[GSOC]Integration of libSyntax with the rest of the compiler pipeline

[rintaro (Rintaro Ishizaki)]

@DexinLi

So for this part, I need to separate the original parser.

Exactly.

@DexinLi

The first part will use SyntaxParsingContext to generate a libSyntax tree and the second part will traverse the libSyntax tree to derive the AST. Am I right? (This would be a huge job to finish.)

I don't think you should use SyntaxParsingContext. Instead, SyntaxBuilder would be the main part of the job. For example, the current Parser::parseExprArray would be something like:

// expr-array  -> '[' expr-array-element* ']'
SyntaxParserResult<ExprSyntax> SyntaxParser::parseExprArray() {
  ArrayExprSyntaxBuilder builder;

  // Parse '['.
  builder.useLeftSquare(consumeToken(tok::l_square));

  // Parse elements.
  SyntaxParserResult<ArrayExprElementSyntax> elementsResult = parseExprArrayElementList();
  if (elementsResult.isError()) {
    // Error handling.
  }
  builder.useElements(elementsResult.get());

  // Parse ']'.
  if (Tok.isNot(tok::r_square)) {
    // Error handling.
  }
  builder.useRightSquare(consumeToken(tok::l_square));

  // Return successful result.
  return makeSyntaxParserResult(builder.build());
}

And yes, this is definitely a huge and challenging job. You also need to modify AST to point to libSyntax nodes for source informations (e.g. getStartLoc()/getEndLoc()). In your proposal, I expect you to plan what you will finish in the time frame, and what you will not.

@DexinLi

For this part, I need to write a serializer and a deserializer to perform conversion between libSyntax tree and JSON. Is that right?

We already have a serializer; try swift -frontend -emit-syntax source.swift with the latest master build. For the deserializer, we are able to use LLVM YAML parser.