Add quote form, to allow expressions literal symbols and lists (lists not yet implemented).

Quoting is a thin lexical concept - a quote of a symbol/list compiles to a symbol/list,
rather than interpreted as code (i.e. a variable/call, respectively).  A quote of anything
else is equivalent to its quotee, e.g. a quote of a String is simply that string (the quote
is removed at an early stage by the compiler).  There is no Quote data type, or explicit
unquoting, or anything like that.


git-svn-id: http://svn.drobilla.net/resp/resp@365 ad02d1e2-f140-0410-9f75-f8b11f17cedd

7 files changed, 52 insertions, 4 deletions

diff --git a/src/c.cpp b/src/c.cpp
index 66a4963..fe0ecfe 100644
--- a/src/c.cpp
+++ b/src/c.cpp
@@ -89,7 +89,7 @@ CEngine::llType(const AST* t)
 		if (sym == "Int")     return new string("int");
 		if (sym == "Float")   return new string("float");
 		if (sym == "String")  return new string("char*");
-		if (sym == "Quote")   return new string("char*");
+		if (sym == "Symbol")  return new string("char*");
 	} else if (is_form(t, "Fn")){
 		ATuple::const_iterator i     = t->as_tuple()->begin();
 		const ATuple*          protT = (*++i)->to_tuple();
diff --git a/src/compile.cpp b/src/compile.cpp
index 393084e..756e90d 100644
--- a/src/compile.cpp
+++ b/src/compile.cpp
@@ -43,7 +43,7 @@ compile_literal_symbol(CEnv& cenv, const ASymbol* sym) throw()
 	if (existing) {
 		return *existing;
 	} else {
-		CVal compiled = cenv.engine()->compileString(cenv, (string("__T_") + sym->sym()).c_str());
+		CVal compiled = cenv.engine()->compileString(cenv, sym->sym());
 		cenv.vals.def(sym, compiled);
 		return compiled;
 	}
@@ -147,6 +147,18 @@ compile_if(CEnv& cenv, const ATuple* aif) throw()
 }
 
 static CVal
+compile_quote(CEnv& cenv, const ATuple* quote) throw()
+{
+	switch (quote->list_ref(1)->tag()) {
+	case T_SYMBOL:
+		return compile_literal_symbol(cenv, quote->list_ref(1)->as_symbol());
+	default:
+		assert(false);
+		return NULL;
+	}	
+}
+
+static CVal
 compile_call(CEnv& cenv, const ATuple* call) throw()
 {
 	CFunc f = resp_compile(cenv, call->head());
@@ -199,6 +211,8 @@ resp_compile(CEnv& cenv, const AST* ast) throw()
 			return compile_fn(cenv, call);
 		else if (form == "if")
 			return compile_if(cenv, call);
+		else if (form == "quote")
+			return compile_quote(cenv, call);
 		else
 			return compile_call(cenv, call);
 	}
diff --git a/src/constrain.cpp b/src/constrain.cpp
index 4bd6c08..f65ad8f 100644
--- a/src/constrain.cpp
+++ b/src/constrain.cpp
@@ -260,6 +260,17 @@ constrain_match(TEnv& tenv, Constraints& c, const ATuple* call) throw(Error)
 }
 
