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//! BigFloatNumber formatting.
use crate::defs::Error;
use crate::defs::Radix;
use crate::defs::RoundingMode;
use crate::num::BigFloatNumber;
use crate::Consts;
use crate::Exponent;
use crate::Sign;
#[cfg(feature = "std")]
use std::fmt::Write;
#[cfg(not(feature = "std"))]
use {alloc::string::String, core::fmt::Write};
const DIGIT_CHARS: [char; 16] =
['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'];
impl BigFloatNumber {
/// Parses the number from the string `s` using radix `rdx`, precision `p`, and rounding mode `rm`.
/// Note, since hexadecimal digits include the character "e", the exponent part is separated
/// from the mantissa by "_".
/// For example, a number with mantissa `123abcdef` and exponent `123` would be formatted as `123abcdef_e+123`.
///
/// ## Errors
///
/// - InvalidArgument: failed to parse input or precision is incorrect.
/// - MemoryAllocation: failed to allocate memory for mantissa.
/// - ExponentOverflow: the resulting exponent becomes greater than the maximum allowed value for the exponent.
#[cfg(test)]
pub fn parse(
s: &str,
rdx: Radix,
p: usize,
rm: RoundingMode,
cc: &mut Consts,
) -> Result<Self, Error> {
let ps = crate::parser::parse(s, rdx)?;
if ps.is_nan() || ps.is_inf() {
Err(Error::InvalidArgument)
} else {
let (m, s, e) = ps.raw_parts();
BigFloatNumber::convert_from_radix(s, m, e, rdx, p, rm, cc)
}
}
/// Formats the number using radix `rdx` and rounding mode `rm`.
/// Note, since hexadecimal digits include the character "e", the exponent part is separated
/// from the mantissa by "_".
/// For example, a number with mantissa `123abcdef` and exponent `123` would be formatted as `123abcdef_e+123`.
///
/// ## Errors
///
/// - MemoryAllocation: failed to allocate memory for mantissa.
/// - ExponentOverflow: the resulting exponent becomes greater than the maximum allowed value for the exponent.
pub fn format(&self, rdx: Radix, rm: RoundingMode, cc: &mut Consts) -> Result<String, Error> {
let (s, m, e) = self.convert_to_radix(rdx, rm, cc)?;
let mut mstr = String::new();
let mstr_sz = 8
+ (self.mantissa_max_bit_len() + core::mem::size_of::<Exponent>() * 8)
/ match rdx {
Radix::Bin => 1,
Radix::Oct => 3,
Radix::Dec => 3,
Radix::Hex => 4,
};
mstr.try_reserve_exact(mstr_sz)?;
if s == Sign::Neg {
mstr.push('-');
}
if m.is_empty() {
mstr.push_str("0.0");
} else {
let mut iter = m.iter();
if self.is_subnormal() {
mstr.push('0');
} else {
mstr.push(DIGIT_CHARS[*iter.next().unwrap() as usize]); // m is not empty as checked above, hence unwrap
}
mstr.push('.');
iter.map(|&d| DIGIT_CHARS[d as usize])
.for_each(|v| mstr.push(v));
if rdx == Radix::Hex {
let _ = write!(mstr, "_");
}
if e < 1 {
let val = if self.is_subnormal() {
e.unsigned_abs() as usize
} else {
(e as isize - 1).unsigned_abs()
};
let _ = match rdx {
Radix::Bin => write!(mstr, "e-{:b}", val),
Radix::Oct => write!(mstr, "e-{:o}", val),
Radix::Dec => write!(mstr, "e-{}", val),
Radix::Hex => write!(mstr, "e-{:x}", val),
};
} else {
let _ = match rdx {
Radix::Bin => write!(mstr, "e+{:b}", e as isize - 1),
Radix::Oct => write!(mstr, "e+{:o}", e as isize - 1),
Radix::Dec => write!(mstr, "e+{}", e as isize - 1),
