xs/nu/commands/
cat_command.rs

1use nu_engine::CallExt;
2use nu_protocol::engine::{Call, Command, EngineState, Stack};
3use nu_protocol::{Category, PipelineData, ShellError, Signature, SyntaxShape, Type};
4
5use crate::store::Store;
6
7#[derive(Clone)]
8pub struct CatCommand {
9    store: Store,
10}
11
12impl CatCommand {
13    pub fn new(store: Store) -> Self {
14        Self { store }
15    }
16}
17
18impl Command for CatCommand {
19    fn name(&self) -> &str {
20        ".cat"
21    }
22
23    fn signature(&self) -> Signature {
24        Signature::build(".cat")
25            .input_output_types(vec![(Type::Nothing, Type::Any)])
26            .named(
27                "limit",
28                SyntaxShape::Int,
29                "limit the number of frames to retrieve",
30                None,
31            )
32            .named(
33                "after",
34                SyntaxShape::String,
35                "start after a specific frame ID (exclusive)",
36                Some('a'),
37            )
38            .named("topic", SyntaxShape::String, "filter by topic", Some('T'))
39            .category(Category::Experimental)
40    }
41
42    fn description(&self) -> &str {
43        "Reads the event stream and returns frames"
44    }
45
46    fn run(
47        &self,
48        engine_state: &EngineState,
49        stack: &mut Stack,
50        call: &Call,
51        _input: PipelineData,
52    ) -> Result<PipelineData, ShellError> {
53        let limit: Option<usize> = call.get_flag(engine_state, stack, "limit")?;
54
55        let after: Option<String> = call.get_flag(engine_state, stack, "after")?;
56        let after: Option<scru128::Scru128Id> = after
57            .as_deref()
58            .map(|s| s.parse().expect("Failed to parse Scru128Id"));
59
60        let topic: Option<String> = call.get_flag(engine_state, stack, "topic")?;
61
62        let frames = self
63            .store
64            .read_sync(after.as_ref(), None)
65            .filter(|frame| match &topic {
66                Some(t) => frame.topic == *t,
67                None => true,
68            })
69            .take(limit.unwrap_or(usize::MAX))
70            .collect::<Vec<_>>();
71
72        use nu_protocol::Value;
73
74        let output = Value::list(
75            frames
76                .into_iter()
77                .map(|frame| crate::nu::util::frame_to_value(&frame, call.head))
78                .collect(),
79            call.head,
80        );
81
82        Ok(PipelineData::Value(output, None))
83    }
84}
xs/nu/commands/cat_command.rs

xs/nu/commands/
cat_command.rs
