Index: src/SymTab/Demangle.cc
===================================================================
--- src/SymTab/Demangle.cc	(revision 0589e83d12bef5409ba2bb4eb9afaa0e0986ead4)
+++ src/SymTab/Demangle.cc	(revision 934fa0fc6af3737f7f5b45e08f4b84e1e8259312)
@@ -17,4 +17,6 @@
 #include <sstream>
 
+#include "AST/Pass.hpp"
+#include "AST/Type.hpp"
 #include "CodeGen/GenType.h"
 #include "CodeGen/OperatorTable.h"
@@ -328,7 +330,294 @@
 } // namespace SymTab
 
+namespace Mangle {
+
+namespace {
+
+struct Demangler {
+private:
+	std::string str;
+	size_t index = 0;
+	using Parser = std::function<ast::Type * ( ast::CV::Qualifiers )>;
+	std::vector<std::pair<std::string, Parser>> parsers;
+public:
+	Demangler( const std::string & str );
+
+	bool done() const { return str.size() <= index; }
+	char cur() const { assert( !done() ); return str[index]; }
+	bool expect( char ch ) { return str[index++] == ch; }
+
+	bool isPrefix( const std::string & pref );
+	bool extractNumber( size_t & out );
+	bool extractName( std::string & out );
+	bool stripMangleName( std::string & name );
+
+	ast::Type * parseFunction( ast::CV::Qualifiers tq );
+	ast::Type * parseTuple( ast::CV::Qualifiers tq );
+	ast::Type * parsePointer( ast::CV::Qualifiers tq );
+	ast::Type * parseArray( ast::CV::Qualifiers tq );
+	ast::Type * parseStruct( ast::CV::Qualifiers tq );
+	ast::Type * parseUnion( ast::CV::Qualifiers tq );
+	ast::Type * parseEnum( ast::CV::Qualifiers tq );
+	ast::Type * parseType( ast::CV::Qualifiers tq );
+	ast::Type * parseZero( ast::CV::Qualifiers tq );
+	ast::Type * parseOne( ast::CV::Qualifiers tq );
+
+	ast::Type * parseType();
+	bool parse( std::string & name, ast::Type *& type );
+};
+
+Demangler::Demangler(const std::string & str) : str(str) {
+	for (size_t k = 0; k < ast::BasicType::NUMBER_OF_BASIC_TYPES; ++k) {
+		parsers.emplace_back(Encoding::basicTypes[k], [k]( ast::CV::Qualifiers tq ) {
+			PRINT( std::cerr << "basic type: " << k << std::endl; )
+			return new ast::BasicType( (ast::BasicType::Kind)k, tq );
+		});
+	}
+
+	for (size_t k = 0; k < ast::TypeDecl::NUMBER_OF_KINDS; ++k) {
+		static const std::string typeVariableNames[] = { "DT", "DST", "OT", "FT", "TT", "ALT", };
+		static_assert(
+			sizeof(typeVariableNames)/sizeof(typeVariableNames[0]) == ast::TypeDecl::NUMBER_OF_KINDS,
+			"Each type variable kind should have a demangle name prefix"
+		);
+		parsers.emplace_back(Encoding::typeVariables[k], [k, this]( ast::CV::Qualifiers tq ) -> ast::TypeInstType * {
+			PRINT( std::cerr << "type variable type: " << k << std::endl; )
+			size_t N;
+			if (!extractNumber(N)) return nullptr;
+			return new ast::TypeInstType(
+				toString(typeVariableNames[k], N),
+				(ast::TypeDecl::Kind)k,
+				tq );
+		});
+	}
+
+	parsers.emplace_back(Encoding::void_t, [this]( ast::CV::Qualifiers tq ) { return new ast::VoidType(tq); });
+	parsers.emplace_back(Encoding::function, [this]( ast::CV::Qualifiers tq ) { return parseFunction(tq); });
+	parsers.emplace_back(Encoding::pointer, [this]( ast::CV::Qualifiers tq ) { return parsePointer(tq); });
+	parsers.emplace_back(Encoding::array, [this]( ast::CV::Qualifiers tq ) { return parseArray(tq); });
+	parsers.emplace_back(Encoding::tuple, [this]( ast::CV::Qualifiers tq ) { return parseTuple(tq); });
+	parsers.emplace_back(Encoding::struct_t, [this]( ast::CV::Qualifiers tq ) { return parseStruct(tq); });
+	parsers.emplace_back(Encoding::union_t, [this]( ast::CV::Qualifiers tq ) { return parseUnion(tq); });
+	parsers.emplace_back(Encoding::enum_t, [this]( ast::CV::Qualifiers tq ) { return parseEnum(tq); });
+	parsers.emplace_back(Encoding::type, [this]( ast::CV::Qualifiers tq ) { return parseType(tq); });
+	parsers.emplace_back(Encoding::zero, []( ast::CV::Qualifiers tq ) { return new ast::ZeroType(tq); });
+	parsers.emplace_back(Encoding::one, []( ast::CV::Qualifiers tq ) { return new ast::OneType(tq); });
+}
+
+bool Demangler::extractNumber( size_t & out ) {
+	std::stringstream numss;
+	if ( str.size() <= index ) return false;
+	while ( isdigit( str[index] ) ) {
+		numss << str[index];
+		++index;
+		if ( str.size() == index ) break;
+	}
+	if ( !(numss >> out) ) return false;
+	PRINT( std::cerr << "extractNumber success: " << out << std::endl; )
+	return true;
+}
+
+bool Demangler::extractName( std::string & out ) {
+	size_t len;
+	if ( !extractNumber(len) ) return false;
+	if ( str.size() < index + len ) return false;
+	out = str.substr( index, len );
+	index += len;
+	PRINT( std::cerr << "extractName success: " << out << std::endl; )
+	return true;
+}
+
+bool Demangler::isPrefix( const std::string & pref ) {
+	// Wraps the utility isPrefix function.
