nihil.ucl: add object comparison and std::format support

4 files changed, 193 insertions, 0 deletions

diff --git a/nihil.ucl/emit.ccm b/nihil.ucl/emit.ccm
index 8fdf616..a451f88 100644
--- a/nihil.ucl/emit.ccm
+++ b/nihil.ucl/emit.ccm
@@ -7,7 +7,9 @@ module;
 #include <array>
 #include <charconv>
 #include <cstdlib>
+#include <format>
 #include <iterator>
+#include <iostream>
 #include <span>
 #include <string>
 #include <utility>
@@ -138,4 +140,75 @@ export auto emit(object const &object, emitter format,
 			       &functions, nullptr);
 }
 
+/*
+ * Basic ostream printer for UCL; default to JSON since it's probably what
+ * most people expect.
+ */
+export auto operator<<(std::ostream &stream, object const &o)
+	-> std::ostream &
+{
+	emit(o, emitter::json, std::ostream_iterator<char>(stream));
+	return stream;
+}
+
 } // namespace nihil::ucl
+
+/*
+ * Specialisation of std::formatter<> for object.
+ */
+template<>
+struct std::formatter<nihil::ucl::object, char>
+{
+	nihil::ucl::emitter emitter = nihil::ucl::emitter::json;
+
+	template<class ParseContext>
+	constexpr ParseContext::iterator parse(ParseContext& ctx)
+	{
+		auto it = ctx.begin();
+		auto end = ctx.end();
+
+		while (it != end) {
+			switch (*it) {
+			case 'j':
+				emitter = nihil::ucl::emitter::json;
+				break;
+			case 'J':
+				emitter = nihil::ucl::emitter::compact_json;
+				break;
+			case 'c':
+				emitter = nihil::ucl::emitter::configuration;
+				break;
+			case 'y':
+				emitter = nihil::ucl::emitter::yaml;
+				break;
+			case '}':
+				return it;
+			default:
+				throw std::format_error("Invalid format string "
+							"for UCL object");
+			}
+
+			++it;
+		}
+
+		return it;
+	}
+
+	template<class FmtContext>
+	FmtContext::iterator format(nihil::ucl::object const &o,
+				    FmtContext& ctx) const
+	{
+		// We can't use emit() here since the context iterator is not
+		// an std::output_iterator.
+
+		auto out = ctx.out();
+
+		auto ucl_format = static_cast<::ucl_emitter>(emitter);
+		auto wrapper = nihil::ucl::emit_wrapper(out);
+		auto functions = wrapper.get_functions();
+
+		::ucl_object_emit_full(o.get_ucl_object(), ucl_format,
+				       &functions, nullptr);
+		return out;
+	}
+};
diff --git a/nihil.ucl/object.ccm b/nihil.ucl/object.ccm
index 0b8c95f..43f36fe 100644
--- a/nihil.ucl/object.ccm
+++ b/nihil.ucl/object.ccm
@@ -170,6 +170,29 @@ private:
 };
 
 /***********************************************************************
+ * Object comparison.
+ */
+
+export auto operator<=>(object const &lhs, object const &rhs)
+	-> std::strong_ordering
+{
+	auto cmp = ::ucl_object_compare(lhs.get_ucl_object(),
+					rhs.get_ucl_object());
+
+	if (cmp < 0)
+		return std::strong_ordering::less;
+	else if (cmp > 0)
+		return std::strong_ordering::greater;
+	else
+		return std::strong_ordering::equal;
+}
+
+export auto operator==(object const &lhs, object const &rhs) -> bool
+{
+	return (lhs <=> rhs) == std::strong_ordering::equal;
+}
+
+/***********************************************************************
  * Object iteration.
  */
 
diff --git a/nihil.ucl/tests/emit.cc b/nihil.ucl/tests/emit.cc
index 13f5914..c7f9757 100644
--- a/nihil.ucl/tests/emit.cc
+++ b/nihil.ucl/tests/emit.cc
@@ -2,7 +2,89 @@
  * This source code is released into the public domain.
  */
 
+#include <format>
+#include <sstream>
+
 #include <catch2/catch_test_macros.hpp>
 
 import nihil;
 import nihil.ucl;
+
+TEST_CASE("ucl: emit to std::ostream", "[ucl]")
+{
+	using namespace std::literals;
+
+	auto obj = nihil::ucl::parse("int = [1, 42, 666]"sv);
+	auto strm = std::ostringstream();
+	strm << obj;
+
+	REQUIRE(strm.str() ==
+"{\n"
+"    \"int\": [\n"
+"        1,\n"
+"        42,\n"
+"        666\n"
+"    ]\n"
+"}");
+}
+
+TEST_CASE("ucl: emit JSON with std::format", "[ucl]")
+{
+	using namespace std::literals;
+
+	auto obj = nihil::ucl::parse("int = [1, 42, 666]"sv);
+	auto str = std::format("{:j}", obj);
+
+	REQUIRE(str ==
+"{\n"
+"    \"int\": [\n"
+"        1,\n"
+"        42,\n"
+"        666\n"
+"    ]\n"
+"}");
+
+	// Make sure JSON is the default format.
+	auto str2 = std::format("{}", obj);
+	REQUIRE(str == str2);
+}
+
+TEST_CASE("ucl: emit compact JSON with std::format", "[ucl]")
+{
+	using namespace std::literals;
+
+	auto obj = nihil::ucl::parse("int = [1, 42, 666]"sv);
+	auto str = std::format("{:J}", obj);
+
+	REQUIRE(str == "{\"int\":[1,42,666]}");
+}
+
+TEST_CASE("ucl: emit configuration with std::format", "[ucl]")
+{
+	using namespace std::literals;
+
+	auto obj = nihil::ucl::parse("int = [1, 42, 666]"sv);
+	auto str = std::format("{:c}", obj);
+
+	REQUIRE(str ==
+"int [\n"
+"    1,\n"
+"    42,\n"
+"    666,\n"
+"]\n");
+}
+
+TEST_CASE("ucl: emit YAML with std::format", "[ucl]")
+{
+	using namespace std::literals;
+
+	auto obj = nihil::ucl::parse("int = [1, 42, 666]"sv);
+	auto str = std::format("{:y}", obj);
+
+	REQUIRE(str ==
+"int: [\n"
+"    1,\n"
+"    42,\n"
+"    666\n"
+"]");
+}
diff --git a/nihil.ucl/tests/object.cc b/nihil.ucl/tests/object.cc
index f9cef9f..1bbcf4f 100644
--- a/nihil.ucl/tests/object.cc
+++ b/nihil.ucl/tests/object.cc
@@ -20,3 +20,18 @@ TEST_CASE("ucl object: get_ucl_object", "[ucl]")
 	static_assert(std::same_as<::ucl_object_t const *,
 		      		   decltype(cobj.get_ucl_object())>);
 }
+
+TEST_CASE("ucl object: compare", "[ucl]")
+{
+	using namespace std::literals;
+
+	auto obj_41 = nihil::ucl::parse("int = 41;"sv);
+	auto obj_42 = nihil::ucl::parse("int = 42;"sv);
+	auto obj_42_2 = nihil::ucl::parse("int = 42;"sv);
+	auto obj_43 = nihil::ucl::parse("int = 43;"sv);
+
+	REQUIRE(obj_42 == obj_42_2);
+	REQUIRE(obj_42 != obj_43);
+	REQUIRE(obj_42 < obj_43);
+	REQUIRE(obj_42 > obj_41);
+}