 static void
+constrain_quote(TEnv& tenv, Constraints& c, const ATuple* call) throw(Error)
+{
+	THROW_IF(call->list_len() != 2, call->loc, "`quote' requires exactly 1 argument");
+	switch (call->list_ref(1)->tag()) {
+	case T_TUPLE:  c.constrain(tenv, call, tenv.named("List"));   return;
+	case T_SYMBOL: c.constrain(tenv, call, tenv.named("Symbol")); return;
+	default: return;
+	}
+}
+
+static void
 constrain_call(TEnv& tenv, Constraints& c, const ATuple* call) throw(Error)
 {
 	const AST* const head = call->head();
@@ -370,6 +381,8 @@ constrain_list(TEnv& tenv, Constraints& c, const ATuple* tup) throw(Error)
 		constrain_let(tenv, c, tup);
 	else if (form == "match")
 		constrain_match(tenv, c, tup);
+	else if (form == "quote")
+		constrain_quote(tenv, c, tup);
 	else
 		constrain_call(tenv, c, tup);
 }
diff --git a/src/expand.cpp b/src/expand.cpp
index eb508f1..f0fed33 100644
--- a/src/expand.cpp
+++ b/src/expand.cpp
@@ -113,7 +113,7 @@ initLang(PEnv& penv, TEnv& tenv)
 {
 	// Types
 	const char* types[] = {
-		"Bool", "Float", "Int",  "Nothing", "Quote", "String", "Symbol", 0 };
+		"Bool", "Float", "Int",  "Nothing", "String", "Symbol", "List", 0 };
 	for (const char** t = types; *t; ++t) {
 		const ASymbol* sym = penv.sym(*t);
 		tenv.def(sym, sym); // FIXME: define to NULL?
diff --git a/src/lift.cpp b/src/lift.cpp
index 201d40f..1991eb5 100644
--- a/src/lift.cpp
+++ b/src/lift.cpp
@@ -271,6 +271,8 @@ resp_lift(CEnv& cenv, Code& code, const AST* ast) throw()
 			return lift_fn(cenv, code, call);
 		else if (form == "if")
 			return lift_args(cenv, code, call);
+		else if (form == "quote")
+			return call;
 		else
 			return lift_call(cenv, code, call);
 	}
diff --git a/src/llvm.cpp b/src/llvm.cpp
index 4c8ff2a..cb2d6c1 100644
--- a/src/llvm.cpp
+++ b/src/llvm.cpp
@@ -140,7 +140,7 @@ LLVMEngine::llType(const AST* t)
 		if (sym == "Int")     return Type::getInt32Ty(context);
 		if (sym == "Float")   return Type::getFloatTy(context);
 		if (sym == "String")  return PointerType::get(Type::getInt8Ty(context), NULL);
-		if (sym == "Quote")   return PointerType::get(Type::getInt8Ty(context), NULL);
+		if (sym == "Symbol")  return PointerType::get(Type::getInt8Ty(context), NULL);
 	} else if (is_form(t, "Fn")) {
 		ATuple::const_iterator i     = t->as_tuple()->begin();
 		const ATuple*          protT = (*++i)->to_tuple();
@@ -466,6 +466,9 @@ LLVMEngine::call(CEnv& cenv, CFunc f, const AST* retT)
 			}
 		}
 		ss << "\"";
+	} else if (retT->str() == "Symbol") {
+		const std::string s(((char* (*)())fp)());
+		ss << s;
 	} else if (t != Type::getVoidTy(context)) {
 		ss << ((void* (*)())fp)();
 	} else {
diff --git a/src/simplify.cpp b/src/simplify.cpp
index 397c2b7..63b5fd6 100644
--- a/src/simplify.cpp
+++ b/src/simplify.cpp
@@ -145,6 +145,20 @@ simplify_let(CEnv& cenv, const ATuple* call) throw()
 	return copy;
 }
 
+static const AST*
+simplify_quote(CEnv& cenv, const ATuple* call) throw()
+{
+	switch (call->list_ref(1)->tag()) {
+	case T_SYMBOL: case T_TUPLE:
+		// Symbols and lists remain quoted (because semantics differ)
+		return call;
+	default:
+		// Other literals (e.g. numbers, strings) are self-evaluating, so the
+		// quote can be removed, e.g. (quote 3) => 3
+		return call->list_ref(1);
+	}
+}
+
 const AST*
 resp_simplify(CEnv& cenv, const AST* ast) throw()
 {
@@ -161,6 +175,8 @@ resp_simplify(CEnv& cenv, const AST* ast) throw()
 		return simplify_if(cenv, list);
 	else if (form == "let")
 		return simplify_let(cenv, list);
+	else if (form == "quote")
+		return simplify_quote(cenv, list);
 	else
 		return simplify_list(cenv, list);
 }