Simplify some C++ abstractions (#1518)

* Remove namespaces
* Prefer `bool operator==`, not `friend auto operator==`
* Prefer not to use `using`
* Use a `constexpr` function instead of a template for `flipTable`

include/gfx/main.hpp

@@ -107,20 +107,18 @@ struct Palette {
 	uint8_t size() const;
 };
 
-namespace detail {
-template<typename T, T... i>
-static constexpr auto flipTable(std::integer_sequence<T, i...>) {
-	return std::array{[](uint8_t byte) {
+// Flipping tends to happen fairly often, so take a bite out of dcache to speed it up
+static constexpr auto flipTable = ([]() constexpr {
+	std::array<uint16_t, 256> table{};
+	for (uint16_t i = 0; i < table.size(); i++) {
 		// To flip all the bits, we'll flip both nibbles, then each nibble half, etc.
+		uint16_t byte = i;
 		byte = (byte & 0b0000'1111) << 4 | (byte & 0b1111'0000) >> 4;
 		byte = (byte & 0b0011'0011) << 2 | (byte & 0b1100'1100) >> 2;
 		byte = (byte & 0b0101'0101) << 1 | (byte & 0b1010'1010) >> 1;
-		return byte;
-	}(i)...};
-}
-} // namespace detail
-
-// Flipping tends to happen fairly often, so take a bite out of dcache to speed it up
-static constexpr auto flipTable = detail::flipTable(std::make_integer_sequence<uint16_t, 256>());
+		table[i] = byte;
+	}
+	return table;
+})();
 
 #endif // RGBDS_GFX_MAIN_HPP

include/gfx/pal_packing.hpp

@@ -6,19 +6,15 @@
 #include <tuple>
 #include <vector>
 
-#include "defaultinitalloc.hpp"
+#include "defaultinitvec.hpp"
 
 struct Palette;
 class ProtoPalette;
 
-namespace packing {
-
 /*
  * Returns which palette each proto-palette maps to, and how many palettes are necessary
  */
 std::tuple<DefaultInitVec<size_t>, size_t>
     overloadAndRemove(std::vector<ProtoPalette> const &protoPalettes);
 
-} // namespace packing
-
 #endif // RGBDS_GFX_PAL_PACKING_HPP

include/gfx/pal_sorting.hpp

@@ -12,20 +12,16 @@
 
 struct Palette;
 
-namespace sorting {
-
-void indexed(
+void sortIndexed(
     std::vector<Palette> &palettes,
     int palSize,
     png_color const *palRGB,
     int palAlphaSize,
     png_byte *palAlpha
 );
-void grayscale(
+void sortGrayscale(
     std::vector<Palette> &palettes, std::array<std::optional<Rgba>, 0x8001> const &colors
 );
-void rgb(std::vector<Palette> &palettes);
-
-} // namespace sorting
+void sortRgb(std::vector<Palette> &palettes);
 
 #endif // RGBDS_GFX_PAL_SORTING_HPP

include/gfx/rgba.hpp

@@ -40,8 +40,8 @@ struct Rgba {
 		auto shl = [](uint8_t val, unsigned shift) { return static_cast<uint32_t>(val) << shift; };
 		return shl(red, 24) | shl(green, 16) | shl(blue, 8) | shl(alpha, 0);
 	}
-	friend bool operator==(Rgba const &lhs, Rgba const &rhs) { return lhs.toCSS() == rhs.toCSS(); }
-	friend bool operator!=(Rgba const &lhs, Rgba const &rhs) { return lhs.toCSS() != rhs.toCSS(); }
+	bool operator==(Rgba const &rhs) const { return toCSS() == rhs.toCSS(); }
+	bool operator!=(Rgba const &rhs) const { return toCSS() != rhs.toCSS(); }
 
 	/*
 	 * CGB colors are RGB555, so we use bit 15 to signify that the color is transparent instead

include/itertools.hpp

@@ -6,52 +6,46 @@
 #include <tuple>
 #include <utility>
 
-template<typename T>
-class EnumSeqIterator {
-	T _value;
-
-public:
-	explicit EnumSeqIterator(T value) : _value(value) {}
-
-	EnumSeqIterator &operator++() {
-		_value = (T)(_value + 1);
-		return *this;
-	}
-
-	auto operator*() const { return _value; }
-
-	friend auto operator==(EnumSeqIterator const &lhs, EnumSeqIterator const &rhs) {
-		return lhs._value == rhs._value;
-	}
-
-	friend auto operator!=(EnumSeqIterator const &lhs, EnumSeqIterator const &rhs) {
-		return lhs._value != rhs._value;
-	}
-};
-
 template<typename T>
 class EnumSeq {
 	T _start;
 	T _stop;
 
