Use getrandom as default (for no-std feature)

Author: Mec-iS

.github/CONTRIBUTING.md

@@ -25,11 +25,17 @@ Take a look to the conventions established by existing code:
 * Every module should provide a Rust doctest, a brief test embedded with the documentation that explains how to use the procedure implemented.
 * Every module should provide comprehensive tests at the end, in its `mod tests {}` sub-module. These tests can be flagged or not with configuration flags to allow WebAssembly target.
 * Run `cargo doc --no-deps --open` and read the generated documentation in the browser to be sure that your changes reflects in the documentation and new code is documented.
+
+#### digging deeper
 * a nice overview of the codebase is given by [static analyzer](https://mozilla.github.io/rust-code-analysis/metrics.html):
 ```
 $ cargo install rust-code-analysis-cli
+// print metrics for every module
 $ rust-code-analysis-cli -m -O json -o . -p src/ --pr
+// print full AST for a module
+$ rust-code-analysis-cli -p src/algorithm/neighbour/fastpair.rs --ls 22 --le 213 -d > ast.txt
 ```
+* find more information about what happens in your binary with [`twiggy`](https://rustwasm.github.io/twiggy/install.html). This need a compiled binary so create a brief `main {}` function using `smartcore` and then point `twiggy` to that file.
 
 ## Issue Report Process
 

.gitignore

@@ -27,4 +27,5 @@ out.svg
 
 FlameGraph/
 out.stacks
-*.json
+*.json
+*.txt

Cargo.toml

@@ -16,6 +16,7 @@ exclude = [
     ".gitignore",
     "smartcore.iml",
     "smartcore.svg",
+    "tests/"
 ]
 
 [dependencies]
@@ -25,32 +26,29 @@ ndarray = { version = "0.15", optional = true }
 num-traits = "0.2.12"
 num = "0.4"
 rand = { version = "0.8.5", default-features = false, features = ["small_rng"] }
+getrandom = { version = "*", features = ["js"] }
 rand_distr = { version = "0.4", optional = true }
 serde = { version = "1", features = ["derive"], optional = true }
 
 [features]
 default = []
 serde = ["dep:serde"]
 ndarray-bindings = ["dep:ndarray"]
-datasets = ["dep:rand_distr", "std", "serde"]
-std = ["rand/std_rng", "rand/std"]
-# wasm32 only
-js = ["getrandom/js"]
+datasets = ["dep:rand_distr", "std_rand", "serde"]
+std_rand = ["rand/std_rng", "rand/std"]
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 getrandom = { version = "0.2", optional = true }
 
+[target.'cfg(all(target_arch = "wasm32", not(target_os = "wasi")))'.dev-dependencies]
+wasm-bindgen-test = "0.3"
+
 [dev-dependencies]
 itertools = "*"
-criterion = { version = "0.4", default-features = false }
 serde_json = "1.0"
 bincode = "1.3.1"
 
-[target.'cfg(all(target_arch = "wasm32", not(target_os = "wasi")))'.dev-dependencies]
-wasm-bindgen-test = "0.3"
-
 [workspace]
-resolver = "2"
 
 [profile.test]
 debug = 1

src/rand_custom.rs

@@ -1,5 +1,7 @@
 #[cfg(not(feature = "std"))]
 pub(crate) use rand::rngs::SmallRng as RngImpl;
+#[cfg(not(feature = "std"))]
+use getrandom;
 #[cfg(feature = "std")]
 pub(crate) use rand::rngs::StdRng as RngImpl;
 use rand::SeedableRng;
@@ -13,7 +15,10 @@ pub(crate) fn get_rng_impl(seed: Option<u64>) -> RngImpl {
                     use rand::RngCore;
                     RngImpl::seed_from_u64(rand::thread_rng().next_u64())
                 } else {
-                    panic!("seed number needed for non-std build");
+                    // non-std build, use getrandom
+                    let mut buf = [0u8; 64];
+                    getrandom::getrandom(&mut buf).unwrap();
+                    RngImpl::seed_from_u64(buf[0] as u64)
                 }
             }
         }