Add unsigned integer printing to core library

source/core.cpp

@@ -515,6 +515,15 @@ export namespace core {
 		return hash_code;
 	}
 
+	/**
+	 * Swaps the values of `element` in `a` and `b` around using copy semantics.
+	 */
+	template<typename element> constexpr void swap(element & a, element & b) {
+		element const temp = a;
+		a = b;
+		b = temp;
+	}
+
 	/**
 	 * Streams the data from `input` to `output`, using `buffer` as temporary transfer space.
 	 *
@@ -550,6 +559,34 @@ export namespace core {
 		return written;
 	}
 
+	/**
+	 * Attempts to format and print `value` as an unsigned integer out to `output`.
+	 *
+	 * The returned [expected] can be used to introspect if `output` encountered any issues during
+	 * printing, otherwise it will contain the number of characters used to print `value` as text.
+	 */
+	expected<usize, io_error> print_unsigned(writable const & output, u64 value) {
+		if (value == 0) return output(slice{"0"}.as_bytes());
+
+		u8 buffer[20]{0};
+		usize buffer_count{0};
+
+		while (value != 0) {
+			constexpr usize radix{10};
+
+			buffer[buffer_count] = static_cast<u8>((value % radix) + '0');
+			value = (value / radix);
+			buffer_count += 1;
+		}
+
+		usize const half_buffer_count{buffer_count / 2};
+
+		for (usize i = 0; i < half_buffer_count; i += 1)
+			swap(buffer[i], buffer[buffer_count - i - 1]);
+
+		return output(slice{buffer, buffer_count});
+	}
+
 	/**
 	 * Returns a reference to a shared [allocator] which will always return `nullptr` on calls to
 	 * [allocator::reallocate].