nushell/crates/nu-cli/src/commands/default.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

75 lines
2 KiB
Rust

use crate::commands::WholeStreamCommand;
use crate::context::CommandRegistry;
use crate::prelude::*;
use nu_errors::ShellError;
use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
use nu_source::Tagged;
use nu_value_ext::ValueExt;
#[derive(Deserialize)]
struct DefaultArgs {
column: Tagged<String>,
value: Value,
}
pub struct Default;
impl WholeStreamCommand for Default {
fn name(&self) -> &str {
"default"
}
fn signature(&self) -> Signature {
Signature::build("default")
.required("column name", SyntaxShape::String, "the name of the column")
.required(
"column value",
SyntaxShape::Any,
"the value of the column to default",
)
}
fn usage(&self) -> &str {
"Sets a default row's column if missing."
}
fn run(
&self,
args: CommandArgs,
registry: &CommandRegistry,
) -> Result<OutputStream, ShellError> {
args.process(registry, default)?.run()
}
}
fn default(
DefaultArgs { column, value }: DefaultArgs,
RunnableContext { input, .. }: RunnableContext,
) -> Result<OutputStream, ShellError> {
let stream = input
.map(move |item| {
let mut result = VecDeque::new();
let should_add = match item {
Value {
value: UntaggedValue::Row(ref r),
..
} => r.get_data(&column.item).borrow().is_none(),
_ => false,
};
if should_add {
match item.insert_data_at_path(&column.item, value.clone()) {
Some(new_value) => result.push_back(ReturnSuccess::value(new_value)),
None => result.push_back(ReturnSuccess::value(item)),
}
} else {
result.push_back(ReturnSuccess::value(item));
}
futures::stream::iter(result)
})
.flatten();
Ok(stream.to_output_stream())
}