[utils] Setup a new utils sub-crate

This is important due to restrictions in Cargo dependency and crate feature resolving.
For example: We currently cannot link to pdsl_core from pdsl_lang since this would cause problems with duplicate panic handlers.
Having another minimally kept pdsl_utils we can use this to offload some common utility from pdsl_core into pdsl_utils to make them usable in pdsl_lang.

Cargo.toml

 [workspace]
 
 members = [
+    "utils",
     "core",
     "model",
     "lang",

utils/Cargo.toml

+[package]
+name = "pdsl_utils"
+version = "0.1.0"
+authors = ["Robin Freyler <robin@parity.io>", "Parity Technologies <admin@parity.io>"]
+edition = "2018"
+
+license = "GPL-3.0"
+readme = "README.md"
+
+# repository = "https://github.com/robbepop/substrate-contract"
+# homepage = "https://github.com/robbepop/substrate-contract"
+# documentation = "https://robbepop.github.io/pwasm-abi/substrate-contract/"
+
+description = "[pDSL: Parity eDSL] Rust based eDSL for writing smart contracts for Substrate"
+keywords = ["wasm", "parity", "webassembly", "blockchain", "edsl"]
+categories = ["no-std", "embedded"]
+
+include = ["/Cargo.toml", "src/**/*.rs", "/README.md", "/LICENSE"]
+
+[dependencies]
+tiny-keccak = "1.4"
+
+[features]
+default = []
+std = []

utils/LICENSE

+../LICENSE
\ No newline at end of file

utils/README.md

+../README.md
\ No newline at end of file

utils/src/hash.rs

+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of pDSL.
+//
+// pDSL is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// pDSL is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with pDSL.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Hashing utilities around the Keccak256 hasher.
+
+use tiny_keccak;
+use core::hash::{
+    Hash,
+    Hasher,
+};
+
+/// Keccak256 hasher.
+#[derive(Clone)]
+pub struct Keccak256Hasher {
+    /// The internal keccak hasher.
+    hasher: tiny_keccak::Keccak,
+}
+
+impl Default for Keccak256Hasher {
+    fn default() -> Self {
+        Keccak256Hasher {
+            hasher: tiny_keccak::Keccak::new_keccak256(),
+        }
+    }
+}
+
+impl Keccak256Hasher {
+    /// Returns the hash value for the values written so far.
+    ///
+    /// If you need to start a fresh hash value, you will have to create a new hasher.
+    pub fn finish256(self) -> [u8; 32] {
+        let mut res = [0; 32];
+        self.hasher.finalize(&mut res);
+        res
+    }
+
+    pub fn finish64(self) -> [u8; 8] {
+        let mut arr = [0; 8];
+        let res = self.finish256();
+        arr[..8].clone_from_slice(&res[..8]);
+        arr
+    }
+}
+
+fn bytes8_to_u64(bytes: [u8; 8]) -> u64 {
+    bytes
+        .iter()
+        .enumerate()
+        .map(|(n, &ext)| u64::from(ext) << (n * 8))
+        .fold(0u64, |acc, ext| acc | ext)
+}
+
+impl Hasher for Keccak256Hasher {
+    /// Returns the hash value for the values written so far.
+    ///
+    /// If you need to start a fresh hash value, you will have to create a new hasher.
+    fn finish(&self) -> u64 {
+        bytes8_to_u64(self.clone().finish64())
+    }
+
+    /// Writes some data into the hasher.
+    fn write(&mut self, bytes: &[u8]) {
+        self.hasher.update(bytes)
+    }
+}
+
+/// Returns the keccak-256 hash for the given byte slice.
+pub fn keccak256<T>(val: &T) -> [u8; 32]
+where
+    T: ?Sized + Hash,
+{
+    let mut hasher = Keccak256Hasher::default();
+    val.hash(&mut hasher);
+    hasher.finish256()
+}

utils/src/lib.rs

+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of pDSL.
+//
+// pDSL is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// pDSL is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with pDSL.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Utilities in use by pDSL.
+//!
+//! These are kept separate from pDSL core to allow for more dynamic inter crate dependencies.
+//! The main problem is that today Cargo manages crate features on a per-crate basis instead of
+//! a per-crate-target basis thus making dependencies from `pdsl_lang` to `pdsl_core` impossible.
+//!
+//! By introducing `pdsl_utils` we have a way to share utility components between `pdsl_core` and
+//! other parts of the framework, like `pdsl_lang`.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+pub mod hash;