Radix::Hex => write!(mstr, "e+{:x}", e as isize - 1),
};
};
}
Ok(mstr)
}
}
#[cfg(test)]
mod tests {
use rand::random;
use crate::{
common::util::random_subnormal, Exponent, EXPONENT_MAX, EXPONENT_MIN, WORD_BIT_SIZE,
};
use super::*;
#[test]
fn test_strop() {
let mut eps = BigFloatNumber::from_word(1, 192).unwrap();
let mut cc = Consts::new().unwrap();
for i in 0..1000 {
let p1 = (random::<usize>() % 32 + 3) * WORD_BIT_SIZE;
let p2 = (random::<usize>() % 32 + 3) * WORD_BIT_SIZE;
let p = p1.min(p2);
let n = if i & 1 == 0 {
BigFloatNumber::random_normal(p1, EXPONENT_MIN + p as Exponent, EXPONENT_MAX)
.unwrap()
} else {
random_subnormal(p1)
};
for rdx in [Radix::Bin, Radix::Oct, Radix::Hex] {
let rm = match random::<u8>() % 7 {
0 => RoundingMode::ToEven,
1 => RoundingMode::Up,
2 => RoundingMode::Down,
3 => RoundingMode::FromZero,
4 => RoundingMode::ToZero,
5 => RoundingMode::ToOdd,
6 => RoundingMode::None,
_ => unreachable!(),
};
let s = n.format(rdx, rm, &mut cc).unwrap();
let d = BigFloatNumber::parse(&s, rdx, p2, rm, &mut cc).unwrap();
if p2 < p1 {
let mut x = n.clone().unwrap();
x.set_precision(p, rm).unwrap();
assert!(x.cmp(&d) == 0);
} else {
assert!(n.cmp(&d) == 0);
}
}
let s = n.format(Radix::Dec, RoundingMode::ToEven, &mut cc).unwrap();
let d =
BigFloatNumber::parse(&s, Radix::Dec, p2, RoundingMode::ToEven, &mut cc).unwrap();
if i & 1 == 0 {
eps.set_exponent(n.exponent() - p as Exponent + 4);
assert!(
d.sub(&n, p, RoundingMode::None)
.unwrap()
.abs()
.unwrap()
.cmp(&eps)
< 0
);
} else {
let mut eps2 = BigFloatNumber::min_positive(p).unwrap();
eps2.set_exponent(eps2.exponent() + 2);
assert!(
d.sub(&n, p, RoundingMode::None)
.unwrap()
.abs()
.unwrap()
.cmp(&eps2)
< 0
);
}
}
// MIN, MAX, min_positive
let p1 = (random::<usize>() % 32 + 1) * WORD_BIT_SIZE;
let p2 = (random::<usize>() % 32 + 1) * WORD_BIT_SIZE;
let p = p1.min(p2);
let rm = RoundingMode::None;
for rdx in [Radix::Bin, Radix::Oct, Radix::Dec, Radix::Hex] {
// min, max
// for p2 < p1 rounding will cause overflow, for p2 >= p1 no rounding is needed.
for mut n in
[BigFloatNumber::max_value(p1).unwrap(), BigFloatNumber::min_value(p1).unwrap()]
{
//println!("\n{:?} {} {}", rdx, p1, p2);
//println!("{:?}", n);
let s = n.format(rdx, rm, &mut cc).unwrap();
let mut g = BigFloatNumber::parse(&s, rdx, p2, rm, &mut cc).unwrap();
//println!("{:?}", g);
if rdx == Radix::Dec {
eps.set_exponent(n.exponent() - p as Exponent + 4); // 4, since rm is none
assert!(n.sub(&g, p, rm).unwrap().abs().unwrap().cmp(&eps) <= 0);
} else {
if p2 < p1 {
n.set_precision(p, rm).unwrap();
} else if p2 > p1 {
g.set_precision(p, rm).unwrap();
}
assert!(n.cmp(&g) == 0);
}
}
// min subnormal
let mut n = BigFloatNumber::min_positive(p1).unwrap();
let s = n.format(rdx, rm, &mut cc).unwrap();
let mut g = BigFloatNumber::parse(&s, rdx, p2, rm, &mut cc).unwrap();
if rdx == Radix::Dec {
let mut eps = BigFloatNumber::min_positive(p).unwrap();
eps.set_exponent(eps.exponent() + 2);
assert!(n.sub(&g, p, rm).unwrap().abs().unwrap().cmp(&eps) < 0);
} else {
if p2 < p1 {
n.set_precision(p, rm).unwrap();
} else if p2 > p1 {
g.set_precision(p, rm).unwrap();
}
assert!(n.cmp(&g) == 0);
}
}
}
}