Add splitReporterSpec helper

src/catch2/internal/catch_reporter_spec_parser.cpp

@@ -0,0 +1,64 @@
+
+//              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_reporter_spec_parser.hpp>
+
+namespace Catch {
+
+    namespace Detail {
+        std::vector<std::string> splitReporterSpec( StringRef reporterSpec ) {
+            static constexpr auto separator = "::";
+            static constexpr size_t separatorSize = 2;
+
+            size_t separatorPos = 0;
+            auto findNextSeparator = [&reporterSpec]( size_t startPos ) {
+                static_assert(
+                    separatorSize == 2,
+                    "The code below currently assumes 2 char separator" );
+
+                auto currentPos = startPos;
+                do {
+                    while ( currentPos < reporterSpec.size() &&
+                            reporterSpec[currentPos] != separator[0] ) {
+                        ++currentPos;
+                    }
+                    if ( currentPos + 1 < reporterSpec.size() &&
+                         reporterSpec[currentPos + 1] == separator[1] ) {
+                        return currentPos;
+                    }
+                    ++currentPos;
+                } while ( currentPos < reporterSpec.size() );
+
+                return static_cast<size_t>( -1 );
+            };
+
+            std::vector<std::string> parts;
+
+            while ( separatorPos < reporterSpec.size() ) {
+                const auto nextSeparator = findNextSeparator( separatorPos );
+                parts.push_back( static_cast<std::string>( reporterSpec.substr(
+                    separatorPos, nextSeparator - separatorPos ) ) );
+
+                if ( nextSeparator == static_cast<size_t>( -1 ) ) {
+                    break;
+                }
+                separatorPos = nextSeparator + separatorSize;
+            }
+
+            // Handle a separator at the end.
+            // This is not a valid spec, but we want to do validation in a
+            // centralized place
+            if ( separatorPos == reporterSpec.size() ) {
+                parts.emplace_back();
+            }
+
+            return parts;
+        }
+    }
+
+} // namespace Catch