Implement WeaklyDivisibleSemiring for BooleanWeight

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## Added
 - Binary serialization & deserialization support for FST caches.
 - Binary serialization & deserialization support for Compose FST op state table.
+- Implement `WeaklyDivisibleSemiring` for `BooleanWeight`
 
 ## [0.8.0] - 2020-16-10
 

rustfst/src/semirings/boolean_weight.rs

@@ -2,6 +2,8 @@ use anyhow::Result;
 
 use crate::semirings::{CompleteSemiring, ReverseBack, Semiring, SemiringProperties, StarSemiring};
 use std::borrow::Borrow;
+
+use super::{DivideType, WeaklyDivisibleSemiring};
 /// Boolean semiring: (&, |, false, true).
 #[derive(Clone, Debug, PartialEq, PartialOrd, Default, Eq, Copy, Hash)]
 pub struct BooleanWeight {
@@ -77,6 +79,15 @@ impl StarSemiring for BooleanWeight {
     }
 }
 
+impl WeaklyDivisibleSemiring for BooleanWeight {
+    fn divide_assign(&mut self, rhs: &Self, _divide_type: DivideType) -> Result<()> {
+        if !rhs.value {
+            bail!("Division by 0")
+        }
+        Ok(()) // x / true == true
+    }
+}
+
 impl From<bool> for BooleanWeight {
     fn from(b: bool) -> Self {
         Self::new(b)