forked from extern/nushell
Refactor drop columns to fix issues (#10903)
# Description This PR refactors `drop columns` and fixes issues #10902 and #6846. Tables with "holes" are now handled consistently, although still somewhat awkwardly. That is, the columns in the first row are used to determine which columns to drop, meaning that the columns displayed all the way to the right by `table` may not be the columns actually being dropped. For example, `[{a: 1}, {b: 2}] | drop column` will drop column `a` instead of `b`. Before, this would give a list of empty records. # User-Facing Changes `drop columns` can now take records as input.
This commit is contained in:
Ian Manske
GitHub
parent
cd75640a90
commit
33a7bc405f
@ -1,11 +1,13 @@
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use nu_engine::CallExt;
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use nu_protocol::ast::{Call, CellPath};
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use nu_protocol::ast::Call;
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use nu_protocol::engine::{Command, EngineState, Stack};
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use nu_protocol::{
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record, Category, Example, FromValue, IntoInterruptiblePipelineData, IntoPipelineData,
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PipelineData, Record, ShellError, Signature, Span, SyntaxShape, Type, Value,
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record, Category, Example, IntoInterruptiblePipelineData, IntoPipelineData, PipelineData,
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ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
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};
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use std::collections::HashSet;
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#[derive(Clone)]
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pub struct DropColumn;
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@ -16,7 +18,10 @@ impl Command for DropColumn {
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fn signature(&self) -> Signature {
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Signature::build(self.name())
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.input_output_types(vec![(Type::Table(vec![]), Type::Table(vec![]))])
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.input_output_types(vec![
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(Type::Table(vec![]), Type::Table(vec![])),
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(Type::Record(vec![]), Type::Record(vec![])),
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])
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.optional(
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"columns",
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SyntaxShape::Int,
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@ -41,148 +46,142 @@ impl Command for DropColumn {
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input: PipelineData,
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) -> Result<PipelineData, ShellError> {
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// the number of columns to drop
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let columns: Option<i64> = call.opt(engine_state, stack, 0)?;
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let span = call.head;
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let columns: Option<Spanned<i64>> = call.opt(engine_state, stack, 0)?;
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let columns_to_drop = if let Some(quantity) = columns {
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quantity
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let columns = if let Some(columns) = columns {
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if columns.item < 0 {
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return Err(ShellError::NeedsPositiveValue(columns.span));
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} else {
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columns.item as usize
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}
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} else {
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1
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};
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// Make columns to drop is positive
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if columns_to_drop < 0 {
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if let Some(expr) = call.positional_nth(0) {
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return Err(ShellError::NeedsPositiveValue(expr.span));
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}
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}
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dropcol(engine_state, span, input, columns_to_drop)
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drop_cols(engine_state, input, call.head, columns)
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}
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fn examples(&self) -> Vec<Example> {
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vec![Example {
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vec![
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Example {
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description: "Remove the last column of a table",
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example: "[[lib, extension]; [nu-lib, rs] [nu-core, rb]] | drop column",
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result: Some(Value::list(
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vec![
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Value::test_record(record!("lib" =>Value::test_string("nu-lib"))),
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Value::test_record(record!("lib" =>Value::test_string("nu-core"))),
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],
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Span::test_data(),
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result: Some(Value::test_list(vec![
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Value::test_record(record! { "lib" => Value::test_string("nu-lib") }),
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Value::test_record(record! { "lib" => Value::test_string("nu-core") }),
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])),
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},
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Example {
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description: "Remove the last column of a record",
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example: "{lib: nu-lib, extension: rs} | drop column",
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result: Some(Value::test_record(
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record! { "lib" => Value::test_string("nu-lib") },
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)),
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}]
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},
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]
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}
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}
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fn dropcol(
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fn drop_cols(
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engine_state: &EngineState,
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span: Span,
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input: PipelineData,
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columns: i64, // the number of columns to drop
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head: Span,
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columns: usize,
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) -> Result<PipelineData, ShellError> {
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let mut keep_columns = vec![];
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// For simplicity and performance, we use the first row's columns
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// as the columns for the whole table, and assume that later rows/records
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// have these same columns. However, this can give weird results like:
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// `[{a: 1}, {b: 2}] | drop column`
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// This will drop the column "a" instead of "b" even though column "b"
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// is displayed farther to the right.
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match input {
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PipelineData::ListStream(stream, ..) => {
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let mut output = vec![];
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PipelineData::ListStream(mut stream, ..) => {
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if let Some(mut first) = stream.next() {
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let drop_cols = drop_cols_set(&mut first, head, columns)?;
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let v: Vec<_> = stream.into_iter().collect();
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let input_cols = get_input_cols(v.clone());
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let kc = get_keep_columns(input_cols, columns);
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keep_columns = get_cellpath_columns(kc, span);
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for input_val in v {
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let mut record = Record::new();
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for path in &keep_columns {
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let fetcher = input_val.clone().follow_cell_path(&path.members, false)?;
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record.push(path.into_string(), fetcher);
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Ok(std::iter::once(first)
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.chain(stream.map(move |mut v| {
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match drop_record_cols(&mut v, head, &drop_cols) {
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Ok(()) => v,
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Err(e) => Value::error(e, head),
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}
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output.push(Value::record(record, span))
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}
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Ok(output
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.into_iter()
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.into_pipeline_data(engine_state.ctrlc.clone()))
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}
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PipelineData::Value(v, ..) => {
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let val_span = v.span();
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if let Value::List {
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vals: input_vals, ..
