Implement Index for PyBytes

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
  * `module` argument to `pyclass` macro. [#499](https://github.com/PyO3/pyo3/pull/499)
  * `py_run!` macro [#512](https://github.com/PyO3/pyo3/pull/512)
  * Use existing fields and methods before calling custom __getattr__. [#505](https://github.com/PyO3/pyo3/pull/512)
+ * `PyBytes` can now be indexed just like `Vec<u8>`
 
 ### Fixed
 

src/types/string.rs

@@ -11,16 +11,22 @@ use crate::types::PyAny;
 use crate::AsPyPointer;
 use crate::Python;
 use std::borrow::Cow;
+use std::ops::Index;
 use std::os::raw::c_char;
+use std::slice::SliceIndex;
 use std::str;
 
 /// Represents a Python `string`.
+///
+/// This type is immutable
 #[repr(transparent)]
 pub struct PyString(PyObject);
 
 pyobject_native_type!(PyString, ffi::PyUnicode_Type, ffi::PyUnicode_Check);
 
-/// Represents a Python `byte` string.
+/// Represents a Python `bytes`.
+///
+/// This type is immutable
 #[repr(transparent)]
 pub struct PyBytes(PyObject);
 
@@ -120,6 +126,15 @@ impl PyBytes {
     }
 }
 
+/// This is the same way [Vec] is indexed
+impl<I: SliceIndex<[u8]>> Index<I> for PyBytes {
+    type Output = I::Output;
+
+    fn index(&self, index: I) -> &Self::Output {
+        &self.as_bytes()[index]
+    }
+}
+
 /// Converts Rust `str` to Python object.
 /// See `PyString::new` for details on the conversion.
 impl ToPyObject for str {
@@ -203,7 +218,7 @@ impl<'source> FromPyObject<'source> for String {
 
 #[cfg(test)]
 mod test {
-    use super::PyString;
+    use super::{PyBytes, PyString};
     use crate::instance::AsPyRef;
     use crate::object::PyObject;
     use crate::Python;
@@ -261,4 +276,12 @@ mod test {
         assert!(py_string.to_string().is_ok());
         assert_eq!(Cow::Borrowed(s), py_string.to_string().unwrap());
     }
+
+    #[test]
+    fn test_bytes_index() {
+        let gil = Python::acquire_gil();
+        let py = gil.python();
+        let bytes = PyBytes::new(py, b"Hello World");
+        assert_eq!(bytes[1], b'e');
+    }
 }