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.
102 lines
2.9 KiB
Rust
102 lines
2.9 KiB
Rust
use nu_engine::{command_prelude::*, get_eval_block, redirect_env};
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use nu_protocol::engine::Closure;
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#[derive(Clone)]
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pub struct Collect;
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impl Command for Collect {
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fn name(&self) -> &str {
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"collect"
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}
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fn signature(&self) -> Signature {
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Signature::build("collect")
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.input_output_types(vec![(Type::Any, Type::Any)])
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.required(
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"closure",
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SyntaxShape::Closure(Some(vec![SyntaxShape::Any])),
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"The closure to run once the stream is collected.",
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)
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.switch(
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"keep-env",
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"let the block affect environment variables",
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None,
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)
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.category(Category::Filters)
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}
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fn usage(&self) -> &str {
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"Collect the stream and pass it to a block."
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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 capture_block: Closure = call.req(engine_state, stack, 0)?;
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let block = engine_state.get_block(capture_block.block_id).clone();
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let mut stack_captures =
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stack.captures_to_stack_preserve_stdio(capture_block.captures.clone());
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let metadata = input.metadata();
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let input: Value = input.into_value(call.head);
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let mut saved_positional = None;
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if let Some(var) = block.signature.get_positional(0) {
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if let Some(var_id) = &var.var_id {
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stack_captures.add_var(*var_id, input.clone());
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saved_positional = Some(*var_id);
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}
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}
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let eval_block = get_eval_block(engine_state);
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let result = eval_block(
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engine_state,
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&mut stack_captures,
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&block,
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input.into_pipeline_data(),
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)
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.map(|x| x.set_metadata(metadata));
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if call.has_flag(engine_state, stack, "keep-env")? {
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redirect_env(engine_state, stack, &stack_captures);
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// for when we support `data | let x = $in;`
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// remove the variables added earlier
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for (var_id, _) in capture_block.captures {
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stack_captures.remove_var(var_id);
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}
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if let Some(u) = saved_positional {
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stack_captures.remove_var(u);
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}
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// add any new variables to the stack
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stack.vars.extend(stack_captures.vars);
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}
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result
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}
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fn examples(&self) -> Vec<Example> {
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vec![Example {
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description: "Use the second value in the stream",
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example: "[1 2 3] | collect { |x| $x.1 }",
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result: Some(Value::test_int(2)),
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}]
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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::*;
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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(Collect {})
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}
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}
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