// Return the value of a target symbol in this or an outer scope.
public JKLVal Get(JKLSym keySymbol)
{
Env e = Find(keySymbol);
if (e == null)
{
switch (keySymbol.ToString(true))
{
// Some symbols are only valid when used in a particular context.
case "unquote":
throw new JKLEvalError("'unquote' used incorrectly (missing macro?)");
case "quasiquote":
throw new JKLEvalError("'quasiquote' used incorrectly (missing macro?)");
case "splice-unquote":
throw new JKLEvalError("'splice-unquote' used incorrectly (missing macro?)");
}
//// If here the symbol simply hasn't been defined or is mis-spelt.
throw new JKLLookupError("Get - Symbol not found '" + keySymbol.ToString(true) + "'");
}
else
{
if (e.data.TryGetValue(keySymbol.getName(), out JKLVal value))
{
return(value);
}
else
{
throw new JKLInternalError("Get - Find successful but symbol retrieval failed '" + keySymbol.ToString(true) + "'");
}
}
}
public void Set(JKLSym keySymbol, JKLVal value)
{
// Takes a symbol key and a JKL value and adds them to the environment.
if (!data.TryAdd(keySymbol.getName(), value))
{
// Symbol can shadow an equivalent in an outer scope but cannot be duped.
throw new JKLEvalError("Attempt to redefine '" + keySymbol.ToString(true) + "'");
}
}
// Search for and return the environment (scope) that contains a target symbol.
public Env Find(JKLSym keySymbol)
{
if (data.ContainsKey(keySymbol.getName()))
{
// Symbol exists in the current scope.
return(this);
}
else if (outer != null)
{
// Recurse to search for the symbol in an outer scope.
return(outer.Find(keySymbol));
}
else
{
// Symbol is not defined.
return(null);
}
}