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display.rs
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//! Implementation of fmt::Display for [GenericFraction] and [Sign] structures
//!
//! Complete support of the [std::fmt] formatting syntax with exceptions for alternate
//! integer types (hexadecimal, octal, binary)
//!
//! There are a couple of extensions on top of std::fmt, which are
//! - Alternate flag (`#`) is used to enable `trailing zeroes` output
//! - Negative sign (`-`) is used to suppress sign output (even negative)
//!
//! Otherwise, the standard formatting is followed as is.
//!
//! # Examples
//!
//! ```
//! use fraction::prelude::Fraction;
//!
//! let fraction = Fraction::from(1.75);
//!
//! assert_eq!("7/4", format!("{}", fraction));
//! assert_eq!("1.75", format!("{:.4}", fraction));
//! assert_eq!("1.7500", format!("{:#.4}", fraction));
//! assert_eq!("-1.75", format!("{:.2}", -fraction));
//! assert_eq!("1.75", format!("{:-.2}", -fraction));
//! ```
use division;
use fraction::{GenericFraction, Sign};
use generic::GenericInteger;
use std::fmt;
/// Same as fmt::Formatter, but allowing to change flags
/// so we can reuse it in recursive format implementations
pub struct Format {
flags: u8,
fill: char,
width: Option<usize>,
precision: Option<usize>,
align: Option<fmt::Alignment>,
}
const SIGN_PLUS: u8 = 1;
const SIGN_MINUS: u8 = 2;
const ALTERNATE: u8 = 4;
const SIGAZEPAD: u8 = 8;
impl Format {
pub const fn empty() -> Self {
Format {
fill: ' ',
align: None,
width: None,
precision: None,
flags: 0,
}
}
pub fn new(formatter: &fmt::Formatter) -> Self {
let sign_plus = if formatter.sign_plus() { SIGN_PLUS } else { 0 };
let sign_minus = if formatter.sign_minus() {
SIGN_MINUS
} else {
0
};
let alternate = if formatter.alternate() { ALTERNATE } else { 0 };
let sigazepad = if formatter.sign_aware_zero_pad() {
SIGAZEPAD
} else {
0
};
let flags = sign_plus | sign_minus | alternate | sigazepad;
Format {
fill: formatter.fill(),
align: formatter.align(),
width: formatter.width(),
precision: formatter.precision(),
flags,
}
}
pub const fn fill(&self) -> char {
self.fill
}
pub const fn cloned_align(&self) -> Option<fmt::Alignment> {
match self.align {
Some(ref align) => match *align {
fmt::Alignment::Left => Some(fmt::Alignment::Left),
fmt::Alignment::Right => Some(fmt::Alignment::Right),
fmt::Alignment::Center => Some(fmt::Alignment::Center),
},
None => None,
}
}
pub const fn align(&self) -> &Option<fmt::Alignment> {
&self.align
}
pub const fn set_align(mut self, align: Option<fmt::Alignment>) -> Self {
self.align = align;
self
}
pub const fn width(&self) -> &Option<usize> {
&self.width
}
pub const fn set_width(mut self, width: Option<usize>) -> Self {
self.width = width;
self
}
pub const fn precision(&self) -> &Option<usize> {
&self.precision
}
pub const fn set_precision(mut self, precision: Option<usize>) -> Self {
self.precision = precision;
self
}
pub const fn sign_plus(&self) -> bool {
self.flags & SIGN_PLUS > 0
}
pub const fn set_sign_plus(mut self, flag: bool) -> Self {
if flag {
self.flags |= SIGN_PLUS;
} else {
self.flags &= !SIGN_PLUS;
}
