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.
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"); ```
Note that the indexing of substrings is based on Unicode Scalar Value. As such, substrings may not always match your intuition:
```rust use substring::Substring;
asserteq!("ã".substring(0, 1), "a"); // As opposed to "ã". asserteq!("ã".substring(1, 2), "\u{0303}") ```
The above example occurs because "ã" is technically made up of two UTF-8 scalar values: the letter "a" and a combining tilde.
As Rust strings are UTF-8 encoded, 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.
This crate is guaranteed to compile on stable Rust 1.6 and up.