340 lines
12 KiB
Rust
340 lines
12 KiB
Rust
// This file is part of the uutils coreutils package.
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//
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// For the full copyright and license information, please view the LICENSE
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// file that was distributed with this source code.
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use rand::distributions::{Distribution, Uniform};
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use rand::{thread_rng, Rng};
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/// Samples alphanumeric characters `[A-Za-z0-9]` including newline `\n`
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///
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/// # Examples
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///
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/// ```rust,ignore
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/// use rand::{Rng, thread_rng};
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///
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/// let vec = thread_rng()
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/// .sample_iter(AlphanumericNewline)
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/// .take(10)
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/// .collect::<Vec<u8>>();
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/// println!("Random chars: {}", String::from_utf8(vec).unwrap());
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/// ```
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#[derive(Clone, Copy, Debug)]
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pub struct AlphanumericNewline;
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impl AlphanumericNewline {
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/// The charset to act upon
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const CHARSET: &'static [u8] =
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b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789\n";
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/// Generate a random byte from [`Self::CHARSET`] and return it as `u8`.
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///
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/// # Arguments
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///
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/// * `rng`: A [`rand::Rng`]
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///
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/// returns: u8
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fn random<R>(rng: &mut R) -> u8
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where
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R: Rng + ?Sized,
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{
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let idx = rng.gen_range(0..Self::CHARSET.len());
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Self::CHARSET[idx]
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}
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}
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impl Distribution<u8> for AlphanumericNewline {
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fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> u8 {
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Self::random(rng)
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}
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}
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/// Generate a random string from a [`Distribution`]
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///
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/// # Examples
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///
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/// ```rust,ignore
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/// use crate::common::random::{AlphanumericNewline, RandomString};
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/// use rand::distributions::Alphanumeric;
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///
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/// // generates a 100 byte string with characters from AlphanumericNewline
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/// let random_string = RandomString::generate(AlphanumericNewline, 100);
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/// assert_eq!(100, random_string.len());
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///
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/// // generates a 100 byte string with 10 newline characters not ending with a newline
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/// let string = RandomString::generate_with_delimiter(Alphanumeric, b'\n', 10, false, 100);
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/// assert_eq!(100, random_string.len());
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/// ```
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pub struct RandomString;
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impl RandomString {
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/// Generate a random string from the given [`Distribution`] with the given `length` in bytes.
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///
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/// # Arguments
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///
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/// * `dist`: A u8 [`Distribution`]
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/// * `length`: the length of the resulting string in bytes
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///
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/// returns: String
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pub fn generate<D>(dist: D, length: usize) -> String
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where
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D: Distribution<u8>,
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{
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thread_rng()
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.sample_iter(dist)
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.take(length)
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.map(|b| b as char)
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.collect()
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}
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/// Generate a random string from the [`Distribution`] with the given `length` in bytes. The
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/// function takes a `delimiter`, which is randomly distributed in the string, such that exactly
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/// `num_delimiter` amount of `delimiter`s occur. If `end_with_delimiter` is set, then the
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/// string ends with the delimiter, else the string does not end with the delimiter.
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///
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/// # Arguments
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///
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/// * `dist`: A `u8` [`Distribution`]
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/// * `delimiter`: A `u8` delimiter, which does not need to be included in the `Distribution`
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/// * `num_delimiter`: The number of `delimiter`s contained in the resulting string
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/// * `end_with_delimiter`: If the string shall end with the given delimiter
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/// * `length`: the length of the resulting string in bytes
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///
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/// returns: String
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///
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/// # Examples
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///
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/// ```rust,ignore
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/// use crate::common::random::{AlphanumericNewline, RandomString};
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///
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/// // generates a 100 byte string with 10 '\0' byte characters not ending with a '\0' byte
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/// let string = RandomString::generate_with_delimiter(AlphanumericNewline, 0, 10, false, 100);
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/// assert_eq!(100, random_string.len());
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/// assert_eq!(
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/// 10,
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/// random_string.as_bytes().iter().filter(|p| **p == 0).count()
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/// );
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/// assert!(!random_string.as_bytes().ends_with(&[0]));
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/// ```
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pub fn generate_with_delimiter<D>(
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dist: D,
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delimiter: u8,
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num_delimiter: usize,
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end_with_delimiter: bool,
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length: usize,
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) -> String
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where
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D: Distribution<u8>,
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{
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if length == 0 {
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return String::new();
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} else if length == 1 {
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return if num_delimiter > 0 {
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String::from(delimiter as char)
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} else {
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String::from(thread_rng().sample(&dist) as char)
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};
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}
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let samples = length - 1;
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let mut result: Vec<u8> = thread_rng().sample_iter(&dist).take(samples).collect();
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if num_delimiter == 0 {
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result.push(thread_rng().sample(&dist));
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return String::from_utf8(result).unwrap();
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}
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let num_delimiter = if end_with_delimiter {
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num_delimiter - 1
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} else {
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num_delimiter
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};
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let between = Uniform::new(0, samples);
