nushell/src/commands/pick.rs
Yehuda Katz f70c6d5d48 Extract nu_source into a crate
This commit extracts Tag, Span, Text, as well as source-related debug
facilities into a new crate called nu_source.

This change is much bigger than one might have expected because the
previous code relied heavily on implementing inherent methods on
`Tagged<T>` and `Spanned<T>`, which is no longer possible.

As a result, this change creates more concrete types instead of using
`Tagged<T>`. One notable example: Tagged<Value> became Value, and Value
became UntaggedValue.

This change clarifies the intent of the code in many places, but it does
make it a big change.
2019-11-25 07:37:33 -08:00

57 lines
1.3 KiB
Rust

use crate::commands::WholeStreamCommand;
use crate::context::CommandRegistry;
use crate::data::base::select_fields;
use crate::errors::ShellError;
use crate::prelude::*;
use nu_source::Tagged;
#[derive(Deserialize)]
struct PickArgs {
rest: Vec<Tagged<String>>,
}
pub struct Pick;
impl WholeStreamCommand for Pick {
fn name(&self) -> &str {
"pick"
}
fn signature(&self) -> Signature {
Signature::build("pick").rest(SyntaxShape::Any, "the columns to select from the table")
}
fn usage(&self) -> &str {
"Down-select table to only these columns."
}
fn run(
&self,
args: CommandArgs,
registry: &CommandRegistry,
) -> Result<OutputStream, ShellError> {
args.process(registry, pick)?.run()
}
}
fn pick(
PickArgs { rest: fields }: PickArgs,
RunnableContext { input, name, .. }: RunnableContext,
) -> Result<OutputStream, ShellError> {
if fields.len() == 0 {
return Err(ShellError::labeled_error(
"Pick requires columns to pick",
"needs parameter",
name,
));
}
let fields: Vec<_> = fields.iter().map(|f| f.item.clone()).collect();
let objects = input
.values
.map(move |value| select_fields(&value, &fields, value.tag.clone()));
Ok(objects.from_input_stream())
}