From bc524d70253a4ab2fe40c3ca3e5666e267c0a4d1 Mon Sep 17 00:00:00 2001
From: Lexi Winter <lexi@le-fay.org>
Date: Sun, 29 Jun 2025 19:25:29 +0100
Subject: import catch2 3.8.1

---
 examples/301-Gen-MapTypeConversion.cpp | 69 ++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 examples/301-Gen-MapTypeConversion.cpp

(limited to 'examples/301-Gen-MapTypeConversion.cpp')

diff --git a/examples/301-Gen-MapTypeConversion.cpp b/examples/301-Gen-MapTypeConversion.cpp
new file mode 100644
index 0000000..0a28448
--- /dev/null
+++ b/examples/301-Gen-MapTypeConversion.cpp
@@ -0,0 +1,69 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+// 301-Gen-MapTypeConversion.cpp
+// Shows how to use map to modify generator's return type.
+
+// Specifically we wrap a std::string returning generator with a generator
+// that converts the strings using stoi, so the returned type is actually
+// an int.
+
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/generators/catch_generators_adapters.hpp>
+
+#include <string>
+#include <sstream>
+
+namespace {
+
+// Returns a line from a stream. You could have it e.g. read lines from
+// a file, but to avoid problems with paths in examples, we will use
+// a fixed stringstream.
+class LineGenerator final : public Catch::Generators::IGenerator<std::string> {
+    std::string m_line;
+    std::stringstream m_stream;
+public:
+    explicit LineGenerator( std::string const& lines ) {
+        m_stream.str( lines );
+        if (!next()) {
+            Catch::Generators::Detail::throw_generator_exception("Couldn't read a single line");
+        }
+    }
+
+    std::string const& get() const override;
+
+    bool next() override {
+        return !!std::getline(m_stream, m_line);
+    }
+};
+
+std::string const& LineGenerator::get() const {
+    return m_line;
+}
+
+// This helper function provides a nicer UX when instantiating the generator
+// Notice that it returns an instance of GeneratorWrapper<std::string>, which
+// is a value-wrapper around std::unique_ptr<IGenerator<std::string>>.
+Catch::Generators::GeneratorWrapper<std::string>
+lines( std::string const& lines ) {
+    return Catch::Generators::GeneratorWrapper<std::string>(
+        new LineGenerator( lines ) );
+}
+
+} // end anonymous namespace
+
+
+TEST_CASE("filter can convert types inside the generator expression", "[example][generator]") {
+    auto num = GENERATE(
+        map<int>( []( std::string const& line ) { return std::stoi( line ); },
+                  lines( "1\n2\n3\n4\n" ) ) );
+
+    REQUIRE(num > 0);
+}
+
+// Compiling and running this file will result in 4 successful assertions
-- 
cgit v1.2.3