Port core util lib to support no_std

src/lib.rs

@@ -1,3 +1,10 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+#![cfg_attr(not(feature = "std"), feature(alloc))]
+
+#[cfg(not(feature = "std"))]
+#[macro_use]
+extern crate alloc;
+
 extern crate parity_wasm;
 extern crate byteorder;
 #[macro_use] extern crate log;
@@ -22,3 +29,13 @@ pub use gas::inject_gas_counter;
 pub use ext::{externalize, externalize_mem, underscore_funcs, ununderscore_funcs, shrink_unknown_stack};
 pub use pack::{pack_instance, Error as PackingError};
 pub use runtime_type::inject_runtime_type;
+
+#[cfg(not(feature = "std"))]
+mod std {
+	pub use core::*;
+	pub use alloc::{vec, string, boxed, borrow};
+
+	pub mod collections {
+		pub use alloc::{BTreeMap, BTreeSet};
+	}
+}