self
}
pub const fn sign_minus(&self) -> bool {
self.flags & SIGN_MINUS > 0
}
pub const fn set_sign_minus(mut self, flag: bool) -> Self {
if flag {
self.flags |= SIGN_MINUS;
} else {
self.flags &= !SIGN_MINUS;
}
self
}
pub const fn alternate(&self) -> bool {
self.flags & ALTERNATE > 0
}
pub const fn set_alternate(mut self, flag: bool) -> Self {
if flag {
self.flags |= ALTERNATE;
} else {
self.flags &= !ALTERNATE;
}
self
}
pub const fn sign_aware_zero_pad(&self) -> bool {
self.flags & SIGAZEPAD > 0
}
pub const fn set_sign_aware_zero_pad(mut self, flag: bool) -> Self {
if flag {
self.flags |= SIGAZEPAD;
} else {
self.flags &= !SIGAZEPAD;
}
self
}
}
impl Clone for Format {
fn clone(&self) -> Self {
Format {
fill: self.fill(),
align: self.cloned_align(),
width: *self.width(),
precision: *self.precision(),
flags: self.flags,
}
}
}
pub fn format_sign(sign: Sign, buffer: &mut dyn fmt::Write, format: &Format) -> fmt::Result {
if format.sign_plus() || (!format.sign_minus() && sign.is_negative()) {
if format.sign_aware_zero_pad() {
let format = format.clone().set_sign_aware_zero_pad(false);
format_value(
buffer,
&format,
None,
|_| 1,
|b, _| {
b.write_char(sign.into())?;
Ok(1)
},
)
} else {
format_value(
buffer,
format,
None,
|_| 1,
|b, _| {
b.write_char(sign.into())?;
Ok(1)
},
)
}
} else {
Ok(())
}
}
pub fn format_fraction<T>(
fraction: &GenericFraction<T>,
buffer: &mut dyn fmt::Write,
format: &Format,
) -> fmt::Result
where
T: Clone + GenericInteger,
{
match *fraction {
GenericFraction::NaN => format_value(
buffer,
format,
None,
|_| 3,
|b, _| {
b.write_str("NaN")?;
Ok(3)
},
),
GenericFraction::Infinity(sign) => format_value(
buffer,
format,
Some(sign),
|_| 3,
|b, _| {
b.write_str("inf")?;
Ok(3)
},
),
GenericFraction::Rational(sign, ref ratio) => format_value(
buffer,
format,
Some(sign),
|format| {
let numer = ratio.numer().clone();
let denom = ratio.denom().clone();
let mut length = 0;
if let Some(precision) = format.precision() {
division::divide_to_callback(
numer,
denom,
*precision,
format.alternate(),
|_| {
length += 1;
Ok(true)
},
)
.ok();
} else {
division::divide_to_callback(numer, T::one(), 0, false, |_| {
length += 1;
Ok(true)
})
.ok();
if !ratio.numer().is_zero() && !ratio.denom().is_one() {
length += 1;
division::divide_to_callback(denom, T::one(), 0, false, |_| {
length += 1;
Ok(true)
})
.ok();
}
}
length
},
|buffer, format| {
let numer = ratio.numer().clone();
let denom = ratio.denom().clone();
let mut length = 0;
if let Some(precision) = format.precision() {
let callback = |digit| {
length += 1;
division::write_digit(buffer, digit)
};
if division::divide_to_callback(
numer,
denom,
*precision,
format.alternate(),
callback,
)
.is_err()
{
return Err(fmt::Error);
}
} else {
let callback = |digit| {
length += 1;
division::write_digit(buffer, digit)
};
if division::divide_to_callback(numer, T::one(), 0, false, callback).is_err() {
return Err(fmt::Error);
}
if !ratio.numer().is_zero() && !ratio.denom().is_one() {
length += 1;
buffer.write_char('/')?;
let callback = |digit| {
length += 1;
division::write_digit(buffer, digit)
};
if division::divide_to_callback(denom, T::one(), 0, false, callback)
