diff options
Diffstat (limited to 'mingling/src/res')
| -rw-r--r-- | mingling/src/res/confirmer.rs | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/mingling/src/res/confirmer.rs b/mingling/src/res/confirmer.rs new file mode 100644 index 0000000..900562b --- /dev/null +++ b/mingling/src/res/confirmer.rs @@ -0,0 +1,268 @@ +use std::io::{BufRead, Write}; + +/// A confirmer for interactive confirmation. +/// +/// This structure caches the confirmed state to avoid repeated prompts. +/// +/// Typically, `Confirmer` is registered via [`ConfirmerSetup`], and then injected into functions +/// through Mingling's resource injection system. +/// +/// # Registration +/// +/// Before use, the [`ConfirmerSetup`] must be registered with the program: +/// +/// ``` +/// # use mingling::MockProgramCollect as ThisProgram; +/// use mingling::setup::ConfirmerSetup; +/// use mingling::Program; +/// +/// let mut program = Program::<ThisProgram>::new(); +/// program.with_setup(ConfirmerSetup); +/// ``` +/// +/// # Examples +/// +/// ``` +/// use mingling::res::{Confirmer, YesConfirm}; +/// +/// // In actual use, obtain the registered confirmer through the resource injection system +/// let confirmer = Confirmer::new_confirmed(); +/// assert!(confirmer.ask::<YesConfirm>("Continue? [y/n] ")); +/// ``` +#[derive(Debug, Default, Clone, Copy)] +pub struct Confirmer { + pub(crate) confirmed: bool, +} + +impl Confirmer { + /// Creates a new `Confirmer` instance. + /// + /// # Examples + /// + /// ``` + /// use mingling::res::Confirmer; + /// + /// let confirmer = Confirmer::new(); + /// ``` + #[must_use] + pub const fn new() -> Self { + Self { confirmed: false } + } + + /// Creates a `Confirmer` instance in the confirmed state. + /// + /// The returned `Confirmer` will directly return `true` when calling [`ask`](Confirmer::ask) or + /// [`try_ask`](Confirmer::try_ask), without prompting the user. + /// + /// # Examples + /// + /// ``` + /// use mingling::res::{Confirmer, YesConfirm}; + /// + /// let confirmer = Confirmer::new_confirmed(); + /// assert!(confirmer.ask::<YesConfirm>("Continue? [y/n] ")); + /// ``` + #[must_use] + pub const fn new_confirmed() -> Self { + Self { confirmed: true } + } + + /// Marks the confirmer as confirmed. + /// + /// After calling this method, subsequent calls to [`ask`](Confirmer::ask) or + /// [`try_ask`](Confirmer::try_ask) on this confirmer will directly return `true` + /// without prompting the user. + /// + /// # Examples + /// + /// ``` + /// use mingling::res::{Confirmer, YesConfirm}; + /// + /// let mut confirmer = Confirmer::new(); + /// confirmer.set_confirmed(); + /// assert!(confirmer.ask::<YesConfirm>("Continue? [y/n] ")); + /// ``` + pub const fn set_confirmed(&mut self) { + self.confirmed = true; + } + + /// Asks the user a confirmation question, with at most one attempt. + /// + /// Returns `false` if the user provides an unrecognizable answer. + /// Returns `true` directly if already confirmed previously. + /// + /// # Parameters + /// + /// * `ask` - The prompt text to display to the user. + /// + /// # Returns + /// + /// Returns a boolean indicating whether the user confirmed. Returns `false` if the user's input + /// could not be parsed or the maximum number of attempts was reached. + /// + /// # Examples + /// + /// ``` + /// use mingling::res::{Confirmer, YesConfirm}; + /// + /// let confirmer = Confirmer::new_confirmed(); + /// let confirmed = confirmer.ask::<YesConfirm>("Delete this file? [y/n] "); + /// ``` + pub fn ask<P: ConfirmerPredicate>(&self, ask: impl AsRef<str>) -> bool { + self.try_ask::<P>(ask, ConfirmerCount::Max(1)) + .unwrap_or(false) + } + + /// Asks the user a confirmation question, allowing a specified maximum number of attempts. + /// + /// # Parameters + /// + /// * `ask` - The prompt text to display to the user. + /// * `count` - The maximum number of