// 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::any::Any;
use ::std::borrow::Cow;
use ::std::future::Future;
use ::std::io::Cursor;
use ::std::pin::Pin;
use crate::strcursor::{StringReader, ReadError};
use crate::suggestion::Suggestions;
use crate::suggestion::SuggestionsBuilder;
// FIXME delete when implemented
/// The parsing context of a command.
pub struct CommandContext<'i, S, E>(::std::marker::PhantomData<(&'i str, S, E)>);
/// 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 ::std::io::Cursor;
///
/// use ::iosonism::args::ArgumentType;
/// use ::iosonism::strcursor::{ReadError, StringReader};
///
/// struct BoolArgumentType;
///
/// impl<S, E> ArgumentType<S, E> for BoolArgumentType
/// where for<'i> E: ReadError<'i, Cursor<&'i str>>
/// {
/// type Result = bool;
/// fn parse<'i>(
/// &self,
/// reader: &mut Cursor<&'i str>,
/// ) -> Result<bool, E> where E: 'i {
/// reader.read_bool()
/// }
/// }
/// ```
pub trait ArgumentType<S, E> {
/// The parsed type of the argument.
type Result: Sized + 'static + Any;
/// Parses an argument of this type, returning the parsed argument.
fn parse<'i>(
&self,
reader: &mut Cursor<&'i str>,
) -> Result<Self::Result, E> where E: 'i;
/// Creates suggestions for this argument.
fn list_suggestions<'i>(
&self,
context: &CommandContext<'i, S, E>,
builder: SuggestionsBuilder<'i>,
) -> Pin<Box<dyn Future<Output=Suggestions> + Send + 'i>> {
let _ = context;
let _ = builder;
Suggestions::empty()
}
/// Returns examples for this argument.
fn get_examples(&self) -> Cow<'static, [&str]> {
Cow::Borrowed(&[])
}
}
/// Wrapper around `ArgumentType`, but with `Any`.
pub(crate) trait ArgumentTypeAny<S, E> {
/// Parses an argument of this type, returning the parsed argument.
fn parse<'i>(
&self,
reader: &mut Cursor<&'i str>,
) -> Result<Box<dyn Any>, E> where E: 'i;
/// Creates suggestions for this argument.
fn list_suggestions<'i>(
&self,
context: &CommandContext<'i, S, E>,
builder: SuggestionsBuilder<'i>,
) -> Pin<Box<dyn Future<Output=Suggestions> + Send + 'i>>;
/// Returns examples for this argument.
fn get_examples(&self) -> Cow<'static, [&str]>;
}
impl<T: ArgumentType<S, E>, S, E> ArgumentTypeAny<S, E> for T {
fn parse<'i>(
&self,
reader: &mut Cursor<&'i str>,
) -> Result<Box<dyn Any>, E> where E: 'i {
self.parse(reader).map(|x| Box::new(x) as _)
}
fn list_suggestions<'i>(
&self,
context: &CommandContext<'i, S, E>,
builder: SuggestionsBuilder<'i>,
) -> Pin<Box<dyn Future<Output=Suggestions> + Send + 'i>> {
self.list_suggestions(context, builder)
}
fn get_examples(&self) -> Cow<'static, [&str]> {
self.get_examples()
}
}
/// A boolean argument.
// FIXME add examples/expand docs
// FIXME add tests
pub struct BoolArgumentType;
/// An `ArgumentType` for `bool`.
impl<S, E> ArgumentType<S, E> for BoolArgumentType
where for<'i> E: ReadError<'i, Cursor<&'i str>>
{
/// A `BoolArgumentType` parses a `bool`.
type Result = bool;
/// Attempts to parse a `bool` from the `reader`.
fn parse<'i>(
&self,
reader: &mut Cursor<&'i str>,
) -> Result<bool, E> where E: 'i {
reader.read_bool()
}
/// Suggests completions for inputting a boolean argument.
fn list_suggestions<'i>(
&self,
context: &CommandContext<'i, S, E>,
mut builder: SuggestionsBuilder<'i>,
) -> Pin<Box<dyn Future<Output=Suggestions> + Send + 'i>> {
let _ = context;
if "true".starts_with(builder.get_remaining()) {
builder.suggest("true".into());
}
if "false".starts_with(builder.get_remaining()) {
builder.suggest("false".into());
}
builder.drain_build_future()
}
/// Returns examples
fn get_examples(&self) -> Cow<'static, [&str]> {
Cow::Borrowed(&["true", "false"])
}
}