+	if ( ::isPrefix( str, pref, index ) ) {
+		index += pref.size();
+		return true;
+	}
+	return false;
+}
+
+// strips __NAME__cfa__TYPE_N, where N is [0-9]+: returns str is a match is found, returns empty string otherwise
+bool Demangler::stripMangleName( std::string & name ) {
+	PRINT( std::cerr << "====== " << str.size() << " " << str << std::endl; )
+	if (str.size() < 2+Encoding::manglePrefix.size()) return false; // +2 for at least _1 suffix
+	if ( !isPrefix(Encoding::manglePrefix) || !isdigit(str.back() ) ) return false;
+
+	if (!extractName(name)) return false;
+
+	// Find bounds for type.
+	PRINT( std::cerr << index << " " << str.size() << std::endl; )
+	PRINT( std::cerr << "[");
+	while (isdigit(str.back())) {
+		PRINT(std::cerr << ".");
+		str.pop_back();
+		if (str.size() <= index) return false;
+	}
+	PRINT( std::cerr << "]" << std::endl );
+	if (str.back() != '_') return false;
+	str.pop_back();
+	PRINT( std::cerr << str.size() << " " << name << " " << str.substr(index) << std::endl; )
+	return index < str.size();
+}
+
+ast::Type * Demangler::parseFunction( ast::CV::Qualifiers tq ) {
+	PRINT( std::cerr << "function..." << std::endl; )
+	if ( done() ) return nullptr;
+	ast::FunctionType * ftype = new ast::FunctionType( ast::FixedArgs, tq );
+	std::unique_ptr<ast::Type> manager( ftype );
+	ast::Type * retVal = parseType();
+	if ( !retVal ) return nullptr;
+	PRINT( std::cerr << "with return type: " << retVal << std::endl; )
+	ftype->returns.emplace_back( retVal );
+	if ( done() || !expect('_') ) return nullptr;
+	while ( !done() ) {
+		PRINT( std::cerr << "got ch: " << cur() << std::endl; )
+		if ( cur() == '_' ) return manager.release();
+		ast::Type * param = parseType();
+		if ( !param ) return nullptr;
+		PRINT( std::cerr << "with parameter : " << param << std::endl; )
+		ftype->params.emplace_back( param );
+	}
+	return nullptr;
+}
+
+ast::Type * Demangler::parseTuple( ast::CV::Qualifiers tq ) {
+	PRINT( std::cerr << "tuple..." << std::endl; )
+	std::vector<ast::ptr<ast::Type>> types;
+	size_t ncomponents;
+	if ( !extractNumber(ncomponents) ) return nullptr;
+	for ( size_t i = 0; i < ncomponents; ++i ) {
+		if ( done() ) return nullptr;
+		PRINT( std::cerr << "got ch: " << cur() << std::endl; )
+		ast::Type * t = parseType();
+		if ( !t ) return nullptr;
+		PRINT( std::cerr << "with type : " << t << std::endl; )
+		types.push_back( t );
+	}
+	return new ast::TupleType( std::move( types ), tq );
+}
+
+ast::Type * Demangler::parsePointer( ast::CV::Qualifiers tq ) {
+	PRINT( std::cerr << "pointer..." << std::endl; )
+	ast::Type * t = parseType();
+	if ( !t ) return nullptr;
+	return new ast::PointerType( t, tq );
+}
+
+ast::Type * Demangler::parseArray( ast::CV::Qualifiers tq ) {
+	PRINT( std::cerr << "array..." << std::endl; )
+	size_t length;
+	if ( !extractNumber(length) ) return nullptr;
+	ast::Type * t = parseType();
+	if ( !t ) return nullptr;
+	return new ast::ArrayType(
+		t,
+		ast::ConstantExpr::from_ulong( CodeLocation(), length ),
+		ast::FixedLen,
+		ast::DynamicDim,
+		tq );
+}
+
+ast::Type * Demangler::parseStruct( ast::CV::Qualifiers tq ) {
+	PRINT( std::cerr << "struct..." << std::endl; )
+	std::string name;
+	if ( !extractName(name) ) return nullptr;
+	return new ast::StructInstType( name, tq );
+}
+
+ast::Type * Demangler::parseUnion( ast::CV::Qualifiers tq ) {
+	PRINT( std::cerr << "union..." << std::endl; )
+	std::string name;