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} = v
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{
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let mut output = vec![];
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let input_cols = get_input_cols(input_vals.clone());
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let kc = get_keep_columns(input_cols, columns);
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keep_columns = get_cellpath_columns(kc, val_span);
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for input_val in input_vals {
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let mut record = Record::new();
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for path in &keep_columns {
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let fetcher = input_val.clone().follow_cell_path(&path.members, false)?;
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record.push(path.into_string(), fetcher);
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}
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output.push(Value::record(record, val_span))
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}
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Ok(output
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.into_iter()
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}))
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.into_pipeline_data(engine_state.ctrlc.clone()))
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} else {
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let mut record = Record::new();
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for cell_path in &keep_columns {
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let result = v.clone().follow_cell_path(&cell_path.members, false)?;
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record.push(cell_path.into_string(), result);
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Ok(PipelineData::Empty)
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}
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}
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PipelineData::Value(v, ..) => {
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let span = v.span();
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match v {
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Value::List { mut vals, .. } => {
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if let Some((first, rest)) = vals.split_first_mut() {
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let drop_cols = drop_cols_set(first, head, columns)?;
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for val in rest {
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drop_record_cols(val, head, &drop_cols)?
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}
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}
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Ok(Value::list(vals, span).into_pipeline_data())
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}
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Value::Record {
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val: mut record, ..
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} => {
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let len = record.len().saturating_sub(columns);
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record.truncate(len);
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Ok(Value::record(record, span).into_pipeline_data())
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}
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// Propagate errors
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Value::Error { error, .. } => Err(*error),
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val => Err(unsupported_value_error(&val, head)),
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}
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x => Ok(x),
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}
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PipelineData::Empty => Ok(PipelineData::Empty),
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PipelineData::ExternalStream { span, .. } => Err(ShellError::OnlySupportsThisInputType {
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exp_input_type: "table or record".into(),
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wrong_type: "raw data".into(),
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dst_span: head,
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src_span: span,
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}),
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}
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}
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fn get_input_cols(input: Vec<Value>) -> Vec<String> {
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let rec = input.first();
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match rec {
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Some(Value::Record { val, .. }) => val.cols.to_vec(),
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_ => vec!["".to_string()],
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fn drop_cols_set(val: &mut Value, head: Span, drop: usize) -> Result<HashSet<String>, ShellError> {
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if let Value::Record { val: record, .. } = val {
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let len = record.len().saturating_sub(drop);
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Ok(record.drain(len..).map(|(col, _)| col).collect())
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} else {
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Err(unsupported_value_error(val, head))
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}
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}
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fn get_cellpath_columns(keep_cols: Vec<String>, span: Span) -> Vec<CellPath> {
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let mut output = vec![];
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for keep_col in keep_cols {
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let val = Value::string(keep_col, span);
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let cell_path = match CellPath::from_value(val) {
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Ok(v) => v,
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Err(_) => return vec![],
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};
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output.push(cell_path);
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fn drop_record_cols(
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val: &mut Value,
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head: Span,
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drop_cols: &HashSet<String>,
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) -> Result<(), ShellError> {
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if let Value::Record { val, .. } = val {
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val.retain(|col, _| !drop_cols.contains(col));
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Ok(())
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} else {
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Err(unsupported_value_error(val, head))
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}
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output
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}
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fn get_keep_columns(input: Vec<String>, mut num_of_columns_to_drop: i64) -> Vec<String> {
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let vlen: i64 = input.len() as i64;
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if num_of_columns_to_drop > vlen {
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num_of_columns_to_drop = vlen;
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fn unsupported_value_error(val: &Value, head: Span) -> ShellError {
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ShellError::OnlySupportsThisInputType {
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exp_input_type: "table or record".into(),
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wrong_type: val.get_type().to_string(),
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dst_span: head,
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src_span: val.span(),
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}
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let num_of_columns_to_keep = (vlen - num_of_columns_to_drop) as usize;
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input[0..num_of_columns_to_keep].to_vec()
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test_examples() {
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use super::DropColumn;
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use crate::test_examples;
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test_examples(DropColumn {})
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crate::test_examples(DropColumn)
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}
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}
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@ -93,3 +93,45 @@ fn fail_on_non_iterator() {
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assert!(actual.err.contains("command doesn't support"));
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}
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#[test]
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fn disjoint_columns_first_row_becomes_empty() {
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let actual = nu!(pipeline(
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"
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[{a: 1}, {b: 2, c: 3}]
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| drop column
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| columns
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| to nuon
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"
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));
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assert_eq!(actual.out, "[b, c]");
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}
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#[test]
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fn disjoint_columns() {
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let actual = nu!(pipeline(
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"
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[{a: 1, b: 2}, {c: 3}]
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| drop column
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| columns
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| to nuon
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"
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));
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assert_eq!(actual.out, "[a, c]");
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}
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#[test]
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fn record() {
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let actual = nu!("{a: 1, b: 2} | drop column | to nuon");
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assert_eq!(actual.out, "{a: 1}");
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}
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#[test]
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fn more_columns_than_record_has() {
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let actual = nu!("{a: 1, b: 2} | drop column 3 | to nuon");
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assert_eq!(actual.out, "{}");
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}
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