c9ae0bbffb
The `fill` value by default should be set to `' '` (space), but the current implementation uses `#[derive(Default)]` which sets it to `\0`
2970 lines
97 KiB
Rust
2970 lines
97 KiB
Rust
//! Utilities for formatting and printing strings.
|
||
|
||
#![stable(feature = "rust1", since = "1.0.0")]
|
||
|
||
use crate::cell::{Cell, Ref, RefCell, RefMut, SyncUnsafeCell, UnsafeCell};
|
||
use crate::char::EscapeDebugExtArgs;
|
||
use crate::marker::PhantomData;
|
||
use crate::num::fmt as numfmt;
|
||
use crate::ops::Deref;
|
||
use crate::{iter, mem, result, str};
|
||
|
||
mod builders;
|
||
#[cfg(not(no_fp_fmt_parse))]
|
||
mod float;
|
||
#[cfg(no_fp_fmt_parse)]
|
||
mod nofloat;
|
||
mod num;
|
||
mod rt;
|
||
|
||
#[stable(feature = "fmt_flags_align", since = "1.28.0")]
|
||
#[cfg_attr(not(test), rustc_diagnostic_item = "Alignment")]
|
||
/// Possible alignments returned by `Formatter::align`
|
||
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
|
||
pub enum Alignment {
|
||
#[stable(feature = "fmt_flags_align", since = "1.28.0")]
|
||
/// Indication that contents should be left-aligned.
|
||
Left,
|
||
#[stable(feature = "fmt_flags_align", since = "1.28.0")]
|
||
/// Indication that contents should be right-aligned.
|
||
Right,
|
||
#[stable(feature = "fmt_flags_align", since = "1.28.0")]
|
||
/// Indication that contents should be center-aligned.
|
||
Center,
|
||
}
|
||
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_internals", reason = "internal to standard library", issue = "none")]
|
||
impl From<rt::Alignment> for Option<Alignment> {
|
||
fn from(value: rt::Alignment) -> Self {
|
||
match value {
|
||
rt::Alignment::Left => Some(Alignment::Left),
|
||
rt::Alignment::Right => Some(Alignment::Right),
|
||
rt::Alignment::Center => Some(Alignment::Center),
|
||
rt::Alignment::Unknown => None,
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "debug_builders", since = "1.2.0")]
|
||
pub use self::builders::{DebugList, DebugMap, DebugSet, DebugStruct, DebugTuple};
|
||
#[unstable(feature = "debug_closure_helpers", issue = "117729")]
|
||
pub use self::builders::{FromFn, from_fn};
|
||
|
||
/// The type returned by formatter methods.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// #[derive(Debug)]
|
||
/// struct Triangle {
|
||
/// a: f32,
|
||
/// b: f32,
|
||
/// c: f32
|
||
/// }
|
||
///
|
||
/// impl fmt::Display for Triangle {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// write!(f, "({}, {}, {})", self.a, self.b, self.c)
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let pythagorean_triple = Triangle { a: 3.0, b: 4.0, c: 5.0 };
|
||
///
|
||
/// assert_eq!(format!("{pythagorean_triple}"), "(3, 4, 5)");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
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||
pub type Result = result::Result<(), Error>;
|
||
|
||
/// The error type which is returned from formatting a message into a stream.
|
||
///
|
||
/// This type does not support transmission of an error other than that an error
|
||
/// occurred. This is because, despite the existence of this error,
|
||
/// string formatting is considered an infallible operation.
|
||
/// `fmt()` implementors should not return this `Error` unless they received it from their
|
||
/// [`Formatter`]. The only time your code should create a new instance of this
|
||
/// error is when implementing `fmt::Write`, in order to cancel the formatting operation when
|
||
/// writing to the underlying stream fails.
|
||
///
|
||
/// Any extra information must be arranged to be transmitted through some other means,
|
||
/// such as storing it in a field to be consulted after the formatting operation has been
|
||
/// cancelled. (For example, this is how [`std::io::Write::write_fmt()`] propagates IO errors
|
||
/// during writing.)
|
||
///
|
||
/// This type, `fmt::Error`, should not be
|
||
/// confused with [`std::io::Error`] or [`std::error::Error`], which you may also
|
||
/// have in scope.
|
||
///
|
||
/// [`std::io::Error`]: ../../std/io/struct.Error.html
|
||
/// [`std::io::Write::write_fmt()`]: ../../std/io/trait.Write.html#method.write_fmt
|
||
/// [`std::error::Error`]: ../../std/error/trait.Error.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```rust
|
||
/// use std::fmt::{self, write};
|
||
///
|
||
/// let mut output = String::new();
|
||
/// if let Err(fmt::Error) = write(&mut output, format_args!("Hello {}!", "world")) {
|
||
/// panic!("An error occurred");
|
||
/// }
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[derive(Copy, Clone, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
|
||
pub struct Error;
|
||
|
||
/// A trait for writing or formatting into Unicode-accepting buffers or streams.
|
||
///
|
||
/// This trait only accepts UTF-8–encoded data and is not [flushable]. If you only
|
||
/// want to accept Unicode and you don't need flushing, you should implement this trait;
|
||
/// otherwise you should implement [`std::io::Write`].
|
||
///
|
||
/// [`std::io::Write`]: ../../std/io/trait.Write.html
|
||
/// [flushable]: ../../std/io/trait.Write.html#tymethod.flush
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub trait Write {
|
||
/// Writes a string slice into this writer, returning whether the write
|
||
/// succeeded.
|
||
///
|
||
/// This method can only succeed if the entire string slice was successfully
|
||
/// written, and this method will not return until all data has been
|
||
/// written or an error occurs.
|
||
///
|
||
/// # Errors
|
||
///
|
||
/// This function will return an instance of [`std::fmt::Error`][Error] on error.
|
||
///
|
||
/// The purpose of that error is to abort the formatting operation when the underlying
|
||
/// destination encounters some error preventing it from accepting more text;
|
||
/// in particular, it does not communicate any information about *what* error occurred.
|
||
/// It should generally be propagated rather than handled, at least when implementing
|
||
/// formatting traits.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt::{Error, Write};
|
||
///
|
||
/// fn writer<W: Write>(f: &mut W, s: &str) -> Result<(), Error> {
|
||
/// f.write_str(s)
|
||
/// }
|
||
///
|
||
/// let mut buf = String::new();
|
||
/// writer(&mut buf, "hola")?;
|
||
/// assert_eq!(&buf, "hola");
|
||
/// # std::fmt::Result::Ok(())
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn write_str(&mut self, s: &str) -> Result;
|
||
|
||
/// Writes a [`char`] into this writer, returning whether the write succeeded.
|
||
///
|
||
/// A single [`char`] may be encoded as more than one byte.
|
||
/// This method can only succeed if the entire byte sequence was successfully
|
||
/// written, and this method will not return until all data has been
|
||
/// written or an error occurs.
|
||
///
|
||
/// # Errors
|
||
///
|
||
/// This function will return an instance of [`Error`] on error.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt::{Error, Write};
|
||
///
|
||
/// fn writer<W: Write>(f: &mut W, c: char) -> Result<(), Error> {
|
||
/// f.write_char(c)
|
||
/// }
|
||
///
|
||
/// let mut buf = String::new();
|
||
/// writer(&mut buf, 'a')?;
|
||
/// writer(&mut buf, 'b')?;
|
||
/// assert_eq!(&buf, "ab");
|
||
/// # std::fmt::Result::Ok(())
|
||
/// ```
|
||
#[stable(feature = "fmt_write_char", since = "1.1.0")]
|
||
fn write_char(&mut self, c: char) -> Result {
|
||
self.write_str(c.encode_utf8(&mut [0; 4]))
|
||
}
|
||
|
||
/// Glue for usage of the [`write!`] macro with implementors of this trait.
|
||
///
|
||
/// This method should generally not be invoked manually, but rather through
|
||
/// the [`write!`] macro itself.
|
||
///
|
||
/// # Errors
|
||
///
|
||
/// This function will return an instance of [`Error`] on error. Please see
|
||
/// [write_str](Write::write_str) for details.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt::{Error, Write};
|
||
///
|
||
/// fn writer<W: Write>(f: &mut W, s: &str) -> Result<(), Error> {
|
||
/// f.write_fmt(format_args!("{s}"))
|
||
/// }
|
||
///
|
||
/// let mut buf = String::new();
|
||
/// writer(&mut buf, "world")?;
|
||
/// assert_eq!(&buf, "world");
|
||
/// # std::fmt::Result::Ok(())
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn write_fmt(&mut self, args: Arguments<'_>) -> Result {
|
||
// We use a specialization for `Sized` types to avoid an indirection
|
||
// through `&mut self`
|
||
trait SpecWriteFmt {
|
||
fn spec_write_fmt(self, args: Arguments<'_>) -> Result;
|
||
}
|
||
|
||
impl<W: Write + ?Sized> SpecWriteFmt for &mut W {
|
||
#[inline]
|
||
default fn spec_write_fmt(mut self, args: Arguments<'_>) -> Result {
|
||
if let Some(s) = args.as_statically_known_str() {
|
||
self.write_str(s)
|
||
} else {
|
||
write(&mut self, args)
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<W: Write> SpecWriteFmt for &mut W {
|
||
#[inline]
|
||
fn spec_write_fmt(self, args: Arguments<'_>) -> Result {
|
||
if let Some(s) = args.as_statically_known_str() {
|
||
self.write_str(s)
|
||
} else {
|
||
write(self, args)
|
||
}
|
||
}
|
||
}
|
||
|
||
self.spec_write_fmt(args)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "fmt_write_blanket_impl", since = "1.4.0")]
|
||
impl<W: Write + ?Sized> Write for &mut W {
|
||
fn write_str(&mut self, s: &str) -> Result {
|
||
(**self).write_str(s)
|
||
}
|
||
|
||
fn write_char(&mut self, c: char) -> Result {
|
||
(**self).write_char(c)
|
||
}
|
||
|
||
fn write_fmt(&mut self, args: Arguments<'_>) -> Result {
|
||
(**self).write_fmt(args)
|
||
}
|
||
}
|
||
|
||
/// The signedness of a [`Formatter`] (or of a [`FormattingOptions`]).
|
||
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub enum Sign {
|
||
/// Represents the `+` flag.
|
||
Plus,
|
||
/// Represents the `-` flag.
|
||
Minus,
|
||
}
|
||
|
||
/// Specifies whether the [`Debug`] trait should use lower-/upper-case
|
||
/// hexadecimal or normal integers.
|
||
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub enum DebugAsHex {
|
||
/// Use lower-case hexadecimal integers for the `Debug` trait (like [the `x?` type](../../std/fmt/index.html#formatting-traits)).
|
||
Lower,
|
||
/// Use upper-case hexadecimal integers for the `Debug` trait (like [the `X?` type](../../std/fmt/index.html#formatting-traits)).
|
||
Upper,
|
||
}
|
||
|
||
/// Options for formatting.
|
||
///
|
||
/// `FormattingOptions` is a [`Formatter`] without an attached [`Write`] trait.
|
||
/// It is mainly used to construct `Formatter` instances.
|
||
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub struct FormattingOptions {
|
||
flags: u32,
|
||
fill: char,
|
||
align: Option<Alignment>,
|
||
width: Option<usize>,
|
||
precision: Option<usize>,
|
||
}
|
||
|
||
impl FormattingOptions {
|
||
/// Construct a new `FormatterBuilder` with the supplied `Write` trait
|
||
/// object for output that is equivalent to the `{}` formatting
|
||
/// specifier:
|
||
///
|
||
/// - no flags,
|
||
/// - filled with spaces,
|
||
/// - no alignment,
|
||
/// - no width,
|
||
/// - no precision, and
|
||
/// - no [`DebugAsHex`] output mode.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn new() -> Self {
|
||
Self { flags: 0, fill: ' ', align: None, width: None, precision: None }
|
||
}
|
||
|
||
/// Sets or removes the sign (the `+` or the `-` flag).
|
||
///
|
||
/// - `+`: This is intended for numeric types and indicates that the sign
|
||
/// should always be printed. By default only the negative sign of signed
|
||
/// values is printed, and the sign of positive or unsigned values is
|
||
/// omitted. This flag indicates that the correct sign (+ or -) should
|
||
/// always be printed.
