use nu_engine::CallExt;
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned,
SyntaxShape, Type, Value,
};
#[derive(Clone)]
pub struct ViewSpan;
impl Command for ViewSpan {
fn name(&self) -> &str {
"view span"
}
fn usage(&self) -> &str {
"View the contents of a span."
}
fn extra_usage(&self) -> &str {
"This command is meant for debugging purposes.\nIt allows you to view the contents of nushell spans.\nOne way to get spans is to pipe something into 'debug --raw'.\nThen you can use the Span { start, end } values as the start and end values for this command."
}
fn signature(&self) -> nu_protocol::Signature {
Signature::build("view span")
.input_output_types(vec![(Type::Nothing, Type::String)])
.required("start", SyntaxShape::Int, "Start of the span.")
.required("end", SyntaxShape::Int, "End of the span.")
.category(Category::Debug)
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
_input: PipelineData,
) -> Result<PipelineData, ShellError> {
let start_span: Spanned<usize> = call.req(engine_state, stack, 0)?;
let end_span: Spanned<usize> = call.req(engine_state, stack, 1)?;
if start_span.item < end_span.item {
let bin_contents =
engine_state.get_span_contents(Span::new(start_span.item, end_span.item));
Ok(
Value::string(String::from_utf8_lossy(bin_contents), call.head)
.into_pipeline_data(),
)
} else {
Err(ShellError::GenericError {
error: "Cannot view span".to_string(),
msg: "this start and end does not correspond to a viewable value".to_string(),
span: Some(call.head),
help: None,
inner: vec![],
})
}
}
fn examples(&self) -> Vec<Example> {
vec![Example {
description: "View the source of a span. 1 and 2 are just example values. Use the return of debug --raw to get the actual values",
example: r#"some | pipeline | or | variable | debug --raw; view span 1 2"#,
result: None,
}]
}
}