feat(util): add missing lbool.* files

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/util/CMakeLists.txt

@@ -8,6 +8,6 @@ add_library(util trace.cpp debug.cpp name.cpp name_set.cpp name_generator.cpp
   exception.cpp interrupt.cpp hash.cpp escaped.cpp bit_tricks.cpp
   safe_arith.cpp ascii.cpp memory.cpp shared_mutex.cpp realpath.cpp
   script_state.cpp script_exception.cpp splay_map.cpp rb_map.cpp lua.cpp
-  luaref.cpp stackinfo.cpp lean_path.cpp serializer.cpp ${THREAD_CPP})
+  luaref.cpp stackinfo.cpp lean_path.cpp serializer.cpp lbool.cpp ${THREAD_CPP})
 
 target_link_libraries(util ${LEAN_LIBS})

src/util/lbool.cpp

@@ -0,0 +1,16 @@
+/*
+Copyright (c) 2014 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+
+Author: Leonardo de Moura
+*/
+#include "util/lbool.h"
+namespace lean {
+std::ostream & operator<<(std::ostream & out, lbool b) {
+    switch (b) {
+    case l_false: return out << "l_false";
+    case l_true:  return out << "l_true";
+    default:      return out << "l_undef";
+    }
+}
+}

src/util/lbool.h

@@ -0,0 +1,17 @@
+/*
+Copyright (c) 2014 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+
+Author: Leonardo de Moura
+*/
+#pragma once
+#include <iostream>
+namespace lean {
+/**
+   \brief lifted Booleans
+*/
+enum lbool { l_false = -1, l_undef, l_true };
+inline lbool operator~(lbool lb) { return static_cast<lbool>(-static_cast<int>(lb)); }
+inline lbool to_lbool(bool b) { return static_cast<lbool>(static_cast<int>(b)*2-1); }
+std::ostream & operator<<(std::ostream & out, lbool b);
+}