diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..529ee4a
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,71 @@
+//! Support for nested invocations of proc-macro-hack expression macros.
+//!
+//! By default, macros defined through proc-macro-hack do not support nested
+//! invocations, i.e. the code emitted by a proc-macro-hack macro invocation
+//! cannot contain recursive calls to the same proc-macro-hack macro nor calls
+//! to any other proc-macro-hack macros.
+//!
+//! This crate provides opt-in support for such nested invocations.
+//!
+//! To make a macro callable recursively, add a dependency on this crate from
+//! your declaration crate and update the `#[proc_macro_hack]` re-export as
+//! follows.
+//!
+//! ```
+//! // Before
+//! # const IGNORE: &str = stringify! {
+//! #[proc_macro_hack]
+//! pub use demo_hack_impl::add_one;
+//! # };
+//! ```
+//!
+//! ```
+//! // After
+//! # const IGNORE: &str = stringify! {
+//! #[proc_macro_hack(support_nested)]
+//! pub use demo_hack_impl::add_one;
+//! # };
+//! ```
+//!
+//! No change is required within your definition crate, only to the re-export in
+//! the declaration crate.
+//!
+//! # Limitations
+//!
+//! - Nested invocations are preprocessed by a TT-muncher, so the caller's crate
+//!   will be required to contain `#![recursion_limit = "..."]` if there are
+//!   lengthy macro invocations.
+//!
+//! - Only up to 64 nested invocations are supported.
+
+#![no_std]
+
+// ANDROID: count.rs generated and put in the out subdirectory.
+// include!(concat!(env!("OUT_DIR"), "/count.rs"));
+include!("../out/count.rs");
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! dispatch {
+    (() $($bang:tt)*) => {
+        $crate::count!($($bang)*)
+    };
+    ((($($first:tt)*) $($rest:tt)*) $($bang:tt)*) => {
+        $crate::dispatch!(($($first)* $($rest)*) $($bang)*)
+    };
+    (([$($first:tt)*] $($rest:tt)*) $($bang:tt)*) => {
+        $crate::dispatch!(($($first)* $($rest)*) $($bang)*)
+    };
+    (({$($first:tt)*} $($rest:tt)*) $($bang:tt)*) => {
+        $crate::dispatch!(($($first)* $($rest)*) $($bang)*)
+    };
+    ((! $($rest:tt)*) $($bang:tt)*) => {
+        $crate::dispatch!(($($rest)*) $($bang)* !)
+    };
+    ((!= $($rest:tt)*) $($bang:tt)*) => {
+        $crate::dispatch!(($($rest)*) $($bang)* !)
+    };
+    (($first:tt $($rest:tt)*) $($bang:tt)*) => {
+        $crate::dispatch!(($($rest)*) $($bang)*)
+    };
+}