|
||
/// - `-`: Currently not used
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn sign(&mut self, sign: Option<Sign>) -> &mut Self {
|
||
self.flags =
|
||
self.flags & !(1 << rt::Flag::SignMinus as u32 | 1 << rt::Flag::SignPlus as u32);
|
||
match sign {
|
||
None => {}
|
||
Some(Sign::Plus) => self.flags |= 1 << rt::Flag::SignPlus as u32,
|
||
Some(Sign::Minus) => self.flags |= 1 << rt::Flag::SignMinus as u32,
|
||
}
|
||
self
|
||
}
|
||
/// Sets or unsets the `0` flag.
|
||
///
|
||
/// This is used to indicate for integer formats that the padding to width should both be done with a 0 character as well as be sign-aware
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn sign_aware_zero_pad(&mut self, sign_aware_zero_pad: bool) -> &mut Self {
|
||
if sign_aware_zero_pad {
|
||
self.flags |= 1 << rt::Flag::SignAwareZeroPad as u32
|
||
} else {
|
||
self.flags &= !(1 << rt::Flag::SignAwareZeroPad as u32)
|
||
}
|
||
self
|
||
}
|
||
/// Sets or unsets the `#` flag.
|
||
///
|
||
/// This flag indicates that the "alternate" form of printing should be
|
||
/// used. The alternate forms are:
|
||
/// - [`Debug`] : pretty-print the [`Debug`] formatting (adds linebreaks and indentation)
|
||
/// - [`LowerHex`] as well as [`UpperHex`] - precedes the argument with a `0x`
|
||
/// - [`Octal`] - precedes the argument with a `0b`
|
||
/// - [`Binary`] - precedes the argument with a `0o`
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn alternate(&mut self, alternate: bool) -> &mut Self {
|
||
if alternate {
|
||
self.flags |= 1 << rt::Flag::Alternate as u32
|
||
} else {
|
||
self.flags &= !(1 << rt::Flag::Alternate as u32)
|
||
}
|
||
self
|
||
}
|
||
/// Sets the fill character.
|
||
///
|
||
/// The optional fill character and alignment is provided normally in
|
||
/// conjunction with the width parameter. This indicates that if the value
|
||
/// being formatted is smaller than width some extra characters will be
|
||
/// printed around it.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn fill(&mut self, fill: char) -> &mut Self {
|
||
self.fill = fill;
|
||
self
|
||
}
|
||
/// Sets or removes the alignment.
|
||
///
|
||
/// The alignment specifies how the value being formatted should be
|
||
/// positioned if it is smaller than the width of the formatter.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn align(&mut self, align: Option<Alignment>) -> &mut Self {
|
||
self.align = align;
|
||
self
|
||
}
|
||
/// Sets or removes the width.
|
||
///
|
||
/// This is a parameter for the “minimum width” that the format should take
|
||
/// up. If the value’s string does not fill up this many characters, then
|
||
/// the padding specified by [`FormattingOptions::fill`]/[`FormattingOptions::align`]
|
||
/// will be used to take up the required space.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn width(&mut self, width: Option<usize>) -> &mut Self {
|
||
self.width = width;
|
||
self
|
||
}
|
||
/// Sets or removes the precision.
|
||
///
|
||
/// - For non-numeric types, this can be considered a “maximum width”. If
|
||
/// the resulting string is longer than this width, then it is truncated
|
||
/// down to this many characters and that truncated value is emitted with
|
||
/// proper fill, alignment and width if those parameters are set.
|
||
/// - For integral types, this is ignored.
|
||
/// - For floating-point types, this indicates how many digits after the
|
||
/// decimal point should be printed.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn precision(&mut self, precision: Option<usize>) -> &mut Self {
|
||
self.precision = precision;
|
||
self
|
||
}
|
||
/// Specifies whether the [`Debug`] trait should use lower-/upper-case
|
||
/// hexadecimal or normal integers
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn debug_as_hex(&mut self, debug_as_hex: Option<DebugAsHex>) -> &mut Self {
|
||
self.flags = self.flags
|
||
& !(1 << rt::Flag::DebugUpperHex as u32 | 1 << rt::Flag::DebugLowerHex as u32);
|
||
match debug_as_hex {
|
||
None => {}
|
||
Some(DebugAsHex::Upper) => self.flags |= 1 << rt::Flag::DebugUpperHex as u32,
|
||
Some(DebugAsHex::Lower) => self.flags |= 1 << rt::Flag::DebugLowerHex as u32,
|
||
}
|
||
self
|
||
}
|
||
|
||
/// Returns the current sign (the `+` or the `-` flag).
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn get_sign(&self) -> Option<Sign> {
|
||
const SIGN_PLUS_BITFIELD: u32 = 1 << rt::Flag::SignPlus as u32;
|
||
const SIGN_MINUS_BITFIELD: u32 = 1 << rt::Flag::SignMinus as u32;
|
||
match self.flags & ((1 << rt::Flag::SignPlus as u32) | (1 << rt::Flag::SignMinus as u32)) {
|
||
SIGN_PLUS_BITFIELD => Some(Sign::Plus),
|
||
SIGN_MINUS_BITFIELD => Some(Sign::Minus),
|
||
0 => None,
|
||
_ => panic!("Invalid sign bits set in flags"),
|
||
}
|
||
}
|
||
/// Returns the current `0` flag.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn get_sign_aware_zero_pad(&self) -> bool {
|
||
self.flags & (1 << rt::Flag::SignAwareZeroPad as u32) != 0
|
||
}
|
||
/// Returns the current `#` flag.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn get_alternate(&self) -> bool {
|
||
self.flags & (1 << rt::Flag::Alternate as u32) != 0
|
||
}
|
||
/// Returns the current fill character.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn get_fill(&self) -> char {
|
||
self.fill
|
||
}
|
||
/// Returns the current alignment.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn get_align(&self) -> Option<Alignment> {
|
||
self.align
|
||
}
|
||
/// Returns the current width.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn get_width(&self) -> Option<usize> {
|
||
self.width
|
||
}
|
||
/// Returns the current precision.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn get_precision(&self) -> Option<usize> {
|
||
self.precision
|
||
}
|
||
/// Returns the current precision.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn get_debug_as_hex(&self) -> Option<DebugAsHex> {
|
||
const DEBUG_UPPER_BITFIELD: u32 = 1 << rt::Flag::DebugUpperHex as u32;
|
||
const DEBUG_LOWER_BITFIELD: u32 = 1 << rt::Flag::DebugLowerHex as u32;
|
||
match self.flags
|
||
& ((1 << rt::Flag::DebugUpperHex as u32) | (1 << rt::Flag::DebugLowerHex as u32))
|
||
{
|
||
DEBUG_UPPER_BITFIELD => Some(DebugAsHex::Upper),
|
||
DEBUG_LOWER_BITFIELD => Some(DebugAsHex::Lower),
|
||
0 => None,
|
||
_ => panic!("Invalid hex debug bits set in flags"),
|
||
}
|
||
}
|
||
|
||
/// Creates a [`Formatter`] that writes its output to the given [`Write`] trait.
|
||
///
|
||
/// You may alternatively use [`Formatter::new()`].
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn create_formatter<'a>(self, write: &'a mut (dyn Write + 'a)) -> Formatter<'a> {
|
||
Formatter { options: self, buf: write }
|
||
}
|
||
|
||
#[doc(hidden)]
|
||
#[unstable(
|
||
feature = "fmt_internals",
|
||
reason = "internal routines only exposed for testing",
|
||
issue = "none"
|
||
)]
|
||
/// Flags for formatting
|
||
pub fn flags(&mut self, flags: u32) {
|
||
self.flags = flags
|
||
}
|
||
#[doc(hidden)]
|
||
#[unstable(
|
||
feature = "fmt_internals",
|
||
reason = "internal routines only exposed for testing",
|
||
issue = "none"
|
||
)]
|
||
/// Flags for formatting
|
||
pub fn get_flags(&self) -> u32 {
|
||
self.flags
|
||
}
|
||
}
|
||
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
impl Default for FormattingOptions {
|
||
/// Same as [`FormattingOptions::new()`].
|
||
fn default() -> Self {
|
||
// The `#[derive(Default)]` implementation would set `fill` to `\0` instead of space.
|
||
Self::new()
|
||
}
|
||
}
|
||
|
||
/// Configuration for formatting.
|
||
///
|
||
/// A `Formatter` represents various options related to formatting. Users do not
|
||
/// construct `Formatter`s directly; a mutable reference to one is passed to
|
||
/// the `fmt` method of all formatting traits, like [`Debug`] and [`Display`].
|
||
///
|
||
/// To interact with a `Formatter`, you'll call various methods to change the
|
||
/// various options related to formatting. For examples, please see the
|
||
/// documentation of the methods defined on `Formatter` below.
|
||
#[allow(missing_debug_implementations)]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_diagnostic_item = "Formatter"]
|
||
pub struct Formatter<'a> {
|
||
options: FormattingOptions,
|
||
|
||
buf: &'a mut (dyn Write + 'a),
|
||
}
|
||
|
||
impl<'a> Formatter<'a> {
|
||
/// Creates a new formatter with given [`FormattingOptions`].
|
||
///
|
||
/// If `write` is a reference to a formatter, it is recommended to use
|
||
/// [`Formatter::with_options`] instead as this can borrow the underlying
|
||
/// `write`, thereby bypassing one layer of indirection.
|
||
///
|
||
/// You may alternatively use [`FormattingOptions::create_formatter()`].
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn new(write: &'a mut (dyn Write + 'a), options: FormattingOptions) -> Self {
|
||
Formatter { options, buf: write }
|
||
}
|
||
|
||
/// Creates a new formatter based on this one with given [`FormattingOptions`].
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub fn with_options<'b>(&'b mut self, options: FormattingOptions) -> Formatter<'b> {
|
||
Formatter { options, buf: self.buf }
|
||
}
|
||
}
|
||
|
||
/// This structure represents a safely precompiled version of a format string
|
||
/// and its arguments. This cannot be generated at runtime because it cannot
|
||
/// safely be done, so no constructors are given and the fields are private
|
||
/// to prevent modification.
|
||
///
|
||
/// The [`format_args!`] macro will safely create an instance of this structure.
|
||
/// The macro validates the format string at compile-time so usage of the
|
||
/// [`write()`] and [`format()`] functions can be safely performed.
|
||
///
|
||
/// You can use the `Arguments<'a>` that [`format_args!`] returns in `Debug`
|
||
/// and `Display` contexts as seen below. The example also shows that `Debug`
|
||
/// and `Display` format to the same thing: the interpolated format string
|
||
/// in `format_args!`.
|
||
///
|
||
/// ```rust
|
||
/// let debug = format!("{:?}", format_args!("{} foo {:?}", 1, 2));
|
||
/// let display = format!("{}", format_args!("{} foo {:?}", 1, 2));
|
||
/// assert_eq!("1 foo 2", display);
|
||
/// assert_eq!(display, debug);
|
||
/// ```
|
||
///
|
||
/// [`format()`]: ../../std/fmt/fn.format.html
|
||
#[lang = "format_arguments"]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[derive(Copy, Clone)]
|
||
pub struct Arguments<'a> {
|
||
// Format string pieces to print.
|
||
pieces: &'a [&'static str],
|
||
|
||
// Placeholder specs, or `None` if all specs are default (as in "{}{}").
|
||
fmt: Option<&'a [rt::Placeholder]>,
|
||
|
||
// Dynamic arguments for interpolation, to be interleaved with string
|
||
// pieces. (Every argument is preceded by a string piece.)
|
||
args: &'a [rt::Argument<'a>],
|
||
}
|
||
|
||
/// Used by the format_args!() macro to create a fmt::Arguments object.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_internals", issue = "none")]
|
||
impl<'a> Arguments<'a> {
|
||
#[inline]
|
||
pub const fn new_const<const N: usize>(pieces: &'a [&'static str; N]) -> Self {
|
||
const { assert!(N <= 1) };
|
||
Arguments { pieces, fmt: None, args: &[] }
|
||
}
|
||
|
||
/// When using the format_args!() macro, this function is used to generate the
|
||
/// Arguments structure.
