forked from extern/nushell
8da27a1a09
# Description
This PR creates a new `Record` type to reduce duplicate code and
possibly bugs as well. (This is an edited version of #9648.)
- `Record` implements `FromIterator` and `IntoIterator` and so can be
iterated over or collected into. For example, this helps with
conversions to and from (hash)maps. (Also, no more
`cols.iter().zip(vals)`!)
- `Record` has a `push(col, val)` function to help insure that the
number of columns is equal to the number of values. I caught a few
potential bugs thanks to this (e.g. in the `ls` command).
- Finally, this PR also adds a `record!` macro that helps simplify
record creation. It is used like so:
```rust
record! {
"key1" => some_value,
"key2" => Value::string("text", span),
"key3" => Value::int(optional_int.unwrap_or(0), span),
"key4" => Value::bool(config.setting, span),
}
```
Since macros hinder formatting, etc., the right hand side values should
be relatively short and sweet like the examples above.
Where possible, prefer `record!` or `.collect()` on an iterator instead
of multiple `Record::push`s, since the first two automatically set the
record capacity and do less work overall.
# User-Facing Changes
Besides the changes in `nu-protocol` the only other breaking changes are
to `nu-table::{ExpandedTable::build_map, JustTable::kv_table}`.
101 lines
2.7 KiB
Rust
101 lines
2.7 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, Record, ShellError, Signature, 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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"dfr 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_output_type(
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Type::Custom("expression".into()),
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Type::Custom("expression".into()),
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)
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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: "dfr col a | dfr as new_a | dfr 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::test_record(Record {
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cols,
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vals: vec![expr, value],
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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::test_record(Record {
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cols,
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vals: vec![expr, value],
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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 search_terms(&self) -> Vec<&str> {
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vec!["aka", "abbr", "otherwise"]
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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::eager::ToNu;
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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(ToNu {}),
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])
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}
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}
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