rename chapters

Chapter17/cib/libs/sc/lazy_string_format.hpp

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+#pragma once
+
+#include <sc/fwd.hpp>
+
+#include <stdx/tuple_algorithms.hpp>
+
+namespace sc {
+template <typename StringConstant, typename ArgTuple>
+struct lazy_string_format {
+    constexpr static StringConstant str{};
+    ArgTuple args{};
+
+    constexpr lazy_string_format() = default;
+    constexpr lazy_string_format(StringConstant, ArgTuple newArgs)
+        : args{newArgs} {}
+
+    template <typename F> constexpr auto apply(F &&f) const {
+        return args.apply(
+            [&](auto const &...as) { return std::forward<F>(f)(str, as...); });
+    }
+};
+
+template <class CharT, CharT... charsLhs, typename ArgsTupleLhs,
+          CharT... charsRhs, typename ArgsTupleRhs>
+[[nodiscard]] constexpr auto operator==(
+    lazy_string_format<string_constant<CharT, charsLhs...>, ArgsTupleLhs> lhs,
+    lazy_string_format<string_constant<CharT, charsRhs...>, ArgsTupleRhs>
+        rhs) noexcept -> bool {
+    return (lhs.str == rhs.str) && (lhs.args == rhs.args);
+}
+
+template <typename StringConstantLhs, typename TupleArgsLhs,
+          typename StringConstantRhs, typename TupleArgsRhs>
+[[nodiscard]] constexpr auto
+operator+(lazy_string_format<StringConstantLhs, TupleArgsLhs> lhs,
+          lazy_string_format<StringConstantRhs, TupleArgsRhs> rhs) noexcept {
+    return lazy_string_format{lhs.str + rhs.str,
+                              stdx::tuple_cat(lhs.args, rhs.args)};
+}
+
+template <typename StringConstantLhs, typename TupleArgsLhs, typename CharT,
+          CharT... chars>
+[[nodiscard]] constexpr auto
+operator+(lazy_string_format<StringConstantLhs, TupleArgsLhs> lhs,
+          string_constant<CharT, chars...> rhs) noexcept {
+    return lazy_string_format{lhs.str + rhs, lhs.args};
+}
+
+template <typename CharT, CharT... chars, typename StringConstantRhs,
+          typename TupleArgsRhs>
+[[nodiscard]] constexpr auto
+operator+(string_constant<CharT, chars...> lhs,
+          lazy_string_format<StringConstantRhs, TupleArgsRhs> rhs) noexcept {
+    return lazy_string_format{lhs + rhs.str, rhs.args};
+}
+} // namespace sc