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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.
87 lines
2.6 KiB
Rust
87 lines
2.6 KiB
Rust
use nu_protocol::{ast::CellPath, PipelineData, ShellError, Span, Value};
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use std::sync::{atomic::AtomicBool, Arc};
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pub trait CmdArgument {
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fn take_cell_paths(&mut self) -> Option<Vec<CellPath>>;
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}
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/// Arguments with only cell_path.
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///
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/// If commands is going to use `operate` function, and it only required optional cell_paths
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/// Using this to simplify code.
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pub struct CellPathOnlyArgs {
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cell_paths: Option<Vec<CellPath>>,
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}
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impl CmdArgument for CellPathOnlyArgs {
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fn take_cell_paths(&mut self) -> Option<Vec<CellPath>> {
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self.cell_paths.take()
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}
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}
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impl From<Vec<CellPath>> for CellPathOnlyArgs {
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fn from(cell_paths: Vec<CellPath>) -> Self {
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Self {
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cell_paths: (!cell_paths.is_empty()).then_some(cell_paths),
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}
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}
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}
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/// A simple wrapper for `PipelineData::map` method.
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///
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/// In detail, for each elements, invoking relative `cmd` with `arg`.
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///
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/// If `arg` tell us that its cell path is not None, only map over data under these columns.
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/// Else it will apply each column inside a table.
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///
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/// The validation of input element should be handle by `cmd` itself.
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pub fn operate<C, A>(
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cmd: C,
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mut arg: A,
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input: PipelineData,
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span: Span,
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ctrlc: Option<Arc<AtomicBool>>,
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) -> Result<PipelineData, ShellError>
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where
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A: CmdArgument + Send + Sync + 'static,
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C: Fn(&Value, &A, Span) -> Value + Send + Sync + 'static + Clone + Copy,
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{
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match arg.take_cell_paths() {
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None => input.map(
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move |v| {
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match v {
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// Propagate errors inside the input
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Value::Error { .. } => v,
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_ => cmd(&v, &arg, span),
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}
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},
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ctrlc,
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),
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Some(column_paths) => {
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let arg = Arc::new(arg);
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input.map(
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move |mut v| {
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for path in &column_paths {
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let opt = arg.clone();
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let r = v.update_cell_path(
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&path.members,
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Box::new(move |old| {
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match old {
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// Propagate errors inside the input
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Value::Error { .. } => old.clone(),
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_ => cmd(old, &opt, span),
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}
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}),
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);
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if let Err(error) = r {
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return Value::error(error, span);
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}
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}
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v
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},
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ctrlc,
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)
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}
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}
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}
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