String comparisons are public interfaces

include/beast/core/string.hpp

@@ -0,0 +1,104 @@
+//
+// Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BEAST_STRING_HPP
+#define BEAST_STRING_HPP
+
+#include <boost/spirit/home/support/char_encoding/ascii.hpp>
+#include <boost/utility/string_ref.hpp>
+
+namespace beast {
+
+/// The type of string view used by the library
+using string_view = boost::string_ref;
+
+/// The type of basic string view used by the library
+template<class CharT, class Traits>
+using basic_string_view =
+    boost::basic_string_ref<CharT, Traits>;
+
+namespace detail {
+
+template<class = void>
+bool
+iequals(
+    beast::string_view const& lhs,
+    beast::string_view const& rhs)
+{
+    auto n = lhs.size();
+    if(rhs.size() != n)
+        return false;
+    auto p1 = lhs.data();
+    auto p2 = rhs.data();
+    using namespace boost::spirit::char_encoding;
+    while(n--)
+        if(ascii::tolower(*p1) != ascii::tolower(*p2))
+            return false;
+    return true;
+}
+
+} // detail
+
+/** Returns `true` if two strings are equal, using a case-insensitive comparison.
+
+    The case-comparison operation is defined only for low-ASCII characters.
+
+    @param lhs The string on the left side of the equality
+
+    @param rhs The string on the right side of the equality
+*/
+inline
+bool
+iequals(
+    beast::string_view const& lhs,
+    beast::string_view const& rhs)
+{
+    return detail::iequals(lhs, rhs);
+}
+
+/** A strictly less predicate for strings, using a case-insensitive comparison.
+
+    The case-comparison operation is defined only for low-ASCII characters.
+*/
+struct iless
+{
+    bool
+    operator()(
+        beast::string_view const& lhs,
+        beast::string_view const& rhs) const
+    {
+        using std::begin;
+        using std::end;
+        using namespace boost::spirit::char_encoding;
+        return std::lexicographical_compare(
+            begin(lhs), end(lhs), begin(rhs), end(rhs),
+            [](char lhs, char rhs)
+            {
+                return ascii::tolower(lhs) < ascii::tolower(rhs);
+            }
+        );
+    }
+};
+
+/** A predicate for string equality, using a case-insensitive comparison.
+
+    The case-comparison operation is defined only for low-ASCII characters.
+*/
+struct iequal
+{
+    bool
+    operator()(
+        beast::string_view const& lhs,
+        beast::string_view const& rhs) const
+    {
+        return iequals(lhs, rhs);
+    }
+};
+
+} // beast
+
+#endif