forked from extern/nushell
113 lines
2.7 KiB
Rust
113 lines
2.7 KiB
Rust
use crate::prelude::*;
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use nu_engine::WholeStreamCommand;
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use nu_errors::ShellError;
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use nu_protocol::{Signature, UntaggedValue, Value};
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pub struct Length;
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#[derive(Deserialize)]
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pub struct LengthArgs {
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column: bool,
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}
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impl WholeStreamCommand for Length {
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fn name(&self) -> &str {
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"length"
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}
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fn signature(&self) -> Signature {
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Signature::build("length").switch(
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"column",
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"Calculate number of columns in table",
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Some('c'),
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)
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}
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fn usage(&self) -> &str {
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"Show the total number of rows or items."
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}
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fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
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let tag = args.call_info.name_tag.clone();
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let (LengthArgs { column }, input) = args.process()?;
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Ok(CountIterator {
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column,
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input,
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done: false,
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tag,
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}
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.to_output_stream())
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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: "Count the number of entries in a list",
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example: "echo [1 2 3 4 5] | length",
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result: Some(vec![UntaggedValue::int(5).into()]),
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},
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Example {
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description: "Count the number of columns in the calendar table",
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example: "cal | length -c",
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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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struct CountIterator {
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column: bool,
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input: InputStream,
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done: bool,
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tag: Tag,
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}
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impl Iterator for CountIterator {
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type Item = Value;
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fn next(&mut self) -> Option<Self::Item> {
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if self.done {
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return None;
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}
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self.done = true;
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let length = if self.column {
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if let Some(first) = self.input.next() {
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match &first.value {
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UntaggedValue::Row(dictionary) => dictionary.length(),
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_ => {
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return Some(Value::error(ShellError::labeled_error(
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"Cannot obtain column length",
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"cannot obtain column length",
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self.tag.clone(),
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)));
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}
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}
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} else {
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0
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}
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} else {
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let input = &mut self.input;
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input.count()
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};
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Some(UntaggedValue::int(length).into_value(self.tag.clone()))
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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::Length;
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use super::ShellError;
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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(Length {})
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}
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}
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