nushell/crates/nu-command/src/platform/ansi/link.rs
Stefan Holderbach a52386e837
Box ShellError in Value::Error (#8375)
# Description

Our `ShellError` at the moment has a `std::mem::size_of<ShellError>` of
136 bytes (on AMD64). As a result `Value` directly storing the struct
also required 136 bytes (thanks to alignment requirements).

This change stores the `Value::Error` `ShellError` on the heap.

Pro:
- Value now needs just 80 bytes
- Should be 1 cacheline less (still at least 2 cachelines)

Con:
- More small heap allocations when dealing with `Value::Error`
  - More heap fragmentation
  - Potential for additional required memcopies

# Further code changes

Includes a small refactor of `try` due to a type mismatch in its large
match.

# User-Facing Changes

None for regular users.

Plugin authors may have to update their matches on `Value` if they use
`nu-protocol`

Needs benchmarking to see if there is a benefit in real world workloads.
**Update** small improvements in runtime for workloads with high volume
of values. Significant reduction in maximum resident set size, when many
values are held in memory.

# Tests + Formatting
2023-03-12 09:57:27 +01:00

168 lines
4.8 KiB
Rust

use nu_engine::CallExt;
use nu_protocol::{
ast::{Call, CellPath},
engine::Command,
engine::EngineState,
engine::Stack,
Category, Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type,
Value,
};
#[derive(Clone)]
pub struct SubCommand;
impl Command for SubCommand {
fn name(&self) -> &str {
"ansi link"
}
fn signature(&self) -> Signature {
Signature::build("ansi link")
.input_output_types(vec![
(Type::String, Type::String),
(
Type::List(Box::new(Type::String)),
Type::List(Box::new(Type::String)),
),
(Type::Table(vec![]), Type::Table(vec![])),
(Type::Record(vec![]), Type::Record(vec![])),
])
.named(
"text",
SyntaxShape::String,
"Link text. Uses uri as text if absent. In case of
tables, records and lists applies this text to all elements",
Some('t'),
)
.rest(
"cell path",
SyntaxShape::CellPath,
"for a data structure input, add links to all strings at the given cell paths",
)
.vectorizes_over_list(true)
.allow_variants_without_examples(true)
.category(Category::Platform)
}
fn usage(&self) -> &str {
"Add a link (using OSC 8 escape sequence) to the given string."
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
operate(engine_state, stack, call, input)
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Create a link to open some file",
example: "'file:///file.txt' | ansi link --text 'Open Me!'",
result: Some(Value::string(
"\u{1b}]8;;file:///file.txt\u{1b}\\Open Me!\u{1b}]8;;\u{1b}\\",
Span::unknown(),
)),
},
Example {
description: "Create a link without text",
example: "'https://www.nushell.sh/' | ansi link",
result: Some(Value::string(
"\u{1b}]8;;https://www.nushell.sh/\u{1b}\\https://www.nushell.sh/\u{1b}]8;;\u{1b}\\",
Span::unknown(),
)),
},
Example {
description: "Format a table column into links",
example: "[[url text]; [https://example.com Text]] | ansi link url",
result: None,
},
]
}
}
fn operate(
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let text: Option<Spanned<String>> = call.get_flag(engine_state, stack, "text")?;
let text = text.map(|e| e.item);
let column_paths: Vec<CellPath> = call.rest(engine_state, stack, 0)?;
let command_span = call.head;
if column_paths.is_empty() {
input.map(
move |v| process_value(&v, &text, &command_span),
engine_state.ctrlc.clone(),
)
} else {
input.map(
move |v| process_each_path(v, &column_paths, &text, &command_span),
engine_state.ctrlc.clone(),
)
}
}
fn process_each_path(
mut value: Value,
column_paths: &Vec<CellPath>,
text: &Option<String>,
command_span: &Span,
) -> Value {
for path in column_paths {
let ret = value.update_cell_path(
&path.members,
Box::new(|v| process_value(v, text, command_span)),
);
if let Err(error) = ret {
return Value::Error {
error: Box::new(error),
};
}
}
value
}
fn process_value(value: &Value, text: &Option<String>, command_span: &Span) -> Value {
match value {
Value::String { val, span } => {
let text = text.as_deref().unwrap_or(val.as_str());
let result = add_osc_link(text, val.as_str());
Value::string(result, *span)
}
other => {
let got = format!("value is {}, not string", other.get_type());
Value::Error {
error: Box::new(ShellError::TypeMismatch {
err_message: got,
span: other.span().unwrap_or(*command_span),
}),
}
}
}
}
fn add_osc_link(text: &str, link: &str) -> String {
format!("\u{1b}]8;;{link}\u{1b}\\{text}\u{1b}]8;;\u{1b}\\")
}
#[cfg(test)]
mod tests {
use super::SubCommand;
#[test]
fn examples_work_as_expected() {
use crate::test_examples;
test_examples(SubCommand {})
}
}