devela/text/str/
ext_string.rs

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1// devela::text::ext::string
2//
3//!
4//
5
6#[cfg(feature = "alloc")]
7use crate::{Arc, Box, Rc, String, ToString};
8
9/// Marker trait to prevent downstream implementations of the [`ExtString`] trait.
10#[cfg(feature = "alloc")]
11trait Sealed {}
12#[cfg(feature = "alloc")]
13impl Sealed for String {}
14
15/// Extension trait providing additional methods for [`String`].
16#[expect(private_bounds, reason = "Sealed")]
17#[cfg(feature = "alloc")]
18#[cfg_attr(feature = "nightly_doc", doc(notable_trait, cfg(feature = "alloc")))]
19pub trait ExtString: Sealed {
20    /// Converts the string into a `Box<str>`.
21    ///
22    /// Allows single ownership with exact allocation,
23    /// for when you don't need to clone or share.
24    fn to_box(self) -> Box<str>;
25
26    /// Converts the string into an `Rc<str>`.
27    ///
28    /// Allows shared ownership with reference counting,
29    /// reducing memory duplication in single-threaded scenarios.
30    fn to_rc(self) -> Rc<str>;
31
32    /// Converts the string into an `Arc<str>`.
33    ///
34    /// When you need shared ownership of a string slice across multiple threads.
35    fn to_arc(self) -> Arc<str>;
36
37    /// Returns a [`String`] where you always know each character's position.
38    ///
39    /// A [*counter string*][0] is a graduated string of arbitrary `length`,
40    /// with a `separator` positioned after the immediately preceding number.
41    ///
42    /// # Examples
43    /// ```
44    /// use devela::ExtString;
45    ///
46    /// assert_eq!("2*4*6*8*11*14*", String::new_counter(14, '*'));
47    /// assert_eq!("_3_5_7_9_12_15_", String::new_counter(15, '_'));
48    /// ```
49    /// [0]: https://www.satisfice.com/blog/archives/22
50    #[must_use]
51    fn new_counter(length: usize, separator: char) -> String;
52}
53
54#[cfg(feature = "alloc")]
55impl ExtString for String {
56    /// It just calls the method [`String::into_boxed_str`].
57    fn to_box(self) -> Box<str> {
58        self.into_boxed_str()
59    }
60    fn to_rc(self) -> Rc<str> {
61        Rc::from(self)
62    }
63    fn to_arc(self) -> Arc<str> {
64        Arc::from(self)
65    }
66
67    fn new_counter(mut length: usize, separator: char) -> String {
68        let mut cstr = String::new();
69
70        while length > 0 {
71            let mut tmpstr = separator.to_string();
72            tmpstr.push_str(&length.to_string().chars().rev().collect::<String>());
73
74            if tmpstr.len() > length {
75                tmpstr = tmpstr[..length].to_string();
76            }
77
78            cstr.push_str(&tmpstr);
79            length -= tmpstr.len();
80        }
81        cstr.chars().rev().collect::<String>()
82    }
83}
devela/text/str/ext_string.rs

devela/text/str/
ext_string.rs
