Move generic circuit gadgets into bellman

Cargo.toml

@@ -10,6 +10,7 @@ version = "0.1.0"
 
 [dependencies]
 bit-vec = "0.4.4"
+blake2s_simd = "0.5"
 ff = { path = "../ff" }
 futures = "0.1"
 futures-cpupool = { version = "0.1", optional = true }
@@ -21,7 +22,10 @@ rand_core = "0.5"
 byteorder = "1"
 
 [dev-dependencies]
+hex-literal = "0.1"
 rand = "0.7"
+rand_xorshift = "0.2"
+sha2 = "0.8"
 
 [features]
 groth16 = ["pairing"]

src/gadgets.rs

@@ -0,0 +1,33 @@
+pub mod test;
+
+pub mod boolean;
+pub mod multieq;
+pub mod uint32;
+pub mod blake2s;
+pub mod num;
+pub mod lookup;
+pub mod multipack;
+pub mod sha256;
+
+use crate::{
+    SynthesisError
+};
+
+// TODO: This should probably be removed and we
+// should use existing helper methods on `Option`
+// for mapping with an error.
+/// This basically is just an extension to `Option`
+/// which allows for a convenient mapping to an
+/// error on `None`.
+pub trait Assignment<T> {
+    fn get(&self) -> Result<&T, SynthesisError>;
+}
+
+impl<T> Assignment<T> for Option<T> {
+    fn get(&self) -> Result<&T, SynthesisError> {
+        match *self {
+            Some(ref v) => Ok(v),
+            None => Err(SynthesisError::AssignmentMissing)
+        }
+    }
+}