nushell/src/commands/default.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

74 lines
1.9 KiB
Rust

use crate::commands::WholeStreamCommand;
use crate::errors::ShellError;
use crate::parser::CommandRegistry;
use crate::prelude::*;
use nu_source::Tagged;
#[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
.values
.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));
}
result
})
.flatten();
Ok(stream.to_output_stream())
}