nushell/src/plugins/skip.rs

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use indexmap::IndexMap;
use nu::{
serve_plugin, CallInfo, CommandConfig, Plugin, Primitive, ReturnSuccess, ReturnValue,
ShellError, Spanned, Value,
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};
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struct Skip {
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skip_amount: i64,
}
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impl Skip {
fn new() -> Skip {
Skip { skip_amount: 0 }
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}
}
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impl Plugin for Skip {
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fn config(&mut self) -> Result<CommandConfig, ShellError> {
Ok(CommandConfig {
name: "skip".to_string(),
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positional: vec![],
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is_filter: true,
is_sink: false,
named: IndexMap::new(),
rest_positional: true,
})
}
fn begin_filter(&mut self, call_info: CallInfo) -> Result<Vec<ReturnValue>, ShellError> {
if let Some(args) = call_info.args.positional {
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for arg in args {
match arg {
Spanned {
item: Value::Primitive(Primitive::Int(i)),
..
} => {
self.skip_amount = i;
}
_ => {
return Err(ShellError::labeled_error(
"Unrecognized type in params",
"expected an integer",
arg.span,
))
}
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}
}
}
Ok(vec![])
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}
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fn filter(&mut self, input: Spanned<Value>) -> Result<Vec<ReturnValue>, ShellError> {
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if self.skip_amount == 0 {
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Ok(vec![ReturnSuccess::value(input)])
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} else {
self.skip_amount -= 1;
Ok(vec![])
}
}
}
fn main() {
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serve_plugin(&mut Skip::new());
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}