/// <summary>
/// classDecl → "class" IDENTIFIER ( "<" IDENTIFIER )?
/// "{" function* "}" ;
/// </summary>
private void ClassDeclaration()
{
Token className = Tokens.Consume(IDENTIFIER, "Expect class name.");
int nameConstant = MakeStringConstant(className.Lexeme); // no fixup needed
DeclareVariable(className); // The class name binds the class object type to a variable of the same name.
// todo? make the class declaration an expression, require explicit binding of class to variable (like var Pie = new Pie()); 27.2
EmitOpcode(className.Line, OP_CLASS);
EmitConstantIndex(className.Line, nameConstant, _FixupStrings);
DefineVariable(className.Line, MakeBitStrConstant(className.Lexeme));
_CurrentClass = new LoxCompilerClass(className, _CurrentClass);
// superclass:
if (Tokens.Match(LESS))
{
Tokens.Consume(IDENTIFIER, "Expect superclass name.");
if (Tokens.Previous().Lexeme == className.Lexeme)
{
throw new CompilerException(Tokens.Previous(), "A class cannot inherit from itself.");
}
NamedVariable(Tokens.Previous(), false); // push super class onto stack
BeginScope();
AddLocal(MakeSyntheticToken(SUPER, "super", LineOfLastToken));
DefineVariable(LineOfLastToken, 0);
NamedVariable(className); // push class onto stack
EmitOpcode(className.Line, OP_INHERIT);
_CurrentClass.HasSuperClass = true;
}
NamedVariable(className); // push class onto stack
// body:
Tokens.Consume(LEFT_BRACE, "Expect '{' before class body.");
while (!Tokens.Check(RIGHT_BRACE) && !Tokens.IsAtEnd())
{
// lox doesn't have field declarations, so anything before the brace that ends the class body must be a method.
// initializer is a special method
MethodDeclaration("method", ELoxFunctionType.TYPE_METHOD);
}
Tokens.Consume(RIGHT_BRACE, "Expect '}' after class body.");
EmitOpcode(LineOfLastToken, OP_POP); // pop class from stack
if (_CurrentClass.HasSuperClass)
{
EndScope();
}
_CurrentClass = _CurrentClass.Enclosing;
return;
}
private LoxCompiler(TokenList tokens, ELoxFunctionType type, string name, LoxCompiler enclosing, LoxCompilerClass enclosingClass)
: base(tokens, name)
{
_FunctionType = type;
Arity = 0;
_Chunk = new GearsChunk(name);
_Rules = new List <Rule>();
_EnclosingCompiler = enclosing;
_CurrentClass = enclosingClass;
// stack slot zero is used for 'this' reference in methods, and is empty for script/functions:
if (type != ELoxFunctionType.TYPE_FUNCTION)
{
_LocalVarData[_LocalCount++] = new LoxCompilerLocal("this", 0);
}
else
{
_LocalVarData[_LocalCount++] = new LoxCompilerLocal(string.Empty, 0);
}
}
public LoxCompilerClass(Token name, LoxCompilerClass enclosing = null)
{
Name = name;
Enclosing = enclosing;
}