|
||
#[inline]
|
||
pub const fn new_v1<const P: usize, const A: usize>(
|
||
pieces: &'a [&'static str; P],
|
||
args: &'a [rt::Argument<'a>; A],
|
||
) -> Arguments<'a> {
|
||
const { assert!(P >= A && P <= A + 1, "invalid args") }
|
||
Arguments { pieces, fmt: None, args }
|
||
}
|
||
|
||
/// Specifies nonstandard formatting parameters.
|
||
///
|
||
/// An `rt::UnsafeArg` is required because the following invariants must be held
|
||
/// in order for this function to be safe:
|
||
/// 1. The `pieces` slice must be at least as long as `fmt`.
|
||
/// 2. Every `rt::Placeholder::position` value within `fmt` must be a valid index of `args`.
|
||
/// 3. Every `rt::Count::Param` within `fmt` must contain a valid index of `args`.
|
||
#[inline]
|
||
pub const fn new_v1_formatted(
|
||
pieces: &'a [&'static str],
|
||
args: &'a [rt::Argument<'a>],
|
||
fmt: &'a [rt::Placeholder],
|
||
_unsafe_arg: rt::UnsafeArg,
|
||
) -> Arguments<'a> {
|
||
Arguments { pieces, fmt: Some(fmt), args }
|
||
}
|
||
|
||
/// Estimates the length of the formatted text.
|
||
///
|
||
/// This is intended to be used for setting initial `String` capacity
|
||
/// when using `format!`. Note: this is neither the lower nor upper bound.
|
||
#[inline]
|
||
pub fn estimated_capacity(&self) -> usize {
|
||
let pieces_length: usize = self.pieces.iter().map(|x| x.len()).sum();
|
||
|
||
if self.args.is_empty() {
|
||
pieces_length
|
||
} else if !self.pieces.is_empty() && self.pieces[0].is_empty() && pieces_length < 16 {
|
||
// If the format string starts with an argument,
|
||
// don't preallocate anything, unless length
|
||
// of pieces is significant.
|
||
0
|
||
} else {
|
||
// There are some arguments, so any additional push
|
||
// will reallocate the string. To avoid that,
|
||
// we're "pre-doubling" the capacity here.
|
||
pieces_length.checked_mul(2).unwrap_or(0)
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<'a> Arguments<'a> {
|
||
/// Gets the formatted string, if it has no arguments to be formatted at runtime.
|
||
///
|
||
/// This can be used to avoid allocations in some cases.
|
||
///
|
||
/// # Guarantees
|
||
///
|
||
/// For `format_args!("just a literal")`, this function is guaranteed to
|
||
/// return `Some("just a literal")`.
|
||
///
|
||
/// For most cases with placeholders, this function will return `None`.
|
||
///
|
||
/// However, the compiler may perform optimizations that can cause this
|
||
/// function to return `Some(_)` even if the format string contains
|
||
/// placeholders. For example, `format_args!("Hello, {}!", "world")` may be
|
||
/// optimized to `format_args!("Hello, world!")`, such that `as_str()`
|
||
/// returns `Some("Hello, world!")`.
|
||
///
|
||
/// The behavior for anything but the trivial case (without placeholders)
|
||
/// is not guaranteed, and should not be relied upon for anything other
|
||
/// than optimization.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```rust
|
||
/// use std::fmt::Arguments;
|
||
///
|
||
/// fn write_str(_: &str) { /* ... */ }
|
||
///
|
||
/// fn write_fmt(args: &Arguments<'_>) {
|
||
/// if let Some(s) = args.as_str() {
|
||
/// write_str(s)
|
||
/// } else {
|
||
/// write_str(&args.to_string());
|
||
/// }
|
||
/// }
|
||
/// ```
|
||
///
|
||
/// ```rust
|
||
/// assert_eq!(format_args!("hello").as_str(), Some("hello"));
|
||
/// assert_eq!(format_args!("").as_str(), Some(""));
|
||
/// assert_eq!(format_args!("{:?}", std::env::current_dir()).as_str(), None);
|
||
/// ```
|
||
#[stable(feature = "fmt_as_str", since = "1.52.0")]
|
||
#[rustc_const_stable(feature = "const_arguments_as_str", since = "1.84.0")]
|
||
#[must_use]
|
||
#[inline]
|
||
pub const fn as_str(&self) -> Option<&'static str> {
|
||
match (self.pieces, self.args) {
|
||
([], []) => Some(""),
|
||
([s], []) => Some(s),
|
||
_ => None,
|
||
}
|
||
}
|
||
|
||
/// Same as [`Arguments::as_str`], but will only return `Some(s)` if it can be determined at compile time.
|
||
#[must_use]
|
||
#[inline]
|
||
fn as_statically_known_str(&self) -> Option<&'static str> {
|
||
let s = self.as_str();
|
||
if core::intrinsics::is_val_statically_known(s.is_some()) { s } else { None }
|
||
}
|
||
}
|
||
|
||
// Manually implementing these results in better error messages.
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl !Send for Arguments<'_> {}
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl !Sync for Arguments<'_> {}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Debug for Arguments<'_> {
|
||
fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
|
||
Display::fmt(self, fmt)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Display for Arguments<'_> {
|
||
fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
|
||
write(fmt.buf, *self)
|
||
}
|
||
}
|
||
|
||
/// `?` formatting.
|
||
///
|
||
/// `Debug` should format the output in a programmer-facing, debugging context.
|
||
///
|
||
/// Generally speaking, you should just `derive` a `Debug` implementation.
|
||
///
|
||
/// When used with the alternate format specifier `#?`, the output is pretty-printed.
|
||
///
|
||
/// For more information on formatters, see [the module-level documentation][module].
|
||
///
|
||
/// [module]: ../../std/fmt/index.html
|
||
///
|
||
/// This trait can be used with `#[derive]` if all fields implement `Debug`. When
|
||
/// `derive`d for structs, it will use the name of the `struct`, then `{`, then a
|
||
/// comma-separated list of each field's name and `Debug` value, then `}`. For
|
||
/// `enum`s, it will use the name of the variant and, if applicable, `(`, then the
|
||
/// `Debug` values of the fields, then `)`.
|
||
///
|
||
/// # Stability
|
||
///
|
||
/// Derived `Debug` formats are not stable, and so may change with future Rust
|
||
/// versions. Additionally, `Debug` implementations of types provided by the
|
||
/// standard library (`std`, `core`, `alloc`, etc.) are not stable, and
|
||
/// may also change with future Rust versions.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Deriving an implementation:
|
||
///
|
||
/// ```
|
||
/// #[derive(Debug)]
|
||
/// struct Point {
|
||
/// x: i32,
|
||
/// y: i32,
|
||
/// }
|
||
///
|
||
/// let origin = Point { x: 0, y: 0 };
|
||
///
|
||
/// assert_eq!(
|
||
/// format!("The origin is: {origin:?}"),
|
||
/// "The origin is: Point { x: 0, y: 0 }",
|
||
/// );
|
||
/// ```
|
||
///
|
||
/// Manually implementing:
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Point {
|
||
/// x: i32,
|
||
/// y: i32,
|
||
/// }
|
||
///
|
||
/// impl fmt::Debug for Point {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// f.debug_struct("Point")
|
||
/// .field("x", &self.x)
|
||
/// .field("y", &self.y)
|
||
/// .finish()
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let origin = Point { x: 0, y: 0 };
|
||
///
|
||
/// assert_eq!(
|
||
/// format!("The origin is: {origin:?}"),
|
||
/// "The origin is: Point { x: 0, y: 0 }",
|
||
/// );
|
||
/// ```
|
||
///
|
||
/// There are a number of helper methods on the [`Formatter`] struct to help you with manual
|
||
/// implementations, such as [`debug_struct`].
|
||
///
|
||
/// [`debug_struct`]: Formatter::debug_struct
|
||
///
|
||
/// Types that do not wish to use the standard suite of debug representations
|
||
/// provided by the `Formatter` trait (`debug_struct`, `debug_tuple`,
|
||
/// `debug_list`, `debug_set`, `debug_map`) can do something totally custom by
|
||
/// manually writing an arbitrary representation to the `Formatter`.
|
||
///
|
||
/// ```
|
||
/// # use std::fmt;
|
||
/// # struct Point {
|
||
/// # x: i32,
|
||
/// # y: i32,
|
||
/// # }
|
||
/// #
|
||
/// impl fmt::Debug for Point {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// write!(f, "Point [{} {}]", self.x, self.y)
|
||
/// }
|
||
/// }
|
||
/// ```
|
||
///
|
||
/// `Debug` implementations using either `derive` or the debug builder API
|
||
/// on [`Formatter`] support pretty-printing using the alternate flag: `{:#?}`.
|
||
///
|
||
/// Pretty-printing with `#?`:
|
||
///
|
||
/// ```
|
||
/// #[derive(Debug)]
|
||
/// struct Point {
|
||
/// x: i32,
|
||
/// y: i32,
|
||
/// }
|
||
///
|
||
/// let origin = Point { x: 0, y: 0 };
|
||
///
|
||
/// let expected = "The origin is: Point {
|
||
/// x: 0,
|
||
/// y: 0,
|
||
/// }";
|
||
/// assert_eq!(format!("The origin is: {origin:#?}"), expected);
|
||
/// ```
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_on_unimplemented(
|
||
on(
|
||
crate_local,
|
||
label = "`{Self}` cannot be formatted using `{{:?}}`",
|
||
note = "add `#[derive(Debug)]` to `{Self}` or manually `impl {Debug} for {Self}`"
|
||
),
|
||
message = "`{Self}` doesn't implement `{Debug}`",
|
||
label = "`{Self}` cannot be formatted using `{{:?}}` because it doesn't implement `{Debug}`"
|
||
)]
|
||
#[doc(alias = "{:?}")]
|
||
#[rustc_diagnostic_item = "Debug"]
|
||
#[rustc_trivial_field_reads]
|
||
pub trait Debug {
|
||
#[doc = include_str!("fmt_trait_method_doc.md")]
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Position {
|
||
/// longitude: f32,
|
||
/// latitude: f32,
|
||
/// }
|
||
///
|
||
/// impl fmt::Debug for Position {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// f.debug_tuple("")
|
||
/// .field(&self.longitude)
|
||
/// .field(&self.latitude)
|
||
/// .finish()
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let position = Position { longitude: 1.987, latitude: 2.983 };
|
||
/// assert_eq!(format!("{position:?}"), "(1.987, 2.983)");
|
||
///
|
||
/// assert_eq!(format!("{position:#?}"), "(
|
||
/// 1.987,
|
||
/// 2.983,
|
||
/// )");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
|
||
}
|
||
|
||
// Separate module to reexport the macro `Debug` from prelude without the trait `Debug`.
|
||
pub(crate) mod macros {
|
||
/// Derive macro generating an impl of the trait `Debug`.
|
||
#[rustc_builtin_macro]
|
||
#[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
|
||
#[allow_internal_unstable(core_intrinsics, fmt_helpers_for_derive)]
|
||
pub macro Debug($item:item) {
|
||
/* compiler built-in */
|
||
}
|
||
}
|
||
#[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
|
||
#[doc(inline)]
|
||
pub use macros::Debug;
|
||
|
||
/// Format trait for an empty format, `{}`.
|
||
///
|
||
/// Implementing this trait for a type will automatically implement the
|
||
/// [`ToString`][tostring] trait for the type, allowing the usage
|
||
/// of the [`.to_string()`][tostring_function] method. Prefer implementing
|
||
/// the `Display` trait for a type, rather than [`ToString`][tostring].
|
||
///
|
||
/// `Display` is similar to [`Debug`], but `Display` is for user-facing
|
||
/// output, and so cannot be derived.
|
||
///
|
||
/// For more information on formatters, see [the module-level documentation][module].
|
||
///
|
||
/// [module]: ../../std/fmt/index.html
|
||
/// [tostring]: ../../std/string/trait.ToString.html
|
||
/// [tostring_function]: ../../std/string/trait.ToString.html#tymethod.to_string
|
||
///
|
||
/// # Internationalization
|
||
///
|
||
/// Because a type can only have one `Display` implementation, it is often preferable
|
||
/// to only implement `Display` when there is a single most "obvious" way that
|
||
/// values can be formatted as text. This could mean formatting according to the
|
||
/// "invariant" culture and "undefined" locale, or it could mean that the type
|
||
/// display is designed for a specific culture/locale, such as developer logs.
