forked from extern/nushell
109 lines
2.8 KiB
Rust
109 lines
2.8 KiB
Rust
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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, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData, ShellError,
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Signature, Span, Value,
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};
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#[derive(Clone)]
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pub struct Columns;
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impl Command for Columns {
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fn name(&self) -> &str {
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"columns"
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}
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fn signature(&self) -> Signature {
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Signature::build(self.name()).category(Category::Filters)
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}
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fn usage(&self) -> &str {
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"Show the columns in the input."
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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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example: "[[name,age,grade]; [bill,20,a]] | columns",
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description: "Get the columns from the table",
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result: None,
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},
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Example {
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example: "[[name,age,grade]; [bill,20,a]] | columns | first",
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description: "Get the first column from the table",
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result: None,
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},
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Example {
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example: "[[name,age,grade]; [bill,20,a]] | columns | nth 1",
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description: "Get the second column from the table",
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result: None,
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},
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]
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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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let span = call.head;
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getcol(engine_state, span, input)
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}
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}
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fn getcol(
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engine_state: &EngineState,
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span: Span,
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input: PipelineData,
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) -> Result<PipelineData, ShellError> {
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match input {
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PipelineData::Value(
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Value::List {
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vals: input_vals,
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span: _,
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},
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..,
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) => {
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let input_cols = get_input_cols(input_vals);
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Ok(input_cols
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.into_iter()
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.into_pipeline_data(engine_state.ctrlc.clone()))
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}
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PipelineData::Stream(stream, ..) => {
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let v: Vec<_> = stream.into_iter().collect();
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let input_cols = get_input_cols(v);
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Ok(input_cols
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.into_iter()
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.into_pipeline_data(engine_state.ctrlc.clone()))
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}
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PipelineData::Value(_v, ..) => {
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let cols = vec![];
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let vals = vec![];
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Ok(Value::Record { cols, vals, span }.into_pipeline_data())
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}
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}
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}
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fn get_input_cols(input: Vec<Value>) -> Vec<String> {
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let rec = input.first();
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match rec {
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Some(Value::Record { cols, vals: _, .. }) => cols.to_vec(),
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_ => vec!["".to_string()],
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}
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test_examples() {
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use crate::test_examples;
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test_examples(Columns {})
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}
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}
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