+	class Iterator {
+		T _value;
+
+	public:
+		explicit Iterator(T value) : _value(value) {}
+
+		Iterator &operator++() {
+			_value = (T)(_value + 1);
+			return *this;
+		}
+
+		auto operator*() const { return _value; }
+
+		bool operator==(Iterator const &rhs) const { return _value == rhs._value; }
+		bool operator!=(Iterator const &rhs) const  { return _value != rhs._value; }
+	};
+
 public:
 	explicit EnumSeq(T stop) : _start((T)0), _stop(stop) {}
 	explicit EnumSeq(T start, T stop) : _start(start), _stop(stop) {}
 
-	EnumSeqIterator<T> begin() { return EnumSeqIterator(_start); }
-	EnumSeqIterator<T> end() { return EnumSeqIterator(_stop); }
+	Iterator begin() { return Iterator(_start); }
+	Iterator end() { return Iterator(_stop); }
 };
 
 // This is not a fully generic implementation; its current use cases only require for-loop behavior.
 // We also assume that all iterators have the same length.
-template<typename... Iters>
-class Zip {
-	std::tuple<Iters...> _iters;
+template<typename... Ts>
+class ZipIterator {
+	std::tuple<Ts...> _iters;
 
 public:
-	explicit Zip(std::tuple<Iters...> &&iters) : _iters(iters) {}
+	explicit ZipIterator(std::tuple<Ts...> &&iters) : _iters(iters) {}
 
-	Zip &operator++() {
+	ZipIterator &operator++() {
 		std::apply([](auto &&...it) { (++it, ...); }, _iters);
 		return *this;
 	}
@@ -62,26 +56,24 @@ public:
 		);
 	}
 
-	friend auto operator==(Zip const &lhs, Zip const &rhs) {
-		return std::get<0>(lhs._iters) == std::get<0>(rhs._iters);
+	bool operator==(ZipIterator const &rhs) const {
+		return std::get<0>(_iters) == std::get<0>(rhs._iters);
 	}
 
-	friend auto operator!=(Zip const &lhs, Zip const &rhs) {
-		return std::get<0>(lhs._iters) != std::get<0>(rhs._iters);
+	bool operator!=(ZipIterator const &rhs) const {
+		return std::get<0>(_iters) != std::get<0>(rhs._iters);
 	}
 };
 
-namespace detail {
-template<typename... Containers>
+template<typename... Ts>
 class ZipContainer {
-	std::tuple<Containers...> _containers;
+	std::tuple<Ts...> _containers;
 
 public:
-	explicit ZipContainer(Containers &&...containers)
-	    : _containers(std::forward<Containers>(containers)...) {}
+	explicit ZipContainer(Ts &&...containers) : _containers(std::forward<Ts>(containers)...) {}
 
 	auto begin() {
-		return Zip(std::apply(
+		return ZipIterator(std::apply(
 		    [](auto &&...containers) {
 			    using std::begin;
 			    return std::make_tuple(begin(containers)...);
@@ -91,7 +83,7 @@ public:
 	}
 
 	auto end() {
-		return Zip(std::apply(
+		return ZipIterator(std::apply(
 		    [](auto &&...containers) {
 			    using std::end;
 			    return std::make_tuple(end(containers)...);
@@ -105,12 +97,11 @@ public:
 template<typename T>
 using Holder = std::
     conditional_t<std::is_lvalue_reference_v<T>, T, std::remove_cv_t<std::remove_reference_t<T>>>;
-} // namespace detail
 
 // Does the same number of iterations as the first container's iterator!
-template<typename... Containers>
-static constexpr auto zip(Containers &&...cs) {
-	return detail::ZipContainer<detail::Holder<Containers>...>(std::forward<Containers>(cs)...);
+template<typename... Ts>
+static constexpr auto zip(Ts &&...cs) {
+	return ZipContainer<Holder<Ts>...>(std::forward<Ts>(cs)...);
 }
 
 #endif // RGBDS_ITERTOOLS_HPP