forked from extern/nushell
111 lines
3.4 KiB
Rust
111 lines
3.4 KiB
Rust
use crate::prelude::*;
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use log::trace;
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use nu_engine::evaluate_baseline_expr;
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use nu_engine::WholeStreamCommand;
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use nu_errors::ShellError;
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use nu_protocol::{hir::ClassifiedCommand, Signature, SyntaxShape, UntaggedValue, Value};
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pub struct SubCommand;
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impl WholeStreamCommand for SubCommand {
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fn name(&self) -> &str {
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"keep while"
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}
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fn signature(&self) -> Signature {
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Signature::build("keep while")
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.required(
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"condition",
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SyntaxShape::RowCondition,
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"The condition that must be met to keep rows",
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)
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.filter()
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}
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fn usage(&self) -> &str {
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"Keeps rows while the condition matches."
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}
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fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
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let ctx = Arc::new(EvaluationContext::from_args(&args));
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let call_info = args.evaluate_once()?;
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let block = call_info.args.expect_nth(0)?.clone();
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let (condition, captured) = match block {
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Value {
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value: UntaggedValue::Block(captured_block),
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tag,
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} => {
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if captured_block.block.block.len() != 1 {
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return Err(ShellError::labeled_error(
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"Expected a condition",
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"expected a condition",
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tag,
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));
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}
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match captured_block.block.block[0].pipelines.get(0) {
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Some(item) => match item.list.get(0) {
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Some(ClassifiedCommand::Expr(expr)) => {
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(Arc::new(expr.clone()), captured_block.captured.clone())
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}
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_ => {
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return Err(ShellError::labeled_error(
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"Expected a condition",
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"expected a condition",
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tag,
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));
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}
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},
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None => {
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return Err(ShellError::labeled_error(
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"Expected a condition",
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"expected a condition",
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tag,
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));
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}
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}
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}
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Value { tag, .. } => {
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return Err(ShellError::labeled_error(
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"Expected a condition",
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"expected a condition",
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tag,
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));
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}
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};
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Ok(call_info
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.input
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.take_while(move |item| {
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let condition = condition.clone();
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let ctx = ctx.clone();
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ctx.scope.enter_scope();
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ctx.scope.add_var("$it", item.clone());
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ctx.scope.add_vars(&captured.entries);
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trace!("ITEM = {:?}", item);
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let result = evaluate_baseline_expr(&*condition, &*ctx);
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ctx.scope.exit_scope();
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trace!("RESULT = {:?}", result);
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matches!(result, Ok(ref v) if v.is_true())
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})
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.to_output_stream())
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}
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}
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#[cfg(test)]
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mod tests {
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use super::ShellError;
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use super::SubCommand;
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#[test]
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fn examples_work_as_expected() -> Result<(), ShellError> {
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use crate::examples::test as test_examples;
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test_examples(SubCommand {})
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}
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}
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