.is_err()
{
return Err(fmt::Error);
};
}
}
Ok(length)
},
),
}
}
fn format_value<L, V>(
buffer: &mut dyn fmt::Write,
format: &Format,
sign: Option<Sign>,
value_length: L,
value: V,
) -> fmt::Result
where
L: Fn(&Format) -> usize,
V: FnOnce(&mut dyn fmt::Write, &Format) -> Result<usize, fmt::Error>,
{
if let Some(width) = format.width() {
let width = *width;
let sign_len = if let Some(sign) = sign {
usize::from(format.sign_plus() || (!format.sign_minus() && sign.is_negative()))
} else {
0
};
if format.sign_aware_zero_pad() {
let value_len = value_length(format);
if sign_len > 0 {
buffer.write_char(sign.unwrap().into())?;
}
if width > sign_len + value_len {
for _ in sign_len + value_len..width {
buffer.write_char('0')?;
}
}
value(buffer, format)?;
} else {
match format.align() {
Some(fmt::Alignment::Center) => {
let value_len = value_length(format) + sign_len;
let mut prefix_len = 0;
let mut excess = 0;
if width > value_len {
excess = width - value_len;
prefix_len = excess / 2;
for _ in 0..prefix_len {
buffer.write_char(format.fill())?;
}
};
if sign_len > 0 {
buffer.write_char(sign.unwrap().into())?;
}
value(buffer, format)?;
if width > value_len {
for _ in 0..excess - prefix_len {
buffer.write_char(format.fill())?;
}
}
}
None | Some(fmt::Alignment::Right) => {
let value_len = value_length(format);
for _ in sign_len + value_len..width {
buffer.write_char(format.fill())?;
}
if sign_len > 0 {
buffer.write_char(sign.unwrap().into())?;
}
value(buffer, format)?;
}
Some(fmt::Alignment::Left) => {
if sign_len > 0 {
buffer.write_char(sign.unwrap().into())?;
}
let value_len = value(buffer, format)?;
if width > sign_len + value_len {
for _ in sign_len + value_len..width {
buffer.write_char(format.fill())?;
}
}
}
}
}
} else {
if let Some(sign) = sign {
if format.sign_plus() || (!format.sign_minus() && sign.is_negative()) {
buffer.write_char(sign.into())?;
}
}
value(buffer, format)?;
}
Ok(())
}
#[cfg(test)]
mod tests {
#[cfg(feature = "with-bigint")]
use prelude::{BigFraction, BigUint};
use super::super::super::{One, Zero};
use prelude::GenericFraction;
type F32 = GenericFraction<i32>;
type F64 = GenericFraction<u64>;
#[test]
fn display() {
assert_eq!("NaN", format!("{}", F32::nan()));
assert_eq!(format!("{}", ::std::f64::NAN), format!("{}", F32::nan()));
assert_eq!("NaN", format!("{:+}", F32::nan()));
assert_eq!(
format!("{:+}", ::std::f64::NAN),
format!("{:+}", F32::nan())
);
assert_eq!("==NaN==", format!("{:=^7}", F32::nan()));
assert_eq!("=NaN==", format!("{:=^6}", F32::nan()));
assert_eq!("NaN====", format!("{:=<7}", F32::nan()));
assert_eq!("====NaN", format!("{:=>7}", F32::nan()));
assert_eq!("0000NaN", format!("{:=>07}", F32::nan()));
assert_eq!("0000NaN", format!("{:07}", F32::nan()));
assert_eq!("0000NaN", format!("{:+07}", F32::nan()));
assert_eq!("inf", format!("{}", F32::infinity()));
assert_eq!(
format!("{}", ::std::f64::INFINITY),
format!("{}", F32::infinity())
);
assert_eq!("==inf==", format!("{:=^7}", F32::infinity()));
assert_eq!("inf====", format!("{:=<7}", F32::infinity()));
assert_eq!("====inf", format!("{:=>7}", F32::infinity()));
