forked from extern/nushell
c747ec75c9
# Description
When implementing a `Command`, one must also import all the types
present in the function signatures for `Command`. This makes it so that
we often import the same set of types in each command implementation
file. E.g., something like this:
```rust
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
ShellError, Signature, Span, Type, Value,
};
```
This PR adds the `nu_engine::command_prelude` module which contains the
necessary and commonly used types to implement a `Command`:
```rust
// command_prelude.rs
pub use crate::CallExt;
pub use nu_protocol::{
ast::{Call, CellPath},
engine::{Command, EngineState, Stack},
record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, IntoSpanned,
PipelineData, Record, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
};
```
This should reduce the boilerplate needed to implement a command and
also gives us a place to track the breadth of the `Command` API. I tried
to be conservative with what went into the prelude modules, since it
might be hard/annoying to remove items from the prelude in the future.
Let me know if something should be included or excluded.
63 lines
2.2 KiB
Rust
63 lines
2.2 KiB
Rust
use nu_engine::command_prelude::*;
|
|
|
|
#[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,
|
|
}]
|
|
}
|
|
}
|