nushell/crates/nu-command/src/math/max.rs
Ian Manske 9996e4a1f8
Shrink the size of Expr (#12610)
# Description
Continuing from #12568, this PR further reduces the size of `Expr` from
64 to 40 bytes. It also reduces `Expression` from 128 to 96 bytes and
`Type` from 32 to 24 bytes.

This was accomplished by:
- for `Expr` with multiple fields (e.g., `Expr::Thing(A, B, C)`),
merging the fields into new AST struct types and then boxing this struct
(e.g. `Expr::Thing(Box<ABC>)`).
- replacing `Vec<T>` with `Box<[T]>` in multiple places. `Expr`s and
`Expression`s should rarely be mutated, if at all, so this optimization
makes sense.

By reducing the size of these types, I didn't notice a large performance
improvement (at least compared to #12568). But this PR does reduce the
memory usage of nushell. My config is somewhat light so I only noticed a
difference of 1.4MiB (38.9MiB vs 37.5MiB).

---------

Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>
2024-04-24 15:46:35 +00:00

90 lines
2.6 KiB
Rust

use crate::math::{
reducers::{reducer_for, Reduce},
utils::run_with_function,
};
use nu_engine::command_prelude::*;
#[derive(Clone)]
pub struct SubCommand;
impl Command for SubCommand {
fn name(&self) -> &str {
"math max"
}
fn signature(&self) -> Signature {
Signature::build("math max")
.input_output_types(vec![
(Type::List(Box::new(Type::Number)), Type::Number),
(Type::List(Box::new(Type::Duration)), Type::Duration),
(Type::List(Box::new(Type::Filesize)), Type::Filesize),
(Type::List(Box::new(Type::Any)), Type::Any),
(Type::Range, Type::Number),
(Type::table(), Type::record()),
(Type::record(), Type::record()),
])
.allow_variants_without_examples(true)
.category(Category::Math)
}
fn usage(&self) -> &str {
"Returns the maximum of a list of values, or of columns in a table."
}
fn search_terms(&self) -> Vec<&str> {
vec!["maximum", "largest"]
}
fn run(
&self,
_engine_state: &EngineState,
_stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
run_with_function(call, input, maximum)
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Find the maximum of a list of numbers",
example: "[-50 100 25] | math max",
result: Some(Value::test_int(100)),
},
Example {
description: "Find the maxima of the columns of a table",
example: "[{a: 1 b: 3} {a: 2 b: -1}] | math max",
result: Some(Value::test_record(record! {
"a" => Value::test_int(2),
"b" => Value::test_int(3),
})),
},
Example {
description: "Find the maximum of a list of dates",
example: "[2022-02-02 2022-12-30 2012-12-12] | math max",
result: Some(Value::test_date(
"2022-12-30 00:00:00Z".parse().unwrap_or_default(),
)),
},
]
}
}
pub fn maximum(values: &[Value], span: Span, head: Span) -> Result<Value, ShellError> {
let max_func = reducer_for(Reduce::Maximum);
max_func(Value::nothing(head), values.to_vec(), span, head)
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(SubCommand {})
}
}