static ast.Node _ExpandMacros(ast.Node node)
{
if (!(node is ast.CallExpression))
{
return(node);
}
ast.CallExpression callExpression = (ast.CallExpression)node;
Object.Macro macro = isMacroCall(callExpression, _env);
if (macro == null)
{
return(node);
}
List <Object.Quote> args = quoteArgs(callExpression);
Object.Environment evalEnv = extendMacroEnv(macro, args);
Object.Object evaluated = evaluator.Eval(macro.Body, evalEnv);
if (!(evaluated is Object.Quote))
{
System.Console.WriteLine("we only support returning AST-nodes from macros");
System.Environment.Exit(-1);
}
Object.Quote quote = (Object.Quote)evaluated;
return(quote.Node);
}
static ast.Expression parseCallExpression(ast.Expression function)
{
ast.CallExpression exp = new ast.CallExpression {
Token = curToken, Function = function
};
exp.Arguments = parseExpressionList(token.RPAREN);
return(exp);
}
static bool isUnquoteCall(ast.Node node)
{
if (!(node is ast.CallExpression))
{
return(false);
}
ast.CallExpression callExpression = (ast.CallExpression)node;
return(callExpression.Function.TokenLiteral() == "unquote");
}
static List <Object.Quote> quoteArgs(ast.CallExpression exp)
{
List <Object.Quote> args = new List <Object.Quote>();
foreach (ast.Expression a in exp.Arguments)
{
args.Add(new Object.Quote {
Node = a
});
}
return(args);
}
private static Object.Environment _env; // to pass the environment on the originally crammed-to-argument function definition
static ast.Node _evalUnquotedCalss(ast.Node node)
{
if (!isUnquoteCall(node))
{
return(node);
}
if (!(node is ast.CallExpression))
{
return(node);
}
ast.CallExpression call = (ast.CallExpression)node;
if (call.Arguments.Count != 1)
{
return(node);
}
Object.Object unquoted = evaluator.Eval(call.Arguments[0], _env); // env needs to reach this
return(convertObjectToASTNode(unquoted));
}
static Object.Macro isMacroCall(ast.CallExpression exp, Object.Environment env)
{
if (!(exp.Function is ast.Identifier))
{
return(null);
}
ast.Identifier identifier = (ast.Identifier)exp.Function;
Object.Object obj = env.Get(identifier.Value);
if (obj == null)
{
return(null);
}
if (!(obj is Object.Macro))
{
return(null);
}
Object.Macro macro = (Object.Macro)obj;
return(macro);
}
