Add parseUInt utility function

There is an increasing number of places where Catch2 wants to parse
strings into numbers, but being stuck in C++14 world, we do not
have good stdlib facilities to do this (`strtoul` and `stoul`
are both bad).

5 files changed, 80 insertions, 0 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index ae51bf8a..599a104f 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -81,6 +81,7 @@ set(INTERNAL_HEADERS
     ${SOURCES_DIR}/internal/catch_istream.hpp
     ${SOURCES_DIR}/internal/catch_unique_name.hpp
     ${SOURCES_DIR}/internal/catch_sharding.hpp
+    ${SOURCES_DIR}/internal/catch_parse_numbers.hpp
     ${SOURCES_DIR}/generators/catch_generator_exception.hpp
     ${SOURCES_DIR}/generators/catch_generators.hpp
     ${SOURCES_DIR}/generators/catch_generators_adapters.hpp
@@ -184,6 +185,7 @@ set(IMPL_SOURCES
     ${SOURCES_DIR}/internal/catch_fatal_condition_handler.cpp
     ${SOURCES_DIR}/internal/catch_floating_point_helpers.cpp
     ${SOURCES_DIR}/internal/catch_istream.cpp
+    ${SOURCES_DIR}/internal/catch_parse_numbers.cpp
     ${SOURCES_DIR}/interfaces/catch_interfaces_generatortracker.cpp
     ${SOURCES_DIR}/interfaces/catch_interfaces_reporter.cpp
     ${SOURCES_DIR}/internal/catch_list.cpp
diff --git a/src/catch2/catch_all.hpp b/src/catch2/catch_all.hpp
index bd83f5a7..3d32ce7f 100644
--- a/src/catch2/catch_all.hpp
+++ b/src/catch2/catch_all.hpp
@@ -78,6 +78,7 @@
 #include <catch2/internal/catch_noncopyable.hpp>
 #include <catch2/internal/catch_optional.hpp>
 #include <catch2/internal/catch_output_redirect.hpp>
+#include <catch2/internal/catch_parse_numbers.hpp>
 #include <catch2/internal/catch_platform.hpp>
 #include <catch2/internal/catch_polyfills.hpp>
 #include <catch2/internal/catch_preprocessor.hpp>
diff --git a/src/catch2/internal/catch_parse_numbers.cpp b/src/catch2/internal/catch_parse_numbers.cpp
new file mode 100644
index 00000000..05649046
--- /dev/null
+++ b/src/catch2/internal/catch_parse_numbers.cpp
@@ -0,0 +1,49 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE_1_0.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+#include <catch2/internal/catch_parse_numbers.hpp>
+
+#include <catch2/internal/catch_compiler_capabilities.hpp>
+#include <catch2/internal/catch_string_manip.hpp>
+
+#include <limits>
+
+namespace Catch {
+
+    Optional<unsigned int> parseUInt(std::string const& input, int base) {
+        auto trimmed = trim( input );
+        // std::stoull is annoying and accepts numbers starting with '-',
+        // it just negates them into unsigned int
+        if ( trimmed.empty() || trimmed[0] == '-' ) {
+            return {};
+        }
+
+        CATCH_TRY {
+            size_t pos = 0;
+            const auto ret = std::stoull( trimmed, &pos, base );
+
+            // We did not consume the whole input, so there is an issue
+            // This can be bunch of different stuff, like multiple numbers
+            // in the input, or invalid digits/characters and so on. Either
+            // way, we do not want to return the partially parsed result.
+            if ( pos != trimmed.size() ) {
+                return {};
+            }
+            // Too large
+            if ( ret > std::numeric_limits<unsigned int>::max() ) {
+                return {};
+            }
+            return static_cast<unsigned int>(ret);
+        } CATCH_CATCH_ANON( std::exception const& ) {
+            // There was a larger issue with the input, e.g. the parsed
+            // number would be too large to fit within ull.
+            return {};
+        }
+    }
+
+} // namespace Catch
diff --git a/src/catch2/internal/catch_parse_numbers.hpp b/src/catch2/internal/catch_parse_numbers.hpp
new file mode 100644
index 00000000..941c0f24
--- /dev/null
+++ b/src/catch2/internal/catch_parse_numbers.hpp
@@ -0,0 +1,26 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE_1_0.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+#ifndef CATCH_PARSE_NUMBERS_HPP_INCLUDED
+#define CATCH_PARSE_NUMBERS_HPP_INCLUDED
+
+#include <catch2/internal/catch_optional.hpp>
+
+#include <string>
+
+namespace Catch {
+
+    /**
+     * Parses unsigned int from the input, using provided base
+     *
+     * Effectively a wrapper around std::stoul but with better error checking
+     * e.g. "-1" is rejected, instead of being parsed as UINT_MAX.
+     */
+    Optional<unsigned int> parseUInt(std::string const& input, int base = 10);
+}
+
+#endif // CATCH_PARSE_NUMBERS_HPP_INCLUDED
diff --git a/src/catch2/meson.build b/src/catch2/meson.build
index 8f1e4331..8b9e288a 100644
--- a/src/catch2/meson.build
+++ b/src/catch2/meson.build
@@ -100,6 +100,7 @@ internal_headers = [
   'internal/catch_noncopyable.hpp',
   'internal/catch_optional.hpp',
   'internal/catch_output_redirect.hpp',
+  'internal/catch_parse_numbers.hpp',
   'internal/catch_platform.hpp',
   'internal/catch_polyfills.hpp',
   'internal/catch_preprocessor.hpp',
@@ -207,6 +208,7 @@ internal_sources = files(
   'internal/catch_list.cpp',
   'internal/catch_message_info.cpp',
   'internal/catch_output_redirect.cpp',
+  'internal/catch_parse_numbers.cpp',
   'internal/catch_polyfills.cpp',
   'internal/catch_random_number_generator.cpp',
   'internal/catch_random_seed_generation.cpp',