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.
113 lines
3.1 KiB
Rust
113 lines
3.1 KiB
Rust
use crate::dataframe::values::NuDataFrame;
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use nu_engine::command_prelude::*;
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#[derive(Clone)]
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pub struct SchemaDF;
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impl Command for SchemaDF {
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fn name(&self) -> &str {
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"dfr schema"
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}
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fn usage(&self) -> &str {
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"Show schema for a dataframe."
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}
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fn signature(&self) -> Signature {
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Signature::build(self.name())
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.switch("datatype-list", "creates a lazy dataframe", Some('l'))
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.input_output_type(
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Type::Custom("dataframe".into()),
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Type::Custom("dataframe".into()),
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)
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.category(Category::Custom("dataframe".into()))
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}
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fn examples(&self) -> Vec<Example> {
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vec![Example {
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description: "Dataframe schema",
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example: r#"[[a b]; [1 "foo"] [3 "bar"]] | dfr into-df | dfr schema"#,
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result: Some(Value::record(
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record! {
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"a" => Value::string("i64", Span::test_data()),
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"b" => Value::string("str", Span::test_data()),
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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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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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if call.has_flag(engine_state, stack, "datatype-list")? {
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Ok(PipelineData::Value(datatype_list(Span::unknown()), None))
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} else {
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command(engine_state, stack, call, input)
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}
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}
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}
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fn command(
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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 df = NuDataFrame::try_from_pipeline(input, call.head)?;
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let schema = df.schema();
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let value: Value = schema.into();
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Ok(PipelineData::Value(value, None))
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}
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fn datatype_list(span: Span) -> Value {
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let types: Vec<Value> = [
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("null", ""),
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("bool", ""),
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("u8", ""),
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("u16", ""),
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("u32", ""),
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("u64", ""),
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("i8", ""),
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("i16", ""),
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("i32", ""),
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("i64", ""),
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("f32", ""),
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("f64", ""),
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("str", ""),
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("binary", ""),
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("date", ""),
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("datetime<time_unit: (ms, us, ns) timezone (optional)>", "Time Unit can be: milliseconds: ms, microseconds: us, nanoseconds: ns. Timezone wildcard is *. Other Timezone examples: UTC, America/Los_Angeles."),
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("duration<time_unit: (ms, us, ns)>", "Time Unit can be: milliseconds: ms, microseconds: us, nanoseconds: ns."),
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("time", ""),
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("object", ""),
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("unknown", ""),
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("list<dtype>", ""),
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]
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.iter()
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.map(|(dtype, note)| {
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Value::record(record! {
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"dtype" => Value::string(*dtype, span),
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"note" => Value::string(*note, span),
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},
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span)
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})
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.collect();
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Value::list(types, span)
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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 super::*;
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#[test]
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fn test_examples() {
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test_dataframe(vec![Box::new(SchemaDF {})])
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}
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}
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