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// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use std::fmt;
/// Contains the API configuration as prescribed by [ECMA 402][ecma].
///
/// [ecma]: https://www.ecma-international.org/publications/standards/Ecma-402.htm
///
/// The meaning of the options is the same as in the similarly named
/// options in the JS version.
///
/// See [Options] for the contents of the options. See the [RelativeTimeFormat::try_new]
/// for the use of the options.
pub mod options {
/// Whether to use numeric formatting in the display, like "1 day ago".
#[derive(Debug, Clone, PartialEq)]
pub enum Numeric {
/// Always use numeric formatting.
Always,
/// Allows not to use numeric formatting, and use "yesterday" instead of "1 day ago".
Auto,
}
/// The length of the internationalized message.
#[derive(Debug, Clone, PartialEq)]
pub enum Style {
/// Default, e.g. "in 1 month"
Long,
/// Short, e.g. "in 1 mo."
Short,
/// Short, e.g. "in 1 mo". The narrow style could be identical to [Style::Short] in some
/// locales.
Narrow,
}
}
/// The options set by the user at construction time.
///
/// Provides as a "bag of options" since we don't expect any
/// implementations to be attached to this struct.
pub struct Options {
pub numeric: options::Numeric,
pub style: options::Style,
}
impl Default for Options {
fn default() -> Self {
Options {
numeric: options::Numeric::Auto,
style: options::Style::Long,
}
}
}
pub trait RelativeTimeFormat {
/// The type of the error reported, if any.
type Error: std::error::Error;
/// Creates a new [RelativeTimeFormat].
///
/// Creation may fail if the locale-specific data is not loaded, or if the supplied options are
/// inconsistent.
fn try_new<L>(l: L, opts: Options) -> Result<Self, Self::Error>
where
L: crate::Locale,
Self: Sized;
/// Formats `days` into the supplied writer.
///
/// A positive value means days in the future. A negative value means days in the past.
///
/// The function implements [`Intl.RelativeDateFormat`][ref] from [ECMA 402][ecma].
///
/// [ref]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/RelativeTimeFormat
/// [ecma]: https://www.ecma-international.org/publications/standards/Ecma-402.htm
///
fn format<W>(&self, days: i32, writer: &mut W) -> fmt::Result
where
W: fmt::Write;
}