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.
102 lines
2.9 KiB
Rust
102 lines
2.9 KiB
Rust
use nu_cmd_base::input_handler::{operate, CellPathOnlyArgs};
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use nu_engine::command_prelude::*;
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#[derive(Clone)]
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pub struct SubCommand;
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impl Command for SubCommand {
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fn name(&self) -> &str {
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"str reverse"
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}
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fn signature(&self) -> Signature {
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Signature::build("str reverse")
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.input_output_types(vec![
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(Type::String, Type::String),
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(
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Type::List(Box::new(Type::String)),
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Type::List(Box::new(Type::String)),
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),
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(Type::Table(vec![]), Type::Table(vec![])),
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(Type::Record(vec![]), Type::Record(vec![])),
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])
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.allow_variants_without_examples(true)
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.rest(
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"rest",
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SyntaxShape::CellPath,
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"For a data structure input, reverse strings at the given cell paths.",
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)
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.category(Category::Strings)
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}
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fn usage(&self) -> &str {
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"Reverse every string in the pipeline."
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}
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fn search_terms(&self) -> Vec<&str> {
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vec!["convert", "inverse", "flip"]
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}
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fn run(
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&self,
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engine_state: &EngineState,
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stack: &mut Stack,
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call: &Call,
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input: PipelineData,
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) -> Result<PipelineData, ShellError> {
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let cell_paths: Vec<CellPath> = call.rest(engine_state, stack, 0)?;
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let args = CellPathOnlyArgs::from(cell_paths);
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operate(action, args, input, call.head, engine_state.ctrlc.clone())
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}
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fn examples(&self) -> Vec<Example> {
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vec![
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Example {
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description: "Reverse a single string",
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example: "'Nushell' | str reverse",
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result: Some(Value::test_string("llehsuN")),
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},
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Example {
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description: "Reverse multiple strings in a list",
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example: "['Nushell' 'is' 'cool'] | str reverse",
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result: Some(Value::list(
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vec![
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Value::test_string("llehsuN"),
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Value::test_string("si"),
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Value::test_string("looc"),
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],
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Span::test_data(),
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)),
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},
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]
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}
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}
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fn action(input: &Value, _arg: &CellPathOnlyArgs, head: Span) -> Value {
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match input {
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Value::String { val, .. } => Value::string(val.chars().rev().collect::<String>(), head),
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Value::Error { .. } => input.clone(),
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_ => Value::error(
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ShellError::OnlySupportsThisInputType {
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exp_input_type: "string".into(),
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wrong_type: input.get_type().to_string(),
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dst_span: head,
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src_span: input.span(),
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},
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head,
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),
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_examples() {
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use crate::test_examples;
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test_examples(SubCommand {})
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}
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}
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