1 files changed, 44 insertions, 12 deletions

diff --git a/src/resp.hpp b/src/resp.hpp
index 9e1e4f7..02d2746 100644
--- a/src/resp.hpp
+++ b/src/resp.hpp
@@ -83,15 +83,16 @@ struct Object;
 
 /// Type tag for an AST node (must be even and > 1 since LSb is used as mark)
 enum Tag {
-	T_UNKNOWN = 2,
-	T_BOOL    = 4,
-	T_FLOAT   = 6,
-	T_INT32   = 8,
-	T_STRING  = 10,
-	T_SYMBOL  = 12,
-	T_LITSYM  = 14,
-	T_TUPLE   = 16,
-	T_TVAR    = 18
+	T_UNKNOWN  = 2,
+	T_BOOL     = 4,
+	T_FLOAT    = 6,
+	T_INT32    = 8,
+	T_STRING   = 10,
+	T_SYMBOL   = 12,
+	T_LITSYM   = 14,
+	T_TUPLE    = 16,
+	T_TVAR     = 18,
+	T_ELLIPSIS = 20
 };
 
 /// Garbage collector
@@ -197,6 +198,15 @@ private:
 	ASymbol(const char* s, Cursor c) : AST(T_SYMBOL, c), _sym(s) {}
 };
 
+/// Ellipsis, e.g. "..."
+struct AEllipsis : public AST {
+	AEllipsis(const AST* pred, Cursor c) : AST(T_ELLIPSIS, c), _pred(pred) {}
+	const AST* pred() const { return _pred; }
+private:
+	friend class PEnv;
+	const AST* _pred;
+};
+
 /// Tuple (heterogeneous sequence of fixed length), e.g. "(a b c)"
 struct ATuple : public AST {
 	explicit ATuple(Cursor c) : AST(T_TUPLE, c), _fst(0), _rst(0) {}
@@ -331,6 +341,16 @@ list_equals(const ATuple* lhs, const ATuple* rhs)
 	return true;
 }
 
+inline void
+list_append(ATuple* head, const AST* child) {
+	for (ATuple* i = head; i; i = const_cast<ATuple*>(i->rst())) {
+		if (!i->rst()) {
+			i->last(new ATuple(child, NULL, child->loc));
+			return;
+		}
+	}
+}
+
 struct AType {
 	static inline bool is_var(const AST* type)  { return type->tag() == T_TVAR; }
 	static inline bool is_name(const AST* type) { return type->tag() == T_SYMBOL; }
@@ -427,6 +447,8 @@ AST::operator==(const AST& rhs) const
 	case T_SYMBOL:
 	case T_LITSYM:
 		return ((ASymbol*)this)->sym() == ((ASymbol*)&rhs)->sym(); // interned
+	case T_ELLIPSIS:
+		return *((AEllipsis*)this)->pred() == *((AEllipsis*)&rhs)->pred();
 	case T_UNKNOWN:
 		return this == &rhs;
 	}
@@ -542,7 +564,8 @@ struct Constraint : public pair<const AST*,const AST*> {
 
 static inline bool
 is_dots(const AST* exp) {
-	return (exp->to_symbol() && exp->as_symbol()->str() == "...");
+	return (exp->tag() == T_ELLIPSIS ||
+	        (exp->to_symbol() && exp->as_symbol()->str() == "..."));
 }
 
 /// Type substitution
@@ -562,14 +585,22 @@ struct Subst : public list<Constraint> {
 				return j;
 		return end();
 	}
+	const_iterator find_ellipsis(const AST* t) const {
+		for (const_iterator j = begin(); j != end(); ++j)
+			if (j->first->tag() == T_ELLIPSIS &&
+			    *((AEllipsis*)j->first)->pred() == *t)
+				return j;
+		return end();
+	}
 	const AST* apply(const AST* in) const {
 		if (AType::is_expr(in)) {
 			if (in->as_tuple()->empty())
 				return in;
 			List out;
-			for (auto i : *in->as_tuple()) {
+			const AST* prev = NULL;
+			for (const auto& i : *in->as_tuple()) {
 				if (is_dots(i)) {
-					const_iterator o = find(i);
+					const_iterator o = find_ellipsis(prev);
 					if (o != end()) {
 						for (auto j : *o->second->as_tuple()) {
 							out.push_back(apply(j));
@@ -578,6 +609,7 @@ struct Subst : public list<Constraint> {
 				} else {
 					out.push_back(apply(i));
 				}
+				prev = i;
 			}
 			if (out.head)
 				out.head->loc = in->loc;