|
||
///
|
||
/// If not all values have a justifiably canonical textual format or if you want
|
||
/// to support alternative formats not covered by the standard set of possible
|
||
/// [formatting traits], the most flexible approach is display adapters: methods
|
||
/// like [`str::escape_default`] or [`Path::display`] which create a wrapper
|
||
/// implementing `Display` to output the specific display format.
|
||
///
|
||
/// [formatting traits]: ../../std/fmt/index.html#formatting-traits
|
||
/// [`Path::display`]: ../../std/path/struct.Path.html#method.display
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Implementing `Display` on a type:
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Point {
|
||
/// x: i32,
|
||
/// y: i32,
|
||
/// }
|
||
///
|
||
/// impl fmt::Display for Point {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// write!(f, "({}, {})", self.x, self.y)
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let origin = Point { x: 0, y: 0 };
|
||
///
|
||
/// assert_eq!(format!("The origin is: {origin}"), "The origin is: (0, 0)");
|
||
/// ```
|
||
#[rustc_on_unimplemented(
|
||
on(
|
||
any(_Self = "std::path::Path", _Self = "std::path::PathBuf"),
|
||
label = "`{Self}` cannot be formatted with the default formatter; call `.display()` on it",
|
||
note = "call `.display()` or `.to_string_lossy()` to safely print paths, \
|
||
as they may contain non-Unicode data"
|
||
),
|
||
message = "`{Self}` doesn't implement `{Display}`",
|
||
label = "`{Self}` cannot be formatted with the default formatter",
|
||
note = "in format strings you may be able to use `{{:?}}` (or {{:#?}} for pretty-print) instead"
|
||
)]
|
||
#[doc(alias = "{}")]
|
||
#[rustc_diagnostic_item = "Display"]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub trait Display {
|
||
#[doc = include_str!("fmt_trait_method_doc.md")]
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Position {
|
||
/// longitude: f32,
|
||
/// latitude: f32,
|
||
/// }
|
||
///
|
||
/// impl fmt::Display for Position {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// write!(f, "({}, {})", self.longitude, self.latitude)
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(
|
||
/// "(1.987, 2.983)",
|
||
/// format!("{}", Position { longitude: 1.987, latitude: 2.983, }),
|
||
/// );
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
|
||
}
|
||
|
||
/// `o` formatting.
|
||
///
|
||
/// The `Octal` trait should format its output as a number in base-8.
|
||
///
|
||
/// For primitive signed integers (`i8` to `i128`, and `isize`),
|
||
/// negative values are formatted as the two’s complement representation.
|
||
///
|
||
/// The alternate flag, `#`, adds a `0o` in front of the output.
|
||
///
|
||
/// For more information on formatters, see [the module-level documentation][module].
|
||
///
|
||
/// [module]: ../../std/fmt/index.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage with `i32`:
|
||
///
|
||
/// ```
|
||
/// let x = 42; // 42 is '52' in octal
|
||
///
|
||
/// assert_eq!(format!("{x:o}"), "52");
|
||
/// assert_eq!(format!("{x:#o}"), "0o52");
|
||
///
|
||
/// assert_eq!(format!("{:o}", -16), "37777777760");
|
||
/// ```
|
||
///
|
||
/// Implementing `Octal` on a type:
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Length(i32);
|
||
///
|
||
/// impl fmt::Octal for Length {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// let val = self.0;
|
||
///
|
||
/// fmt::Octal::fmt(&val, f) // delegate to i32's implementation
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let l = Length(9);
|
||
///
|
||
/// assert_eq!(format!("l as octal is: {l:o}"), "l as octal is: 11");
|
||
///
|
||
/// assert_eq!(format!("l as octal is: {l:#06o}"), "l as octal is: 0o0011");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub trait Octal {
|
||
#[doc = include_str!("fmt_trait_method_doc.md")]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
|
||
}
|
||
|
||
/// `b` formatting.
|
||
///
|
||
/// The `Binary` trait should format its output as a number in binary.
|
||
///
|
||
/// For primitive signed integers ([`i8`] to [`i128`], and [`isize`]),
|
||
/// negative values are formatted as the two’s complement representation.
|
||
///
|
||
/// The alternate flag, `#`, adds a `0b` in front of the output.
|
||
///
|
||
/// For more information on formatters, see [the module-level documentation][module].
|
||
///
|
||
/// [module]: ../../std/fmt/index.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage with [`i32`]:
|
||
///
|
||
/// ```
|
||
/// let x = 42; // 42 is '101010' in binary
|
||
///
|
||
/// assert_eq!(format!("{x:b}"), "101010");
|
||
/// assert_eq!(format!("{x:#b}"), "0b101010");
|
||
///
|
||
/// assert_eq!(format!("{:b}", -16), "11111111111111111111111111110000");
|
||
/// ```
|
||
///
|
||
/// Implementing `Binary` on a type:
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Length(i32);
|
||
///
|
||
/// impl fmt::Binary for Length {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// let val = self.0;
|
||
///
|
||
/// fmt::Binary::fmt(&val, f) // delegate to i32's implementation
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let l = Length(107);
|
||
///
|
||
/// assert_eq!(format!("l as binary is: {l:b}"), "l as binary is: 1101011");
|
||
///
|
||
/// assert_eq!(
|
||
/// // Note that the `0b` prefix added by `#` is included in the total width, so we
|
||
/// // need to add two to correctly display all 32 bits.
|
||
/// format!("l as binary is: {l:#034b}"),
|
||
/// "l as binary is: 0b00000000000000000000000001101011"
|
||
/// );
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub trait Binary {
|
||
#[doc = include_str!("fmt_trait_method_doc.md")]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
|
||
}
|
||
|
||
/// `x` formatting.
|
||
///
|
||
/// The `LowerHex` trait should format its output as a number in hexadecimal, with `a` through `f`
|
||
/// in lower case.
|
||
///
|
||
/// For primitive signed integers (`i8` to `i128`, and `isize`),
|
||
/// negative values are formatted as the two’s complement representation.
|
||
///
|
||
/// The alternate flag, `#`, adds a `0x` in front of the output.
|
||
///
|
||
/// For more information on formatters, see [the module-level documentation][module].
|
||
///
|
||
/// [module]: ../../std/fmt/index.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage with `i32`:
|
||
///
|
||
/// ```
|
||
/// let y = 42; // 42 is '2a' in hex
|
||
///
|
||
/// assert_eq!(format!("{y:x}"), "2a");
|
||
/// assert_eq!(format!("{y:#x}"), "0x2a");
|
||
///
|
||
/// assert_eq!(format!("{:x}", -16), "fffffff0");
|
||
/// ```
|
||
///
|
||
/// Implementing `LowerHex` on a type:
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Length(i32);
|
||
///
|
||
/// impl fmt::LowerHex for Length {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// let val = self.0;
|
||
///
|
||
/// fmt::LowerHex::fmt(&val, f) // delegate to i32's implementation
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let l = Length(9);
|
||
///
|
||
/// assert_eq!(format!("l as hex is: {l:x}"), "l as hex is: 9");
|
||
///
|
||
/// assert_eq!(format!("l as hex is: {l:#010x}"), "l as hex is: 0x00000009");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub trait LowerHex {
|
||
#[doc = include_str!("fmt_trait_method_doc.md")]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
|
||
}
|
||
|
||
/// `X` formatting.
|
||
///
|
||
/// The `UpperHex` trait should format its output as a number in hexadecimal, with `A` through `F`
|
||
/// in upper case.
|
||
///
|
||
/// For primitive signed integers (`i8` to `i128`, and `isize`),
|
||
/// negative values are formatted as the two’s complement representation.
|
||
///
|
||
/// The alternate flag, `#`, adds a `0x` in front of the output.
|
||
///
|
||
/// For more information on formatters, see [the module-level documentation][module].
|
||
///
|
||
/// [module]: ../../std/fmt/index.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage with `i32`:
|
||
///
|
||
/// ```
|
||
/// let y = 42; // 42 is '2A' in hex
|
||
///
|
||
/// assert_eq!(format!("{y:X}"), "2A");
|
||
/// assert_eq!(format!("{y:#X}"), "0x2A");
|
||
///
|
||
/// assert_eq!(format!("{:X}", -16), "FFFFFFF0");
|
||
/// ```
|
||
///
|
||
/// Implementing `UpperHex` on a type:
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Length(i32);
|
||
///
|
||
/// impl fmt::UpperHex for Length {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// let val = self.0;
|
||
///
|
||
/// fmt::UpperHex::fmt(&val, f) // delegate to i32's implementation
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let l = Length(i32::MAX);
|
||
///
|
||
/// assert_eq!(format!("l as hex is: {l:X}"), "l as hex is: 7FFFFFFF");
|
||
///
|
||
/// assert_eq!(format!("l as hex is: {l:#010X}"), "l as hex is: 0x7FFFFFFF");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub trait UpperHex {
|
||
#[doc = include_str!("fmt_trait_method_doc.md")]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
|
||
}
|
||
|
||
/// `p` formatting.
|
||
///
|
||
/// The `Pointer` trait should format its output as a memory location. This is commonly presented
|
||
/// as hexadecimal. For more information on formatters, see [the module-level documentation][module].
|
||
///
|
||
/// Printing of pointers is not a reliable way to discover how Rust programs are implemented.
|
||
/// The act of reading an address changes the program itself, and may change how the data is represented
|
||
/// in memory, and may affect which optimizations are applied to the code.
|
||
///
|
||
/// The printed pointer values are not guaranteed to be stable nor unique identifiers of objects.
|
||
/// Rust allows moving values to different memory locations, and may reuse the same memory locations
|
||
/// for different purposes.
|
||
///
|
||
/// There is no guarantee that the printed value can be converted back to a pointer.
|
||
///
|
||
/// [module]: ../../std/fmt/index.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage with `&i32`:
|
||
///
|
||
/// ```
|
||
/// let x = &42;
|
||
///
|
||
/// let address = format!("{x:p}"); // this produces something like '0x7f06092ac6d0'
|
||
/// ```
|
||
///
|
||
/// Implementing `Pointer` on a type:
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Length(i32);
|
||
///
|
||
/// impl fmt::Pointer for Length {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// // use `as` to convert to a `*const T`, which implements Pointer, which we can use
|
||
///
|
||
/// let ptr = self as *const Self;
|
||
/// fmt::Pointer::fmt(&ptr, f)
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let l = Length(42);
|
||
///
|
||
/// println!("l is in memory here: {l:p}");
|
||
///
|
||
/// let l_ptr = format!("{l:018p}");
|
||
/// assert_eq!(l_ptr.len(), 18);
|
||
/// assert_eq!(&l_ptr[..2], "0x");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_diagnostic_item = "Pointer"]
|
||
pub trait Pointer {
|
||
#[doc = include_str!("fmt_trait_method_doc.md")]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
|
||
}
|
||
|
||
/// `e` formatting.
|
||
///
|
||
/// The `LowerExp` trait should format its output in scientific notation with a lower-case `e`.
|
||
///
|
||
/// For more information on formatters, see [the module-level documentation][module].
|
||
///
|
||
/// [module]: ../../std/fmt/index.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage with `f64`:
|
||
///
|
||
/// ```
|
||
/// let x = 42.0; // 42.0 is '4.2e1' in scientific notation
|
||
///
|
||
/// assert_eq!(format!("{x:e}"), "4.2e1");
|
||
/// ```
|
||
///
|
||
/// Implementing `LowerExp` on a type:
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Length(i32);
|
||
///
|
||
/// impl fmt::LowerExp for Length {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// let val = f64::from(self.0);
|
||
/// fmt::LowerExp::fmt(&val, f) // delegate to f64's implementation
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let l = Length(100);
|
||
///
|
||
/// assert_eq!(
|
||
/// format!("l in scientific notation is: {l:e}"),
|
||
/// "l in scientific notation is: 1e2"
|
||
/// );
|
||
///
|
||
/// assert_eq!(
|
||
/// format!("l in scientific notation is: {l:05e}"),
|
||
/// "l in scientific notation is: 001e2"
|
||
/// );
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub trait LowerExp {
|
||
#[doc = include_str!("fmt_trait_method_doc.md")]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
|
||
}
|
||
|
||
/// `E` formatting.
|
||
///
|
||
/// The `UpperExp` trait should format its output in scientific notation with an upper-case `E`.
