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}`.
80 lines
2.2 KiB
Rust
80 lines
2.2 KiB
Rust
use crate::math::reducers::{reducer_for, Reduce};
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use crate::math::utils::run_with_function;
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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, PipelineData, Record, ShellError, Signature, Span, Type, Value,
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};
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#[derive(Clone)]
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pub struct SubCommand;
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impl Command for SubCommand {
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fn name(&self) -> &str {
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"math max"
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}
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fn signature(&self) -> Signature {
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Signature::build("math max")
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.input_output_types(vec![
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(Type::List(Box::new(Type::Any)), Type::Any),
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(Type::Table(vec![]), Type::Record(vec![])),
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])
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.allow_variants_without_examples(true)
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.category(Category::Math)
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}
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fn usage(&self) -> &str {
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"Returns the maximum of a list of values, or of columns in a table."
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}
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fn search_terms(&self) -> Vec<&str> {
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vec!["maximum", "largest"]
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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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run_with_function(call, input, maximum)
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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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description: "Find the maximum of list of numbers",
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example: "[-50 100 25] | math max",
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result: Some(Value::test_int(100)),
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},
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Example {
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description: "Find the maxima of the columns of a table",
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example: "[{a: 1 b: 3} {a: 2 b: -1}] | math max",
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result: Some(Value::test_record(Record {
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cols: vec!["a".to_string(), "b".to_string()],
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vals: vec![Value::test_int(2), Value::test_int(3)],
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})),
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},
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]
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}
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}
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pub fn maximum(values: &[Value], span: Span, head: Span) -> Result<Value, ShellError> {
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let max_func = reducer_for(Reduce::Maximum);
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max_func(Value::nothing(head), values.to_vec(), span, head)
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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(SubCommand {})
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}
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}
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