From 8ec662aa4e6c7443cfca82e3085f71c5f944ec1a Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Sat, 4 Jul 2009 01:06:07 +0000
Subject: Safer Exp.

git-svn-id: http://svn.drobilla.net/resp/tuplr@179 ad02d1e2-f140-0410-9f75-f8b11f17cedd
---
 src/tuplr.hpp | 47 ++++++++++++++++++++++++++++-------------------
 1 file changed, 28 insertions(+), 19 deletions(-)

(limited to 'src/tuplr.hpp')

diff --git a/src/tuplr.hpp b/src/tuplr.hpp
index 5deff71..aaa0867 100644
--- a/src/tuplr.hpp
+++ b/src/tuplr.hpp
@@ -64,21 +64,30 @@ struct Error {
 /// Expression ::= Atom | (Expression*)
 template<typename Atom>
 struct Exp : private std::vector< Exp<Atom> > {
-	Exp(Cursor c)                : type(LIST), loc(c)          {}
-	Exp(Cursor c, const Atom& a) : type(ATOM), loc(c), atom(a) {}
+	Exp(Cursor c)                : type(LIST), loc(c)           {}
+	Exp(Cursor c, const Atom& a) : type(ATOM), loc(c), _atom(a) {}
 
-	void push_back(const Exp<Atom>& exp) { vector< Exp<Atom> >::push_back(exp); }
+	enum { ATOM, LIST } type;
 
-	bool             empty() const { return vector< Exp<Atom> >::empty(); }
-	const Exp<Atom>& front() const { return vector< Exp<Atom> >::front(); }
+	inline const Atom& atom() const { assert(type == ATOM); return _atom; }
 
-	typedef typename vector< Exp<Atom> >::const_iterator const_iterator;
-	const_iterator begin() const { return vector< Exp<Atom> >::begin(); }
-	const_iterator end()   const { return vector< Exp<Atom> >::end(); }
+private:
+	typedef std::vector< Exp<Atom> > ListImpl;
 
-	enum { ATOM, LIST } type;
-	Cursor              loc;
-	Atom                atom;
+public:
+	void push_back(const Exp<Atom>& exp) { assert(type == LIST); ListImpl::push_back(exp); }
+
+	bool             empty() const { assert(type == LIST); return ListImpl::empty(); }
+	const Exp<Atom>& front() const { assert(type == LIST); return ListImpl::front(); }
+
+	typedef typename ListImpl::const_iterator const_iterator;
+	const_iterator begin() const { assert(type == LIST); return ListImpl::begin(); }
+	const_iterator end()   const { assert(type == LIST); return ListImpl::end(); }
+
+	Cursor loc;
+
+private:
+	Atom _atom;
 };
 
 template<typename Atom>
@@ -527,25 +536,25 @@ struct PEnv : private map<const string, ASymbol*> {
 		if (exp.type == SExp::LIST) {
 			if (exp.empty()) throw Error(exp.loc, "call to empty list");
 			if (exp.front().type == SExp::ATOM) {
-				MF mf = mac(exp.front().atom);
+				MF mf = mac(exp.front().atom());
 				SExp expanded = (mf ? mf(*this, exp) : exp);
 
-				const PEnv::Handler* h = handler(true, expanded.front().atom);
+				const PEnv::Handler* h = handler(true, expanded.front().atom());
 				if (h)
 					return h->func(*this, expanded, h->arg);
 			}
 			return new ACall(exp, parseTuple(exp)); // Parse as regular call
-		} else if (isdigit(exp.atom[0])) {
-			if (exp.atom.find('.') == string::npos)
-				return new ALiteral<int32_t>(strtol(exp.atom.c_str(), NULL, 10), exp.loc);
+		} else if (isdigit(exp.atom()[0])) {
+			if (exp.atom().find('.') == string::npos)
+				return new ALiteral<int32_t>(strtol(exp.atom().c_str(), NULL, 10), exp.loc);
 			else
-				return new ALiteral<float>(strtod(exp.atom.c_str(), NULL), exp.loc);
+				return new ALiteral<float>(strtod(exp.atom().c_str(), NULL), exp.loc);
 		} else {
-			const PEnv::Handler* h = handler(false, exp.atom);
+			const PEnv::Handler* h = handler(false, exp.atom());
 			if (h)
 				return h->func(*this, exp, h->arg);
 		}
-		return sym(exp.atom, exp.loc);
+		return sym(exp.atom(), exp.loc);
 	}
 	unsigned symID;
 };
-- 
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