[FEATURE] Add sharg::istreamable concept. (#53)

* [MISC] Move argument_parser_compatible_option to concept.hpp

* [FEATURE] Add sharg istreamable concept.

* [MISC] Remove dependency on seqan3::input_stream_over.

* add return type constraint

* Update include/sharg/concept.hpp

* Update include/sharg/concept.hpp

* remove todo

Co-authored-by: Enrico Seiler <[email protected]>

include/sharg/auxiliary.hpp

@@ -17,7 +17,6 @@
 
 #include <seqan3/core/debug_stream/debug_stream_type.hpp>
 #include <seqan3/core/detail/customisation_point.hpp>
-#include <seqan3/io/stream/concept.hpp>
 
 #include <sharg/platform.hpp>
 
@@ -186,24 +185,6 @@ concept named_enumeration = requires
     { sharg::enumeration_names<option_type> };
 };
 
-/*!\concept sharg::argument_parser_compatible_option
- * \brief Checks whether the the type can be used in an add_(positional_)option call on the argument parser.
- * \ingroup argument_parser
- * \tparam option_type The type to check.
- *
- * ### Requirements
- *
- * In order to model this concept, the type must either be streamable to std::istringstream or
- * model sharg::named_enumeration<option_type>.
- *
- * \remark For a complete overview, take a look at \ref argument_parser
- */
-template <typename option_type>
-concept argument_parser_compatible_option = seqan3::input_stream_over<std::istringstream, option_type> ||
-                                            named_enumeration<option_type>;
-
-
-
 /*!\brief Used to further specify argument_parser options/flags.
  * \ingroup argument_parser
  *

include/sharg/concept.hpp

@@ -0,0 +1,52 @@
+// -----------------------------------------------------------------------------------------------------------
+// Copyright (c) 2006-2021, Knut Reinert & Freie Universität Berlin
+// Copyright (c) 2016-2021, Knut Reinert & MPI für molekulare Genetik
+// This file may be used, modified and/or redistributed under the terms of the 3-clause BSD-License
+// shipped with this file and also available at: https://github.com/seqan/sharg-parser/blob/master/LICENSE.md
+// -----------------------------------------------------------------------------------------------------------
+
+/*!\file
+ * \author Svenja Mehringer <svenja.mehringer AT fu-berlin.de>
+ * \brief Provides helper concepts.
+ */
+
+#pragma once
+
+#include <seqan3/std/concepts>
+
+#include <sharg/auxiliary.hpp>
+
+namespace sharg
+{
+
+/*!\concept sharg::istreamable
+ * \ingroup argument_parser
+ * \brief Concept for types that can be parsed from a std::istream via the stream operator.
+ * \tparam value_type The type to check whether it's stremable via std::istream.
+ *
+ * ### Requirements
+ *
+ * `std::istream` must support the (un)formatted input function (`operator>>`) for an l-value of a given `value_type`.
+ */
+template <typename value_type>
+concept istreamable = requires (std::istream & is, value_type & val)
+{
+    SHARG_RETURN_TYPE_CONSTRAINT(is >> val, std::same_as, std::istream&);
+};
+
+/*!\concept sharg::argument_parser_compatible_option
+ * \brief Checks whether the the type can be used in an add_(positional_)option call on the argument parser.
+ * \ingroup argument_parser
+ * \tparam option_type The type to check.
+ *
+ * ### Requirements
+ *
+ * In order to model this concept, the type must either model sharg::istreamable and sharg::ostreamable or
+ * model sharg::named_enumeration<option_type>.
+ *
+ * \remark For a complete overview, take a look at \ref argument_parser
+ */
+template <typename option_type>
+concept argument_parser_compatible_option = sharg::istreamable<option_type> || named_enumeration<option_type>;
+
+} // namespace sharg

include/sharg/detail/format_parse.hpp

@@ -15,6 +15,7 @@
 #include <sharg/std/charconv>
 
 #include <sharg/detail/format_base.hpp>
+#include <sharg/concept.hpp>
 
 namespace sharg::detail
 {
@@ -284,15 +285,15 @@ class format_parse : public format_base
     }
 
     /*!\brief Tries to parse an input string into a value using the stream `operator>>`.
-     * \tparam option_t Must model seqan3::input_stream_over.
+     * \tparam option_t Must model sharg::istreamable.
      * \param[out] value Stores the parsed value.
      * \param[in] in The input argument to be parsed.
      * \returns sharg::option_parse_result::error if `in` could not be parsed via the stream
      *          operator and otherwise sharg::option_parse_result::success.
      */
     template <typename option_t>
     //!\cond
-        requires seqan3::input_stream_over<std::istringstream, option_t>
+        requires istreamable<option_t>
     //!\endcond
     option_parse_result parse_option_value(option_t & value, std::string const & in)
     {
@@ -407,7 +408,7 @@ class format_parse : public format_base
      */
     template <typename option_t>
     //!\cond
-        requires std::is_arithmetic_v<option_t> && seqan3::input_stream_over<std::istringstream, option_t>
+        requires std::is_arithmetic_v<option_t> && istreamable<option_t>
     //!\endcond
     option_parse_result parse_option_value(option_t & value, std::string const & in)
     {