Implement a simple config file parser

Tests/SimpleConf/CMakeLists.txt

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+add_executable(TestSimpleConf)
+
+target_compile_features(TestSimpleConf
+    PRIVATE
+    cxx_std_20
+)
+
+target_link_libraries(TestSimpleConf
+    PRIVATE
+    Garbage
+    Catch2::Catch2WithMain
+)
+
+target_sources(TestSimpleConf
+    PRIVATE
+    Comments.cpp
+    Conversions.cpp
+    EmptyConfigs.cpp
+    Optionality.cpp
+    Parsing.cpp
+    WhitespaceBehaviour.cpp
+)
+
+add_custom_command(
+    TARGET TestSimpleConf POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy_directory
+            ${CMAKE_CURRENT_SOURCE_DIR}/TestConfigs
+            ${CMAKE_CURRENT_BINARY_DIR}/TestConfigs
+)

Tests/SimpleConf/Comments.cpp

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+#include <catch2/catch_test_macros.hpp>
+#include <Garbage/SimpleConf.hpp>
+
+TEST_CASE("Comments and empty lines are ignored")
+{
+    using Required = Garbage::SimpleConf::Required;
+    using LookupError = Garbage::SimpleConfImplementation::LookupError;
+
+    std::filesystem::path path("TestConfigs/Comments.conf");
+
+    Garbage::SimpleConf config(path);
+
+    REQUIRE_THROWS_AS((config.Get<std::string, Required>("this shouldn't")), LookupError);
+    REQUIRE(config.Get<std::string, Required>("while this") == "is accessible");
+}

Tests/SimpleConf/Conversions.cpp

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+#include <catch2/catch_test_macros.hpp>
+#include <Garbage/SimpleConf.hpp>
+
+TEST_CASE("Check if type conversions work correctly")
+{
+    using Required = Garbage::SimpleConf::Required;
+
+    std::filesystem::path path("TestConfigs/BasicConversions.conf");
+
+    Garbage::SimpleConf config(path);
+
+    SECTION("Basic stuff that should be correct")
+    {
+        REQUIRE(config.Get<std::string, Required>("an int") == "123456");
+        REQUIRE(config.Get<std::string, Required>("a float") == "3.5");
+        REQUIRE(config.Get<std::string, Required>("a long (8B)") == "121212121212121212");
+        REQUIRE(config.Get<std::string, Required>("a double") == "0.0000128");
+
+        REQUIRE(config.Get<std::int32_t>("an int") == 123456);
+        REQUIRE(config.Get<float>("a float") == 3.5f);
+        REQUIRE(config.Get<std::int64_t>("a long (8B)") == 121212121212121212);
+        REQUIRE(config.Get<double>("a double") == 0.0000128);
+    }
+
+    SECTION("Stuff that should fail to parse")
+    {
+        REQUIRE(config.Get<std::string, Required>("an incorrect char") == "256");
+        REQUIRE(config.Get<std::string, Required>("unsigned") == "-34");
+        REQUIRE(config.Get<std::string, Required>("signed, but large") == "3000000000");
+        REQUIRE(config.Get<std::string, Required>("mangled float") == "3.f4");
+        REQUIRE(config.Get<std::string, Required>("mangled float 2") == "2.4f");
+
+        using ConversionError = Garbage::SimpleConfImplementation::ConversionError;
+
+        REQUIRE_THROWS_AS(config.Get<std::uint8_t>("an incorrect char"), ConversionError);
+        REQUIRE_THROWS_AS(config.Get<std::uint32_t>("unsigned"), ConversionError);
+        REQUIRE_THROWS_AS(config.Get<std::int32_t>("signed, but large"), ConversionError);
+        REQUIRE_THROWS_AS(config.Get<float>("mangled float"), ConversionError);
+        REQUIRE_THROWS_AS(config.Get<float>("mangled float 2"), ConversionError);
+    }
+}

