Extension methods

[jchitel]

Extensions

Dependencies: Overloads, Interfaces

New syntactic features:

New Tokens:

WITH ::= with
THIS ::= this
DOUBLE_COLON ::= ::

New NonTerminals:

MethodDeclaration ::= Type IDENT TypeParamList? ParameterList FAT_ARROW (Expression | Statement)
MethodInvoation ::= Expression DOT IDENT TypeArgList? LPAREN (Expression (COMMA Expression)*)? RPAREN
MethodReference ::= Expression DOUBLE_COLON IDENT

Extended NonTerminals:

Type ::= Type WITH LBRACE MethodDeclaration* RBRACE
Expression ::= THIS
             | MethodInvocation
             | MethodReference

New semantic features:

• Extensions add methods to types
• Methods are functions "bound" to a type, and can be called with a method invocation
• Methods can also be referenced using a method reference expression
• Methods can use the 'this' expression to refer to the instance of the type it was invoked on
• Extensions include the methods as part of the types, and are included in interface assignability checks
• Assignability to extensions ignores the methods, based on structure only

Transformation:

• Will require invocation instruction and method reference instruction