bun_css 0.1.0

A Rust-native programmable browser runtime built on Servo and SpiderMonkey
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use crate::css_parser as css;
use crate::css_parser::{
    CssResult as Result, Maybe, Parser, ParserError, PrintErr, Printer, Token,
};
use crate::values::calc::Calc;
use crate::values::number::{CSSNumber, CSSNumberFns};
use crate::values::percentage::DimensionPercentage;

use core::cmp::Ordering;

const TAG_DEG: u8 = 1;
const TAG_RAD: u8 = 2;
const TAG_GRAD: u8 = 4;
const TAG_TURN: u8 = 8;

/// A CSS [`<angle>`](https://www.w3.org/TR/css-values-4/#angles) value.
///
/// Angles may be explicit or computed by `calc()`, but are always stored and serialized
/// as their computed value.
#[repr(u8)]
#[derive(Clone, Copy, PartialEq, crate::generics::CssHash, crate::generics::DeepClone)]
pub enum Angle {
    /// An angle in degrees. There are 360 degrees in a full circle.
    Deg(CSSNumber) = TAG_DEG,
    /// An angle in radians. There are 2π radians in a full circle.
    Rad(CSSNumber) = TAG_RAD,
    /// An angle in gradians. There are 400 gradians in a full circle.
    Grad(CSSNumber) = TAG_GRAD,
    /// An angle in turns. There is 1 turn in a full circle.
    Turn(CSSNumber) = TAG_TURN,
}

impl Angle {
    // ~toCssImpl

    pub(crate) fn parse(input: &mut Parser) -> Result<Angle> {
        Angle::parse_internal(input, false)
    }

    fn parse_internal(input: &mut Parser, allow_unitless_zero: bool) -> Result<Angle> {
        if let Ok(calc_value) = input.try_parse(Calc::<Angle>::parse) {
            if let Calc::Value(value) = calc_value {
                return Ok(*value);
            }
            // Angles are always compatible, so they will always compute to a value.
            return Err(input.new_custom_error(ParserError::invalid_value));
        }

        let location = input.current_source_location();
        let token = input.next()?.clone();
        match &token {
            Token::Dimension(dim) => {
                let value = dim.num.value;
                let unit = dim.unit;
                return crate::match_ignore_ascii_case! { unit, {
                    b"deg" => Ok(Angle::Deg(value)),
                    b"grad" => Ok(Angle::Grad(value)),
                    b"turn" => Ok(Angle::Turn(value)),
                    b"rad" => Ok(Angle::Rad(value)),
                    _ => Err(location.new_unexpected_token_error(token)),
                }};
            }
            Token::Number(num) => {
                if num.value == 0.0 && allow_unitless_zero {
                    return Ok(Angle::zero());
                }
            }
            _ => {}
        }
        Err(location.new_unexpected_token_error(token))
    }

    pub(crate) fn parse_with_unitless_zero(input: &mut Parser) -> Result<Angle> {
        Angle::parse_internal(input, true)
    }

    pub(crate) fn to_css(self, dest: &mut Printer) -> core::result::Result<(), PrintErr> {
        let (value, unit): (f32, &'static str) = match self {
            Angle::Deg(val) => (val, "deg"),
            Angle::Grad(val) => (val, "grad"),
            Angle::Rad(val) => 'brk: {
                let deg = self.to_degrees();

                // We print 5 digits of precision by default.
                // Switch to degrees if length is smaller than rad.
                if css::f32_length_with_5_digits(deg) < css::f32_length_with_5_digits(val) {
                    break 'brk (deg, "deg");
                } else {
                    break 'brk (val, "rad");
                }
            }
            Angle::Turn(val) => (val, "turn"),
        };
        css::serializer::serialize_dimension(value, unit.as_bytes(), dest)
    }

    pub(crate) fn to_css_with_unitless_zero(
        self,
        dest: &mut Printer,
    ) -> core::result::Result<(), PrintErr> {
        if self.is_zero() {
            let v: f32 = 0.0;
            CSSNumberFns::to_css(v, dest)
        } else {
            self.to_css(dest)
        }
    }

    pub(crate) fn try_from_token(token: &Token) -> Maybe<Angle, ()> {
        if let Token::Dimension(dimension) = token {
            let value = dimension.num.value;
            let unit = dimension.unit;
            return crate::match_ignore_ascii_case! { unit, {
                b"deg" => Ok(Angle::Deg(value)),
                b"grad" => Ok(Angle::Grad(value)),
                b"turn" => Ok(Angle::Turn(value)),
                b"rad" => Ok(Angle::Rad(value)),
                _ => Err(()),
            }};
        }
        Err(())
    }

