forked from extern/nushell
585e104608
# Description This breaks out the core_commands into a separate crate called nu_cmd_lang _(Thank you for improving Nushell. Please, check our [contributing guide](../CONTRIBUTING.md) and talk to the core team before making major changes.)_ _(Description of your pull request goes here. **Provide examples and/or screenshots** if your changes affect the user experience.)_ # User-Facing Changes _(List of all changes that impact the user experience here. This helps us keep track of breaking changes.)_ # Tests + Formatting Don't forget to add tests that cover your changes. Make sure you've run and fixed any issues with these commands: - `cargo fmt --all -- --check` to check standard code formatting (`cargo fmt --all` applies these changes) - `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A clippy::needless_collect` to check that you're using the standard code style - `cargo test --workspace` to check that all tests pass # After Submitting If your PR had any user-facing changes, update [the documentation](https://github.com/nushell/nushell.github.io) after the PR is merged, if necessary. This will help us keep the docs up to date.
88 lines
2.7 KiB
Rust
88 lines
2.7 KiB
Rust
use nu_engine::CallExt;
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use nu_protocol::ast::Call;
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use nu_protocol::engine::{Command, EngineState, Stack};
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use nu_protocol::{
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Category, Example, ListStream, PipelineData, ShellError, Signature, Span, SyntaxShape, Type,
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Value,
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};
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#[derive(Clone)]
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pub struct Echo;
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impl Command for Echo {
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fn name(&self) -> &str {
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"echo"
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}
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fn usage(&self) -> &str {
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"Returns its arguments, ignoring the piped-in value."
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}
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fn signature(&self) -> Signature {
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Signature::build("echo")
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.input_output_types(vec![(Type::Nothing, Type::Any)])
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.rest("rest", SyntaxShape::Any, "the values to echo")
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.category(Category::Core)
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}
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fn extra_usage(&self) -> &str {
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r#"When given no arguments, it returns an empty string. When given one argument,
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it returns it. Otherwise, it returns a list of the arguments. There is usually
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little reason to use this over just writing the values as-is."#
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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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call.rest(engine_state, stack, 0).map(|to_be_echoed| {
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let n = to_be_echoed.len();
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match n.cmp(&1usize) {
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// More than one value is converted in a stream of values
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std::cmp::Ordering::Greater => PipelineData::ListStream(
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ListStream::from_stream(to_be_echoed.into_iter(), engine_state.ctrlc.clone()),
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None,
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),
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// But a single value can be forwarded as it is
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std::cmp::Ordering::Equal => PipelineData::Value(to_be_echoed[0].clone(), None),
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// When there are no elements, we echo the empty string
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std::cmp::Ordering::Less => PipelineData::Value(Value::string("", call.head), None),
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}
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})
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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: "Put a list of numbers in the pipeline. This is the same as [1 2 3].",
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example: "echo 1 2 3",
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result: Some(Value::List {
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vals: vec![Value::test_int(1), Value::test_int(2), Value::test_int(3)],
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span: Span::test_data(),
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}),
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},
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Example {
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description:
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"Returns the piped-in value, by using the special $in variable to obtain it.",
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example: "echo $in",
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result: None,
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},
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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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#[test]
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fn test_examples() {
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use super::Echo;
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use crate::test_examples;
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test_examples(Echo {})
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}
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}
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