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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.
81 lines
2.2 KiB
Rust
81 lines
2.2 KiB
Rust
use crate::dataframe::values::NuDataFrame;
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use nu_engine::command_prelude::*;
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use polars::prelude::{JsonWriter, SerWriter};
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use std::{fs::File, io::BufWriter, path::PathBuf};
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#[derive(Clone)]
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pub struct ToJsonLines;
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impl Command for ToJsonLines {
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fn name(&self) -> &str {
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"dfr to-jsonl"
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}
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fn usage(&self) -> &str {
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"Saves dataframe to a JSON lines file."
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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("file", SyntaxShape::Filepath, "file path to save dataframe")
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.input_output_type(Type::Custom("dataframe".into()), Type::Any)
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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: "Saves dataframe to JSON lines file",
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example: "[[a b]; [1 2] [3 4]] | dfr into-df | dfr to-jsonl test.jsonl",
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result: None,
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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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command(engine_state, stack, call, input)
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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 file_name: Spanned<PathBuf> = call.req(engine_state, stack, 0)?;
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let mut df = NuDataFrame::try_from_pipeline(input, call.head)?;
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let file = File::create(&file_name.item).map_err(|e| ShellError::GenericError {
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error: "Error with file name".into(),
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msg: e.to_string(),
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span: Some(file_name.span),
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help: None,
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inner: vec![],
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})?;
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let buf_writer = BufWriter::new(file);
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JsonWriter::new(buf_writer)
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.finish(df.as_mut())
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.map_err(|e| ShellError::GenericError {
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error: "Error saving file".into(),
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msg: e.to_string(),
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span: Some(file_name.span),
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help: None,
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inner: vec![],
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})?;
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let file_value = Value::string(format!("saved {:?}", &file_name.item), file_name.span);
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Ok(PipelineData::Value(
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Value::list(vec![file_value], call.head),
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None,
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))
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}
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