attempts. Passing `0` means unlimited attempts (loop + /// indefinitely), passing a positive integer means at most that many attempts. + /// + /// # Returns + /// + /// Returns `Some(true)` for confirmation, `Some(false)` for rejection. + /// Returns `None` if the maximum number of attempts is reached without being able to parse + /// the user's input. + /// + /// # Panics + /// + /// This function panics when the standard error output (`stderr`) cannot be flushed or when + /// reading from standard input fails. + /// + /// # Examples + /// + /// ``` + /// use mingling::res::{Confirmer, YesConfirm}; + /// + /// let confirmer = Confirmer::new_confirmed(); + /// let confirmed = confirmer.try_ask::<YesConfirm>("Confirm execution? [y/n] ", 3); + /// ``` + pub fn try_ask<P: ConfirmerPredicate>( + &self, + ask: impl AsRef<str>, + count: impl Into<ConfirmerCount>, + ) -> Option<bool> { + if self.confirmed { + return Some(true); + } + + let count = count.into(); + let mut attempts = 0usize; + + loop { + eprint!("{}", ask.as_ref()); + std::io::stderr().flush().unwrap(); + + let stdin = std::io::stdin(); + let mut input = String::new(); + stdin.lock().read_line(&mut input).unwrap(); + if let Some(result) = P::is_yes(&input) { + return Some(result); + } + + attempts += 1; + match count { + ConfirmerCount::Loop => {} + ConfirmerCount::Max(max) => { + if attempts >= max { + return None; + } + } + } + } + } +} + +/// Specifies the maximum number of attempts for a confirmation prompt. +#[derive(Debug, Clone, Copy, PartialEq, Eq)] +pub enum ConfirmerCount { + /// Loop indefinitely until the user gives a parseable answer. + Loop, + /// Ask at most the specified number of times. + Max(usize), +} + +macro_rules! impl_from_for_confirmer_count { + ($($t:ty),*) => { + $( + impl From<$t> for ConfirmerCount { + fn from(n: $t) -> Self { + if n == 0 { + ConfirmerCount::Loop + } else { + match usize::try_from(n) { + Ok(max) => ConfirmerCount::Max(max), + Err(_) => ConfirmerCount::Max(usize::MAX), + } + } + } + } + )* + }; +} + +impl_from_for_confirmer_count!( + i8, i16, i32, i64, i128, isize, u8, u16, u32, u64, u128, usize +); + +/// Defines how to parse user confirmation input. +/// +/// A type implementing this trait determines which user input strings are treated as "yes" or "no". +pub trait ConfirmerPredicate { + /// Parses the user's input string, returning whether it is "yes". + /// + /// Returns `Some(true)` for yes, `Some(false)` for no, + /// and `None` if the input cannot be parsed (requiring re-entry). + fn is_yes(str: &str) -> Option<bool>; +} + +/// A `ConfirmerPredicate` implementation that accepts "y"/"yes" as yes and "n"/"no" as no. +/// +/// Input comparison is case-insensitive and automatically trims leading/trailing whitespace. +/// +/// # Examples +/// +/// ``` +/// use mingling::res::{Confirmer, YesConfirm}; +/// +/// let confirmer = Confirmer::default(); +/// let confirmed = confirmer.ask::<YesConfirm>("Continue? [y/n] "); +/// ``` +pub struct YesConfirm; + +/// A `ConfirmerPredicate` implementation that accepts "true"/"t" as yes and "false"/"f" as no. +/// +/// Input comparison is case-insensitive and automatically trims leading/trailing whitespace. +/// +/// # Examples +/// +/// ``` +/// use mingling::res::{Confirmer, TrueConfirm}; +/// +/// let confirmer = Confirmer::default(); +/// let confirmed = confirmer.ask::<TrueConfirm>("Enable this feature? [true/false] "); +/// ``` +pub struct TrueConfirm; + +impl ConfirmerPredicate for YesConfirm { + fn is_yes(str: &str) -> Option<bool> { + match str.trim().to_lowercase().as_str() { + "y" | "yes" => Some(true), + "n" | "no" => Some(false), + _ => None, + } + } +} + +impl ConfirmerPredicate for TrueConfirm { + fn is_yes(str: &str) -> Option<bool> { + match str.trim().to_lowercase().as_str() { + "true" | "t" => Some(true), + "false" | "f" => Some(false), + _ => None, + } + } +} |