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for _ in 0..num_delimiter {
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let mut pos = between.sample(&mut thread_rng());
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let turn = pos;
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while result[pos] == delimiter {
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pos += 1;
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if pos >= samples {
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pos = 0;
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}
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if pos == turn {
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break;
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}
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}
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result[pos] = delimiter;
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}
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if end_with_delimiter {
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result.push(delimiter);
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} else {
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result.push(thread_rng().sample(&dist));
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}
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String::from_utf8(result).unwrap()
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use rand::distributions::Alphanumeric;
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#[test]
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fn test_random_string_generate() {
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let random_string = RandomString::generate(AlphanumericNewline, 0);
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assert_eq!(0, random_string.len());
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let random_string = RandomString::generate(AlphanumericNewline, 1);
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assert_eq!(1, random_string.len());
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let random_string = RandomString::generate(AlphanumericNewline, 100);
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assert_eq!(100, random_string.len());
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}
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#[test]
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fn test_random_string_generate_with_delimiter_when_length_is_zero() {
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 0, false, 0);
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assert_eq!(0, random_string.len());
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}
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#[test]
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fn test_random_string_generate_with_delimiter_when_num_delimiter_is_greater_than_length() {
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 2, false, 1);
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assert_eq!(1, random_string.len());
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assert!(random_string.as_bytes().contains(&0));
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assert!(random_string.as_bytes().ends_with(&[0]));
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}
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#[test]
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fn test_random_string_generate_with_delimiter_should_end_with_delimiter() {
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 1, true, 1);
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assert_eq!(1, random_string.len());
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assert_eq!(
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1,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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assert!(random_string.as_bytes().ends_with(&[0]));
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 1, false, 1);
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assert_eq!(1, random_string.len());
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assert_eq!(
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1,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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assert!(random_string.as_bytes().ends_with(&[0]));
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 1, true, 2);
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assert_eq!(2, random_string.len());
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assert_eq!(
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1,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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assert!(random_string.as_bytes().ends_with(&[0]));
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 2, true, 2);
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assert_eq!(2, random_string.len());
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assert_eq!(
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2,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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assert!(random_string.as_bytes().ends_with(&[0]));
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 1, true, 3);
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assert_eq!(3, random_string.len());
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assert_eq!(
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1,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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assert!(random_string.as_bytes().ends_with(&[0]));
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}
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#[test]
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fn test_random_string_generate_with_delimiter_should_not_end_with_delimiter() {
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 0, false, 1);
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assert_eq!(1, random_string.len());
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assert_eq!(
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0,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 0, true, 1);
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assert_eq!(1, random_string.len());
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assert_eq!(
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0,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 1, false, 2);
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assert_eq!(2, random_string.len());
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assert_eq!(
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1,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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assert!(!random_string.as_bytes().ends_with(&[0]));
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 1, false, 3);
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assert_eq!(3, random_string.len());
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assert_eq!(
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1,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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assert!(!random_string.as_bytes().ends_with(&[0]));
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 2, false, 3);
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assert_eq!(3, random_string.len());
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assert_eq!(
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2,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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assert!(!random_string.as_bytes().ends_with(&[0]));
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}
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#[test]
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fn test_generate_with_delimiter_with_greater_length() {
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let random_string =
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RandomString::generate_with_delimiter(Alphanumeric, 0, 100, false, 1000);
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assert_eq!(1000, random_string.len());
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assert_eq!(
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100,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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assert!(!random_string.as_bytes().ends_with(&[0]));
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let random_string = RandomString::generate_with_delimiter(Alphanumeric, 0, 100, true, 1000);
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assert_eq!(1000, random_string.len());
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assert_eq!(
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100,
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random_string.as_bytes().iter().filter(|p| **p == 0).count()
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);
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assert!(random_string.as_bytes().ends_with(&[0]));
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}
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/// Originally used to exclude an error within the `random` module. The two
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/// affected tests timed out on windows, but only in the ci. These tests are
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/// also the source for the concrete numbers. The timed out tests are
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/// `test_tail.rs::test_pipe_when_lines_option_given_input_size_has_multiple_size_of_buffer_size`
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/// `test_tail.rs::test_pipe_when_bytes_option_given_input_size_has_multiple_size_of_buffer_size`.
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#[test]
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fn test_generate_random_strings_when_length_is_around_critical_buffer_sizes() {
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let length = 8192 * 3;
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let random_string = RandomString::generate(AlphanumericNewline, length);
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assert_eq!(length, random_string.len());
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let length = 8192 * 3 + 1;
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let random_string =
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RandomString::generate_with_delimiter(Alphanumeric, b'\n', 100, true, length);
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assert_eq!(length, random_string.len());
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assert_eq!(
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100,
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random_string
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.as_bytes()
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.iter()
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.filter(|p| **p == b'\n')
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.count()
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);
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assert!(!random_string.as_bytes().ends_with(&[0]));
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}
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}
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