Make it possible to disable parallel feature

Cargo.toml

@@ -24,14 +24,14 @@ travis-ci = { repository = "slide-rs/specs" }
 crossbeam = "0.4.1"
 derivative = "1"
 fnv = "1.0"
-hibitset = { version = "0.5.2", features = ["parallel"] }
+hibitset = { version = "0.5.2", default-features = false }
 log = "0.4"
 mopa = "0.2"
-shred = "0.7.0"
+shred = { version = "0.7.0", default-features = false }
 shrev = "1.0.0"
 shred-derive = "0.5.0"
 tuple_utils = "0.2"
-rayon = "1.0.0"
+rayon = { version = "1.0.0", optional = true }
 nonzero_signed = "1.0.1"
 
 futures = { version = "0.1", optional = true }
@@ -41,6 +41,8 @@ serde = { version = "1.0", optional = true, features = ["serde_derive"] }
 rudy = { version = "0.1", optional = true }
 
 [features]
+default = ["parallel"]
+parallel = ["rayon", "shred/parallel", "hibitset/parallel"]
 common = ["futures"]
 nightly = ["shred/nightly"]
 

src/bitset.rs

@@ -6,7 +6,9 @@
 
 use hibitset::{AtomicBitSet, BitSet, BitSetAnd, BitSetLike, BitSetNot, BitSetOr, BitSetXor};
 
-use join::{Join, ParJoin};
+use join::Join;
+#[cfg(feature = "parallel")]
+use join::ParJoin;
 use world::Index;
 
 macro_rules! define_bit_join {
@@ -25,6 +27,7 @@ macro_rules! define_bit_join {
             }
         }
 
+        #[cfg(feature = "parallel")]
         unsafe impl<$( $lifetime, )* $( $arg ),*> ParJoin for $bitset
             where $( $arg: BitSetLike ),*
         { }

src/join.rs

@@ -1,10 +1,18 @@
 //! Joining of components for iteration over entities with specific components.
 
 use std;
+#[cfg(feature = "parallel")]
 use std::cell::UnsafeCell;
 
-use hibitset::{BitIter, BitProducer, BitSetAll, BitSetAnd, BitSetLike};
+use hibitset::{BitIter, BitSetAll, BitSetAnd, BitSetLike};
+
+#[cfg(feature = "parallel")]
+use hibitset::BitProducer;
+
+#[cfg(feature = "parallel")]
 use rayon::iter::plumbing::{bridge_unindexed, Folder, UnindexedConsumer, UnindexedProducer};
+
+#[cfg(feature = "parallel")]
 use rayon::iter::ParallelIterator;
 use std::ops::{Deref, DerefMut};
 use tuple_utils::Split;
@@ -241,6 +249,7 @@ pub trait Join {
 /// The purpose of the `ParJoin` trait is to provide a way
 /// to access multiple storages in parallel at the same time with
 /// the merged bit set.
+#[cfg(feature = "parallel")]
 pub unsafe trait ParJoin: Join {
     /// Create a joined parallel iterator over the contents.
     fn par_join(self) -> JoinParIter<Self>
@@ -399,9 +408,11 @@ impl<J: Join> std::iter::Iterator for JoinIter<J> {
 }
 
 /// `JoinParIter` is a `ParallelIterator` over a group of `Storages`.
+#[cfg(feature = "parallel")]
 #[must_use]
 pub struct JoinParIter<J>(J);
 
+#[cfg(feature = "parallel")]
 impl<J> ParallelIterator for JoinParIter<J>
 where
     J: Join + Send,
@@ -424,6 +435,7 @@ where
     }
 }
 
+#[cfg(feature = "parallel")]
 struct JoinProducer<'a, J>
 where
     J: Join + Send,
@@ -435,6 +447,7 @@ where
     values: &'a UnsafeCell<J::Value>,
 }
 
+#[cfg(feature = "parallel")]
 impl<'a, J> JoinProducer<'a, J>
 where
     J: Join + Send,
@@ -447,6 +460,7 @@ where
     }
 }
 
+#[cfg(feature = "parallel")]
 unsafe impl<'a, J> Send for JoinProducer<'a, J>
 where
     J: Join + Send,
@@ -455,6 +469,7 @@ where
     J::Mask: 'a + Send + Sync,
 {}
 
+#[cfg(feature = "parallel")]
 impl<'a, J> UnindexedProducer for JoinProducer<'a, J>
 where
     J: Join + Send,
@@ -523,6 +538,7 @@ macro_rules! define_open {
                 unconstrained
             }
         }
+        #[cfg(feature = "parallel")]
         unsafe impl<$($from,)*> ParJoin for ($($from),*,)
             where $($from: ParJoin),*,
                   ($(<$from as Join>::Mask,)*): BitAnd,
@@ -582,6 +598,7 @@ macro_rules! immutable_resource_join {
             }
         }
 
+        #[cfg(feature = "parallel")]
         unsafe impl<'a, 'b, T> ParJoin for &'a $ty
         where
             &'a T: ParJoin,
@@ -616,6 +633,7 @@ macro_rules! mutable_resource_join {
             }
         }
 