|
||
///
|
||
/// For more information on formatters, see [the module-level documentation][module].
|
||
///
|
||
/// [module]: ../../std/fmt/index.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage with `f64`:
|
||
///
|
||
/// ```
|
||
/// let x = 42.0; // 42.0 is '4.2E1' in scientific notation
|
||
///
|
||
/// assert_eq!(format!("{x:E}"), "4.2E1");
|
||
/// ```
|
||
///
|
||
/// Implementing `UpperExp` on a type:
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Length(i32);
|
||
///
|
||
/// impl fmt::UpperExp for Length {
|
||
/// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// let val = f64::from(self.0);
|
||
/// fmt::UpperExp::fmt(&val, f) // delegate to f64's implementation
|
||
/// }
|
||
/// }
|
||
///
|
||
/// let l = Length(100);
|
||
///
|
||
/// assert_eq!(
|
||
/// format!("l in scientific notation is: {l:E}"),
|
||
/// "l in scientific notation is: 1E2"
|
||
/// );
|
||
///
|
||
/// assert_eq!(
|
||
/// format!("l in scientific notation is: {l:05E}"),
|
||
/// "l in scientific notation is: 001E2"
|
||
/// );
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub trait UpperExp {
|
||
#[doc = include_str!("fmt_trait_method_doc.md")]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
|
||
}
|
||
|
||
/// Takes an output stream and an `Arguments` struct that can be precompiled with
|
||
/// the `format_args!` macro.
|
||
///
|
||
/// The arguments will be formatted according to the specified format string
|
||
/// into the output stream provided.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// let mut output = String::new();
|
||
/// fmt::write(&mut output, format_args!("Hello {}!", "world"))
|
||
/// .expect("Error occurred while trying to write in String");
|
||
/// assert_eq!(output, "Hello world!");
|
||
/// ```
|
||
///
|
||
/// Please note that using [`write!`] might be preferable. Example:
|
||
///
|
||
/// ```
|
||
/// use std::fmt::Write;
|
||
///
|
||
/// let mut output = String::new();
|
||
/// write!(&mut output, "Hello {}!", "world")
|
||
/// .expect("Error occurred while trying to write in String");
|
||
/// assert_eq!(output, "Hello world!");
|
||
/// ```
|
||
///
|
||
/// [`write!`]: crate::write!
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn write(output: &mut dyn Write, args: Arguments<'_>) -> Result {
|
||
let mut formatter = Formatter::new(output, FormattingOptions::new());
|
||
let mut idx = 0;
|
||
|
||
match args.fmt {
|
||
None => {
|
||
// We can use default formatting parameters for all arguments.
|
||
for (i, arg) in args.args.iter().enumerate() {
|
||
// SAFETY: args.args and args.pieces come from the same Arguments,
|
||
// which guarantees the indexes are always within bounds.
|
||
let piece = unsafe { args.pieces.get_unchecked(i) };
|
||
if !piece.is_empty() {
|
||
formatter.buf.write_str(*piece)?;
|
||
}
|
||
|
||
// SAFETY: There are no formatting parameters and hence no
|
||
// count arguments.
|
||
unsafe {
|
||
arg.fmt(&mut formatter)?;
|
||
}
|
||
idx += 1;
|
||
}
|
||
}
|
||
Some(fmt) => {
|
||
// Every spec has a corresponding argument that is preceded by
|
||
// a string piece.
|
||
for (i, arg) in fmt.iter().enumerate() {
|
||
// SAFETY: fmt and args.pieces come from the same Arguments,
|
||
// which guarantees the indexes are always within bounds.
|
||
let piece = unsafe { args.pieces.get_unchecked(i) };
|
||
if !piece.is_empty() {
|
||
formatter.buf.write_str(*piece)?;
|
||
}
|
||
// SAFETY: arg and args.args come from the same Arguments,
|
||
// which guarantees the indexes are always within bounds.
|
||
unsafe { run(&mut formatter, arg, args.args) }?;
|
||
idx += 1;
|
||
}
|
||
}
|
||
}
|
||
|
||
// There can be only one trailing string piece left.
|
||
if let Some(piece) = args.pieces.get(idx) {
|
||
formatter.buf.write_str(*piece)?;
|
||
}
|
||
|
||
Ok(())
|
||
}
|
||
|
||
unsafe fn run(fmt: &mut Formatter<'_>, arg: &rt::Placeholder, args: &[rt::Argument<'_>]) -> Result {
|
||
fmt.options.fill = arg.fill;
|
||
fmt.options.align = arg.align.into();
|
||
fmt.options.flags = arg.flags;
|
||
// SAFETY: arg and args come from the same Arguments,
|
||
// which guarantees the indexes are always within bounds.
|
||
unsafe {
|
||
fmt.options.width = getcount(args, &arg.width);
|
||
fmt.options.precision = getcount(args, &arg.precision);
|
||
}
|
||
|
||
// Extract the correct argument
|
||
debug_assert!(arg.position < args.len());
|
||
// SAFETY: arg and args come from the same Arguments,
|
||
// which guarantees its index is always within bounds.
|
||
let value = unsafe { args.get_unchecked(arg.position) };
|
||
|
||
// Then actually do some printing
|
||
// SAFETY: this is a placeholder argument.
|
||
unsafe { value.fmt(fmt) }
|
||
}
|
||
|
||
unsafe fn getcount(args: &[rt::Argument<'_>], cnt: &rt::Count) -> Option<usize> {
|
||
match *cnt {
|
||
rt::Count::Is(n) => Some(n),
|
||
rt::Count::Implied => None,
|
||
rt::Count::Param(i) => {
|
||
debug_assert!(i < args.len());
|
||
// SAFETY: cnt and args come from the same Arguments,
|
||
// which guarantees this index is always within bounds.
|
||
unsafe { args.get_unchecked(i).as_usize() }
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Padding after the end of something. Returned by `Formatter::padding`.
|
||
#[must_use = "don't forget to write the post padding"]
|
||
pub(crate) struct PostPadding {
|
||
fill: char,
|
||
padding: usize,
|
||
}
|
||
|
||
impl PostPadding {
|
||
fn new(fill: char, padding: usize) -> PostPadding {
|
||
PostPadding { fill, padding }
|
||
}
|
||
|
||
/// Writes this post padding.
|
||
pub(crate) fn write(self, f: &mut Formatter<'_>) -> Result {
|
||
for _ in 0..self.padding {
|
||
f.buf.write_char(self.fill)?;
|
||
}
|
||
Ok(())
|
||
}
|
||
}
|
||
|
||
impl<'a> Formatter<'a> {
|
||
fn wrap_buf<'b, 'c, F>(&'b mut self, wrap: F) -> Formatter<'c>
|
||
where
|
||
'b: 'c,
|
||
F: FnOnce(&'b mut (dyn Write + 'b)) -> &'c mut (dyn Write + 'c),
|
||
{
|
||
Formatter {
|
||
// We want to change this
|
||
buf: wrap(self.buf),
|
||
|
||
// And preserve these
|
||
options: self.options,
|
||
}
|
||
}
|
||
|
||
// Helper methods used for padding and processing formatting arguments that
|
||
// all formatting traits can use.
|
||
|
||
/// Performs the correct padding for an integer which has already been
|
||
/// emitted into a str. The str should *not* contain the sign for the
|
||
/// integer, that will be added by this method.
|
||
///
|
||
/// # Arguments
|
||
///
|
||
/// * is_nonnegative - whether the original integer was either positive or zero.
|
||
/// * prefix - if the '#' character (Alternate) is provided, this
|
||
/// is the prefix to put in front of the number.
|
||
/// * buf - the byte array that the number has been formatted into
|
||
///
|
||
/// This function will correctly account for the flags provided as well as
|
||
/// the minimum width. It will not take precision into account.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo { nb: i32 }
|
||
///
|
||
/// impl Foo {
|
||
/// fn new(nb: i32) -> Foo {
|
||
/// Foo {
|
||
/// nb,
|
||
/// }
|
||
/// }
|
||
/// }
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// // We need to remove "-" from the number output.
|
||
/// let tmp = self.nb.abs().to_string();
|
||
///
|
||
/// formatter.pad_integral(self.nb >= 0, "Foo ", &tmp)
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{}", Foo::new(2)), "2");
|
||
/// assert_eq!(format!("{}", Foo::new(-1)), "-1");
|
||
/// assert_eq!(format!("{}", Foo::new(0)), "0");
|
||
/// assert_eq!(format!("{:#}", Foo::new(-1)), "-Foo 1");
|
||
/// assert_eq!(format!("{:0>#8}", Foo::new(-1)), "00-Foo 1");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn pad_integral(&mut self, is_nonnegative: bool, prefix: &str, buf: &str) -> Result {
|
||
let mut width = buf.len();
|
||
|
||
let mut sign = None;
|
||
if !is_nonnegative {
|
||
sign = Some('-');
|
||
width += 1;
|
||
} else if self.sign_plus() {
|
||
sign = Some('+');
|
||
width += 1;
|
||
}
|
||
|
||
let prefix = if self.alternate() {
|
||
width += prefix.chars().count();
|
||
Some(prefix)
|
||
} else {
|
||
None
|
||
};
|
||
|
||
// Writes the sign if it exists, and then the prefix if it was requested
|
||
#[inline(never)]
|
||
fn write_prefix(f: &mut Formatter<'_>, sign: Option<char>, prefix: Option<&str>) -> Result {
|
||
if let Some(c) = sign {
|
||
f.buf.write_char(c)?;
|
||
}
|
||
if let Some(prefix) = prefix { f.buf.write_str(prefix) } else { Ok(()) }
|
||
}
|
||
|
||
// The `width` field is more of a `min-width` parameter at this point.
|
||
match self.options.width {
|
||
// If there's no minimum length requirements then we can just
|
||
// write the bytes.
|
||
None => {
|
||
write_prefix(self, sign, prefix)?;
|
||
self.buf.write_str(buf)
|
||
}
|
||
// Check if we're over the minimum width, if so then we can also
|
||
// just write the bytes.
|
||
Some(min) if width >= min => {
|
||
write_prefix(self, sign, prefix)?;
|
||
self.buf.write_str(buf)
|
||
}
|
||
// The sign and prefix goes before the padding if the fill character
|
||
// is zero
|
||
Some(min) if self.sign_aware_zero_pad() => {
|
||
let old_fill = crate::mem::replace(&mut self.options.fill, '0');
|
||
let old_align =
|
||
crate::mem::replace(&mut self.options.align, Some(Alignment::Right));
|
||
write_prefix(self, sign, prefix)?;
|
||
let post_padding = self.padding(min - width, Alignment::Right)?;
|
||
self.buf.write_str(buf)?;
|
||
post_padding.write(self)?;
|
||
self.options.fill = old_fill;
|
||
self.options.align = old_align;
|
||
Ok(())
|
||
}
|
||
// Otherwise, the sign and prefix goes after the padding
|
||
Some(min) => {
|
||
let post_padding = self.padding(min - width, Alignment::Right)?;
|
||
write_prefix(self, sign, prefix)?;
|
||
self.buf.write_str(buf)?;
|
||
post_padding.write(self)
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Takes a string slice and emits it to the internal buffer after applying
|
||
/// the relevant formatting flags specified.
|
||
///
|
||
/// The flags recognized for generic strings are:
|
||
///
|
||
/// * width - the minimum width of what to emit
|
||
/// * fill/align - what to emit and where to emit it if the string
|
||
/// provided needs to be padded
|
||
/// * precision - the maximum length to emit, the string is truncated if it
|
||
/// is longer than this length
|
||
///
|
||
/// Notably this function ignores the `flag` parameters.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo;
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// formatter.pad("Foo")
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{Foo:<4}"), "Foo ");
|
||
/// assert_eq!(format!("{Foo:0>4}"), "0Foo");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn pad(&mut self, s: &str) -> Result {
|
||
// Make sure there's a fast path up front
|
||
if self.options.width.is_none() && self.options.precision.is_none() {
|
||
return self.buf.write_str(s);
|
||
}
|
||
// The `precision` field can be interpreted as a `max-width` for the
|
||
// string being formatted.
|
||
let s = if let Some(max) = self.options.precision {
|
||
// If our string is longer that the precision, then we must have
|
||
// truncation. However other flags like `fill`, `width` and `align`
|
||
// must act as always.