+	if ( !extractName(name) ) return nullptr;
+	return new ast::UnionInstType( name, tq );
+}
+
+ast::Type * Demangler::parseEnum( ast::CV::Qualifiers tq ) {
+	PRINT( std::cerr << "enum..." << std::endl; )
+	std::string name;
+	if ( !extractName(name) ) return nullptr;
+	return new ast::EnumInstType( name, tq );
+}
+
+ast::Type * Demangler::parseType( ast::CV::Qualifiers tq ) {
+	PRINT( std::cerr << "type..." << std::endl; )
+	std::string name;
+	if ( !extractName(name) ) return nullptr;
+	PRINT( std::cerr << "typename..." << name << std::endl; )
+	return new ast::TypeInstType( name, ast::TypeDecl::Dtype, tq );
+}
+
+ast::Type * Demangler::parseType() {
+	if (done()) return nullptr;
+
+	std::list<TypeDecl *> forall;
+	if (isPrefix(Encoding::forall)) {
+		PRINT( std::cerr << "polymorphic with..." << std::endl; )
+		size_t dcount, fcount, vcount, acount;
+		if ( !extractNumber(dcount) ) return nullptr;
+		PRINT( std::cerr << dcount << " dtypes" << std::endl; )
+		if ( !expect('_') ) return nullptr;
+		if ( !extractNumber(fcount) ) return nullptr;
+		PRINT( std::cerr << fcount << " ftypes" << std::endl; )
+		if ( !expect('_')) return nullptr;
+		if ( !extractNumber(vcount)) return nullptr;
+		PRINT( std::cerr << vcount << " ttypes" << std::endl; )
+		if ( !expect('_') ) return nullptr;
+		if ( !extractNumber(acount) ) return nullptr;
+		PRINT( std::cerr << acount << " assertions" << std::endl; )
+		if ( !expect('_') ) return nullptr;
+		for ( size_t i = 0 ; i < acount ; ++i ) {
+			// TODO: need to recursively parse assertions, but for now just return nullptr so that
+			// demangler does not crash if there are assertions
+			return nullptr;
+		}
+		if ( !expect('_') ) return nullptr;
+	}
+
+	ast::CV::Qualifiers tq;
+	while (true) {
+		auto qual = std::find_if(Encoding::qualifiers.begin(), Encoding::qualifiers.end(), [this](decltype(Encoding::qualifiers)::value_type val) {
+			return isPrefix(val.second);
+		});
+		if (qual == Encoding::qualifiers.end()) break;
+		tq |= qual->first;
+	}
+
+	// Find the correct type parser and then apply it.
+	auto iter = std::find_if(parsers.begin(), parsers.end(), [this](std::pair<std::string, Parser> & p) {
+		return isPrefix(p.first);
+	});
+	assertf(iter != parsers.end(), "Unhandled type letter: %c at index: %zd", cur(), index);
+	ast::Type * ret = iter->second(tq);
+	if ( !ret ) return nullptr;
+	return ret;
+}
+
+bool Demangler::parse( std::string & name, ast::Type *& type) {
+	if ( !stripMangleName(name) ) return false;
+	PRINT( std::cerr << "stripped name: " << name << std::endl; )
+	ast::Type * t = parseType();
+	if ( !t ) return false;
+	type = t;
+	return true;
+}
+
+std::string demangle( const std::string & mangleName ) {
+	using namespace CodeGen;
+	Demangler demangler( mangleName );
+	std::string name;
+	ast::Type * type = nullptr;
+	if ( !demangler.parse( name, type ) ) return mangleName;
+	ast::readonly<ast::Type> roType = type;
+	if ( auto info = operatorLookupByOutput( name ) ) name = info->inputName;
+	return genType( type, name, Options( false, false, false, false ) );
+}
+
+} // namespace
+
+} // namespace Mangle
+
 extern "C" {
 	char * cforall_demangle(const char * mangleName, int option __attribute__((unused))) {
-		const std::string & demangleName = SymTab::Mangler::demangle(mangleName);
+		const std::string & demangleName = Mangle::demangle(mangleName);
 		return strdup(demangleName.c_str());
 	}