assert_eq!("0000inf", format!("{:=<07}", F32::infinity()));
assert_eq!("+000inf", format!("{:=<+07}", F32::infinity()));
assert_eq!("+inf", format!("{:+}", F32::infinity()));
assert_eq!(
format!("{:+}", ::std::f64::INFINITY),
format!("{:+}", F32::infinity())
);
assert_eq!("=+inf==", format!("{:=^+7}", F32::infinity()));
assert_eq!("-inf", format!("{}", F32::neg_infinity()));
assert_eq!(
format!("{}", ::std::f64::NEG_INFINITY),
format!("{}", F32::neg_infinity())
);
assert_eq!("=-inf==", format!("{:=^7}", F32::neg_infinity()));
assert_eq!("-inf", format!("{:+}", F32::neg_infinity()));
assert_eq!(
format!("{:+}", ::std::f64::NEG_INFINITY),
format!("{:+}", F32::neg_infinity())
);
assert_eq!("=-inf==", format!("{:=^+7}", F32::neg_infinity()));
// zero
assert_eq!("0", format!("{}", F32::zero()));
assert_eq!(format!("{}", 0.0f64), format!("{}", F32::zero()));
assert_eq!("+0", format!("{:+}", F32::zero()));
assert_eq!(format!("{:+}", 0.0f64), format!("{:+}", F32::zero()));
assert_eq!("0", format!("{:.2}", F32::zero()));
assert_eq!("+0", format!("{:+.2}", F32::zero()));
assert_eq!("0", format!("{:-.2}", F32::zero()));
assert_eq!("0.00", format!("{:#.2}", F32::zero()));
assert_eq!("+0.00", format!("{:+#.2}", F32::zero()));
assert_eq!("0.00", format!("{:-#.2}", F32::zero()));
// neg zero
assert_eq!("-0", format!("{}", F32::neg_zero()));
assert_eq!("-0", format!("{:+}", F32::neg_zero()));
assert_eq!("0", format!("{:-}", F32::neg_zero()));
assert_eq!("-0", format!("{:.2}", F32::neg_zero()));
assert_eq!("-0", format!("{:+.2}", F32::neg_zero()));
assert_eq!("0", format!("{:-.2}", F32::neg_zero()));
// positive whole
assert_eq!("1", format!("{}", F32::one()));
assert_eq!("+1", format!("{:+}", F32::one()));
assert_eq!("1", format!("{:-}", F32::one()));
assert_eq!("0001", format!("{:04}", F32::one()));
assert_eq!("+001", format!("{:+04}", F32::one()));
assert_eq!("=1==", format!("{:=^4}", F32::one()));
assert_eq!("===1", format!("{:=>4}", F32::one()));
assert_eq!("1===", format!("{:=<4}", F32::one()));
assert_eq!("=+1=", format!("{:=^+4}", F32::one()));
// negative whole
assert_eq!("-1", format!("{}", -F32::one()));
assert_eq!("-1", format!("{:+}", -F32::one()));
assert_eq!("1", format!("{:-}", -F32::one()));
assert_eq!("=-1=", format!("{:=^4}", -F32::one()));
assert_eq!("=1==", format!("{:=^-4}", -F32::one()));
assert_eq!("=-1=", format!("{:=^+4}", -F32::one()));
// positive fraction
assert_eq!("00.5", format!("{:04.1}", F32::new(1, 2)));
assert_eq!("+0.5", format!("{:+04.1}", F32::new(1, 2)));
assert_eq!("00.5", format!("{:-04.1}", F32::new(1, 2)));
assert_eq!("0.5", format!("{:.16}", F32::new(1, 2)));
assert_eq!("+0.5", format!("{:+.16}", F32::new(1, 2)));
assert_eq!("+1.75", format!("{:=^+.4}", F32::new(7, 4)));
assert_eq!("=+1.75==", format!("{:=^+8.4}", F32::new(7, 4)));
assert_eq!(" +1.75", format!("{:+8.4}", F32::new(7, 4)));
assert_eq!(" +1.75", format!("{:>+8.4}", F32::new(7, 4)));
assert_eq!("+1.75 ", format!("{:<+8.4}", F32::new(7, 4)));
assert_eq!("+0001.75", format!("{:<+08.4}", F32::new(7, 4)));
// negative fraction
assert_eq!("-00.5", format!("{:05.2}", -F32::new(1, 2)));
