nu_command/debug/
view_span.rs

1use nu_engine::command_prelude::*;
2use nu_protocol::PipelineMetadata;
3
4#[derive(Clone)]
5pub struct ViewSpan;
6
7impl Command for ViewSpan {
8    fn name(&self) -> &str {
9        "view span"
10    }
11
12    fn description(&self) -> &str {
13        "View the contents of a span."
14    }
15
16    fn extra_description(&self) -> &str {
17        "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."
18    }
19
20    fn signature(&self) -> nu_protocol::Signature {
21        Signature::build("view span")
22            .input_output_types(vec![(Type::Nothing, Type::String)])
23            .required("start", SyntaxShape::Int, "Start of the span.")
24            .required("end", SyntaxShape::Int, "End of the span.")
25            .category(Category::Debug)
26    }
27
28    fn run(
29        &self,
30        engine_state: &EngineState,
31        stack: &mut Stack,
32        call: &Call,
33        _input: PipelineData,
34    ) -> Result<PipelineData, ShellError> {
35        let start_span: Spanned<usize> = call.req(engine_state, stack, 0)?;
36        let end_span: Spanned<usize> = call.req(engine_state, stack, 1)?;
37
38        let span = if start_span.item <= end_span.item {
39            Ok(Span::new(start_span.item, end_span.item))
40        } else {
41            Err(ShellError::GenericError {
42                error: "Invalid span".to_string(),
43                msg: "the start position of this span is later than the end position".to_string(),
44                span: Some(call.head),
45                help: None,
46                inner: vec![],
47            })
48        }?;
49
50        let bin_contents = engine_state
51            .try_get_file_contents(span)
52            .map(String::from_utf8_lossy)
53            .ok_or_else(|| ShellError::GenericError {
54                error: "Cannot view span".to_string(),
55                msg: "this start and end does not correspond to a viewable value".to_string(),
56                span: Some(call.head),
57                help: None,
58                inner: vec![],
59            })?;
60
61        let metadata = PipelineMetadata {
62            content_type: Some("application/x-nuscript".into()),
63            ..Default::default()
64        };
65
66        let value = Value::string(bin_contents, call.head)
67            .into_pipeline_data()
68            .set_metadata(Some(metadata));
69        Ok(value)
70    }
71
72    fn examples(&self) -> Vec<Example<'_>> {
73        vec![Example {
74            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.",
75            example: r#"some | pipeline | or | variable | debug --raw; view span 1 2"#,
76            result: None,
77        }]
78    }
79}
nu_command/debug/view_span.rs

nu_command/debug/
view_span.rs
