/// Abstracts over reading the current process environment variables as a

/// zero-cost abstraction to support threaded in-process testing.

use std::env;

use std::ffi::OsString;

use std::marker::PhantomData;

use enum_dispatch::enum_dispatch;

#[enum_dispatch]

pub trait ArgSource {

fn args(&self) -> Box<dyn Iterator<Item = String>>;

fn args_os(&self) -> Box<dyn Iterator<Item = OsString>>;

}

/// Implements ArgSource with `std::env::args`

impl ArgSource for super::OSProcess {

fn args(&self) -> Box<dyn Iterator<Item = String>> {

Box::new(env::args())

}

fn args_os(&self) -> Box<dyn Iterator<Item = OsString>> {

Box::new(env::args_os())

}

}

/// Helper for ArgSource over `Vec<String>`

pub(crate) struct VecArgs<T> {

v: Vec<String>,

i: usize,

_marker: PhantomData<T>,

}

impl<T> From<&Vec<String>> for VecArgs<T> {

fn from(source: &Vec<String>) -> Self {

let v = source.clone();

VecArgs {

v,

i: 0,

_marker: PhantomData,

}

}

}

impl<T: From<String>> Iterator for VecArgs<T> {

type Item = T;

fn next(&mut self) -> Option<T> {

if self.i == self.v.len() {

return None;

}

let i = self.i;

self.i += 1;

Some(T::from(self.v[i].clone()))

}

fn size_hint(&self) -> (usize, Option<usize>) {

(self.v.len(), Some(self.v.len()))

}

}

#[cfg(feature = "test")]

impl ArgSource for super::TestProcess {

fn args(&self) -> Box<dyn Iterator<Item = String>> {

Box::new(VecArgs::<String>::from(&self.args))

}

fn args_os(&self) -> Box<dyn Iterator<Item = OsString>> {

Box::new(VecArgs::<OsString>::from(&self.args))

}

}