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.
127 lines
4.2 KiB
Rust
127 lines
4.2 KiB
Rust
use crate::dataframe::values::{Column, NuDataFrame, NuExpression, NuWhen};
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use nu_engine::command_prelude::*;
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#[derive(Clone)]
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pub struct ExprOtherwise;
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impl Command for ExprOtherwise {
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fn name(&self) -> &str {
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"dfr otherwise"
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}
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fn usage(&self) -> &str {
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"Completes a when expression."
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}
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fn signature(&self) -> Signature {
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Signature::build(self.name())
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.required(
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"otherwise expression",
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SyntaxShape::Any,
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"expression to apply when no when predicate matches",
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)
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.input_output_type(Type::Any, Type::Custom("expression".into()))
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.category(Category::Custom("expression".into()))
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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: "Create a when conditions",
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example: "dfr when ((dfr col a) > 2) 4 | dfr otherwise 5",
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result: None,
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},
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Example {
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description: "Create a when conditions",
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example:
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"dfr when ((dfr col a) > 2) 4 | dfr when ((dfr col a) < 0) 6 | dfr otherwise 0",
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result: None,
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},
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Example {
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description: "Create a new column for the dataframe",
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example: r#"[[a b]; [6 2] [1 4] [4 1]]
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| dfr into-lazy
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| dfr with-column (
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dfr when ((dfr col a) > 2) 4 | dfr otherwise 5 | dfr as c
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)
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| dfr with-column (
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dfr when ((dfr col a) > 5) 10 | dfr when ((dfr col a) < 2) 6 | dfr otherwise 0 | dfr as d
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)
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| dfr collect"#,
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result: Some(
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NuDataFrame::try_from_columns(
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vec![
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Column::new(
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"a".to_string(),
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vec![Value::test_int(6), Value::test_int(1), Value::test_int(4)],
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),
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Column::new(
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"b".to_string(),
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vec![Value::test_int(2), Value::test_int(4), Value::test_int(1)],
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),
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Column::new(
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"c".to_string(),
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vec![Value::test_int(4), Value::test_int(5), Value::test_int(4)],
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),
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Column::new(
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"d".to_string(),
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vec![Value::test_int(10), Value::test_int(6), Value::test_int(0)],
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),
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],
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None,
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)
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.expect("simple df for test should not fail")
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.into_value(Span::test_data()),
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),
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},
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]
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}
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fn search_terms(&self) -> Vec<&str> {
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vec!["condition", "else"]
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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 otherwise_predicate: Value = call.req(engine_state, stack, 0)?;
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let otherwise_predicate = NuExpression::try_from_value(otherwise_predicate)?;
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let value = input.into_value(call.head);
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let complete: NuExpression = match NuWhen::try_from_value(value)? {
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NuWhen::Then(then) => then.otherwise(otherwise_predicate.into_polars()).into(),
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NuWhen::ChainedThen(chained_when) => chained_when
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.otherwise(otherwise_predicate.into_polars())
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.into(),
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};
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Ok(PipelineData::Value(complete.into_value(call.head), None))
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}
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}
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#[cfg(test)]
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mod test {
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use super::super::super::test_dataframe::test_dataframe;
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use crate::dataframe::eager::{ToNu, WithColumn};
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use crate::dataframe::expressions::when::ExprWhen;
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use crate::dataframe::expressions::{ExprAlias, ExprCol};
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use super::*;
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#[test]
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fn test_examples() {
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test_dataframe(vec![
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Box::new(WithColumn {}),
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Box::new(ExprCol {}),
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Box::new(ExprAlias {}),
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Box::new(ExprWhen {}),
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Box::new(ExprOtherwise {}),
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Box::new(ToNu {}),
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])
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}
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}
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