commit 1.2

source/io.cxx

@@ -0,0 +1,69 @@
+module;
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+module io;
+
+import std;
+
+namespace brc {
+
+std::string read_file(const std::filesystem::path& path) {
+	auto file = std::ifstream(path);
+	if (!file.is_open()) {
+		throw std::runtime_error(std::format("could not open file: {}", path.string()));
+	}
+	auto stream = std::stringstream();
+	stream << file.rdbuf();
+	return stream.str();
+}
+
+mapped_file::mapped_file(const std::filesystem::path& path) {
+	const auto file_size = std::filesystem::file_size(path);
+
+	fd = open(path.generic_string().data(), O_RDONLY);
+	data = mmap(nullptr, file_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	length = file_size;
+
+	if (data == MAP_FAILED) {
+		close(fd);
+		throw std::runtime_error("failed to map file");
+	}
+}
+
+mapped_file::mapped_file(mapped_file&& other) noexcept
+	: fd(other.fd), data(std::exchange(other.data, nullptr)), length(other.length) {}
+
+mapped_file& mapped_file::operator=(mapped_file&& other) noexcept {
+	if (&other == this) {
+		return *this;
+	}
+
+	auto moved = std::move(other);
+
+	std::swap(moved.fd, this->fd);
+	std::swap(moved.data, this->data);
+	std::swap(moved.length, this->length);
+
+	return *this;
+}
+
+mapped_file::~mapped_file() {
+	if (data != nullptr) {
+		munmap(data, length);
+		close(fd);
+	}
+}
+
+mapped_file::operator std::string_view() const noexcept {
+	return std::string_view(reinterpret_cast<const char*>(data), length);
+}
+
+std::size_t mapped_file::size() const noexcept { return length; }
+
+}  // namespace brc