ascii: add constexpr ascii manipulators

Makefile.am

@@ -32,6 +32,7 @@ UTIL_FILES   =			\
     alloc/null.hpp		\
     alloc/stack.cpp		\
     alloc/stack.hpp		\
+    ascii.hpp			\
     backtrace.hpp   		\
     bezier.cpp			\
     bezier.hpp			\

ascii.hpp

@@ -0,0 +1,57 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2016 Danny Robson <danny@nerdcruft.net>
+ */
+
+#ifndef __CRUFT_UTIL_ASCII_HPP
+#define __CRUFT_UTIL_ASCII_HPP
+
+namespace util { namespace ascii {
+    ///////////////////////////////////////////////////////////////////////////
+    constexpr inline
+    bool
+    is_digit (char c) noexcept
+    {
+        return c >= '0' && c <= '9';
+    }
+
+
+    //-------------------------------------------------------------------------
+    constexpr inline
+    bool
+    is_upper (char c) noexcept
+    {
+        return c >= 'A' && c <= 'Z';
+    }
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    constexpr inline
+    char
+    to_upper (char c) noexcept
+    {
+        return c - 'a' + 'A';
+    }
+
+
+    //-------------------------------------------------------------------------
+    constexpr inline
+    char
+    to_lower (char c) noexcept
+    {
+        return c - 'A' + 'a';
+    }
+} }
+
+#endif