Substring method for string types.

This crate provides a substring method on Rust string types. The method takes a start and end character index and returns a string slice of the characters within that range.

The method is provided via the Substring trait which is implemented on the &str primitive.

Usage

To use this crate, simply bring the Substring trait into scope and call the substring method on your string types.

```rust use substring::Substring;

assert_eq!("hello, world!".substring(7, 12), "world"); ```

Performance

As Rust strings are UTF-8, the algorithm for finding a character substring has temporal complexity O(n), where n is the byte length of the string. This is due to characters not being of predictible byte lengths.