Struct kvarn::prelude::Formatter

1.0.0 · source ·
pub struct Formatter<'a> { /* private fields */ }
Expand description

Configuration for formatting.

A Formatter represents various options related to formatting. Users do not construct Formatters 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.

Implementations§

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impl<'a> Formatter<'a>

1.0.0 · source

pub fn pad_integral( &mut self, is_nonnegative: bool, prefix: &str, buf: &str ) -> Result<(), Error>

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");
1.0.0 · source

pub fn pad(&mut self, s: &str) -> Result<(), Error>

This function 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");
1.0.0 · source

pub fn write_str(&mut self, data: &str) -> Result<(), Error>

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");
1.0.0 · source

pub fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>

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");
1.0.0 · source

pub fn flags(&self) -> u32

👎Deprecated since 1.24.0: use the sign_plus, sign_minus, alternate, or sign_aware_zero_pad methods instead

Flags for formatting

1.5.0 · source

pub fn fill(&self) -> char

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");
1.28.0 · source

pub fn align(&self) -> Option<Alignment>

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");
1.5.0 · source

pub fn width(&self) -> Option<usize>

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)");
1.5.0 · source

pub fn precision(&self) -> Option<usize>

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)");
1.5.0 · source

pub fn sign_plus(&self) -> bool

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)");
1.5.0 · source

pub fn sign_minus(&self) -> bool

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)");
1.5.0 · source

pub fn alternate(&self) -> bool

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");
1.5.0 · source

pub fn sign_aware_zero_pad(&self) -> bool

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");
1.2.0 · source

pub fn debug_struct<'b>(&'b mut self, name: &str) -> DebugStruct<'b, 'a>

Creates a DebugStruct builder designed to assist with creation of fmt::Debug implementations for structs.

§Examples
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),
    })
);
1.2.0 · source

pub fn debug_tuple<'b>(&'b mut self, name: &str) -> DebugTuple<'b, 'a>

Creates a DebugTuple builder designed to assist with creation of fmt::Debug implementations for tuple structs.

§Examples
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>))
);
1.2.0 · source

pub fn debug_list<'b>(&'b mut self) -> DebugList<'b, 'a>

Creates a DebugList builder designed to assist with creation of fmt::Debug implementations for list-like structures.

§Examples
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]");
1.2.0 · source

pub fn debug_set<'b>(&'b mut self) -> DebugSet<'b, 'a>

Creates a DebugSet builder designed to assist with creation of fmt::Debug implementations for set-like structures.

§Examples
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}");

In this more complex example, we use format_args! and .debug_set() to build a list of match arms:

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()
    }
}
1.2.0 · source

pub fn debug_map<'b>(&'b mut self) -> DebugMap<'b, 'a>

Creates a DebugMap builder designed to assist with creation of fmt::Debug implementations for map-like structures.

§Examples
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}"#
 );

Trait Implementations§

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impl FormatterExt for Formatter<'_>

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fn pad_with_width( &mut self, args_width: usize, args: Arguments<'_> ) -> Result<(), Error>

Writes the given arguments to the formatter, padding them with the given width. If width is incorrect, the resulting output will not be the requested width.
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impl From<&Formatter<'_>> for FormatterOptions

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fn from(value: &Formatter<'_>) -> FormatterOptions

Converts to this type from the input type.
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impl From<&mut Formatter<'_>> for FormatterOptions

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fn from(value: &mut Formatter<'_>) -> FormatterOptions

Converts to this type from the input type.
1.2.0 · source§

impl Write for Formatter<'_>

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fn write_str(&mut self, s: &str) -> Result<(), Error>

Writes a string slice into this writer, returning whether the write succeeded. Read more
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fn write_char(&mut self, c: char) -> Result<(), Error>

Writes a char into this writer, returning whether the write succeeded. Read more
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fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

Glue for usage of the write! macro with implementors of this trait. Read more

Auto Trait Implementations§

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impl<'a> Freeze for Formatter<'a>

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impl<'a> !RefUnwindSafe for Formatter<'a>

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impl<'a> !Send for Formatter<'a>

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impl<'a> !Sync for Formatter<'a>

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impl<'a> Unpin for Formatter<'a>

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impl<'a> !UnwindSafe for Formatter<'a>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided [Span], returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> Pointable for T

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const ALIGN: usize = _

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> Same for T

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type Output = T

Should always be Self
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a [WithDispatch] wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a [WithDispatch] wrapper. Read more