core/num/
error.rs

1//! Error types for conversion to integral types.
2
3use crate::convert::Infallible;
4use crate::error::Error;
5use crate::fmt;
6
7/// The error type returned when a checked integral type conversion fails.
8#[stable(feature = "try_from", since = "1.34.0")]
9#[derive(Debug, Copy, Clone, PartialEq, Eq)]
10pub struct TryFromIntError(pub(crate) ());
11
12#[stable(feature = "try_from", since = "1.34.0")]
13impl fmt::Display for TryFromIntError {
14    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
15        #[allow(deprecated)]
16        self.description().fmt(fmt)
17    }
18}
19
20#[stable(feature = "try_from", since = "1.34.0")]
21impl Error for TryFromIntError {
22    #[allow(deprecated)]
23    fn description(&self) -> &str {
24        "out of range integral type conversion attempted"
25    }
26}
27
28#[stable(feature = "try_from", since = "1.34.0")]
29impl From<Infallible> for TryFromIntError {
30    fn from(x: Infallible) -> TryFromIntError {
31        match x {}
32    }
33}
34
35#[unstable(feature = "never_type", issue = "35121")]
36impl From<!> for TryFromIntError {
37    #[inline]
38    fn from(never: !) -> TryFromIntError {
39        // Match rather than coerce to make sure that code like
40        // `From<Infallible> for TryFromIntError` above will keep working
41        // when `Infallible` becomes an alias to `!`.
42        match never {}
43    }
44}
45
46/// An error which can be returned when parsing an integer.
47///
48/// This error is used as the error type for the `from_str_radix()` functions
49/// on the primitive integer types, such as [`i8::from_str_radix`].
50///
51/// # Potential causes
52///
53/// Among other causes, `ParseIntError` can be thrown because of leading or trailing whitespace
54/// in the string e.g., when it is obtained from the standard input.
55/// Using the [`str::trim()`] method ensures that no whitespace remains before parsing.
56///
57/// # Example
58///
59/// ```
60/// if let Err(e) = i32::from_str_radix("a12", 10) {
61///     println!("Failed conversion to i32: {e}");
62/// }
63/// ```
64#[derive(Debug, Clone, PartialEq, Eq)]
65#[stable(feature = "rust1", since = "1.0.0")]
66pub struct ParseIntError {
67    pub(super) kind: IntErrorKind,
68}
69
70/// Enum to store the various types of errors that can cause parsing an integer to fail.
71///
72/// # Example
73///
74/// ```
75/// # fn main() {
76/// if let Err(e) = i32::from_str_radix("a12", 10) {
77///     println!("Failed conversion to i32: {:?}", e.kind());
78/// }
79/// # }
80/// ```
81#[stable(feature = "int_error_matching", since = "1.55.0")]
82#[derive(Debug, Clone, PartialEq, Eq)]
83#[non_exhaustive]
84pub enum IntErrorKind {
85    /// Value being parsed is empty.
86    ///
87    /// This variant will be constructed when parsing an empty string.
88    #[stable(feature = "int_error_matching", since = "1.55.0")]
89    Empty,
90    /// Contains an invalid digit in its context.
91    ///
92    /// Among other causes, this variant will be constructed when parsing a string that
93    /// contains a non-ASCII char.
94    ///
95    /// This variant is also constructed when a `+` or `-` is misplaced within a string
96    /// either on its own or in the middle of a number.
97    #[stable(feature = "int_error_matching", since = "1.55.0")]
98    InvalidDigit,
99    /// Integer is too large to store in target integer type.
100    #[stable(feature = "int_error_matching", since = "1.55.0")]
101    PosOverflow,
102    /// Integer is too small to store in target integer type.
103    #[stable(feature = "int_error_matching", since = "1.55.0")]
104    NegOverflow,
105    /// Value was Zero
106    ///
107    /// This variant will be emitted when the parsing string has a value of zero, which
108    /// would be illegal for non-zero types.
109    #[stable(feature = "int_error_matching", since = "1.55.0")]
110    Zero,
111}
112
113impl ParseIntError {
114    /// Outputs the detailed cause of parsing an integer failing.
115    #[must_use]
116    #[rustc_const_stable(feature = "const_int_from_str", since = "1.82.0")]
117    #[stable(feature = "int_error_matching", since = "1.55.0")]
118    pub const fn kind(&self) -> &IntErrorKind {
119        &self.kind
120    }
121}
122
123#[stable(feature = "rust1", since = "1.0.0")]
124impl fmt::Display for ParseIntError {
125    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
126        #[allow(deprecated)]
127        self.description().fmt(f)
128    }
129}
130
131#[stable(feature = "rust1", since = "1.0.0")]
132impl Error for ParseIntError {
133    #[allow(deprecated)]
134    fn description(&self) -> &str {
135        match self.kind {
136            IntErrorKind::Empty => "cannot parse integer from empty string",
137            IntErrorKind::InvalidDigit => "invalid digit found in string",
138            IntErrorKind::PosOverflow => "number too large to fit in target type",
139            IntErrorKind::NegOverflow => "number too small to fit in target type",
140            IntErrorKind::Zero => "number would be zero for non-zero type",
141        }
142    }
143}
core/num/error.rs

core/num/
error.rs