|
||
if let Some((i, _)) = s.char_indices().nth(max) {
|
||
// LLVM here can't prove that `..i` won't panic `&s[..i]`, but
|
||
// we know that it can't panic. Use `get` + `unwrap_or` to avoid
|
||
// `unsafe` and otherwise don't emit any panic-related code
|
||
// here.
|
||
s.get(..i).unwrap_or(s)
|
||
} else {
|
||
&s
|
||
}
|
||
} else {
|
||
&s
|
||
};
|
||
// The `width` field is more of a `min-width` parameter at this point.
|
||
match self.options.width {
|
||
// If we're under the maximum length, and there's no minimum length
|
||
// requirements, then we can just emit the string
|
||
None => self.buf.write_str(s),
|
||
Some(width) => {
|
||
let chars_count = s.chars().count();
|
||
// If we're under the maximum width, check if we're over the minimum
|
||
// width, if so it's as easy as just emitting the string.
|
||
if chars_count >= width {
|
||
self.buf.write_str(s)
|
||
}
|
||
// If we're under both the maximum and the minimum width, then fill
|
||
// up the minimum width with the specified string + some alignment.
|
||
else {
|
||
let align = Alignment::Left;
|
||
let post_padding = self.padding(width - chars_count, align)?;
|
||
self.buf.write_str(s)?;
|
||
post_padding.write(self)
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Writes the pre-padding and returns the unwritten post-padding.
|
||
///
|
||
/// Callers are responsible for ensuring post-padding is written after the
|
||
/// thing that is being padded.
|
||
pub(crate) fn padding(
|
||
&mut self,
|
||
padding: usize,
|
||
default: Alignment,
|
||
) -> result::Result<PostPadding, Error> {
|
||
let align = self.align().unwrap_or(default);
|
||
|
||
let (pre_pad, post_pad) = match align {
|
||
Alignment::Left => (0, padding),
|
||
Alignment::Right => (padding, 0),
|
||
Alignment::Center => (padding / 2, (padding + 1) / 2),
|
||
};
|
||
|
||
for _ in 0..pre_pad {
|
||
self.buf.write_char(self.options.fill)?;
|
||
}
|
||
|
||
Ok(PostPadding::new(self.options.fill, post_pad))
|
||
}
|
||
|
||
/// Takes the formatted parts and applies the padding.
|
||
///
|
||
/// Assumes that the caller already has rendered the parts with required precision,
|
||
/// so that `self.precision` can be ignored.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// Any `numfmt::Part::Copy` parts in `formatted` must contain valid UTF-8.
|
||
unsafe fn pad_formatted_parts(&mut self, formatted: &numfmt::Formatted<'_>) -> Result {
|
||
if let Some(mut width) = self.options.width {
|
||
// for the sign-aware zero padding, we render the sign first and
|
||
// behave as if we had no sign from the beginning.
|
||
let mut formatted = formatted.clone();
|
||
let old_fill = self.options.fill;
|
||
let old_align = self.options.align;
|
||
if self.sign_aware_zero_pad() {
|
||
// a sign always goes first
|
||
let sign = formatted.sign;
|
||
self.buf.write_str(sign)?;
|
||
|
||
// remove the sign from the formatted parts
|
||
formatted.sign = "";
|
||
width = width.saturating_sub(sign.len());
|
||
self.options.fill = '0';
|
||
self.options.align = Some(Alignment::Right);
|
||
}
|
||
|
||
// remaining parts go through the ordinary padding process.
|
||
let len = formatted.len();
|
||
let ret = if width <= len {
|
||
// no padding
|
||
// SAFETY: Per the precondition.
|
||
unsafe { self.write_formatted_parts(&formatted) }
|
||
} else {
|
||
let post_padding = self.padding(width - len, Alignment::Right)?;
|
||
// SAFETY: Per the precondition.
|
||
unsafe {
|
||
self.write_formatted_parts(&formatted)?;
|
||
}
|
||
post_padding.write(self)
|
||
};
|
||
self.options.fill = old_fill;
|
||
self.options.align = old_align;
|
||
ret
|
||
} else {
|
||
// this is the common case and we take a shortcut
|
||
// SAFETY: Per the precondition.
|
||
unsafe { self.write_formatted_parts(formatted) }
|
||
}
|
||
}
|
||
|
||
/// # Safety
|
||
///
|
||
/// Any `numfmt::Part::Copy` parts in `formatted` must contain valid UTF-8.
|
||
unsafe fn write_formatted_parts(&mut self, formatted: &numfmt::Formatted<'_>) -> Result {
|
||
unsafe fn write_bytes(buf: &mut dyn Write, s: &[u8]) -> Result {
|
||
// SAFETY: This is used for `numfmt::Part::Num` and `numfmt::Part::Copy`.
|
||
// It's safe to use for `numfmt::Part::Num` since every char `c` is between
|
||
// `b'0'` and `b'9'`, which means `s` is valid UTF-8. It's safe to use for
|
||
// `numfmt::Part::Copy` due to this function's precondition.
|
||
buf.write_str(unsafe { str::from_utf8_unchecked(s) })
|
||
}
|
||
|
||
if !formatted.sign.is_empty() {
|
||
self.buf.write_str(formatted.sign)?;
|
||
}
|
||
for part in formatted.parts {
|
||
match *part {
|
||
numfmt::Part::Zero(mut nzeroes) => {
|
||
const ZEROES: &str = // 64 zeroes
|
||
"0000000000000000000000000000000000000000000000000000000000000000";
|
||
while nzeroes > ZEROES.len() {
|
||
self.buf.write_str(ZEROES)?;
|
||
nzeroes -= ZEROES.len();
|
||
}
|
||
if nzeroes > 0 {
|
||
self.buf.write_str(&ZEROES[..nzeroes])?;
|
||
}
|
||
}
|
||
numfmt::Part::Num(mut v) => {
|
||
let mut s = [0; 5];
|
||
let len = part.len();
|
||
for c in s[..len].iter_mut().rev() {
|
||
*c = b'0' + (v % 10) as u8;
|
||
v /= 10;
|
||
}
|
||
// SAFETY: Per the precondition.
|
||
unsafe {
|
||
write_bytes(self.buf, &s[..len])?;
|
||
}
|
||
}
|
||
// SAFETY: Per the precondition.
|
||
numfmt::Part::Copy(buf) => unsafe {
|
||
write_bytes(self.buf, buf)?;
|
||
},
|
||
}
|
||
}
|
||
Ok(())
|
||
}
|
||
|
||
/// Writes some data to the underlying buffer contained within this
|
||
/// formatter.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo;
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// formatter.write_str("Foo")
|
||
/// // This is equivalent to:
|
||
/// // write!(formatter, "Foo")
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{Foo}"), "Foo");
|
||
/// assert_eq!(format!("{Foo:0>8}"), "Foo");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn write_str(&mut self, data: &str) -> Result {
|
||
self.buf.write_str(data)
|
||
}
|
||
|
||
/// Glue for usage of the [`write!`] macro with implementors of this trait.
|
||
///
|
||
/// This method should generally not be invoked manually, but rather through
|
||
/// the [`write!`] macro itself.
|
||
///
|
||
/// Writes some formatted information into this instance.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo(i32);
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// formatter.write_fmt(format_args!("Foo {}", self.0))
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{}", Foo(-1)), "Foo -1");
|
||
/// assert_eq!(format!("{:0>8}", Foo(2)), "Foo 2");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result {
|
||
if let Some(s) = fmt.as_statically_known_str() {
|
||
self.buf.write_str(s)
|
||
} else {
|
||
write(self.buf, fmt)
|
||
}
|
||
}
|
||
|
||
/// Returns flags for formatting.
|
||
#[must_use]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[deprecated(
|
||
since = "1.24.0",
|
||
note = "use the `sign_plus`, `sign_minus`, `alternate`, \
|
||
or `sign_aware_zero_pad` methods instead"
|
||
)]
|
||
pub fn flags(&self) -> u32 {
|
||
self.options.flags
|
||
}
|
||
|
||
/// Returns the character used as 'fill' whenever there is alignment.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo;
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// let c = formatter.fill();
|
||
/// if let Some(width) = formatter.width() {
|
||
/// for _ in 0..width {
|
||
/// write!(formatter, "{c}")?;
|
||
/// }
|
||
/// Ok(())
|
||
/// } else {
|
||
/// write!(formatter, "{c}")
|
||
/// }
|
||
/// }
|
||
/// }
|
||
///
|
||
/// // We set alignment to the right with ">".
|
||
/// assert_eq!(format!("{Foo:G>3}"), "GGG");
|
||
/// assert_eq!(format!("{Foo:t>6}"), "tttttt");
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "fmt_flags", since = "1.5.0")]
|
||
pub fn fill(&self) -> char {
|
||
self.options.fill
|
||
}
|
||
|
||
/// Returns a flag indicating what form of alignment was requested.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt::{self, Alignment};
|
||
///
|
||
/// struct Foo;
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// let s = if let Some(s) = formatter.align() {
|
||
/// match s {
|
||
/// Alignment::Left => "left",
|
||
/// Alignment::Right => "right",
|
||
/// Alignment::Center => "center",
|
||
/// }
|
||
/// } else {
|
||
/// "into the void"
|
||
/// };
|
||
/// write!(formatter, "{s}")
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{Foo:<}"), "left");
|
||
/// assert_eq!(format!("{Foo:>}"), "right");
|
||
/// assert_eq!(format!("{Foo:^}"), "center");
|
||
/// assert_eq!(format!("{Foo}"), "into the void");
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "fmt_flags_align", since = "1.28.0")]
|
||
pub fn align(&self) -> Option<Alignment> {
|
||
self.options.align
|
||
}
|
||
|
||
/// Returns the optionally specified integer width that the output should be.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo(i32);
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// if let Some(width) = formatter.width() {
|
||
/// // If we received a width, we use it
|
||
/// write!(formatter, "{:width$}", format!("Foo({})", self.0), width = width)
|
||
/// } else {
|
||
/// // Otherwise we do nothing special
|
||
/// write!(formatter, "Foo({})", self.0)
|
||
/// }
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{:10}", Foo(23)), "Foo(23) ");
|
||
/// assert_eq!(format!("{}", Foo(23)), "Foo(23)");
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "fmt_flags", since = "1.5.0")]
|
||
pub fn width(&self) -> Option<usize> {
|
||
self.options.width
|
||
}
|
||
|
||
/// Returns the optionally specified precision for numeric types.
|
||
/// Alternatively, the maximum width for string types.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo(f32);
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// if let Some(precision) = formatter.precision() {
|
||
/// // If we received a precision, we use it.
|
||
/// write!(formatter, "Foo({1:.*})", precision, self.0)
|
||
/// } else {
|
||
/// // Otherwise we default to 2.
|
||
/// write!(formatter, "Foo({:.2})", self.0)
|
||
/// }
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{:.4}", Foo(23.2)), "Foo(23.2000)");
|
||
/// assert_eq!(format!("{}", Foo(23.2)), "Foo(23.20)");
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "fmt_flags", since = "1.5.0")]
|
||
pub fn precision(&self) -> Option<usize> {
|
||
self.options.precision
|
||
}
|
||
|
||
/// Determines if the `+` flag was specified.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo(i32);
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// if formatter.sign_plus() {
|
||
/// write!(formatter,
|
||
/// "Foo({}{})",
|
||
/// if self.0 < 0 { '-' } else { '+' },
|
||
/// self.0.abs())
|
||
/// } else {
|
||
/// write!(formatter, "Foo({})", self.0)
|
||
/// }
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{:+}", Foo(23)), "Foo(+23)");
|
||
/// assert_eq!(format!("{:+}", Foo(-23)), "Foo(-23)");
|
||
/// assert_eq!(format!("{}", Foo(23)), "Foo(23)");
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "fmt_flags", since = "1.5.0")]
|
||
pub fn sign_plus(&self) -> bool {
|
||
self.options.flags & (1 << rt::Flag::SignPlus as u32) != 0
|
||
}
|
||
|
||
/// Determines if the `-` flag was specified.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo(i32);
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// if formatter.sign_minus() {
|
||
/// // You want a minus sign? Have one!
