nushell/src/commands/where_.rs

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use crate::commands::PerItemCommand;
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use crate::errors::ShellError;
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use crate::parser::hir::SyntaxType;
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use crate::parser::registry;
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use crate::prelude::*;
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pub struct Where;
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impl PerItemCommand for Where {
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fn name(&self) -> &str {
"where"
}
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fn signature(&self) -> registry::Signature {
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Signature::build("where").required("condition", SyntaxType::Block)
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}
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fn run(
&self,
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call_info: &CallInfo,
_registry: &registry::CommandRegistry,
_shell_manager: &ShellManager,
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input: Tagged<Value>,
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) -> Result<OutputStream, ShellError> {
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let input_clone = input.clone();
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let condition = call_info.args.expect_nth(0)?;
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let stream = match condition {
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Tagged {
item: Value::Block(block),
tag,
} => {
let result = block.invoke(&input_clone);
match result {
Ok(v) => {
if v.is_true() {
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VecDeque::from(vec![Ok(ReturnSuccess::Value(input_clone))])
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} else {
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VecDeque::new()
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}
}
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Err(e) => {
return Err(ShellError::labeled_error(
format!("Could not evaluate ({})", e.to_string()),
"could not evaluate",
tag.span,
))
}
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}
}
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Tagged { tag, .. } => {
return Err(ShellError::labeled_error(
"Expected a condition",
"where needs a condition",
tag.span,
))
}
};
Ok(stream.to_output_stream())
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}
}