feat(engine): allow choosing engine per executor call

1 files changed, 15 insertions, 6 deletions

diff --git a/src/engine.rs b/src/engine.rs
index 508178a..8cf2726 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -4,17 +4,22 @@
 
 use std::io::Read;
 
-use crate::executor::{Error, Executor};
+use num_traits::{One, Unsigned, WrappingAdd, WrappingSub, Zero};
+
+use crate::executor::{self, Error};
 
 /// Generic engine implementation for the Brainfuck interpreter.
-pub trait Engine<T> {
+pub trait Engine {
+	/// Inner type of the Tape.
+	type TapeInner: Clone + Copy + Unsigned + WrappingAdd + WrappingSub + One + Zero;
+
 	/// Read one byte from stdin.
 	///
 	/// # Errors
 	///
 	/// This function will return an error if it is unable to read from stdin,
 	/// or if it indexes out of bounds.
-	fn read_byte() -> Result<T, Error>;
+	fn read_byte() -> Result<Self::TapeInner, Error>;
 
 	/// Write the provided byte to stdout.
 	///
@@ -22,10 +27,12 @@ pub trait Engine<T> {
 	///
 	/// This function will return an error if it is unable to write a byte to
 	/// stdout.
-	fn write_byte(byte: T) -> Result<(), Error>;
+	fn write_byte(byte: Self::TapeInner) -> Result<(), Error>;
 }
 
-impl Engine<u8> for Executor {
+impl Engine for executor::U8 {
+	type TapeInner = u8;
+
 	fn read_byte() -> Result<u8, Error> {
 		let mut input: [u8; 1] = [0; 1];
 
@@ -41,7 +48,9 @@ impl Engine<u8> for Executor {
 	}
 }
 
-impl Engine<u16> for Executor {
+impl Engine for executor::U16 {
+	type TapeInner = u16;
+
 	fn read_byte() -> Result<u16, Error> {
 		let mut input: [u8; 2] = [0; 2];