diff --git a/src/parser/boxed_parser.rs b/src/parser/boxed_parser.rs
new file mode 100644
index 0000000..8883910
--- /dev/null
+++ b/src/parser/boxed_parser.rs
@@ -0,0 +1,33 @@
+use crate::bnf::Bnf;
+use crate::parser::{ParseResult, Parser, ParserInput};
+
+pub struct BoxedParser<'a, I, O, E>
+where
+    I: ParserInput,
+{
+    inner: Box<dyn Parser<I, O, E> + 'a>,
+}
+
+impl<'a, I, O, E> BoxedParser<'a, I, O, E>
+where
+    I: ParserInput,
+{
+    pub(crate) fn new<P>(inner: P) -> Self
+    where
+        P: Parser<I, O, E> + 'a,
+    {
+        BoxedParser {
+            inner: Box::new(inner),
+        }
+    }
+}
+
+impl<'a, I: ParserInput, O, E> Parser<I, O, E> for BoxedParser<'a, I, O, E> {
+    fn parse(&self, input: I) -> ParseResult<I, O, E> {
+        self.inner.parse(input)
+    }
+
+    fn bnf(&self) -> Option<Bnf> {
+        self.inner.bnf()
+    }
+}
diff --git a/src/parser.rs b/src/parser/mod.rs
similarity index 86%
rename from src/parser.rs
rename to src/parser/mod.rs
index 7b2019b..244aed8 100644
--- a/src/parser.rs
+++ b/src/parser/mod.rs
@@ -1,6 +1,10 @@
+mod boxed_parser;
+
 use crate::bnf::Bnf;
 use std::rc::Rc;
 
+pub use boxed_parser::BoxedParser;
+
 pub type ParseResult<I, O, E> = Result<(O, I), E>;
 
 pub trait ParserInput: std::fmt::Debug {}
@@ -122,37 +126,6 @@ where
     }
 }
 
-pub struct BoxedParser<'a, I, O, E>
-where
-    I: ParserInput,
-{
-    inner: Box<dyn Parser<I, O, E> + 'a>,
-}
-
-impl<'a, I, O, E> BoxedParser<'a, I, O, E>
-where
-    I: ParserInput,
-{
-    pub(crate) fn new<P>(inner: P) -> Self
-    where
-        P: Parser<I, O, E> + 'a,
-    {
-        BoxedParser {
-            inner: Box::new(inner),
-        }
-    }
-}
-
-impl<'a, I: ParserInput, O, E> Parser<I, O, E> for BoxedParser<'a, I, O, E> {
-    fn parse(&self, input: I) -> ParseResult<I, O, E> {
-        self.inner.parse(input)
-    }
-
-    fn bnf(&self) -> Option<Bnf> {
-        self.inner.bnf()
-    }
-}
-
 impl<I: ParserInput, O, E, F> Parser<I, O, E> for F
 where
     F: Fn(I) -> ParseResult<I, O, E>,