protocol ListBuilder

[RoBo-Inc]

Introducing the ListBuilder protocol with a default function implementation can significantly reduce the amount of generated code in the Sources/SwiftSyntaxBuilder/generated/ResultBuilders.swift file. Additionally, it makes the codebase more comprehensible by emphasizing similarities among all the result builders and highlighting differences between them.

Apart from this, the PR addresses another issue that requires detailed explanation. Two generated result builders (ExprListBuilder and UnexpectedNodesBuilder) stood out from the others. They were "special" because their Expression was not a concrete type; instead, it was a protocol (ExprSyntaxProtocol and SyntaxProtocol respectively). So we were dealing with existentials here, which are not very good. Furthermore, we had to create additional extensions dedicated to these two result builders, located at the bottom of the Sources/SwiftSyntaxBuilder/ResultBuilderExtensions.swift file, accompanied by a lengthy comment.

The key point is that these two result builders don't need to be treated as special cases, and they don't have to involve existentials. They can conform to the ListBuilder protocol, just like all the other builders do. Despite this, we can still make them work with protocols just as before, maintaining the same approach used for some other result builders in the same file (Sources/SwiftSyntaxBuilder/ResultBuilderExtensions.swift). This eliminates the need for special treatment and enhances codebase consistency.

In summary, this PR represents a refactoring. All the functionality remains unchanged. However, the refactoring is significant, making the code more structured, consistent, and efficient.

[ahoppen]

Removing >3000 LOC. I love it 😍

[RoBo-Inc]

Updated ✅

1. generated/ResultBuilders file:

• Removed the unnecessary comments as requested.
• Added "MARK: -" separators instead, for better readability.

2. Put the extensions back, but:

• Moved them from ResultBuilderExtensions to ConvenienceInitializers file. Because these extensions are not specifically related to the result builders anymore. At the same time they indeed are convenience initializers.
• Improved its bodies a bit.
• Made the both initializers to be public for consistency (before only one of them was public).

Note: The ConvenienceInitializers file has warning to insert new extensions in alphabetical order. But I just append the two extensions (which I moved) to the end of the file. Because the extensions are related and has the common comment. Besides the other extensions in the file actually are not in alphabetical order anyways... 😳

[ahoppen]

Thank you. Let’s keep the ordering in ConvenienceInitializers.swift alphabetical, though. Or at least not break it any more than it’s already broken.

[RoBo-Inc]

Done ✅
All alphabetical now 😃

[ahoppen]

@swift-ci Please test

[ahoppen]

@swift-ci Please test

[ahoppen]

@swift-ci Please test Windows