forked from extern/nushell
117 lines
3.3 KiB
Rust
117 lines
3.3 KiB
Rust
use super::super::super::values::{Column, NuDataFrame};
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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::{IntoSeries, Utf8NameSpaceImpl};
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#[derive(Clone)]
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pub struct StrSlice;
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impl Command for StrSlice {
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fn name(&self) -> &str {
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"str-slice"
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}
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fn usage(&self) -> &str {
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"Slices the string from the start position until the selected length"
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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("start", SyntaxShape::Int, "start of slice")
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.named("length", SyntaxShape::Int, "optional length", Some('l'))
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.category(Category::Custom("dataframe".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 slices from the strings",
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example: "[abcded abc321 abc123] | to-df | str-slice 1 -l 2",
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result: Some(
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NuDataFrame::try_from_columns(vec![Column::new(
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"0".to_string(),
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vec![
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Value::test_string("bc"),
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Value::test_string("bc"),
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Value::test_string("bc"),
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],
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)])
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.expect("simple df for test should not fail")
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.into_value(Span::test_data()),
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),
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}]
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}
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fn input_type(&self) -> Type {
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Type::Custom("dataframe".into())
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}
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fn output_type(&self) -> Type {
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Type::Custom("dataframe".into())
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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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command(engine_state, stack, call, input)
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}
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}
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fn command(
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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 start: i64 = call.req(engine_state, stack, 0)?;
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let length: Option<i64> = call.get_flag(engine_state, stack, "length")?;
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let length = length.map(|v| v as u64);
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let df = NuDataFrame::try_from_pipeline(input, call.head)?;
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let series = df.as_series(call.head)?;
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let chunked = series.utf8().map_err(|e| {
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ShellError::GenericError(
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"Error casting to string".into(),
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e.to_string(),
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Some(call.head),
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Some("The str-slice command can only be used with string columns".into()),
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Vec::new(),
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)
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})?;
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let mut res = chunked.str_slice(start, length).map_err(|e| {
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ShellError::GenericError(
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"Error slicing series".into(),
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e.to_string(),
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Some(call.head),
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None,
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Vec::new(),
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)
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})?;
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res.rename(series.name());
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NuDataFrame::try_from_series(vec![res.into_series()], call.head)
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.map(|df| PipelineData::Value(NuDataFrame::into_value(df, call.head), None))
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}
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#[cfg(test)]
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mod test {
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use super::super::super::super::test_dataframe::test_dataframe;
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use super::*;
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#[test]
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fn test_examples() {
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test_dataframe(vec![Box::new(StrSlice {})])
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}
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}
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