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0.1.11 | Jun 21, 2024 |
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0.1.10 | Apr 4, 2024 |
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Used in 4 crates
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safe-string
This crate provides replacement types for String
and &str
that allow for safe
indexing by character to avoid panics and the usual pitfalls of working with multi-byte UTF-8
characters, namely the scenario where the byte length of a string and the character length
of that same string are not the same.
Specifically, IndexedString
(replaces String
) and IndexedSlice
(replaces &str
) allow
for O(1) slicing and indexing by character, and they will never panic when indexing or slicing.
This is accomplished by storing the character offsets of each character in the string, along
with the original String
, and using this information to calculate the byte offsets of each
character on the fly. Thus IndexedString
uses ~2x the memory of a normal String
, but
IndexedSlice
and other types implementing IndexedStr
have only one usize
extra in
overhead over that of a regular &str
slice / fat pointer. In theory this could be reduced
down to the same size as a fat pointer using unsafe rust, but this way we get to have
completely safe code and the difference is negligible.
Examples
use safe_string::{IndexedString, IndexedStr, IndexedSlice};
let message = IndexedString::from("Hello, 世界! 👋😊");
assert_eq!(message.as_str(), "Hello, 世界! 👋😊");
assert_eq!(message, "Hello, 世界! 👋😊"); // handy PartialEq impls
// Access characters by index
assert_eq!(message.char_at(7), Some('世'));
assert_eq!(message.char_at(100), None); // Out of bounds access returns None
// Slice the IndexedString
let slice = message.slice(7..9);
assert_eq!(slice.as_str(), "世界");
// Convert slice back to IndexedString
let sliced_message = slice.to_indexed_string();
assert_eq!(sliced_message.as_str(), "世界");
// Nested slicing
let slice = message.slice(0..10);
let nested_slice = slice.slice(3..6);
assert_eq!(nested_slice.as_str(), "lo,");
// Display byte length and character length
assert_eq!(IndexedString::from_str("世界").byte_len(), 6); // "世界" is 6 bytes in UTF-8
assert_eq!(IndexedString::from_str("世界").len(), 2); // "世界" has 2 characters
// Demonstrate clamped slicing (no panic)
let clamped_slice = message.slice(20..30);
assert_eq!(clamped_slice.as_str(), "");
// Using `as_str` to interface with standard Rust string handling
let slice = message.slice(0..5);
let standard_str_slice = slice.as_str();
assert_eq!(standard_str_slice, "Hello");