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use std::num::ParseFloatError;
use ecow::{eco_format, EcoString};
use crate::diag::StrResult;
use crate::foundations::{
bail, cast, func, repr, scope, ty, Bytes, Decimal, Endianness, Repr, Str,
};
use crate::layout::Ratio;
/// A floating-point number.
///
/// A limited-precision representation of a real number. Typst uses 64 bits to
/// store floats. Wherever a float is expected, you can also pass an
/// [integer]($int).
///
/// You can convert a value to a float with this type's constructor.
///
/// NaN and positive infinity are available as `{float.nan}` and `{float.inf}`
/// respectively.
///
/// # Example
/// ```example
/// #3.14 \
/// #1e4 \
/// #(10 / 4)
/// ```
#[ty(scope, cast, name = "float")]
type f64;
#[scope]
impl f64 {
/// Positive infinity.
const INF: f64 = f64::INFINITY;
/// A NaN value, as defined by the
/// [IEEE 754 standard](https://en.wikipedia.org/wiki/IEEE_754).
const NAN: f64 = f64::NAN;
/// Converts a value to a float.
///
/// - Booleans are converted to `0.0` or `1.0`.
/// - Integers are converted to the closest 64-bit float. For integers with
/// absolute value less than `{calc.pow(2, 53)}`, this conversion is
/// exact.
/// - Ratios are divided by 100%.
/// - Strings are parsed in base 10 to the closest 64-bit float. Exponential
/// notation is supported.
///
/// ```example
/// #float(false) \
/// #float(true) \
/// #float(4) \
/// #float(40%) \
/// #float("2.7") \
/// #float("1e5")
/// ```
#[func(constructor)]
pub fn construct(
/// The value that should be converted to a float.
value: ToFloat,
) -> f64 {
value.0
}
/// Checks if a float is not a number.
///
/// In IEEE 754, more than one bit pattern represents a NaN. This function
/// returns `true` if the float is any of those bit patterns.
///
/// ```example
/// #float.is-nan(0) \
/// #float.is-nan(1) \
/// #float.is-nan(float.nan)
/// ```
#[func]
pub fn is_nan(self) -> bool {
f64::is_nan(self)
}
/// Checks if a float is infinite.
///
/// Floats can represent positive infinity and negative infinity. This
/// function returns `{true}` if the float is an infinity.
///
/// ```example
/// #float.is-infinite(0) \
/// #float.is-infinite(1) \
/// #float.is-infinite(float.inf)
/// ```
#[func]
pub fn is_infinite(self) -> bool {
f64::is_infinite(self)
}
/// Calculates the sign of a floating point number.
///
/// - If the number is positive (including `{+0.0}`), returns `{1.0}`.
/// - If the number is negative (including `{-0.0}`), returns `{-1.0}`.
/// - If the number is NaN, returns `{float.nan}`.
///
/// ```example
/// #(5.0).signum() \
/// #(-5.0).signum() \
/// #(0.0).signum() \
/// #float.nan.signum()
/// ```
#[func]
pub fn signum(self) -> f64 {
f64::signum(self)
}
/// Converts bytes to a float.
///
/// ```example
/// #float.from-bytes(bytes((0, 0, 0, 0, 0, 0, 240, 63))) \
/// #float.from-bytes(bytes((63, 240, 0, 0, 0, 0, 0, 0)), endian: "big")
/// ```
#[func]
pub fn from_bytes(
/// The bytes that should be converted to a float.
///
/// Must be of length exactly 8 so that the result fits into a 64-bit
/// float.
bytes: Bytes,
/// The endianness of the conversion.
#[named]
#[default(Endianness::Little)]
endian: Endianness,
) -> StrResult<f64> {
// Convert slice to an array of length 8.
let buf: [u8; 8] = match bytes.as_ref().try_into() {
Ok(buffer) => buffer,
Err(_) => bail!("bytes must have a length of exactly 8"),
};
Ok(match endian {
Endianness::Little => f64::from_le_bytes(buf),
Endianness::Big => f64::from_be_bytes(buf),
})
}
/// Converts a float to bytes.
///
/// ```example
/// #array(1.0.to-bytes(endian: "big")) \
/// #array(1.0.to-bytes())
/// ```
#[func]
pub fn to_bytes(
self,
/// The endianness of the conversion.
#[named]
#[default(Endianness::Little)]
endian: Endianness,
) -> Bytes {
match endian {
Endianness::Little => self.to_le_bytes(),
Endianness::Big => self.to_be_bytes(),
}
.as_slice()
.into()
}
}
impl Repr for f64 {
fn repr(&self) -> EcoString {
repr::format_float(*self, None, true, "")
}
}
/// A value that can be cast to a float.
pub struct ToFloat(f64);
cast! {
ToFloat,
v: f64 => Self(v),
v: bool => Self(v as i64 as f64),
v: i64 => Self(v as f64),
v: Decimal => Self(f64::try_from(v).map_err(|_| eco_format!("invalid float: {}", v))?),
v: Ratio => Self(v.get()),
v: Str => Self(
parse_float(v.clone().into())
.map_err(|_| eco_format!("invalid float: {}", v))?
),
}
fn parse_float(s: EcoString) -> Result<f64, ParseFloatError> {
s.replace(repr::MINUS_SIGN, "-").parse()
}