|
||
/// write!(formatter, "-Foo({})", self.0)
|
||
/// } else {
|
||
/// write!(formatter, "Foo({})", self.0)
|
||
/// }
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{:-}", Foo(23)), "-Foo(23)");
|
||
/// assert_eq!(format!("{}", Foo(23)), "Foo(23)");
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "fmt_flags", since = "1.5.0")]
|
||
pub fn sign_minus(&self) -> bool {
|
||
self.options.flags & (1 << rt::Flag::SignMinus as u32) != 0
|
||
}
|
||
|
||
/// Determines if the `#` flag was specified.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo(i32);
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// if formatter.alternate() {
|
||
/// write!(formatter, "Foo({})", self.0)
|
||
/// } else {
|
||
/// write!(formatter, "{}", self.0)
|
||
/// }
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{:#}", Foo(23)), "Foo(23)");
|
||
/// assert_eq!(format!("{}", Foo(23)), "23");
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "fmt_flags", since = "1.5.0")]
|
||
pub fn alternate(&self) -> bool {
|
||
self.options.flags & (1 << rt::Flag::Alternate as u32) != 0
|
||
}
|
||
|
||
/// Determines if the `0` flag was specified.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo(i32);
|
||
///
|
||
/// impl fmt::Display for Foo {
|
||
/// fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// assert!(formatter.sign_aware_zero_pad());
|
||
/// assert_eq!(formatter.width(), Some(4));
|
||
/// // We ignore the formatter's options.
|
||
/// write!(formatter, "{}", self.0)
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{:04}", Foo(23)), "23");
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "fmt_flags", since = "1.5.0")]
|
||
pub fn sign_aware_zero_pad(&self) -> bool {
|
||
self.options.flags & (1 << rt::Flag::SignAwareZeroPad as u32) != 0
|
||
}
|
||
|
||
// FIXME: Decide what public API we want for these two flags.
|
||
// https://github.com/rust-lang/rust/issues/48584
|
||
fn debug_lower_hex(&self) -> bool {
|
||
self.options.flags & (1 << rt::Flag::DebugLowerHex as u32) != 0
|
||
}
|
||
|
||
fn debug_upper_hex(&self) -> bool {
|
||
self.options.flags & (1 << rt::Flag::DebugUpperHex as u32) != 0
|
||
}
|
||
|
||
/// Creates a [`DebugStruct`] builder designed to assist with creation of
|
||
/// [`fmt::Debug`] implementations for structs.
|
||
///
|
||
/// [`fmt::Debug`]: self::Debug
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```rust
|
||
/// use std::fmt;
|
||
/// use std::net::Ipv4Addr;
|
||
///
|
||
/// struct Foo {
|
||
/// bar: i32,
|
||
/// baz: String,
|
||
/// addr: Ipv4Addr,
|
||
/// }
|
||
///
|
||
/// impl fmt::Debug for Foo {
|
||
/// fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// fmt.debug_struct("Foo")
|
||
/// .field("bar", &self.bar)
|
||
/// .field("baz", &self.baz)
|
||
/// .field("addr", &format_args!("{}", self.addr))
|
||
/// .finish()
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(
|
||
/// "Foo { bar: 10, baz: \"Hello World\", addr: 127.0.0.1 }",
|
||
/// format!("{:?}", Foo {
|
||
/// bar: 10,
|
||
/// baz: "Hello World".to_string(),
|
||
/// addr: Ipv4Addr::new(127, 0, 0, 1),
|
||
/// })
|
||
/// );
|
||
/// ```
|
||
#[stable(feature = "debug_builders", since = "1.2.0")]
|
||
pub fn debug_struct<'b>(&'b mut self, name: &str) -> DebugStruct<'b, 'a> {
|
||
builders::debug_struct_new(self, name)
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. `debug_struct_fields_finish` is more general, but this is
|
||
/// faster for 1 field.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_struct_field1_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
name1: &str,
|
||
value1: &dyn Debug,
|
||
) -> Result {
|
||
let mut builder = builders::debug_struct_new(self, name);
|
||
builder.field(name1, value1);
|
||
builder.finish()
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. `debug_struct_fields_finish` is more general, but this is
|
||
/// faster for 2 fields.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_struct_field2_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
name1: &str,
|
||
value1: &dyn Debug,
|
||
name2: &str,
|
||
value2: &dyn Debug,
|
||
) -> Result {
|
||
let mut builder = builders::debug_struct_new(self, name);
|
||
builder.field(name1, value1);
|
||
builder.field(name2, value2);
|
||
builder.finish()
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. `debug_struct_fields_finish` is more general, but this is
|
||
/// faster for 3 fields.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_struct_field3_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
name1: &str,
|
||
value1: &dyn Debug,
|
||
name2: &str,
|
||
value2: &dyn Debug,
|
||
name3: &str,
|
||
value3: &dyn Debug,
|
||
) -> Result {
|
||
let mut builder = builders::debug_struct_new(self, name);
|
||
builder.field(name1, value1);
|
||
builder.field(name2, value2);
|
||
builder.field(name3, value3);
|
||
builder.finish()
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. `debug_struct_fields_finish` is more general, but this is
|
||
/// faster for 4 fields.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_struct_field4_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
name1: &str,
|
||
value1: &dyn Debug,
|
||
name2: &str,
|
||
value2: &dyn Debug,
|
||
name3: &str,
|
||
value3: &dyn Debug,
|
||
name4: &str,
|
||
value4: &dyn Debug,
|
||
) -> Result {
|
||
let mut builder = builders::debug_struct_new(self, name);
|
||
builder.field(name1, value1);
|
||
builder.field(name2, value2);
|
||
builder.field(name3, value3);
|
||
builder.field(name4, value4);
|
||
builder.finish()
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. `debug_struct_fields_finish` is more general, but this is
|
||
/// faster for 5 fields.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_struct_field5_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
name1: &str,
|
||
value1: &dyn Debug,
|
||
name2: &str,
|
||
value2: &dyn Debug,
|
||
name3: &str,
|
||
value3: &dyn Debug,
|
||
name4: &str,
|
||
value4: &dyn Debug,
|
||
name5: &str,
|
||
value5: &dyn Debug,
|
||
) -> Result {
|
||
let mut builder = builders::debug_struct_new(self, name);
|
||
builder.field(name1, value1);
|
||
builder.field(name2, value2);
|
||
builder.field(name3, value3);
|
||
builder.field(name4, value4);
|
||
builder.field(name5, value5);
|
||
builder.finish()
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller binaries.
|
||
/// For the cases not covered by `debug_struct_field[12345]_finish`.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_struct_fields_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
names: &[&str],
|
||
values: &[&dyn Debug],
|
||
) -> Result {
|
||
assert_eq!(names.len(), values.len());
|
||
let mut builder = builders::debug_struct_new(self, name);
|
||
for (name, value) in iter::zip(names, values) {
|
||
builder.field(name, value);
|
||
}
|
||
builder.finish()
|
||
}
|
||
|
||
/// Creates a `DebugTuple` builder designed to assist with creation of
|
||
/// `fmt::Debug` implementations for tuple structs.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```rust
|
||
/// use std::fmt;
|
||
/// use std::marker::PhantomData;
|
||
///
|
||
/// struct Foo<T>(i32, String, PhantomData<T>);
|
||
///
|
||
/// impl<T> fmt::Debug for Foo<T> {
|
||
/// fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// fmt.debug_tuple("Foo")
|
||
/// .field(&self.0)
|
||
/// .field(&self.1)
|
||
/// .field(&format_args!("_"))
|
||
/// .finish()
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(
|
||
/// "Foo(10, \"Hello\", _)",
|
||
/// format!("{:?}", Foo(10, "Hello".to_string(), PhantomData::<u8>))
|
||
/// );
|
||
/// ```
|
||
#[stable(feature = "debug_builders", since = "1.2.0")]
|
||
pub fn debug_tuple<'b>(&'b mut self, name: &str) -> DebugTuple<'b, 'a> {
|
||
builders::debug_tuple_new(self, name)
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. `debug_tuple_fields_finish` is more general, but this is faster
|
||
/// for 1 field.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_tuple_field1_finish<'b>(&'b mut self, name: &str, value1: &dyn Debug) -> Result {
|
||
let mut builder = builders::debug_tuple_new(self, name);
|
||
builder.field(value1);
|
||
builder.finish()
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. `debug_tuple_fields_finish` is more general, but this is faster
|
||
/// for 2 fields.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_tuple_field2_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
value1: &dyn Debug,
|
||
value2: &dyn Debug,
|
||
) -> Result {
|
||
let mut builder = builders::debug_tuple_new(self, name);
|
||
builder.field(value1);
|
||
builder.field(value2);
|
||
builder.finish()
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. `debug_tuple_fields_finish` is more general, but this is faster
|
||
/// for 3 fields.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_tuple_field3_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
value1: &dyn Debug,
|
||
value2: &dyn Debug,
|
||
value3: &dyn Debug,
|
||
) -> Result {
|
||
let mut builder = builders::debug_tuple_new(self, name);
|
||
builder.field(value1);
|
||
builder.field(value2);
|
||
builder.field(value3);
|
||
builder.finish()
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. `debug_tuple_fields_finish` is more general, but this is faster
|
||
/// for 4 fields.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_tuple_field4_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
value1: &dyn Debug,
|
||
value2: &dyn Debug,
|
||
value3: &dyn Debug,
|
||
value4: &dyn Debug,
|
||
) -> Result {
|
||
let mut builder = builders::debug_tuple_new(self, name);
|
||
builder.field(value1);
|
||
builder.field(value2);
|
||
builder.field(value3);
|
||
builder.field(value4);
|
||
builder.finish()
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. `debug_tuple_fields_finish` is more general, but this is faster
|
||
/// for 5 fields.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_tuple_field5_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
value1: &dyn Debug,
|
||
value2: &dyn Debug,
|
||
value3: &dyn Debug,
|
||
value4: &dyn Debug,
|
||
value5: &dyn Debug,
|
||
) -> Result {
|
||
let mut builder = builders::debug_tuple_new(self, name);
|
||
builder.field(value1);
|
||
builder.field(value2);
|
||
builder.field(value3);
|
||
builder.field(value4);
|
||
builder.field(value5);
|
||
builder.finish()
|
||
}
|
||
|
||
/// Shrinks `derive(Debug)` code, for faster compilation and smaller
|
||
/// binaries. For the cases not covered by `debug_tuple_field[12345]_finish`.
