Handle Alias Syntax Errors

[rcosta358]

Previously, when a @RefinementAlias contained an invalid definition, e.g. missing parameter type, it silently failed parsing and then would return a not found error when it was trying to be used.

Example

@RefinementAlias("Positive(v) { v > 0 }")
public class Example {
    void example() {
        @Refinement("Positive(x)")
        int x = 1; // error
    }
}

Before:

Failed to check refinement at: 

Alias 'Positive' not found
@liquidjava.specification.Refinement("Positive(x)")
int x = 1

After:

Syntax error with message
Alias definitions should be in format <name>(<parameters>) { <definition> }
Found in refinement:
Positive(v) { v > 0 }

[CatarinaGamboa]

Good short fix, do you think in the future we can pinpoint why it is invalid? Like in this case the type of v is missing right, it could be great to add that so we can be more specific on the issues

[rcosta358]

Yeah sure!

[rcosta358]

The issue is that the parsing doesn't fail here:

public static AliasDTO getAliasDeclaration(String s) throws ParsingException {
  Optional<String> os = getErrors(s);
  if (os.isPresent()) // should fail here
      throw new ParsingException(os.get());
  // ...
}

Since it doesn't throw a ParsingException, we can't the proper error message containing the next token the parser was expecting (a type in this case).

It only fails when it sees that the parse tree is not an alias (by returning null):

public AliasDTO getAlias(ParseTree rc) {
  if (rc instanceof AliasContext) {
      // ...
      return new AliasDTO(name, varTypes, varNames, ref);

  } else if (rc.getChildCount() > 0) {
      int i = rc.getChildCount();
      if (i > 0) {
          return getAlias(rc.getChild(0));
      }
  }
  return null;
}

Fow now I'll just follow the approach done in the ghost declaration parsing:

AliasDTO alias = av.getAlias(rc);
if (alias == null)
    throw new ParsingException("The alias should be in format <name>(<parameters>) { <definition> }");
return alias;