nushell/crates/nu-command/src/bytes/length.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

99 lines
2.9 KiB
Rust

use nu_cmd_base::input_handler::{operate, CellPathOnlyArgs};
use nu_engine::command_prelude::*;
#[derive(Clone)]
pub struct BytesLen;
impl Command for BytesLen {
fn name(&self) -> &str {
"bytes length"
}
fn signature(&self) -> Signature {
Signature::build("bytes length")
.input_output_types(vec![
(Type::Binary, Type::Int),
(
Type::List(Box::new(Type::Binary)),
Type::List(Box::new(Type::Int)),
),
(Type::table(), Type::table()),
(Type::record(), Type::record()),
])
.allow_variants_without_examples(true)
.rest(
"rest",
SyntaxShape::CellPath,
"For a data structure input, find the length of data at the given cell paths.",
)
.category(Category::Bytes)
}
fn usage(&self) -> &str {
"Output the length of any bytes in the pipeline."
}
fn search_terms(&self) -> Vec<&str> {
vec!["size", "count"]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let cell_paths: Vec<CellPath> = call.rest(engine_state, stack, 1)?;
let arg = CellPathOnlyArgs::from(cell_paths);
operate(length, arg, input, call.head, engine_state.ctrlc.clone())
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Return the length of a binary",
example: "0x[1F FF AA AB] | bytes length",
result: Some(Value::test_int(4)),
},
Example {
description: "Return the lengths of multiple binaries",
example: "[0x[1F FF AA AB] 0x[1F]] | bytes length",
result: Some(Value::list(
vec![Value::test_int(4), Value::test_int(1)],
Span::test_data(),
)),
},
]
}
}
fn length(val: &Value, _args: &CellPathOnlyArgs, span: Span) -> Value {
let val_span = val.span();
match val {
Value::Binary { val, .. } => Value::int(val.len() as i64, val_span),
// Propagate errors by explicitly matching them before the final case.
Value::Error { .. } => val.clone(),
other => Value::error(
ShellError::OnlySupportsThisInputType {
exp_input_type: "binary".into(),
wrong_type: other.get_type().to_string(),
dst_span: span,
src_span: other.span(),
},
span,
),
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(BytesLen {})
}
}