71 lines
1.9 KiB
Rust
71 lines
1.9 KiB
Rust
use crate::dataframe::values::NuExpression;
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use nu_engine::CallExt;
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use nu_protocol::{
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ast::Call,
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engine::{Command, EngineState, Stack},
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Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
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};
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use polars::prelude::col;
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#[derive(Clone)]
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pub struct ExprCol;
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impl Command for ExprCol {
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fn name(&self) -> &str {
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"col"
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}
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fn usage(&self) -> &str {
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"Creates a named column expression"
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}
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fn signature(&self) -> Signature {
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Signature::build(self.name())
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.required(
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"column name",
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SyntaxShape::String,
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"Name of column to be used",
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)
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.input_type(Type::Any)
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.output_type(Type::Custom("expression".into()))
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.category(Category::Custom("expression".into()))
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}
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fn examples(&self) -> Vec<Example> {
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vec![Example {
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description: "Creates a named column expression and converts it to a nu object",
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example: "col a | into nu",
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result: Some(Value::Record {
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cols: vec!["expr".into(), "value".into()],
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vals: vec![Value::test_string("column"), Value::test_string("a")],
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span: Span::test_data(),
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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 name: String = call.req(engine_state, stack, 0)?;
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let expr: NuExpression = col(name.as_str()).into();
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Ok(PipelineData::Value(expr.into_value(call.head), None))
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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::super::super::test_dataframe::test_dataframe;
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use super::*;
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use crate::dataframe::expressions::as_nu::ExprAsNu;
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#[test]
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fn test_examples() {
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test_dataframe(vec![Box::new(ExprCol {}), Box::new(ExprAsNu {})])
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}
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}
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