forked from extern/nushell
97 lines
2.6 KiB
Rust
97 lines
2.6 KiB
Rust
use super::super::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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#[derive(Clone)]
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pub struct ExprAlias;
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impl Command for ExprAlias {
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fn name(&self) -> &str {
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"as"
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}
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fn usage(&self) -> &str {
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"Creates an alias 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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"Alias name",
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SyntaxShape::String,
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"Alias name for the expression",
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)
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.input_type(Type::Custom("expression".into()))
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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 and alias expression",
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example: "col a | as new_a | into nu",
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result: {
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let cols = vec!["expr".into(), "value".into()];
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let expr = Value::test_string("column");
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let value = Value::test_string("a");
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let expr = Value::Record {
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cols,
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vals: vec![expr, value],
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span: Span::test_data(),
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};
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let cols = vec!["expr".into(), "alias".into()];
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let value = Value::test_string("new_a");
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let record = Value::Record {
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cols,
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vals: vec![expr, value],
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span: Span::test_data(),
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};
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Some(record)
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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 alias: String = call.req(engine_state, stack, 0)?;
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let expr = NuExpression::try_from_pipeline(input, call.head)?;
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let expr: NuExpression = expr.into_polars().alias(alias.as_str()).into();
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Ok(PipelineData::Value(
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NuExpression::into_value(expr, call.head),
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None,
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))
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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::ExprAsNu;
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use crate::dataframe::expressions::ExprCol;
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#[test]
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fn test_examples() {
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test_dataframe(vec![
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Box::new(ExprAlias {}),
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Box::new(ExprCol {}),
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Box::new(ExprAsNu {}),
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])
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}
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}
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