    /// Returns the angle in radians.
    pub(crate) fn to_radians(self) -> CSSNumber {
        const RAD_PER_DEG: f32 = core::f32::consts::PI / 180.0;
        match self {
            Angle::Deg(deg) => deg * RAD_PER_DEG,
            Angle::Rad(rad) => rad,
            Angle::Grad(grad) => grad * 180.0 / 200.0 * RAD_PER_DEG,
            Angle::Turn(turn) => turn * 360.0 * RAD_PER_DEG,
        }
    }

    /// Returns the angle in degrees.
    pub(crate) fn to_degrees(self) -> CSSNumber {
        const DEG_PER_RAD: f32 = 180.0 / core::f32::consts::PI;
        match self {
            Angle::Deg(deg) => deg,
            Angle::Rad(rad) => rad * DEG_PER_RAD,
            Angle::Grad(grad) => grad * 180.0 / 200.0,
            Angle::Turn(turn) => turn * 360.0,
        }
    }

    pub(crate) fn zero() -> Angle {
        Angle::Deg(0.0)
    }

    pub(crate) fn is_zero(self) -> bool {
        let v = match self {
            Angle::Deg(deg) => deg,
            Angle::Rad(rad) => rad,
            Angle::Grad(grad) => grad,
            Angle::Turn(turn) => turn,
        };
        v == 0.0
    }

    pub(crate) fn map(self, opfn: impl Fn(f32) -> f32) -> Angle {
        match self {
            Angle::Deg(deg) => Angle::Deg(opfn(deg)),
            Angle::Rad(rad) => Angle::Rad(opfn(rad)),
            Angle::Grad(grad) => Angle::Grad(opfn(grad)),
            Angle::Turn(turn) => Angle::Turn(opfn(turn)),
        }
    }

    pub(crate) fn add_internal(self, other: Angle) -> Angle {
        self.add(other)
    }

    pub(crate) fn add(self, rhs: Angle) -> Angle {
        Angle::op(self, rhs, (), |_: (), a: f32, b: f32| a + b)
    }

    pub(crate) fn try_add(self, rhs: Angle) -> Option<Angle> {
        Some(Angle::Deg(self.to_degrees() + rhs.to_degrees()))
    }

    pub(crate) fn eql(self, rhs: Angle) -> bool {
        self.to_degrees() == rhs.to_degrees()
    }

    pub(crate) fn mul_f32(self, other: f32) -> Angle {
        // return Angle.op(&this, &other, Angle.mulF32);
        match self {
            Angle::Deg(v) => Angle::Deg(v * other),
            Angle::Rad(v) => Angle::Rad(v * other),
            Angle::Grad(v) => Angle::Grad(v * other),
            Angle::Turn(v) => Angle::Turn(v * other),
        }
    }

    pub(crate) fn partial_cmp(self, other: Angle) -> Option<Ordering> {
        crate::generic::partial_cmp_f32(self.to_degrees(), other.to_degrees())
    }

    pub(crate) fn op<C>(self, other: Angle, ctx: C, op_fn: fn(C, f32, f32) -> f32) -> Angle {
        // PERF: not sure if this is faster
        // PORT NOTE: reshaped for borrowck — Zig used packed-tag bit-twiddling switch; Rust match on (tag, tag) is equivalent.
        match (self, other) {
            (Angle::Deg(a), Angle::Deg(b)) => Angle::Deg(op_fn(ctx, a, b)),
            (Angle::Rad(a), Angle::Rad(b)) => Angle::Rad(op_fn(ctx, a, b)),
            (Angle::Grad(a), Angle::Grad(b)) => Angle::Grad(op_fn(ctx, a, b)),
            (Angle::Turn(a), Angle::Turn(b)) => Angle::Turn(op_fn(ctx, a, b)),
            _ => Angle::Deg(op_fn(ctx, self.to_degrees(), other.to_degrees())),
        }
        // PERF(port): was comptime monomorphization (fn-ptr arg) — profile if it shows up on a hot path.
    }

    pub(crate) fn sign(self) -> f32 {
        match self {
            Angle::Deg(v) | Angle::Rad(v) | Angle::Grad(v) | Angle::Turn(v) => {
                CSSNumberFns::sign(v)
            }
        }
    }

    // css.implementHash / css.implementDeepClone — provided by
    // `#[derive(CssHash, DeepClone)]` above (POD f32 payload → bitwise).
}

impl crate::generics::CssEql for Angle {
    #[inline]
    fn eql(&self, other: &Self) -> bool {
        // Spec angle.zig:200-202 — `lhs.toDegrees() == rhs.toDegrees()`.
        // NOT structural variant comparison: Deg(180) eql Rad(PI) eql Turn(0.5).
        self.to_degrees() == other.to_degrees()
    }
}

/// A CSS [`<angle-percentage>`](https://www.w3.org/TR/css-values-4/#typedef-angle-percentage) value.
/// May be specified as either an angle or a percentage that resolves to an angle.
pub(crate) type AnglePercentage = DimensionPercentage<Angle>;

// ported from: src/css/values/angle.zig