// Copyright (c) 2021 Soni L.
// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license.
// Documentation and comments licensed under CC BY-SA 4.0.
//! Argument processing.
use ::std::future::Future;
use ::std::pin::Pin;
use crate::strcursor::StringReader;
use crate::suggestion::Suggestions;
use crate::suggestion::SuggestionsBuilder;
// FIXME delete when implemented
pub struct CommandContext<'a, T>(::std::marker::PhantomData<(&'a str, T)>);
/// An argument parser.
///
/// # Type params
///
/// - `'i`: Lifetime of the input.
/// - `R`: The reader accepted by this argument type.
/// - `S`: The source type accepted by this argument type.
/// - `E`: The error type accepted by this argument type.
///
/// # Examples
///
/// A very basic `bool` argument type:
///
/// ```
/// use ::iosonism::args::ArgumentType;
/// use ::iosonism::strcursor::{ReadError, StringReader};
///
/// struct BoolArgumentType;
///
/// impl<'i, R, S, E> ArgumentType<'i, R, S, E> for BoolArgumentType
/// where R: StringReader<'i>, E: ReadError<'i, R> {
/// type Result = bool;
/// fn parse(&self, reader: &mut R) -> Result<bool, E> {
/// reader.read_bool()
/// }
/// }
/// ```
pub trait ArgumentType<'i, T: StringReader<'i>, S, E> {
/// The parsed type of the argument.
type Result: Sized + 'static + ::std::any::Any;
/// Parses an argument of this type, returning the parsed argument.
fn parse(&self, reader: &mut T) -> Result<Self::Result, E>;
/// Creates suggestions for this argument.
// The hope here is that S is lightweight enough for one to clone into the
// closure. Unfortunately making it borrowable would be a pain.
// FIXME: this API doesn't look great, can we make it better somehow?
fn list_suggestions(
&self,
context: &CommandContext<'i, S>,
builder: SuggestionsBuilder<'i>,
) -> Pin<Box<dyn Future<Output=Suggestions> + Send + 'i>> {
let _ = context;
let _ = builder;
todo!()
}
/// Returns examples for this argument.
fn get_examples(&self) -> Vec<&str> {
Vec::new()
}
}