firefox/servo/components/style/values/specified/time.rs

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

//! Specified time values.

use crate::parser::{Parse, ParserContext};
use crate::values::computed::time::Time as ComputedTime;
use crate::values::computed::{Context, ToComputedValue};
use crate::values::specified::calc::CalcNode;
use crate::values::CSSFloat;
use crate::Zero;
use cssparser::{Parser, Token};
use std::fmt::{self, Write};
use style_traits::values::specified::AllowedNumericType;
use style_traits::{CssWriter, ParseError, SpecifiedValueInfo, StyleParseErrorKind, ToCss};

/// A time value according to CSS-VALUES § 6.2.
#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToShmem)]
pub struct Time {
    seconds: CSSFloat,
    unit: TimeUnit,
    calc_clamping_mode: Option<AllowedNumericType>,
}

/// A time unit.
#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, PartialEq, ToShmem)]
pub enum TimeUnit {
    /// `s`
    Second,
    /// `ms`
    Millisecond,
}

impl Time {
    /// Returns a time value that represents `seconds` seconds.
    pub fn from_seconds_with_calc_clamping_mode(
        seconds: CSSFloat,
        calc_clamping_mode: Option<AllowedNumericType>,
    ) -> Self {
        Time {
            seconds,
            unit: TimeUnit::Second,
            calc_clamping_mode,
        }
    }

    /// Returns a time value that represents `seconds` seconds.
    pub fn from_seconds(seconds: CSSFloat) -> Self {
        Self::from_seconds_with_calc_clamping_mode(seconds, None)
    }

    /// Returns the time in fractional seconds.
    pub fn seconds(self) -> CSSFloat {
        self.seconds
    }

    /// Returns the unit of the time.
    #[inline]
    pub fn unit(&self) -> &'static str {
        match self.unit {
            TimeUnit::Second => "s",
            TimeUnit::Millisecond => "ms",
        }
    }

    #[inline]
    fn unitless_value(&self) -> CSSFloat {
        match self.unit {
            TimeUnit::Second => self.seconds,
            TimeUnit::Millisecond => self.seconds * 1000.,
        }
    }

    /// Parses a time according to CSS-VALUES § 6.2.
    pub fn parse_dimension(value: CSSFloat, unit: &str) -> Result<Time, ()> {
        let (seconds, unit) = match_ignore_ascii_case! { unit,
            "s" => (value, TimeUnit::Second),
            "ms" => (value / 1000.0, TimeUnit::Millisecond),
            _ => return Err(())
        };

        Ok(Time {
            seconds,
            unit,
            calc_clamping_mode: None,
        })
    }

    fn parse_with_clamping_mode<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
        clamping_mode: AllowedNumericType,
    ) -> Result<Self, ParseError<'i>> {
        use style_traits::ParsingMode;

        let location = input.current_source_location();
        match *input.next()? {
            // Note that we generally pass ParserContext to is_ok() to check
            // that the ParserMode of the ParserContext allows all numeric
            // values for SMIL regardless of clamping_mode, but in this Time
            // value case, the value does not animate for SMIL at all, so we use
            // ParsingMode::DEFAULT directly.
            Token::Dimension {
                value, ref unit, ..
            } if clamping_mode.is_ok(ParsingMode::DEFAULT, value) => {
                Time::parse_dimension(value, unit)
                    .map_err(|()| location.new_custom_error(StyleParseErrorKind::UnspecifiedError))
            },
            Token::Function(ref name) => {
                let function = CalcNode::math_function(context, name, location)?;
                CalcNode::parse_time(context, input, clamping_mode, function)
            },
            ref t => return Err(location.new_unexpected_token_error(t.clone())),
        }
    }

    /// Parses a non-negative time value.
    pub fn parse_non_negative<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
    ) -> Result<Self, ParseError<'i>> {
        Self::parse_with_clamping_mode(context, input, AllowedNumericType::NonNegative)
    }
}

impl Zero for Time {
    #[inline]
    fn zero() -> Self {
        Self::from_seconds(0.0)
    }

    #[inline]
    fn is_zero(&self) -> bool {
        // The unit doesn't matter, i.e. `s` and `ms` are the same for zero.
        self.seconds == 0.0 && self.calc_clamping_mode.is_none()
    }
}

impl ToComputedValue for Time {
    type ComputedValue = ComputedTime;

    fn to_computed_value(&self, _context: &Context) -> Self::ComputedValue {
        let seconds = self
            .calc_clamping_mode
            .map_or(self.seconds(), |mode| mode.clamp(self.seconds()));

        ComputedTime::from_seconds(crate::values::normalize(seconds))
    }

    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
        Time {
            seconds: computed.seconds(),
            unit: TimeUnit::Second,
            calc_clamping_mode: None,
        }
    }
}

impl Parse for Time {
    fn parse<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
    ) -> Result<Self, ParseError<'i>> {
        Self::parse_with_clamping_mode(context, input, AllowedNumericType::All)
    }
}

impl ToCss for Time {
    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
    where
        W: Write,
    {
        crate::values::serialize_specified_dimension(
            self.unitless_value(),
            self.unit(),
            self.calc_clamping_mode.is_some(),
            dest,
        )
    }
}

impl SpecifiedValueInfo for Time {}