such as TypeStringUtilsTest and TableDescriptorTest.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
• The serializers: (no)
• The runtime per-record code paths (performance sensitive): (no)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (no)
• If yes, how is the feature documented? (not applicable)

[Jiayi-Liao]

@tragicjun +1, this is good, but can you implement the same thing on other types like array? I think they should be in one PR.

[twalthr]

Thanks for the PR @tragicjun. The changes look good to me. One thing that we could improve is making the current implementation more consistent. So far we are using ROW(...) (with parenthesis), but after looking into other implementations such as Hive, we should have used Row<> as well. We should update this in a backwards compatible way. Either in this PR or in a follow-up issue. What do you think?

Can you also update the documentation?

[jerryjzhang]

@twalthr In the latest commit, I've replaced bracket () with <> for all complex types and updated the documentation. To ensure backward compatibility, bracket () is still supported by the parsers. Please let me know if anything else is missing.

[jerryjzhang]

@twalthr could you review this again? Anything else I should do before the merge, thanks.

[jerryjzhang]

@buptljy In the latest commit, the array types are supported as well, please check it out.

[Jiayi-Liao]

lgtm.

[jerryjzhang]

Ready to be merged, could you take a look @fhueske @twalthr ?

[twalthr]

Thank you @tragicjun. The changes look good to me. I will take care of merging this...