nushell/crates/nu-cli/src/commands/sum.rs
Jason Gedge 522a828687
Move external closer to internal (#1611)
* Refactor InputStream and affected commands.

First, making `values` private and leaning on the `Stream` implementation makes
consumes of `InputStream` less likely to have to change in the future, if we
change what an `InputStream` is internally.

Second, we're dropping `Option<InputStream>` as the input to pipelines,
internals, and externals. Instead, `InputStream.is_empty` can be used to check
for "emptiness". Empty streams are typically only ever used as the first input
to a pipeline.

* Add run_external internal command.

We want to push external commands closer to internal commands, eventually
eliminating the concept of "external" completely. This means we can consolidate
a couple of things:

- Variable evaluation (for example, `$it`, `$nu`, alias vars)
- Behaviour of whole stream vs per-item external execution

It should also make it easier for us to start introducing argument signatures
for external commands,

* Update run_external.rs

* Update run_external.rs

* Update run_external.rs

* Update run_external.rs

Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>
2020-04-20 15:30:44 +12:00

55 lines
1.4 KiB
Rust

use crate::commands::WholeStreamCommand;
use crate::prelude::*;
use crate::utils::data_processing::{reducer_for, Reduce};
use nu_errors::ShellError;
use nu_protocol::{ReturnSuccess, ReturnValue, Signature, Value};
use num_traits::identities::Zero;
pub struct Sum;
impl WholeStreamCommand for Sum {
fn name(&self) -> &str {
"sum"
}
fn signature(&self) -> Signature {
Signature::build("sum")
}
fn usage(&self) -> &str {
"Sums the values."
}
fn run(
&self,
args: CommandArgs,
registry: &CommandRegistry,
) -> Result<OutputStream, ShellError> {
sum(RunnableContext {
input: args.input,
registry: registry.clone(),
shell_manager: args.shell_manager,
host: args.host,
ctrl_c: args.ctrl_c,
name: args.call_info.name_tag,
})
}
}
fn sum(RunnableContext { mut input, .. }: RunnableContext) -> Result<OutputStream, ShellError> {
let stream = async_stream! {
let mut values = input.drain_vec().await;
let action = reducer_for(Reduce::Sum);
match action(Value::zero(), values) {
Ok(total) => yield ReturnSuccess::value(total),
Err(err) => yield Err(err),
}
};
let stream: BoxStream<'static, ReturnValue> = stream.boxed();
Ok(stream.to_output_stream())
}