|
||
#[doc(hidden)]
|
||
#[unstable(feature = "fmt_helpers_for_derive", issue = "none")]
|
||
pub fn debug_tuple_fields_finish<'b>(
|
||
&'b mut self,
|
||
name: &str,
|
||
values: &[&dyn Debug],
|
||
) -> Result {
|
||
let mut builder = builders::debug_tuple_new(self, name);
|
||
for value in values {
|
||
builder.field(value);
|
||
}
|
||
builder.finish()
|
||
}
|
||
|
||
/// Creates a `DebugList` builder designed to assist with creation of
|
||
/// `fmt::Debug` implementations for list-like structures.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```rust
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo(Vec<i32>);
|
||
///
|
||
/// impl fmt::Debug for Foo {
|
||
/// fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// fmt.debug_list().entries(self.0.iter()).finish()
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{:?}", Foo(vec![10, 11])), "[10, 11]");
|
||
/// ```
|
||
#[stable(feature = "debug_builders", since = "1.2.0")]
|
||
pub fn debug_list<'b>(&'b mut self) -> DebugList<'b, 'a> {
|
||
builders::debug_list_new(self)
|
||
}
|
||
|
||
/// Creates a `DebugSet` builder designed to assist with creation of
|
||
/// `fmt::Debug` implementations for set-like structures.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```rust
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo(Vec<i32>);
|
||
///
|
||
/// impl fmt::Debug for Foo {
|
||
/// fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// fmt.debug_set().entries(self.0.iter()).finish()
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(format!("{:?}", Foo(vec![10, 11])), "{10, 11}");
|
||
/// ```
|
||
///
|
||
/// [`format_args!`]: crate::format_args
|
||
///
|
||
/// In this more complex example, we use [`format_args!`] and `.debug_set()`
|
||
/// to build a list of match arms:
|
||
///
|
||
/// ```rust
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Arm<'a, L, R>(&'a (L, R));
|
||
/// struct Table<'a, K, V>(&'a [(K, V)], V);
|
||
///
|
||
/// impl<'a, L, R> fmt::Debug for Arm<'a, L, R>
|
||
/// where
|
||
/// L: 'a + fmt::Debug, R: 'a + fmt::Debug
|
||
/// {
|
||
/// fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// L::fmt(&(self.0).0, fmt)?;
|
||
/// fmt.write_str(" => ")?;
|
||
/// R::fmt(&(self.0).1, fmt)
|
||
/// }
|
||
/// }
|
||
///
|
||
/// impl<'a, K, V> fmt::Debug for Table<'a, K, V>
|
||
/// where
|
||
/// K: 'a + fmt::Debug, V: 'a + fmt::Debug
|
||
/// {
|
||
/// fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// fmt.debug_set()
|
||
/// .entries(self.0.iter().map(Arm))
|
||
/// .entry(&Arm(&(format_args!("_"), &self.1)))
|
||
/// .finish()
|
||
/// }
|
||
/// }
|
||
/// ```
|
||
#[stable(feature = "debug_builders", since = "1.2.0")]
|
||
pub fn debug_set<'b>(&'b mut self) -> DebugSet<'b, 'a> {
|
||
builders::debug_set_new(self)
|
||
}
|
||
|
||
/// Creates a `DebugMap` builder designed to assist with creation of
|
||
/// `fmt::Debug` implementations for map-like structures.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```rust
|
||
/// use std::fmt;
|
||
///
|
||
/// struct Foo(Vec<(String, i32)>);
|
||
///
|
||
/// impl fmt::Debug for Foo {
|
||
/// fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
/// fmt.debug_map().entries(self.0.iter().map(|&(ref k, ref v)| (k, v))).finish()
|
||
/// }
|
||
/// }
|
||
///
|
||
/// assert_eq!(
|
||
/// format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])),
|
||
/// r#"{"A": 10, "B": 11}"#
|
||
/// );
|
||
/// ```
|
||
#[stable(feature = "debug_builders", since = "1.2.0")]
|
||
pub fn debug_map<'b>(&'b mut self) -> DebugMap<'b, 'a> {
|
||
builders::debug_map_new(self)
|
||
}
|
||
|
||
/// Returns the sign of this formatter (`+` or `-`).
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn sign(&self) -> Option<Sign> {
|
||
self.options.get_sign()
|
||
}
|
||
|
||
/// Returns the formatting options this formatter corresponds to.
|
||
#[unstable(feature = "formatting_options", issue = "118117")]
|
||
pub const fn options(&self) -> FormattingOptions {
|
||
self.options
|
||
}
|
||
}
|
||
|
||
#[stable(since = "1.2.0", feature = "formatter_write")]
|
||
impl Write for Formatter<'_> {
|
||
fn write_str(&mut self, s: &str) -> Result {
|
||
self.buf.write_str(s)
|
||
}
|
||
|
||
fn write_char(&mut self, c: char) -> Result {
|
||
self.buf.write_char(c)
|
||
}
|
||
|
||
#[inline]
|
||
fn write_fmt(&mut self, args: Arguments<'_>) -> Result {
|
||
if let Some(s) = args.as_statically_known_str() {
|
||
self.buf.write_str(s)
|
||
} else {
|
||
write(self.buf, args)
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Display for Error {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
Display::fmt("an error occurred when formatting an argument", f)
|
||
}
|
||
}
|
||
|
||
// Implementations of the core formatting traits
|
||
|
||
macro_rules! fmt_refs {
|
||
($($tr:ident),*) => {
|
||
$(
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized + $tr> $tr for &T {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result { $tr::fmt(&**self, f) }
|
||
}
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized + $tr> $tr for &mut T {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result { $tr::fmt(&**self, f) }
|
||
}
|
||
)*
|
||
}
|
||
}
|
||
|
||
fmt_refs! { Debug, Display, Octal, Binary, LowerHex, UpperHex, LowerExp, UpperExp }
|
||
|
||
#[unstable(feature = "never_type", issue = "35121")]
|
||
impl Debug for ! {
|
||
#[inline]
|
||
fn fmt(&self, _: &mut Formatter<'_>) -> Result {
|
||
*self
|
||
}
|
||
}
|
||
|
||
#[unstable(feature = "never_type", issue = "35121")]
|
||
impl Display for ! {
|
||
#[inline]
|
||
fn fmt(&self, _: &mut Formatter<'_>) -> Result {
|
||
*self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Debug for bool {
|
||
#[inline]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
Display::fmt(self, f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Display for bool {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
Display::fmt(if *self { "true" } else { "false" }, f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Debug for str {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
f.write_char('"')?;
|
||
|
||
// substring we know is printable
|
||
let mut printable_range = 0..0;
|
||
|
||
fn needs_escape(b: u8) -> bool {
|
||
b > 0x7E || b < 0x20 || b == b'\\' || b == b'"'
|
||
}
|
||
|
||
// the loop here first skips over runs of printable ASCII as a fast path.
|
||
// other chars (unicode, or ASCII that needs escaping) are then handled per-`char`.
|
||
let mut rest = self;
|
||
while rest.len() > 0 {
|
||
let Some(non_printable_start) = rest.as_bytes().iter().position(|&b| needs_escape(b))
|
||
else {
|
||
printable_range.end += rest.len();
|
||
break;
|
||
};
|
||
|
||
printable_range.end += non_printable_start;
|
||
// SAFETY: the position was derived from an iterator, so is known to be within bounds, and at a char boundary
|
||
rest = unsafe { rest.get_unchecked(non_printable_start..) };
|
||
|
||
let mut chars = rest.chars();
|
||
if let Some(c) = chars.next() {
|
||
let esc = c.escape_debug_ext(EscapeDebugExtArgs {
|
||
escape_grapheme_extended: true,
|
||
escape_single_quote: false,
|
||
escape_double_quote: true,
|
||
});
|
||
if esc.len() != 1 {
|
||
f.write_str(&self[printable_range.clone()])?;
|
||
Display::fmt(&esc, f)?;
|
||
printable_range.start = printable_range.end + c.len_utf8();
|
||
}
|
||
printable_range.end += c.len_utf8();
|
||
}
|
||
rest = chars.as_str();
|
||
}
|
||
|
||
f.write_str(&self[printable_range])?;
|
||
|
||
f.write_char('"')
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Display for str {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
f.pad(self)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Debug for char {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
f.write_char('\'')?;
|
||
let esc = self.escape_debug_ext(EscapeDebugExtArgs {
|
||
escape_grapheme_extended: true,
|
||
escape_single_quote: true,
|
||
escape_double_quote: false,
|
||
});
|
||
Display::fmt(&esc, f)?;
|
||
f.write_char('\'')
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Display for char {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
if f.options.width.is_none() && f.options.precision.is_none() {
|
||
f.write_char(*self)
|
||
} else {
|
||
f.pad(self.encode_utf8(&mut [0; 4]))
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized> Pointer for *const T {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
pointer_fmt_inner(self.expose_provenance(), f)
|
||
}
|
||
}
|
||
|
||
/// Since the formatting will be identical for all pointer types, uses a
|
||
/// non-monomorphized implementation for the actual formatting to reduce the
|
||
/// amount of codegen work needed.
|
||
///
|
||
/// This uses `ptr_addr: usize` and not `ptr: *const ()` to be able to use this for
|
||
/// `fn(...) -> ...` without using [problematic] "Oxford Casts".
|
||
///
|
||
/// [problematic]: https://github.com/rust-lang/rust/issues/95489
|
||
pub(crate) fn pointer_fmt_inner(ptr_addr: usize, f: &mut Formatter<'_>) -> Result {
|
||
let old_width = f.options.width;
|
||
let old_flags = f.options.flags;
|
||
|
||
// The alternate flag is already treated by LowerHex as being special-
|
||
// it denotes whether to prefix with 0x. We use it to work out whether
|
||
// or not to zero extend, and then unconditionally set it to get the
|
||
// prefix.
|
||
if f.alternate() {
|
||
f.options.flags |= 1 << (rt::Flag::SignAwareZeroPad as u32);
|
||
|
||
if f.options.width.is_none() {
|
||
f.options.width = Some((usize::BITS / 4) as usize + 2);
|
||
}
|
||
}
|
||
f.options.flags |= 1 << (rt::Flag::Alternate as u32);
|
||
|
||
let ret = LowerHex::fmt(&ptr_addr, f);
|
||
|
||
f.options.width = old_width;
|
||
f.options.flags = old_flags;
|
||
|
||
ret
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized> Pointer for *mut T {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
Pointer::fmt(&(*self as *const T), f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized> Pointer for &T {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
Pointer::fmt(&(*self as *const T), f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized> Pointer for &mut T {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
Pointer::fmt(&(&**self as *const T), f)
|
||
}
|
||
}
|
||
|
||
// Implementation of Display/Debug for various core types
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized> Debug for *const T {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
Pointer::fmt(self, f)
|
||
}
|
||
}
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized> Debug for *mut T {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
Pointer::fmt(self, f)
|
||
}
|
||
}
|
||
|
||
macro_rules! peel {
|
||
($name:ident, $($other:ident,)*) => (tuple! { $($other,)* })
|
||
}
|
||
|
||
macro_rules! tuple {
|
||
() => ();
|
||
( $($name:ident,)+ ) => (
|
||
maybe_tuple_doc! {
|
||
$($name)+ @
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<$($name:Debug),+> Debug for ($($name,)+) where last_type!($($name,)+): ?Sized {
|
||
#[allow(non_snake_case, unused_assignments)]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
let mut builder = f.debug_tuple("");
|
||
let ($(ref $name,)+) = *self;
|
||
$(
|
||
builder.field(&$name);
|
||
)+
|
||
|
||
builder.finish()
|
||
}
|
||
}
|
||
}
|
||
peel! { $($name,)+ }
|
||
)
|
||
}
|
||
|
||
macro_rules! maybe_tuple_doc {
|
||
($a:ident @ #[$meta:meta] $item:item) => {
|
||
#[doc(fake_variadic)]
|
||
#[doc = "This trait is implemented for tuples up to twelve items long."]
|
||
#[$meta]
|
||
$item
|
||
};
|
||
($a:ident $($rest_a:ident)+ @ #[$meta:meta] $item:item) => {
|
||
#[doc(hidden)]
|
||
#[$meta]
|
||
$item
|
||
};
|
||
}
|
||
|
||
macro_rules! last_type {
|
||
($a:ident,) => { $a };
|
||
($a:ident, $($rest_a:ident,)+) => { last_type!($($rest_a,)+) };
|
||
}
|
||
|
||
tuple! { E, D, C, B, A, Z, Y, X, W, V, U, T, }
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Debug> Debug for [T] {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
f.debug_list().entries(self.iter()).finish()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Debug for () {
|
||
#[inline]
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
f.pad("()")
|
||
}
|
||
}
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized> Debug for PhantomData<T> {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
write!(f, "PhantomData<{}>", crate::any::type_name::<T>())
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Copy + Debug> Debug for Cell<T> {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
f.debug_struct("Cell").field("value", &self.get()).finish()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized + Debug> Debug for RefCell<T> {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
let mut d = f.debug_struct("RefCell");
|
||
match self.try_borrow() {
|
||
Ok(borrow) => d.field("value", &borrow),
|
||
Err(_) => d.field("value", &format_args!("<borrowed>")),
|
||
};
|
||
d.finish()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized + Debug> Debug for Ref<'_, T> {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
Debug::fmt(&**self, f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: ?Sized + Debug> Debug for RefMut<'_, T> {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
Debug::fmt(&*(self.deref()), f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "core_impl_debug", since = "1.9.0")]
|
||
impl<T: ?Sized> Debug for UnsafeCell<T> {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
f.debug_struct("UnsafeCell").finish_non_exhaustive()
|
||
}
|
||
}
|
||
|
||
#[unstable(feature = "sync_unsafe_cell", issue = "95439")]
|
||
impl<T: ?Sized> Debug for SyncUnsafeCell<T> {
|
||
fn fmt(&self, f: &mut Formatter<'_>) -> Result {
|
||
f.debug_struct("SyncUnsafeCell").finish_non_exhaustive()
|
||
}
|
||
}
|
||
|
||
// If you expected tests to be here, look instead at the core/tests/fmt.rs file,
|
||
// it's a lot easier than creating all of the rt::Piece structures here.
|
||
// There are also tests in the alloc crate, for those that need allocations.
|