private Expression ParseExpression()
{
Expression first = ParseExpressionAtom();
while (IsOperator(_lookahead.Kind))
{
Token token = ReadToken();
string name = TokenKindToOperatorName(token.Position, token.Kind);
Expression other = ParseExpressionAtom();
first = new FunctionExpression(token.Position, name, new Expression[] { first, other });
}
return first;
}
public void visit(FunctionExpression that)
{
Console.Write("{0}(", that.Name);
foreach (Expression argument in that.Arguments)
{
argument.visit(this);
if (argument != that.Arguments[that.Arguments.Length - 1])
Console.Write(", ");
}
Console.Write(")");
}
public void visit(FunctionExpression that)
{
// let the arguments resolve their types
foreach (Expression argument in that.Arguments)
argument.visit(this);
// mangle the parameter list so as to be able to look up the mangled symbol
System.Text.StringBuilder mangled = new System.Text.StringBuilder(64);
that.Encode(mangled);
string name = mangled.ToString();
// look up the function declaration
Declaration declaration = _symbols.Lookup(name);
if (declaration == null)
throw new CheckerError(that.Position, "Unknown function name '" + Demangler.Decode(name) + "' in function call");
// check that the symbol is actually a function
switch (declaration.Kind)
{
case SymbolKind.Constant:
throw new CheckerError(that.Position, "Cannot call constant");
case SymbolKind.Function:
break;
case SymbolKind.Parameter:
throw new CheckerError(that.Position, "Cannot call parameter");
case SymbolKind.Variable:
throw new CheckerError(that.Position, "Cannot call variable");
default:
throw new CheckerError(declaration.Position, "Unknown symbol kind: " + declaration.Kind.ToString());
}
// check that the number of arguments match the number of parameters
FunctionDeclaration function = (FunctionDeclaration) declaration;
if (that.Arguments.Length != function.Parameters.Length)
throw new CheckerError(that.Position, "Incorrect number of parameters in function call");
// check that the argument types match the parameter types
for (int i = 0; i < that.Arguments.Length; i++)
{
if (that.Arguments[i].Type.Kind != function.Parameters[i].Type.Kind)
throw new CheckerError(that.Arguments[i].Position, "Type mismatch in argument to function");
}
that.Type = declaration.Type;
}