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.
88 lines
2.5 KiB
Rust
88 lines
2.5 KiB
Rust
use crate::math::{
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reducers::{reducer_for, Reduce},
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utils::run_with_function,
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};
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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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"math min"
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}
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fn signature(&self) -> Signature {
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Signature::build("math min")
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.input_output_types(vec![
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(Type::List(Box::new(Type::Number)), Type::Number),
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(Type::List(Box::new(Type::Duration)), Type::Duration),
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(Type::List(Box::new(Type::Filesize)), Type::Filesize),
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(Type::List(Box::new(Type::Any)), Type::Any),
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(Type::Range, Type::Number),
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(Type::Table(vec![]), Type::Record(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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.category(Category::Math)
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}
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fn usage(&self) -> &str {
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"Finds the minimum within a list of values or tables."
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}
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fn search_terms(&self) -> Vec<&str> {
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vec!["minimum", "smallest"]
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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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run_with_function(call, input, minimum)
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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: "Compute the minimum of a list of numbers",
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example: "[-50 100 25] | math min",
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result: Some(Value::test_int(-50)),
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},
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Example {
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description: "Compute the minima of the columns of a table",
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example: "[{a: 1 b: 3} {a: 2 b: -1}] | math min",
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result: Some(Value::test_record(record! {
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"a" => Value::test_int(1),
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"b" => Value::test_int(-1),
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})),
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},
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Example {
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description: "Find the minimum of a list of arbitrary values (Warning: Weird)",
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example: "[-50 'hello' true] | math min",
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result: Some(Value::test_bool(true)),
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},
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]
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}
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}
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pub fn minimum(values: &[Value], span: Span, head: Span) -> Result<Value, ShellError> {
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let min_func = reducer_for(Reduce::Minimum);
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min_func(Value::nothing(head), values.to_vec(), span, head)
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}
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#[cfg(test)]
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mod test {
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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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