nushell/crates/nu-command/src/strings/split/column.rs
JT 1e3e034021
Spanned Value step 1: span all value cases (#10042)
# Description

This doesn't really do much that the user could see, but it helps get us
ready to do the steps of the refactor to split the span off of Value, so
that values can be spanless. This allows us to have top-level values
that can hold both a Value and a Span, without requiring that all values
have them.

We expect to see significant memory reduction by removing so many
unnecessary spans from values. For example, a table of 100,000 rows and
5 columns would have a savings of ~8megs in just spans that are almost
always duplicated.

# User-Facing Changes

Nothing yet

# Tests + Formatting
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2023-08-25 08:48:05 +12:00

237 lines
7.8 KiB
Rust

use nu_engine::CallExt;
use nu_protocol::{
ast::Call,
engine::{Command, EngineState, Stack},
Category, Example, PipelineData, Record, ShellError, Signature, Span, Spanned, SyntaxShape,
Type, Value,
};
use regex::Regex;
#[derive(Clone)]
pub struct SubCommand;
impl Command for SubCommand {
fn name(&self) -> &str {
"split column"
}
fn signature(&self) -> Signature {
Signature::build("split column")
.input_output_types(vec![
(Type::String, Type::Table(vec![])),
(
// TODO: no test coverage (is this behavior a bug or a feature?)
Type::List(Box::new(Type::String)),
Type::Table(vec![]),
),
])
.required(
"separator",
SyntaxShape::String,
"the character or string that denotes what separates columns",
)
.switch("collapse-empty", "remove empty columns", Some('c'))
.switch("regex", "separator is a regular expression", Some('r'))
.rest(
"rest",
SyntaxShape::String,
"column names to give the new columns",
)
.category(Category::Strings)
}
fn usage(&self) -> &str {
"Split a string into multiple columns using a separator."
}
fn search_terms(&self) -> Vec<&str> {
vec!["separate", "divide", "regex"]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
split_column(engine_state, stack, call, input)
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Split a string into columns by the specified separator",
example: "'a--b--c' | split column '--'",
result: Some(Value::List {
vals: vec![Value::test_record(Record {
cols: vec![
"column1".to_string(),
"column2".to_string(),
"column3".to_string(),
],
vals: vec![
Value::test_string("a"),
Value::test_string("b"),
Value::test_string("c"),
],
})],
span: Span::test_data(),
}),
},
Example {
description: "Split a string into columns of char and remove the empty columns",
example: "'abc' | split column -c ''",
result: Some(Value::List {
vals: vec![Value::test_record(Record {
cols: vec![
"column1".to_string(),
"column2".to_string(),
"column3".to_string(),
],
vals: vec![
Value::test_string("a"),
Value::test_string("b"),
Value::test_string("c"),
],
})],
span: Span::test_data(),
}),
},
Example {
description: "Split a list of strings into a table",
example: "['a-b' 'c-d'] | split column -",
result: Some(Value::List {
vals: vec![
Value::test_record(Record {
cols: vec!["column1".to_string(), "column2".to_string()],
vals: vec![Value::test_string("a"), Value::test_string("b")],
}),
Value::test_record(Record {
cols: vec!["column1".to_string(), "column2".to_string()],
vals: vec![Value::test_string("c"), Value::test_string("d")],
}),
],
span: Span::test_data(),
}),
},
Example {
description: "Split a list of strings into a table, ignoring padding",
example: r"['a - b' 'c - d'] | split column -r '\s*-\s*'",
result: Some(Value::List {
vals: vec![
Value::test_record(Record {
cols: vec!["column1".to_string(), "column2".to_string()],
vals: vec![Value::test_string("a"), Value::test_string("b")],
}),
Value::test_record(Record {
cols: vec!["column1".to_string(), "column2".to_string()],
vals: vec![Value::test_string("c"), Value::test_string("d")],
}),
],
span: Span::test_data(),
}),
},
]
}
}
fn split_column(
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let name_span = call.head;
let separator: Spanned<String> = call.req(engine_state, stack, 0)?;
let rest: Vec<Spanned<String>> = call.rest(engine_state, stack, 1)?;
let collapse_empty = call.has_flag("collapse-empty");
let regex = if call.has_flag("regex") {
Regex::new(&separator.item)
} else {
let escaped = regex::escape(&separator.item);
Regex::new(&escaped)
}
.map_err(|err| {
ShellError::GenericError(
"Error with regular expression".into(),
err.to_string(),
Some(separator.span),
None,
Vec::new(),
)
})?;
input.flat_map(
move |x| split_column_helper(&x, &regex, &rest, collapse_empty, name_span),
engine_state.ctrlc.clone(),
)
}
fn split_column_helper(
v: &Value,
separator: &Regex,
rest: &[Spanned<String>],
collapse_empty: bool,
head: Span,
) -> Vec<Value> {
if let Ok(s) = v.as_string() {
let split_result: Vec<_> = separator
.split(&s)
.filter(|x| !(collapse_empty && x.is_empty()))
.collect();
let positional: Vec<_> = rest.iter().map(|f| f.item.clone()).collect();
// If they didn't provide column names, make up our own
let mut record = Record::new();
if positional.is_empty() {
let mut gen_columns = vec![];
for i in 0..split_result.len() {
gen_columns.push(format!("column{}", i + 1));
}
for (&k, v) in split_result.iter().zip(&gen_columns) {
record.push(v, Value::string(k, head));
}
} else {
for (&k, v) in split_result.iter().zip(&positional) {
record.push(v, Value::string(k, head));
}
}
vec![Value::record(record, head)]
} else {
match v {
Value::Error { error, .. } => {
vec![Value::Error {
error: Box::new(*error.clone()),
span: head,
}]
}
v => {
let span = v.span();
vec![Value::Error {
error: Box::new(ShellError::PipelineMismatch {
exp_input_type: "string".into(),
dst_span: head,
src_span: span,
}),
span,
}]
}
}
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(SubCommand {})
}
}