public LoxFunction Bind(LoxInstance instance)
{
VariableEnvironment environment = new VariableEnvironment(closure);
environment.Define("this", instance);
return(new LoxFunction(declaration, environment, isInitializer));
}
public object Call(Interpreter interpreter, List <object> arguments)
{
VariableEnvironment environment = new VariableEnvironment(closure);
for (int i = 0; i < declaration.parameters.Count; i++)
{
environment.Define(declaration.parameters[i].lexeme, arguments[i]);
}
try
{
interpreter.ExecuteBlock(declaration.body, environment);
}
catch (Return returnValue)
{
// Allow an empty return ("return;") in a constructor. When this happens, return "this".
if (isInitializer)
{
return(closure.GetAt(0, "this"));
}
return(returnValue.value);
}
return(null);
}
public Interpreter()
{
this.globals = new VariableEnvironment();
this.environment = globals;
//Define built-in function to get the time in milliseconds
globals.Define("clock", new ClockFn());
}
VariableEnvironment Ancestor(int distance)
{
VariableEnvironment environment = this;
for (int i = 0; i < distance; i++)
{
environment = environment.enclosing;
}
return(environment);
}
public void ExecuteBlock(List <Stmt> statements, VariableEnvironment environment)
{
//save the last environment (to be restored later)
VariableEnvironment previous = this.environment;
try
{
//change environment to the given one, and execute statments with this new environment
this.environment = environment;
foreach (Stmt statement in statements)
{
Execute(statement);
}
}
finally
{
//even if there's an exception, we need to restore the last environment before continuing
this.environment = previous;
}
}
public VariableEnvironment(VariableEnvironment enclosing)
{
this.enclosing = enclosing;
}
public VariableEnvironment()
{
enclosing = null;
}
public LoxFunction(Stmt.Function declaration, VariableEnvironment closure, Boolean isInitializer)
{
this.closure = closure;
this.declaration = declaration;
this.isInitializer = isInitializer;
}