string_more

string_more is a Rust crate that enhances the String and &str types from the standard library with powerful extension traits: StringExt and StrExt. These traits introduce additional methods to efficiently manipulate strings, focusing on minimizing allocations by allowing in-place modifications for String and allocating when necessary for &str.

• StringExt: Provides in-place operations for the String type, modifying the string directly without creating a new allocation.
• StrExt: Offers the same operations for &str, but allocates and returns a new String, leaving the original &str intact.

Features

• In-place Operations: Modify String values directly with StringExt, minimizing memory allocations.
• Immutable Operations: Use StrExt to perform operations on &str that allocate and return new strings.
• Flexible and Efficient: Designed to extend the standard string functionality without sacrificing performance.

Installation

Add string_more to your Cargo.toml:

cargo add string_more

or edit your Cargo.toml manually by adding:

[dependencies]
string_more = "0.3"

Then, in your Rust code:

use string_more::{StringExt, StrExt}; // Import traits

fn main() {
    let mut my_string = String::from("  Hello, Rust!  ");
    my_string.trim_in_place(); // In-place operation on String
    println!("{}", my_string); // "Hello, Rust!"

    let s = "Hello, Rust!";
    let new_s = s.center(' ', 2); // Immutable operation on &str
    println!("{}", new_s); // "  Hello, Rust!  "

    println!("{}", "Hello, Rust!".levenshtein_distance("Hello, World!")); // 5
}

Why string_more?

Rust’s standard library provides robust string handling, but when additional flexibility is needed, string_more steps in with efficient, allocation-friendly operations. With both in-place and immutable operations, string_more is ideal for optimizing string manipulation in your Rust projects.

Methods Overview

StringExt (In-place operations for String)

• trim_in_place: Removes leading and trailing whitespace.

  let mut s = String::from("  Hello ");
  s.trim_in_place();
  assert_eq!(s, "Hello");
  

• trim_start_in_place: Removes leading whitespace only.

  let mut s = String::from("  Hello ");
  s.trim_start_in_place();
  assert_eq!(s, "Hello ");
  

• trim_end_in_place: Removes trailing whitespace only.

  let mut s = String::from("  Hello ");
  s.trim_end_in_place();
  assert_eq!(s, "  Hello");
  

• fill_start_in_place: Fills the start of the string with the provided &str, repeated a specified number of times.

  let mut s = String::from("Hello");
  s.fill_start_in_place("-", 3);
  assert_eq!(s, "---Hello");
  

• fill_end_in_place: Fills the end of the string with the provided &str, repeated a specified number of times.

  let mut s = String::from("Hello");
  s.fill_end_in_place("-", 3);
  assert_eq!(s, "Hello---");
  

• center_in_place: Centers the string by padding both the start and end with the same string.

  let mut s = String::from("Hello");
  s.center_in_place("-", 3);
  assert_eq!(s, "---Hello---");
  

• enclose_in_place: Encloses the string with two separate &str values, one at the start and one at the end.

  let mut s = String::from("Hello");
  s.enclose_in_place("[", "]");
  assert_eq!(s, "[Hello]");
  

• expand_tabs_in_place: Replaces tab characters with the specified number of spaces.

  let mut s = String::from("Hello\tRust");
  s.expand_tabs_in_place(4);
  assert_eq!(s, "Hello    Rust");
  

• shift_in_place: Shifts the string at the given index repeating fill pattern n times.

let s = "HelloWorld!".to_string();
s.shift_in_place(4, 2, ' ');
assert_eq!(s, "Hello  World!")

• replace_in_place: Replaces a substring with another substring.

let s = "HelloWorld!".to_string();
s.replace_in_place("World", " world");
assert_eq!(s, "Hello world!")

StrExt (Immutable operations for &str)

The StrExt trait provides operations that return a new String rather than modifying the original &str.

• fill_start: Fills the start of the string with the provided &str and returns a new String.

  let s = "Hello";
  let filled = s.fill_start("-", 3);
  assert_eq!(filled, "---Hello");
  

• fill_end: Fills the end of the string with the provided &str and returns a new String.

  let s = "Hello";
  let filled = s.fill_end("-", 3);
  assert_eq!(filled, "Hello---");
  

• center: Centers the string with padding on both sides and returns a new String.

  let s = "Hello";
  let centered = s.center("-", 3);
  assert_eq!(centered, "---Hello---");
  

• enclose: Encloses the string with two &str values, returning a new String.

  let s = "Hello";
  let enclosed = s.enclose("[", "]");
  assert_eq!(enclosed, "[Hello]");
  

• expand_tabs: Replaces tab characters with the specified number of spaces, returning a new String.

  let s = "Hello\tRust";
  let expanded = s.expand_tabs(4);
  assert_eq!(expanded, "Hello    Rust");
  

• shift: Shifts the string at the given index repeating fill pattern n times, returning a new String.

let s = "HelloWorld!";
let shifted = s.shift(4, 2, ' ');
assert_eq!(shifted, "Hello  World!")

• levenshtein_distance: Computes the Levenshtein's distance between two strings.

let s = "kitten";
assert_eq!(s.levenshtein_distance("sitting"), 3);

• hamming_distance: Computes the Hamming's distance between two strings.

let s = "update";
assert_eq!(s.hamming_distance("udpate"), 2);

• char_frequencies: Computes the frequencies of chars in the string.

let s = "Hello";
s.char_frequencies::<BTreeMap<_, _>>(); // H:1 e:1 l:2 o:1

• longest_common_substring: Returns the longest common substring.

let s = "sparrow";
s.longest_common_substring("crow"); // "row"

• next_char_boundary: Returns the byte index of the next char boundary in string starting from index.

let s = "🦀";
s.next_char_boundary(2); // 4

• previous_char_boundary: Returns the byte index of the previous char boundary in string starting from index.

let s = "🦀";
s.previous_char_boundary(2); // 0

Safety and Coverage

This crate contains a small portion of unsafe code. All tests run under miri and the tests cover about 90% of the code. You can generate the coverage report using tarpaulin.

Contributions

Contributions are always welcome! If you have ideas for new string operations or performance improvements, feel free to open an issue or submit a pull request.

License

This crate is licensed under the MIT License. See LICENSE for more details.