use nu_engine::command_prelude::*;
use nu_protocol::{
ast::{Expr, Expression},
DataSource, PipelineMetadata,
};
#[derive(Clone)]
pub struct Metadata;
impl Command for Metadata {
fn name(&self) -> &str {
"metadata"
}
fn usage(&self) -> &str {
"Get the metadata for items in the stream."
}
fn signature(&self) -> nu_protocol::Signature {
Signature::build("metadata")
.input_output_types(vec![(Type::Any, Type::record())])
.allow_variants_without_examples(true)
.optional(
"expression",
SyntaxShape::Any,
"The expression you want metadata for.",
)
.category(Category::Debug)
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let arg = call.positional_nth(0);
let head = call.head;
match arg {
Some(Expression {
expr: Expr::FullCellPath(full_cell_path),
span,
..
}) => {
if full_cell_path.tail.is_empty() {
match &full_cell_path.head {
Expression {
expr: Expr::Var(var_id),
..
} => {
let origin = stack.get_var_with_origin(*var_id, *span)?;
Ok(
build_metadata_record(&origin, input.metadata().as_ref(), head)
.into_pipeline_data(),
)
}
_ => {
let val: Value = call.req(engine_state, stack, 0)?;
Ok(build_metadata_record(&val, input.metadata().as_ref(), head)
.into_pipeline_data())
}
}
} else {
let val: Value = call.req(engine_state, stack, 0)?;
Ok(build_metadata_record(&val, input.metadata().as_ref(), head)
.into_pipeline_data())
}
}
Some(_) => {
let val: Value = call.req(engine_state, stack, 0)?;
Ok(build_metadata_record(&val, input.metadata().as_ref(), head)
.into_pipeline_data())
}
None => {
let mut record = Record::new();
if let Some(x) = input.metadata().as_ref() {
match x {
PipelineMetadata {
data_source: DataSource::Ls,
} => record.push("source", Value::string("ls", head)),
PipelineMetadata {
data_source: DataSource::HtmlThemes,
} => record.push("source", Value::string("into html --list", head)),
PipelineMetadata {
data_source: DataSource::FilePath(path),
} => record.push(
"source",
Value::string(path.to_string_lossy().to_string(), head),
),
}
}
Ok(Value::record(record, head).into_pipeline_data())
}
}
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Get the metadata of a variable",
example: "let a = 42; metadata $a",
result: None,
},
Example {
description: "Get the metadata of the input",
example: "ls | metadata",
result: None,
},
]
}
}
fn build_metadata_record(arg: &Value, metadata: Option<&PipelineMetadata>, head: Span) -> Value {
let mut record = Record::new();
let span = arg.span();
record.push(
"span",
Value::record(
record! {
"start" => Value::int(span.start as i64,span),
"end" => Value::int(span.end as i64, span),
},
head,
),
);
if let Some(x) = metadata {
match x {
PipelineMetadata {
data_source: DataSource::Ls,
} => record.push("source", Value::string("ls", head)),
PipelineMetadata {
data_source: DataSource::HtmlThemes,
} => record.push("source", Value::string("into html --list", head)),
PipelineMetadata {
data_source: DataSource::FilePath(path),
} => record.push(
"source",
Value::string(path.to_string_lossy().to_string(), head),
),
}
}
Value::record(record, head)
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(Metadata {})
}
}