Tests/SimpleConf/EmptyConfigs.cpp

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+#include <catch2/catch_test_macros.hpp>
+#include <Garbage/SimpleConf.hpp>
+
+TEST_CASE("Config files with no key value pairs")
+{
+    SECTION("Empty file")
+    {
+        std::filesystem::path path("TestConfigs/Empty.conf");
+        REQUIRE_NOTHROW(Garbage::SimpleConf(path));
+    }
+
+    SECTION("File with comments")
+    {
+        std::filesystem::path path("TestConfigs/CommentsOnly.conf");
+        REQUIRE_NOTHROW(Garbage::SimpleConf(path));
+    }
+}

Tests/SimpleConf/Optionality.cpp

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+#include <catch2/catch_test_macros.hpp>
+#include <Garbage/SimpleConf.hpp>
+
+TEST_CASE("Check handling of optional values")
+{
+    std::filesystem::path path("TestConfigs/Optionality.conf");
+
+    Garbage::SimpleConf config(path);
+
+    SECTION("GetOptional behaviour")
+    {
+        REQUIRE(!config.GetOptional<std::string>("non-existent key"));
+        REQUIRE(*config.GetOptional<std::string>("existing key") == "existing value");
+    }
+
+    SECTION("Get behaviour")
+    {
+        using Required = Garbage::SimpleConf::Required;
+        using LookupError = Garbage::SimpleConfImplementation::LookupError;
+
+        REQUIRE(config.Get<std::string>("non-existent key", "a default") == "a default");
+        REQUIRE(config.Get<std::string>("existing key") == "existing value");
+        REQUIRE_THROWS_AS((config.Get<std::string, Required>("non-existent key")), LookupError);
+    }
+}

Tests/SimpleConf/Parsing.cpp

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+#include <catch2/catch_test_macros.hpp>
+#include <catch2/matchers/catch_matchers_string.hpp>
+#include <Garbage/SimpleConf.hpp>
+
+TEST_CASE("Ensure robust parsing")
+{
+    std::filesystem::path configs("TestConfigs");
+
+    using Catch::Matchers::ContainsSubstring;
+
+    SECTION("Multiple assignments")
+    {
+        REQUIRE_THROWS_WITH(Garbage::SimpleConf(configs / "Parsing-MultipleEquals.conf"),
+                            ContainsSubstring("[Line 3]"));
+    }
+
+    SECTION("Multiple assignments")
+    {
+        REQUIRE_THROWS_WITH(Garbage::SimpleConf(configs / "Parsing-HashInKey.conf"),
+                            ContainsSubstring("[Line 5]"));
+    }
+
+    SECTION("No equals")
+    {
+        REQUIRE_THROWS_WITH(Garbage::SimpleConf(configs / "Parsing-OnlyKey.conf"),
+                            ContainsSubstring("[Line 7]"));
+    }
+
+    SECTION("Empty key")
+    {
+        REQUIRE_THROWS_WITH(Garbage::SimpleConf(configs / "Parsing-EmptyKey.conf"),
+                            ContainsSubstring("[Line 7]"));
+    }
+
+    SECTION("Key at end of file")
+    {
+        REQUIRE_THROWS_WITH(Garbage::SimpleConf(configs / "Parsing-KeyAtEnd.conf"),
+                            ContainsSubstring("[Line 10]"));
+    }
+}

Tests/SimpleConf/TestConfigs/BasicConversions.conf

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+# First, we wanna test if it can even do the basics
+an int = 123456
+a float = 3.5
+a long (8B) = 121212121212121212
+a double = 0.0000128
+
+# Now we want to see if it correctly blows up
+an incorrect char = 256
+unsigned = -34
+signed, but large = 3000000000
+mangled float = 3.f4
+mangled float 2 = 2.4f

Tests/SimpleConf/TestConfigs/Comments.conf

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+# Test whether comments behave correctly
+
+# this shouldn't = be accessible
+while this = is accessible # and this comment doesn't interfere

