1 files changed, 212 insertions, 0 deletions
diff --git a/lazy-static/src/lib.rs b/lazy-static/src/lib.rs
new file mode 100644
index 0000000..42dc405
--- /dev/null
+++ b/lazy-static/src/lib.rs
@@ -0,0 +1,212 @@
+// Copyright 2016 lazy-static.rs Developers
+//
+// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
+// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+// http://opensource.org/licenses/MIT>, at your option. This file may not be
+// copied, modified, or distributed except according to those terms.
+
+/*!
+A macro for declaring lazily evaluated statics.
+
+Using this macro, it is possible to have `static`s that require code to be
+executed at runtime in order to be initialized.
+This includes anything requiring heap allocations, like vectors or hash maps,
+as well as anything that requires function calls to be computed.
+
+# Syntax
+
+```ignore
+lazy_static! {
+    [pub] static ref NAME_1: TYPE_1 = EXPR_1;
+    [pub] static ref NAME_2: TYPE_2 = EXPR_2;
+    ...
+    [pub] static ref NAME_N: TYPE_N = EXPR_N;
+}
+```
+
+Attributes (including doc comments) are supported as well:
+
+```rust
+# #[macro_use]
+# extern crate lazy_static;
+# fn main() {
+lazy_static! {
+    /// This is an example for using doc comment attributes
+    static ref EXAMPLE: u8 = 42;
+}
+# }
+```
+
+# Semantics
+
+For a given `static ref NAME: TYPE = EXPR;`, the macro generates a unique type that
+implements `Deref<TYPE>` and stores it in a static with name `NAME`. (Attributes end up
+attaching to this type.)
+
+On first deref, `EXPR` gets evaluated and stored internally, such that all further derefs
+can return a reference to the same object. Note that this can lead to deadlocks
+if you have multiple lazy statics that depend on each other in their initialization.
+
+Apart from the lazy initialization, the resulting "static ref" variables
+have generally the same properties as regular "static" variables:
+
+- Any type in them needs to fulfill the `Sync` trait.
+- If the type has a destructor, then it will not run when the process exits.
+
+# Example
+
+Using the macro:
+
+```rust
+#[macro_use]
+extern crate lazy_static;
+
+use std::collections::HashMap;
+
+lazy_static! {
+    static ref HASHMAP: HashMap<u32, &'static str> = {
+        let mut m = HashMap::new();
+        m.insert(0, "foo");
+        m.insert(1, "bar");
+        m.insert(2, "baz");
+        m
+    };
+    static ref COUNT: usize = HASHMAP.len();
+    static ref NUMBER: u32 = times_two(21);
+}
+
+fn times_two(n: u32) -> u32 { n * 2 }
+
+fn main() {
+    println!("The map has {} entries.", *COUNT);
+    println!("The entry for `0` is \"{}\".", HASHMAP.get(&0).unwrap());
+    println!("A expensive calculation on a static results in: {}.", *NUMBER);
+}
+```
+
+# Implementation details
+
+The `Deref` implementation uses a hidden static variable that is guarded by an atomic check on each access.
+
+# Cargo features
+
+This crate provides two cargo features:
+
+- `nightly`: This uses unstable language features only available on the nightly release channel for a more optimal implementation. In practice this currently means avoiding a heap allocation per static. This feature might get deprecated at a later point once all relevant optimizations are usable from stable.
+- `spin_no_std` (implies `nightly`): This allows using this crate in a no-std environment, by depending on the standalone `spin` crate.
+
+Both features depend on unstable language features, which means
+no guarantees can be made about them in regard to SemVer stability.
+
+*/
+
+#![doc(html_root_url = "https://docs.rs/lazy_static/1.2.0")]
+#![no_std]
+
+#[cfg(not(feature = "spin_no_std"))]
+#[path="inline_lazy.rs"]
+#[doc(hidden)]
+pub mod lazy;
+
+#[cfg(feature = "spin_no_std")]
+#[path="core_lazy.rs"]
+#[doc(hidden)]
+pub mod lazy;
+
+#[doc(hidden)]
+pub use core::ops::Deref as __Deref;
+
+#[macro_export(local_inner_macros)]
+#[doc(hidden)]
+macro_rules! __lazy_static_internal {
+    // optional visibility restrictions are wrapped in `()` to allow for
+    // explicitly passing otherwise implicit information about private items
+    ($(#[$attr:meta])* ($($vis:tt)*) static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
+        __lazy_static_internal!(@MAKE TY, $(#[$attr])*, ($($vis)*), $N);
+        __lazy_static_internal!(@TAIL, $N : $T = $e);
+        lazy_static!($($t)*);
+    };
+    (@TAIL, $N:ident : $T:ty = $e:expr) => {
+        impl $crate::__Deref for $N {
+            type Target = $T;
+            fn deref(&self) -> &$T {
+                #[inline(always)]
+                fn __static_ref_initialize() -> $T { $e }
+
+                #[inline(always)]
+                fn __stability() -> &'static $T {
+                    __lazy_static_create!(LAZY, $T);
+                    LAZY.get(__static_ref_initialize)
+                }
+                __stability()
+            }
+        }
+        impl $crate::LazyStatic for $N {
+            fn initialize(lazy: &Self) {
+                let _ = &**lazy;
+            }
+        }
+    };
+    // `vis` is wrapped in `()` to prevent parsing ambiguity
+    (@MAKE TY, $(#[$attr:meta])*, ($($vis:tt)*), $N:ident) => {
+        #[allow(missing_copy_implementations)]
+        #[allow(non_camel_case_types)]
+        #[allow(dead_code)]
+        $(#[$attr])*
+        $($vis)* struct $N {__private_field: ()}
+        #[doc(hidden)]
+        $($vis)* static $N: $N = $N {__private_field: ()};
+    };
+    () => ()
+}
+
+#[macro_export(local_inner_macros)]
+macro_rules! lazy_static {
+    ($(#[$attr:meta])* static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
+        // use `()` to explicitly forward the information about private items
+        __lazy_static_internal!($(#[$attr])* () static ref $N : $T = $e; $($t)*);
+    };
+    ($(#[$attr:meta])* pub static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
+        __lazy_static_internal!($(#[$attr])* (pub) static ref $N : $T = $e; $($t)*);
+    };
+    ($(#[$attr:meta])* pub ($($vis:tt)+) static ref $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
+        __lazy_static_internal!($(#[$attr])* (pub ($($vis)+)) static ref $N : $T = $e; $($t)*);
+    };
+    () => ()
+}
+
+/// Support trait for enabling a few common operation on lazy static values.
+///
+/// This is implemented by each defined lazy static, and
+/// used by the free functions in this crate.
+pub trait LazyStatic {
+    #[doc(hidden)]
+    fn initialize(lazy: &Self);
+}
+
+/// Takes a shared reference to a lazy static and initializes
+/// it if it has not been already.
+///
+/// This can be used to control the initialization point of a lazy static.
+///
+/// Example:
+///
+/// ```rust
+/// #[macro_use]
+/// extern crate lazy_static;
+///
+/// lazy_static! {
+///     static ref BUFFER: Vec<u8> = (0..65537).collect();
+/// }
+///
+/// fn main() {
+///     lazy_static::initialize(&BUFFER);
+///
+///     // ...
+///     work_with_initialized_data(&BUFFER);
+/// }
+/// # fn work_with_initialized_data(_: &[u8]) {}
+/// ```
+pub fn initialize<T: LazyStatic>(lazy: &T) {
+    LazyStatic::initialize(lazy);
+}