assert_eq!("-00.5", format!("{:05.2}", -F32::new(1, 2)));
assert_eq!("-00.5", format!("{:+05.2}", -F32::new(1, 2)));
assert_eq!("000.5", format!("{:-05.2}", -F32::new(1, 2)));
assert_eq!("-0.5", format!("{:.16}", -F32::new(1, 2)));
assert_eq!("0.5", format!("{:-.16}", -F32::new(1, 2)));
assert_eq!("-0.5", format!("{:+.16}", -F32::new(1, 2)));
assert_eq!("-1.75", format!("{:=^+.4}", -F32::new(7, 4)));
assert_eq!("=-1.75==", format!("{:=^+8.4}", -F32::new(7, 4)));
assert_eq!(" -1.75", format!("{:+8.4}", -F32::new(7, 4)));
assert_eq!(" -1.75", format!("{:>+8.4}", -F32::new(7, 4)));
assert_eq!("-1.75 ", format!("{:<+8.4}", -F32::new(7, 4)));
assert_eq!("-0001.75", format!("{:<+08.4}", -F32::new(7, 4)));
assert_eq!("-1.75", format!("{:=^.4}", -F32::new(7, 4)));
assert_eq!("=-1.75==", format!("{:=^8.4}", -F32::new(7, 4)));
assert_eq!(" -1.75", format!("{:8.4}", -F32::new(7, 4)));
assert_eq!(" -1.75", format!("{:>8.4}", -F32::new(7, 4)));
assert_eq!("-1.75 ", format!("{:<8.4}", -F32::new(7, 4)));
assert_eq!("-0001.75", format!("{:<08.4}", -F32::new(7, 4)));
assert_eq!("-01.7500", format!("{:<#08.4}", -F32::new(7, 4)));
assert_eq!("1.75", format!("{:=^-.4}", -F32::new(7, 4)));
assert_eq!("==1.75==", format!("{:=^-8.4}", -F32::new(7, 4)));
assert_eq!(" 1.75", format!("{:-8.4}", -F32::new(7, 4)));
assert_eq!(" 1.75", format!("{:>-8.4}", -F32::new(7, 4)));
assert_eq!("1.75 ", format!("{:<-8.4}", -F32::new(7, 4)));
assert_eq!("00001.75", format!("{:<-08.4}", -F32::new(7, 4)));
// ratios
assert_eq!("7/4", format!("{}", F32::new(7, 4)));
assert_eq!("7/4", format!("{:-}", F32::new(7, 4)));
assert_eq!("+7/4", format!("{:+}", F32::new(7, 4)));
assert_eq!("-7/4", format!("{}", -F32::new(7, 4)));
assert_eq!("7/4", format!("{:-}", -F32::new(7, 4)));
assert_eq!("-7/4", format!("{:+}", -F32::new(7, 4)));
assert_eq!("07/4", format!("{:04}", F32::new(7, 4)));
assert_eq!("-7/4", format!("{:+04}", -F32::new(7, 4)));
assert_eq!("==7/4==", format!("{:=^7}", F32::new(7, 4)));
assert_eq!("=-7/4==", format!("{:=^7}", -F32::new(7, 4)));
assert_eq!(" 7/4", format!("{:7}", F32::new(7, 4)));
assert_eq!("7/4 ", format!("{:<7}", F32::new(7, 4)));
assert_eq!("-7/4 ", format!("{:<7}", -F32::new(7, 4)));
assert_eq!("+7/4 ", format!("{:<+7}", F32::new(7, 4)));
assert_eq!("+0007/4", format!("{:<+07}", F32::new(7, 4)));
// former format_as_decimal tests
assert_eq!("NaN", format!("{:.64}", F32::from(::std::f32::NAN)));
assert_eq!("inf", format!("{:.64}", F32::from(::std::f32::INFINITY)));
assert_eq!(
"-inf",
format!("{:.64}", F32::from(::std::f32::NEG_INFINITY))
);
assert_eq!("0.75", format!("{:.64}", F32::from(0.75)));
assert_eq!("-0.75", format!("{:.64}", F32::from(-0.75)));
assert_eq!("0.33", format!("{:.64}", F32::from((33, 100))));
assert_eq!(
"0.0000000456",
format!("{:.64}", F64::new(456u64, 10000000000u64))
);
#[cfg(feature = "with-bigint")]
{
let fra = BigFraction::new(
BigUint::from(42u8),
BigUint::from(1000000000000000u64)
* BigUint::from(1000000000000000u64)
* BigUint::from(1000000000000000u64),
);
assert_eq!(
"0.000000000000000000000000000000000000000000042",
format!("{:.64}", fra)
);
}
}
}