// Return the value of a target symbol in this or an outer scope.
public MalVal Get(MalSym 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 MalEvalError("'unquote' used incorrectly (missing macro?)");
case "quasiquote":
throw new MalEvalError("'quasiquote' used incorrectly (missing macro?)");
case "splice-unquote":
throw new MalEvalError("'splice-unquote' used incorrectly (missing macro?)");
}
//// If here the symbol simply hasn't been defined or is mis-spelt.
throw new MalLookupError("Get - Symbol not found '" + keySymbol.ToString(true) + "'");
}
else
{
if (e.data.TryGetValue(keySymbol.getName(), out MalVal value))
{
return(value);
}
else
{
throw new MalInternalError("Get - Find successful but symbol retrieval failed '" + keySymbol.ToString(true) + "'");
}
}
}
public void Set(MalSym keySymbol, MalVal value)
{
// Takes a symbol key and a mal 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 MalEvalError("Attempt to redefine '" + keySymbol.ToString(true) + "'");
}
}
// Return the value of a target symbol in this or an outer scope.
public MalVal Get(MalSym keySymbol)
{
Env e = Find(keySymbol);
if (e != null && e.data.TryGetValue(keySymbol.getName(), out MalVal value))
{
return(value);
}
throw new MalEvalError("Symbol not found '" + keySymbol.ToString(true) + "'");
}
// Search for and return the environment (scope) that contains a target symbol.
public Env Find(MalSym 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);
}
}
// Return the value of a target symbol in this or an outer scope.
public MalVal Get(MalSym keySymbol)
{
Env e = Find(keySymbol);
if (e != null && e.data.TryGetValue(keySymbol.getName(), out MalVal value))
{
return(value);
}
switch (keySymbol.ToString(true))
{
case "quote":
throw new MalEvalError("'quote' used where expression expected");
case "quasiquote":
throw new MalEvalError("'quasiquote' used where expression expected");
case "splice-unquote":
throw new MalEvalError("'splice-unquote' used where expression expected");
default:
throw new MalEvalError("Symbol not found '" + keySymbol.ToString(true) + "'");
}
}
