nushell/crates/nu_plugin_formats/src/from/vcf.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

165 lines
5.6 KiB
Rust

use ical::parser::vcard::component::*;
use ical::property::Property;
use indexmap::map::IndexMap;
use nu_plugin::{EvaluatedCall, LabeledError};
use nu_protocol::{PluginExample, ShellError, Span, Spanned, Value};
pub const CMD_NAME: &str = "from vcf";
pub fn from_vcf_call(call: &EvaluatedCall, input: &Value) -> Result<Value, LabeledError> {
let span = input.span().unwrap_or(call.head);
let input_string = input.as_string()?;
let head = call.head;
let input_string = input_string
.lines()
.map(|x| x.trim().to_string())
.collect::<Vec<_>>()
.join("\n");
let input_bytes = input_string.as_bytes();
let cursor = std::io::Cursor::new(input_bytes);
let parser = ical::VcardParser::new(cursor);
let iter = parser.map(move |contact| match contact {
Ok(c) => contact_to_value(c, head),
Err(e) => Value::Error {
error: Box::new(ShellError::UnsupportedInput(
format!("input cannot be parsed as .vcf ({e})"),
"value originates from here".into(),
head,
span,
)),
},
});
let collected: Vec<_> = iter.collect();
Ok(Value::List {
vals: collected,
span: head,
})
}
pub fn examples() -> Vec<PluginExample> {
vec![PluginExample {
example: "'BEGIN:VCARD
N:Foo
FN:Bar
EMAIL:foo@bar.com
END:VCARD' | from vcf"
.into(),
description: "Converts ics formatted string to table".into(),
result: Some(Value::List {
vals: vec![Value::Record {
cols: vec!["properties".to_string()],
vals: vec![Value::List {
vals: vec![
Value::Record {
cols: vec![
"name".to_string(),
"value".to_string(),
"params".to_string(),
],
vals: vec![
Value::test_string("N"),
Value::test_string("Foo"),
Value::Nothing {
span: Span::test_data(),
},
],
span: Span::test_data(),
},
Value::Record {
cols: vec![
"name".to_string(),
"value".to_string(),
"params".to_string(),
],
vals: vec![
Value::test_string("FN"),
Value::test_string("Bar"),
Value::Nothing {
span: Span::test_data(),
},
],
span: Span::test_data(),
},
Value::Record {
cols: vec![
"name".to_string(),
"value".to_string(),
"params".to_string(),
],
vals: vec![
Value::test_string("EMAIL"),
Value::test_string("foo@bar.com"),
Value::Nothing {
span: Span::test_data(),
},
],
span: Span::test_data(),
},
],
span: Span::test_data(),
}],
span: Span::test_data(),
}],
span: Span::test_data(),
}),
}]
}
fn contact_to_value(contact: VcardContact, span: Span) -> Value {
let mut row = IndexMap::new();
row.insert(
"properties".to_string(),
properties_to_value(contact.properties, span),
);
Value::from(Spanned { item: row, span })
}
fn properties_to_value(properties: Vec<Property>, span: Span) -> Value {
Value::List {
vals: properties
.into_iter()
.map(|prop| {
let mut row = IndexMap::new();
let name = Value::String {
val: prop.name,
span,
};
let value = match prop.value {
Some(val) => Value::String { val, span },
None => Value::Nothing { span },
};
let params = match prop.params {
Some(param_list) => params_to_value(param_list, span),
None => Value::Nothing { span },
};
row.insert("name".to_string(), name);
row.insert("value".to_string(), value);
row.insert("params".to_string(), params);
Value::from(Spanned { item: row, span })
})
.collect::<Vec<Value>>(),
span,
}
}
fn params_to_value(params: Vec<(String, Vec<String>)>, span: Span) -> Value {
let mut row = IndexMap::new();
for (param_name, param_values) in params {
let values: Vec<Value> = param_values
.into_iter()
.map(|val| Value::string(val, span))
.collect();
let values = Value::List { vals: values, span };
row.insert(param_name, values);
}
Value::from(Spanned { item: row, span })
}