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+// Copyright (c) 2017 Gilad Naaman
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+//! A crate used for calculating offsets of struct members and their spans.
+//!
+//! Some of the funcationality of the crate makes no sense when used along with structs that
+//! are not `#[repr(C, packed)]`, but it is up to the user to make sure that they are.
+//!
+//! This functionality should work for `const`s but presently doesn't work on `const fn`. Storing a
+//! value in a const and then returning it from a `const fn` should workaround most cases.
+//!
+//! ## Examples
+//! ```
+//! #[macro_use]
+//! extern crate memoffset;
+//!
+//! #[repr(C, packed)]
+//! struct HelpMeIAmTrappedInAStructFactory {
+//!     help_me_before_they_: [u8; 15],
+//!     a: u32
+//! }
+//!
+//! fn main() {
+//!     assert_eq!(offset_of!(HelpMeIAmTrappedInAStructFactory, a), 15);
+//!     assert_eq!(span_of!(HelpMeIAmTrappedInAStructFactory, a), 15..19);
+//!     assert_eq!(span_of!(HelpMeIAmTrappedInAStructFactory, help_me_before_they_ .. a), 0..15);
+//! }
+//! ```
+//!
+//! This functionality can be useful, for example, for checksum calculations:
+//!
+//! ```ignore
+//! #[repr(C, packed)]
+//! struct Message {
+//!     header: MessageHeader,
+//!     fragment_index: u32,
+//!     fragment_count: u32,
+//!     payload: [u8; 1024],
+//!     checksum: u16
+//! }
+//!
+//! let checksum_range = &raw[span_of!(Message, header..checksum)];
+//! let checksum = crc16(checksum_range);
+//! ```
+
+#![no_std]
+
+// This `use` statement enables the macros to use `$crate::mem`.
+// Doing this enables this crate to function under both std and no-std crates.
+#[doc(hidden)]
+pub use core::mem;
+
+#[doc(hidden)]
+pub use core::ptr;
+
+#[macro_use]
+mod offset_of;
+#[macro_use]
+mod span_of;