// Parse a single node, either an atom or a list in parens
// Handle macro expansion too
Node ParseNode()
{
// atom node
var sym = Take();
switch (sym.Atom)
{
case Atoms.IDENT:
return(IdentNode.Create(sym.Name, sym));
case Atoms.LITERAL:
return(LiteralNode.Create(sym.Value));
case Atoms.LP:
if (Check(Atoms.MACRO))
{
ExpandMacro(Take());
return(ParseNode());
}
else
{
var nodes = new List <Node>();
while (!Match(Atoms.RP))
{
nodes.Add(ParseNode());
}
return(ListNode.Create(nodes));
}
default:
throw ErrNotExpect(sym.Atom);
}
}
// check ident, return new node if undef or base scope
internal Node CheckedIdent(Node node)
{
if (node.IsIdent)
{
var ident = node as IdentNode;
if (!(ident.Sym.IsUndef || ident.Sym.IsBase))
{
throw Error.Assert("checked ident {0}", ident);
}
var newsym = _symbols.Find(ident.Sym.Name);
if (newsym != null && !newsym.IsUndef)
{
return(IdentNode.Create(ident.Name, newsym));
}
}
return(node);
}
// these functions serve to ensure that symbols in nodes are defined as the right type
protected TypedValue DefSymbolValue(IdentNode node, TypedValue value)
{
if (node.Sym.IsValue && node.Sym.DataType == value.DataType)
{
return(node.Sym.Value);
}
Logger.WriteLine(3, "Getsym adding {0} value:{1} type:{2}", node.Sym.Name, value, value.DataType);
// will create new symbol and store in symbol table, so other nodes see the same thing
if (node.Sym.IsUndef)
{
Symbols.DefineValue(node.Name, value);
}
else if (value.GetType() == typeof(IdentValue) && node.Sym.Value is IdentValue)
{
; // any subclass will do for flag. TODO: reverse operation if flag defined first
}
else
{
_currentparser.Syntax("already defined {0} as type {1}", node.Name, node.Sym.DataType);
}
return(value);
}
protected ZoneValue DefZone(IdentNode node)
{
return(DefSymbolValue(node, new ZoneValue {
Value = node.Name
}) as ZoneValue);
}
protected IdentValue DefIdent(IdentNode node)
{
return(DefSymbolValue(node, new IdentValue {
Value = node.Name
}) as IdentValue);
}
protected PositionValue DefPosition(IdentNode node)
{
return(DefSymbolValue(node, PositionValue.Create(node.Name)) as PositionValue);
}
protected PlayerValue DefPlayer(IdentNode node)
{
return(DefSymbolValue(node, PlayerValue.Create(node.Name)) as PlayerValue);
}
protected PieceValue DefPiece(IdentNode node)
{
return(DefSymbolValue(node, PieceValue.Create(node.Name)) as PieceValue);
}
protected MoveTypeValue DefMoveType(IdentNode node)
{
return(DefSymbolValue(node, new MoveTypeValue {
Value = node.Name
}) as MoveTypeValue);
}
protected DirectionValue DefDirection(IdentNode node)
{
return(DefSymbolValue(node, new DirectionValue {
Value = node.Name
}) as DirectionValue);
}
protected AttributeValue DefAttribute(IdentNode node)
{
return(DefSymbolValue(node, AttributeValue.Create(node.Name)) as AttributeValue);
}