Assignables

[jchitel]

Assignables

Dependencies: Import/Export Additions

Description:

As of now, the only way to assign things is to use local variables. Obviously, other things are assignable:

• fields/properties of structs/classes
• array indices
• this variable in class constructors Eventually:
• destructuring
  • array destructuring
  • array rest
  • struct destructuring
  • struct rest

To support these things, we need assignable expressions. Assignable expressions are a subset of expressions that can appear on the left side of an assignment statement.

New syntactic features:

New Tokens:

none

New NonTerminals:

Assignment ::= AssignableExpression EQUALS Expression
AssignableExpression ::= THIS
                       | IDENT
                       | FieldAccess
                       | ArrayAccess

Extended NonTerminals:

Expression ::= INTEGER_LITERAL |
               FLOATING_POINT_LITERAL |
               STRING_LITERAL |
               CHARACTER_LITERAL |
               VALUE |
               ArrayLiteral |
               StructLiteral |
               TupleLiteral |
               FunctionApplication |
               UnaryOperation |
               BinaryOperation |
               Assignment |           -- replaces VarDeclaration
               AssignableExpression | -- replaces FieldAccess, ArrayAccess, IDENT, and THIS
               LambdaExpression |
               IfElseExpression |
               MethodInvocation |
               MethodReference |
               NewObject |
               SuperCall |
               SuperMethodCall |
               LPAREN Expression RPAREN

New semantic features:

• Assignments behave the same way as VarDeclarations
• But this time there are things on the left side that already have a type, and are not inferred
• The right side needs to be assignable to the left side

Transformation:

• Assignable expressions will almost certainly require some sort of reference resolution logic

[jchitel]

4 has been completed, so this is now open for development.