Tests/SimpleConf/TestConfigs/CommentsOnly.conf

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+# Another example of an empty config
+# The config should initialize successfully,
+# but there should be no kv-pairs inside it

Tests/SimpleConf/TestConfigs/Optionality.conf

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+# This probably doesn't need to exist, but eh
+existing key = existing value

Tests/SimpleConf/TestConfigs/Parsing-EmptyKey.conf

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+# A simple config file that
+
+normal_key=normal_value
+another_key=another_value
+generic=generic
+another_one=another_value
+            = oh no, an empty key
+another_one=...
+
+# It doesn't really matter what's here, because the parser won't reach it

Tests/SimpleConf/TestConfigs/Parsing-HashInKey.conf

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+# A simple config file that contains a # character inside the key
+
+normal_key=normal_value
+another_key=another_value
+a_very_bas#ic_key=generic_value
+another_one=...
+
+# It doesn't really matter what's here, because the parser won't reach it

Tests/SimpleConf/TestConfigs/Parsing-KeyAtEnd.conf

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+# A simple config file that
+
+normal_key=normal_value
+another_key=another_value
+generic=generic
+another_one=another_value
+another_one=...
+
+# It doesn't really matter what's here, because the parser won't reach it
+sneaky_key

Tests/SimpleConf/TestConfigs/Parsing-MultipleEquals.conf

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+# A simple config
+that appears = correct
+but it = has = an invalid line # Should blow up here
+another=pair

Tests/SimpleConf/TestConfigs/Parsing-OnlyKey.conf

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+# A simple config file that contains only the key on a single line
+
+normal_key=normal_value
+another_key=another_value
+generic=generic
+another_one=another_value
+a_very_basic_key
+another_one=...
+
+# It doesn't really matter what's here, because the parser won't reach it

Tests/SimpleConf/WhitespaceBehaviour.cpp

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+#include <catch2/catch_test_macros.hpp>
+#include <Garbage/SimpleConf.hpp>
+
+TEST_CASE("Check behavior when whitespace is involved")
+{
+    SECTION("Simple multi-line config")
+    {
+        using Required = Garbage::SimpleConf::Required;
+
+        std::string rawConfig =
+            "       key with    whitespace   =      and value too     \n"
+            "another=one\n"
+            "     and yet = another";
+
+        Garbage::SimpleConf config(std::move(rawConfig));
+
+        REQUIRE(config.Get<std::string, Required>("key with    whitespace") == "and value too");
+        REQUIRE(config.Get<std::string, Required>("another") == "one");
+        REQUIRE(config.Get<std::string, Required>("and yet") == "another");
+    }
+
+    SECTION("Deal with CRLF correctly")
+    {
+        using Required = Garbage::SimpleConf::Required;
+
+        std::string rawConfig =
+            " simple key=simple value \r\n"
+            " another = one\r\n"
+            "  and one = more\r\n";
+
+        Garbage::SimpleConf config(std::move(rawConfig));
+
+        REQUIRE(config.Get<std::string, Required>("simple key") == "simple value");
+        REQUIRE(config.Get<std::string, Required>("another") == "one");
+        REQUIRE(config.Get<std::string, Required>("and one") == "more");
+    }
+
+    SECTION("Weirder whitespace shenanigans")
+    {
+        using Required = Garbage::SimpleConf::Required;
+
+        std::string rawConfig =
+            "let's+start_simple=with some\tbasics\n"
+            "\t\tnow we get \tsome=\t \tweirder\tstuff\r\n"
+            "\t\tinsa+nity\twith\t\t=\t  white \t space \t\t";
+
+        Garbage::SimpleConf config(std::move(rawConfig));
+
+        REQUIRE(config.Get<std::string, Required>("let's+start_simple") == "with some\tbasics");
+        REQUIRE(config.Get<std::string, Required>("now we get \tsome") == "weirder\tstuff");
+        REQUIRE(config.Get<std::string, Required>("insa+nity\twith") == "white \t space");
+    }
+}