substring-replace: Substring manipulation for Rust

This crate adds intuitive substring methods for manipulating Rust string slices (&str) with character indices, handling multibyte characters with ease, similar to substring() in JavaScript, Java, or C#, and substr() in C++ or PHP.

Features

• Core substring Method: Compatible with the simpler substring crate but includes additional safe handling for out-of-range indices and negative offsets.

• Avoiding Conflicts: Do not use this crate alongside the existing substring crate. If you need advanced features, replace use substring::*; with use substring_replace::*; after removing the substring dependency.

• Character vs Byte Indices: Unlike Rust's standard string slicing by byte indices, this crate uses character indices for intuitive handling, especially with Unicode.

Key Methods

substring(start: usize, end: i64) -> &str

Extracts a substring based on character indices. Negative end indices count from the string's end.

let sample_str = "/long/file/path";
assert_eq!(sample_str.substring(5, 9), "file");

substring_replace(replacement: &str, start: usize, end: i64) -> String

Replaces a substring with another, using character indices.

let new_str = "azdefgh".substring_replace("bc", 1, 2);
assert_eq!(new_str, "abcdefgh");

substring_insert(insertion: &str, index: usize) -> String

Inserts a string at a character index.

let result = "a/c".substring_insert("/b", 1);
assert_eq!(result, "a/b/c");

substring_start(end: i64) -> &str and substring_end(start: i64) -> &str

Extract substrings from the start or end based on character indices.

let sample_str = "/long/file/path";
assert_eq!(sample_str.substring_start(5), "/long");
assert_eq!(sample_str.substring_end(5), "/file/path");

substring_replace_start(replacement: &str, end: i64) -> String and substring_replace_end(replacement: &str, start: i64) -> String

Replaces from the start or end up to a specified index.

assert_eq!("abcdefgh".substring_replace_start("xyz", 2), "xyzcdefgh");

substring_remove(start: usize, end: usize) -> String

Removes a substring by indices.

assert_eq!("abcdefghij".substring_remove(3, 6), "abcfghij");

substring_offset(position: usize, length: i32) -> &str and substring_pull(position: usize, length: i32) -> String

Extract or remove substrings based on a start position and length.

assert_eq!("indian-elephant".substring_offset(7, 3), "ele");

to_start_byte_index(index: usize) -> usize and to_end_byte_index(index: i64) -> usize

Convert character indices to byte indices for slice creation.

let byte_index = "नमस्ते".to_start_byte_index(2);

char_len() -> usize

Returns the character count of a string.

println!("{}", "😎".char_len()); // prints 1

char_find(pattern: &str) -> String

This finds the first character index of a plain string pattern. Like the standard find method, it returns an optional unsigned integer (usize). To search from right to left, but still returning the index of the first character in the matched sequence, you can use char_rfind,

let greek_words = "μήλα και πορτοκάλια";
let search_word = "και";
let character_index = greek_words.char_find(search_word);
let byte_index = greek_words.find(search_word);
println!("The word {search_word} starts at a character index of {character_index} and a byte index of {byte_index}");
// The word $search_word starts at a character index of 5 and a byte index of 9

insert_before_first, insert_before_last, insert_after_first, insert_after_last and insert_between

These new methods combine the functionality of char_find or char_rfind and substring_insert or substring_replace to insert strings before, after or between the first and/or last occurrence of a given sequence. The first four methods are wrappers for insert_adjacent.

Prepend -cropped before a file name extension.

let file_name = "greek-holiday-snap.jpg";
let new_file_name = file_name.insert_before_last("--cropped", ".");
assert_eq!(new_file_name, "greek-holiday-snap--cropped.jpg");

NB: This is an alpha release, but the crate is feature-complete and supplements string-patterns and simple-string-patterns .

Version history

0.1.3: Added new methods .substring_remove(start: usize, end: usize) and .substring_pull(position: usize, length: i32).

0.1.5: Added new methods .char_find(pat: &str) and .char_rfind(pat: &str).

0.2.0: The last parameter of .substring_start(end: i64), .substring_end(start: i64), .substring_replace_start(replacement: &str, end: i64) and .substring_replace_end(replacement: &str, start: i64) is now a 64-bit integer to let you assign a negative index as character offset from the end, e.g. "abcdefghi".substring_end(-3) would yield "ghi". Two new variant methods that accept negative end offsets were also introduced: substring_range(start; usize, end: i64) and substring_replace_range(replacement: &str, start; usize, end: i64).

0.2.1 Two new features:

• Added a set of convenience methods to insert strings before or after the first or last character.
• The crate now depends on the ToOffset trait to allow the core substring and substring_replace methods to alow negative offsets in the last parameter (i32, i64) as well as the default usize. A a result, substring_range and substring_replace_range are deprecated.