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use std::{fs::File, io, process::Stdio, sync::Arc};
/// Describes where to direct a command's stdout or stderr.
///
/// Used both for external-process stdio wiring and for Nushell's internal
/// pipeline destination (print vs pipe vs collect-to-value, etc.).
#[derive(Debug, Clone)]
pub enum OutDest {
/// Redirect the stdout and/or stderr of one command as the input for the next command in the pipeline.
///
/// The output pipe will be available as the `stdout` of [`ChildProcess`](crate::process::ChildProcess).
///
/// If stdout and stderr are both set to `Pipe`,
/// then they will combined into the `stdout` of [`ChildProcess`](crate::process::ChildProcess).
Pipe,
/// Redirect the stdout and/or stderr of one command as the input for the next command in the pipeline.
///
/// The output stream(s) will be available in the `stdout` or `stderr` of [`ChildProcess`](crate::process::ChildProcess).
///
/// This is similar to `Pipe` but will never combine stdout and stderr
/// or place an external command's stderr into `stdout` of [`ChildProcess`](crate::process::ChildProcess).
PipeSeparate,
/// Signifies the result of the pipeline will be immediately collected into a value after this command.
///
/// So, it is fine to collect the stream ahead of time in the current command.
Value,
/// Ignore output.
///
/// This will forward output to the null device for the platform.
Null,
/// Output to nushell's stdout or stderr (only for external commands).
///
/// This causes external commands to inherit nushell's stdout or stderr. This also causes
/// [`ListStream`](crate::ListStream)s to be drained, but not to be printed.
Inherit,
/// Print to nushell's stdout or stderr.
///
/// This is just like `Inherit`, except that [`ListStream`](crate::ListStream)s and
/// [`Value`](crate::Value)s are also printed.
///
/// This is the only destination treated as "not redirected" by
/// [`OutDest::is_redirected`] / the `is-redirected` command.
Print,
/// Redirect output to a file.
File(Arc<File>), // Arc<File>, since we sometimes need to clone `OutDest` into iterators, etc.
}
impl OutDest {
/// Returns `true` when output is *not* sent through the interactive display path.
///
/// Only [`OutDest::Print`] is treated as displayed. Every other variant means the
/// pipeline result is consumed elsewhere (next command, `let`/subexpression,
/// file, null device, or inherit-without-printing).
///
/// This is **not** an OS-level TTY check. For whether process stdio is a terminal,
/// use the `is-terminal` command (`std::io::IsTerminal`).
///
/// # Examples
///
/// ```
/// # use nu_protocol::OutDest;
/// assert!(!OutDest::Print.is_redirected());
/// assert!(OutDest::Pipe.is_redirected());
/// assert!(OutDest::Value.is_redirected());
/// ```
#[must_use]
pub fn is_redirected(&self) -> bool {
!matches!(self, Self::Print)
}
}
impl From<File> for OutDest {
fn from(file: File) -> Self {
Arc::new(file).into()
}
}
impl From<Arc<File>> for OutDest {
fn from(file: Arc<File>) -> Self {
Self::File(file)
}
}
impl TryFrom<&OutDest> for Stdio {
type Error = io::Error;
fn try_from(out_dest: &OutDest) -> Result<Self, Self::Error> {
match out_dest {
OutDest::Pipe | OutDest::PipeSeparate | OutDest::Value => Ok(Self::piped()),
OutDest::Null => Ok(Self::null()),
OutDest::Print | OutDest::Inherit => Ok(Self::inherit()),
OutDest::File(file) => Ok(file.try_clone()?.into()),
}
}
}