rustyline/
validate.rs

1//! Input validation API (Multi-line editing)
2
3use crate::keymap::Invoke;
4use crate::Result;
5
6/// Input validation result
7#[non_exhaustive]
8pub enum ValidationResult {
9    /// Incomplete input
10    Incomplete,
11    /// Validation fails with an optional error message. User must fix the
12    /// input.
13    Invalid(Option<String>),
14    /// Validation succeeds with an optional message
15    Valid(Option<String>),
16}
17
18impl ValidationResult {
19    pub(crate) fn is_valid(&self) -> bool {
20        matches!(self, Self::Valid(_))
21    }
22
23    pub(crate) fn has_message(&self) -> bool {
24        matches!(self, Self::Valid(Some(_)) | Self::Invalid(Some(_)))
25    }
26}
27
28/// Give access to user input.
29pub struct ValidationContext<'i> {
30    i: &'i mut dyn Invoke,
31}
32
33impl<'i> ValidationContext<'i> {
34    pub(crate) fn new(i: &'i mut dyn Invoke) -> Self {
35        ValidationContext { i }
36    }
37
38    /// Returns user input.
39    #[must_use]
40    pub fn input(&self) -> &str {
41        self.i.input()
42    }
43
44    // TODO
45    //fn invoke(&mut self, cmd: Cmd) -> Result<?> {
46    //    self.i.invoke(cmd)
47    //}
48}
49
50/// This trait provides an extension interface for determining whether
51/// the current input buffer is valid.
52///
53/// Rustyline uses the method provided by this trait to decide whether hitting
54/// the enter key will end the current editing session and return the current
55/// line buffer to the caller of `Editor::readline` or variants.
56pub trait Validator {
57    /// Takes the currently edited `input` and returns a
58    /// `ValidationResult` indicating whether it is valid or not along
59    /// with an option message to display about the result. The most
60    /// common validity check to implement is probably whether the
61    /// input is complete or not, for instance ensuring that all
62    /// delimiters are fully balanced.
63    ///
64    /// If you implement more complex validation checks it's probably
65    /// a good idea to also implement a `Hinter` to provide feedback
66    /// about what is invalid.
67    ///
68    /// For auto-correction like a missing closing quote or to reject invalid
69    /// char while typing, the input will be mutable (TODO).
70    fn validate(&self, ctx: &mut ValidationContext) -> Result<ValidationResult> {
71        let _ = ctx;
72        Ok(ValidationResult::Valid(None))
73    }
74
75    /// Configure whether validation is performed while typing or only
76    /// when user presses the Enter key.
77    ///
78    /// Default is `false`.
79    ///
80    /// This feature is not yet implemented, so this function is currently a
81    /// no-op
82    fn validate_while_typing(&self) -> bool {
83        false
84    }
85}
86
87impl Validator for () {}
88
89/// Simple matching bracket validator.
90#[derive(Default)]
91pub struct MatchingBracketValidator {
92    _priv: (),
93}
94
95impl MatchingBracketValidator {
96    /// Constructor
97    #[must_use]
98    pub fn new() -> Self {
99        Self { _priv: () }
100    }
101}
102
103impl Validator for MatchingBracketValidator {
104    fn validate(&self, ctx: &mut ValidationContext) -> Result<ValidationResult> {
105        Ok(validate_brackets(ctx.input()))
106    }
107}
108
109fn validate_brackets(input: &str) -> ValidationResult {
110    let mut stack = vec![];
111    for c in input.chars() {
112        match c {
113            '(' | '[' | '{' => stack.push(c),
114            ')' | ']' | '}' => match (stack.pop(), c) {
115                (Some('('), ')') | (Some('['), ']') | (Some('{'), '}') => {}
116                (Some(wanted), _) => {
117                    return ValidationResult::Invalid(Some(format!(
118                        "Mismatched brackets: {wanted:?} is not properly closed"
119                    )))
120                }
121                (None, c) => {
122                    return ValidationResult::Invalid(Some(format!(
123                        "Mismatched brackets: {c:?} is unpaired"
124                    )))
125                }
126            },
127            _ => {}
128        }
129    }
130    if stack.is_empty() {
131        ValidationResult::Valid(None)
132    } else {
133        ValidationResult::Incomplete
134    }
135}
rustyline/validate.rs

rustyline/
validate.rs
