Remove unnecessary mut (#101)

README.md

@@ -5,7 +5,7 @@ A fast implementation of the Aho-Corasick algorithm using the compact double-arr
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 The main technical ideas behind this library appear in the following paper:

src/bytewise/builder.rs

@@ -227,7 +227,7 @@ impl DoubleArrayAhoCorasickBuilder {
         })
     }
 
-    fn build_sparse_nfa<I, P, V>(&mut self, patvals: I) -> Result<BytewiseNfaBuilder<V>>
+    fn build_sparse_nfa<I, P, V>(&self, patvals: I) -> Result<BytewiseNfaBuilder<V>>
     where
         I: IntoIterator<Item = (P, V)>,
         P: AsRef<[u8]>,

src/nfa_builder.rs

@@ -120,7 +120,7 @@ where
         Ok(())
     }
 
-    pub(crate) fn build_fails(&mut self) -> Vec<u32> {
+    pub(crate) fn build_fails(&self) -> Vec<u32> {
         let mut q = Vec::with_capacity(self.states.len());
         for &child_id in self.states[usize::from_u32(ROOT_STATE_ID)]
             .borrow()
@@ -155,7 +155,7 @@ where
         q
     }
 
-    pub(crate) fn build_fails_leftmost(&mut self) -> Vec<u32> {
+    pub(crate) fn build_fails_leftmost(&self) -> Vec<u32> {
         let mut q = Vec::with_capacity(self.states.len());
         for &child_id in self.states[usize::from_u32(ROOT_STATE_ID)]
             .borrow()