feat: add no-std support

closes #5

.github/workflows/ci.yml

@@ -7,14 +7,39 @@ on:
     types: [opened, repoened, synchronize]
 
 jobs:
-  test:
-    name: Test Rust ${{matrix.toolchain}} on ${{matrix.os}}
+  build:
+    name: Build ${{matrix.toolchain}} on ${{matrix.os}} with ${{matrix.args}}
     runs-on: ${{matrix.os}}-latest
     strategy:
       fail-fast: false
       matrix:
         toolchain: [stable, nightly]
         os: [ubuntu]
+        target: [wasm32-unknown-unknown]
+        args: [--no-default-features --target wasm32-unknown-unknown]
+    steps:
+      - uses: actions/checkout@main
+      - name: Install rust
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{matrix.toolchain}}
+          override: true
+      - run: rustup target add ${{matrix.target}}
+      - name: Test
+        uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: ${{matrix.args}}
+
+  test:
+    name: Test ${{matrix.toolchain}} on ${{matrix.os}} with ${{matrix.features}}
+    runs-on: ${{matrix.os}}-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        toolchain: [stable, nightly]
+        os: [ubuntu]
+        features: [--all-features, --no-default-features]
     steps:
       - uses: actions/checkout@main
       - name: Install rust
@@ -26,25 +51,29 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: test
+          args: ${{matrix.features}}
 
   clippy:
-    name: Clippy
+    name: Clippy with ${{matrix.features}}
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        features: [--all-features, --no-default-features]
     steps:
       - uses: actions/checkout@main
-      - name: Install minimal stable with clippy
+      - name: Install minimal nightly with clippy
         uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: stable
+          toolchain: nightly
           components: clippy
           override: true
-
       - name: Clippy
         uses: actions-rs/cargo@v1
         with:
           command: clippy
-          args: --all -- -D clippy::all -D warnings
+          args: --all ${{matrix.features}} -- -D clippy::all -D warnings
 
   rustfmt:
     name: rustfmt

Cargo.toml

@@ -10,10 +10,14 @@ categories = ["cryptography", "no-std"]
 keywords = ["miden", "crypto", "hash", "merkle"]
 edition = "2021"
 
+[features]
+default = ["std", "winter_crypto/default", "winter_math/default", "winter_utils/default"]
+std = ["winter_crypto/std", "winter_math/std", "winter_utils/std"]
+
 [dependencies]
-winter_crypto = { version = "0.4.1", package = "winter-crypto" }
-winter_math = { version = "0.4.1", package = "winter-math" }
-winter_utils = { version = "0.4.1", package = "winter-utils" }
+winter_crypto = { version = "0.4.1", package = "winter-crypto", default-features = false }
+winter_math = { version = "0.4.1", package = "winter-math", default-features = false }
+winter_utils = { version = "0.4.1", package = "winter-utils", default-features = false }
 
 [dev-dependencies]
 proptest = "1.0.0"

src/hash/rpo/digest.rs

@@ -1,7 +1,7 @@
 use super::DIGEST_SIZE;
 use crate::{
     ByteReader, ByteWriter, Deserializable, DeserializationError, Digest, Felt, Serializable,
-    StarkField, ZERO,
+    StarkField, String, ZERO,
 };
 use core::ops::Deref;
 
@@ -59,9 +59,9 @@ impl Deserializable for RpoDigest256 {
         for inner in inner.iter_mut() {
             let e = source.read_u64()?;
             if e >= Felt::MODULUS {
-                return Err(DeserializationError::InvalidValue(
-                    "Value not in the appropriate range".to_owned(),
-                ));
+                return Err(DeserializationError::InvalidValue(String::from(
+                    "Value not in the appropriate range",
+                )));
             }
             *inner = Felt::new(e);
         }

src/lib.rs

@@ -1,3 +1,9 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+
+#[cfg(not(feature = "std"))]
+#[cfg_attr(test, macro_use)]
+extern crate alloc;
+
 pub use winter_crypto::{Digest, ElementHasher, Hasher as HashFn};
 pub use winter_math::{
     fields::{f64::BaseElement as Felt, QuadExtension},
@@ -5,6 +11,7 @@ pub use winter_math::{
 };
 pub use winter_utils::{
     collections::{BTreeMap, Vec},
+    string::String,
     uninit_vector, ByteReader, ByteWriter, Deserializable, DeserializationError, Serializable,
     SliceReader,
 };

src/merkle/merkle_path_set.rs

@@ -57,7 +57,7 @@ impl MerklePathSet {
         let pos = 2u64.pow(self.total_depth) + index;
 
         // Index of the leaf path in map. Paths of neighboring leaves are stored in one key-value pair
-        let half_pos = (pos / 2) as u64;
+        let half_pos = pos / 2;
 
         let mut extended_path = path;
         if is_even(pos) {
@@ -104,7 +104,7 @@ impl MerklePathSet {
         }
 
         let pos = 2u64.pow(depth) + index;
-        let index = (pos / 2) as u64;
+        let index = pos / 2;
 
         match self.paths.get(&index) {
             None => Err(MerkleError::NodeNotInSet(index)),

src/merkle/merkle_tree.rs

@@ -1,7 +1,7 @@
 use super::MerkleError;
 use crate::{
     hash::{merge, Digest},
-    log2, uninit_vector, Felt, FieldElement, Word,
+    log2, uninit_vector, Felt, FieldElement, Vec, Word,
 };
 use core::slice;
 
@@ -80,7 +80,7 @@ impl MerkleTree {
             return Err(MerkleError::InvalidIndex(depth, index));
         }
 
-        let pos = 2usize.pow(depth as u32) + (index as usize);
+        let pos = 2_usize.pow(depth) + (index as usize);
         Ok(self.nodes[pos])
     }
 
@@ -102,7 +102,7 @@ impl MerkleTree {
         }
 
         let mut path = Vec::with_capacity(depth as usize);
-        let mut pos = 2usize.pow(depth as u32) + (index as usize);
+        let mut pos = 2_usize.pow(depth) + (index as usize);
 
         while pos > 1 {
             path.push(self.nodes[pos ^ 1]);

src/merkle/mod.rs

@@ -1,4 +1,4 @@
-use crate::Word;
+use crate::{Vec, Word};
 
 #[cfg(test)]
 use crate::{Felt, ZERO};