+        #[cfg(feature = "parallel")]
         unsafe impl<'a, 'b, T> ParJoin for &'a mut $ty
         where
             &'a mut T: ParJoin,

src/lib.rs

@@ -194,6 +194,7 @@ extern crate hibitset;
 extern crate log;
 extern crate nonzero_signed;
 extern crate mopa;
+#[cfg(feature = "parallel")]
 extern crate rayon;
 extern crate shrev;
 extern crate tuple_utils;
@@ -222,12 +223,14 @@ pub mod storage;
 pub mod world;
 
 pub use hibitset::BitSet;
-pub use join::{Join, ParJoin};
+pub use join::Join;
+#[cfg(feature = "parallel")]
+pub use join::ParJoin;
 pub use shred::{Accessor, Dispatcher, DispatcherBuilder, Read, ReadExpect, Resources, RunNow,
                 StaticAccessor, System, SystemData, Write, WriteExpect};
 pub use shrev::ReaderId;
 
-#[cfg(not(target_os = "emscripten"))]
+#[cfg(feature = "parallel")]
 pub use shred::AsyncDispatcher;
 
 pub use changeset::ChangeSet;

src/prelude.rs

@@ -3,14 +3,16 @@
 //! Contains all of the most common traits, structures,
 
 pub use hibitset::BitSet;
-pub use join::{Join, ParJoin};
+pub use join::Join;
+#[cfg(feature = "parallel")]
+pub use join::ParJoin;
 pub use shred::{Accessor, Dispatcher, DispatcherBuilder, Read, ReadExpect, Resources, RunNow,
                 StaticAccessor, System, SystemData, Write, WriteExpect};
 pub use shrev::ReaderId;
 
-#[cfg(not(target_os = "emscripten"))]
+#[cfg(feature = "parallel")]
 pub use rayon::iter::ParallelIterator;
-#[cfg(not(target_os = "emscripten"))]
+#[cfg(feature = "parallel")]
 pub use shred::AsyncDispatcher;
 
 pub use changeset::ChangeSet;

src/storage/mod.rs

@@ -19,7 +19,9 @@ use shred::{CastFrom, Fetch};
 
 use self::drain::Drain;
 use error::{Error, WrongGeneration};
-use join::{Join, ParJoin};
+use join::Join;
+#[cfg(feature = "parallel")]
+use join::ParJoin;
 use world::{Component, EntitiesRes, Entity, Generation, Index};
 
 mod data;
@@ -52,6 +54,7 @@ impl<'a> Join for AntiStorage<'a> {
 
 unsafe impl<'a> DistinctStorage for AntiStorage<'a> {}
 
+#[cfg(feature = "parallel")]
 unsafe impl<'a> ParJoin for AntiStorage<'a> {}
 
 /// A dynamic storage.
@@ -478,6 +481,7 @@ where
     }
 }
 
+#[cfg(feature = "parallel")]
 unsafe impl<'a, 'e, T, D> ParJoin for &'a Storage<'e, T, D>
 where
     T: Component,
@@ -508,6 +512,7 @@ where
     }
 }
 
+#[cfg(feature = "parallel")]
 unsafe impl<'a, 'e, T, D> ParJoin for &'a mut Storage<'e, T, D>
 where
     T: Component,

src/storage/restrict.rs

@@ -5,7 +5,10 @@ use std::ops::{Deref, DerefMut};
 use hibitset::BitSet;
 use shred::Fetch;
 
-use join::{Join, ParJoin};
+use join::Join;
+
+#[cfg(feature = "parallel")]
+use join::ParJoin;
 use storage::{MaskedStorage, Storage, UnprotectedStorage};
 use world::{Component, EntitiesRes, Entity, Index};
 
@@ -76,6 +79,7 @@ where
     phantom: PhantomData<(C, Restrict)>,
 }
 
+#[cfg(feature = "parallel")]
 unsafe impl<'rf, 'st: 'rf, C, S, B> ParJoin
     for &'rf mut RestrictedStorage<'rf, 'st, C, S, B, MutableParallelRestriction>
 where
@@ -85,6 +89,7 @@ where
 {
 }
 
+#[cfg(feature = "parallel")]
 unsafe impl<'rf, 'st: 'rf, C, S, B, Restrict> ParJoin
     for &'rf RestrictedStorage<'rf, 'st, C, S, B, Restrict>
 where

src/world/entity.rs

@@ -6,7 +6,9 @@ use nonzero_signed::NonZeroI32;
 use shred::Read;
 
 use error::WrongGeneration;
-use join::{Join, ParJoin};
+use join::Join;
+#[cfg(feature = "parallel")]
+use join::ParJoin;
 use storage::WriteStorage;
 use world::Component;
 
@@ -327,6 +329,7 @@ impl<'a> Join for &'a EntitiesRes {
     }
 }
 
+#[cfg(feature = "parallel")]
 unsafe impl<'a> ParJoin for &'a EntitiesRes {}
 
 /// An entity builder from `EntitiesRes`.  Allows building an entity with its