mirror of
https://github.com/nushell/nushell
synced 2024-12-27 13:33:16 +00:00
Refactor flatten command (#11017)
# Description
Refactors the `flatten` command to remove a bunch of cloning. This was
down by passing ownership of the `Value` to `flat_value`, removing the
lifetime on `TableInside`, and using `Vec<Record>` in `FlattenedRows`
instead of a pair of `Vec` of columns and values.
For the quick benchmark below, it seems to be twice as fast now:
```nushell
let data = ls crates | where type == dir | each { ls $'($in.name)/**/*' }
timeit { for x in 0..1000 { $data | flatten } }
```
This took 550ms on v0.86.0 and only 230ms on this PR.
But considering that
```nushell
timeit { for x in 0..1000 { $data } }
```
takes 200ms on both versions, then the difference for `flatten` itself
is really 250ms vs 30ms -- 8x faster.
This commit is contained in:
Ian Manske
GitHub
parent
fe92051bb3
commit
523d0bca16
1 changed files with 153 additions and 188 deletions
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@ -81,7 +81,7 @@ impl Command for Flatten {
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},
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Example {
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description: "Flatten inner table",
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example: "{ a: b, d: [ 1 2 3 4 ], e: [ 4 3 ] } | flatten d --all",
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example: "{ a: b, d: [ 1 2 3 4 ], e: [ 4 3 ] } | flatten d --all",
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result: Some(Value::list(
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vec![
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Value::test_record(record! {
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@ -126,232 +126,197 @@ fn flatten(
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call: &Call,
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input: PipelineData,
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) -> Result<PipelineData, ShellError> {
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let tag = call.head;
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let columns: Vec<CellPath> = call.rest(engine_state, stack, 0)?;
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let metadata = input.metadata();
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let flatten_all = call.has_flag("all");
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input
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.flat_map(
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move |item| flat_value(&columns, &item, tag, flatten_all),
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move |item| flat_value(&columns, item, flatten_all),
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engine_state.ctrlc.clone(),
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)
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.map(|x| x.set_metadata(metadata))
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}
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enum TableInside<'a> {
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enum TableInside {
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// handle for a column which contains a single list(but not list of records)
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// it contains (column, span, values in the column, column index).
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Entries(&'a str, &'a Span, Vec<&'a Value>, usize),
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Entries(String, Vec<Value>, usize),
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// handle for a column which contains a table, we can flatten the inner column to outer level
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// `columns` means that for the given row, it contains `len(columns)` nested rows, and each nested row contains a list of column name.
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// Likely, `values` means that for the given row, it contains `len(values)` nested rows, and each nested row contains a list of values.
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//
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// `records` is the nested/inner table to flatten to the outer level
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// `parent_column_name` is handled for conflicting column name, the nested table may contains columns which has the same name
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// to outer level, for that case, the output column name should be f"{parent_column_name}_{inner_column_name}".
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// `parent_column_index` is the column index in original table.
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FlattenedRows {
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columns: Vec<Vec<String>>,
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_span: &'a Span,
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values: Vec<Vec<Value>>,
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parent_column_name: &'a str,
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records: Vec<Record>,
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parent_column_name: String,
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parent_column_index: usize,
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},
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}
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fn flat_value(columns: &[CellPath], item: &Value, name_tag: Span, all: bool) -> Vec<Value> {
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fn flat_value(columns: &[CellPath], item: Value, all: bool) -> Vec<Value> {
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let tag = item.span();
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if item.as_record().is_ok() {
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let mut out = IndexMap::<String, Value>::new();
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let mut inner_table = None;
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match item {
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Value::Record { val, .. } => {
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let mut out = IndexMap::<String, Value>::new();
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let mut inner_table = None;
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let record = match item {
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Value::Record { val, .. } => val,
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// Propagate errors by explicitly matching them before the final case.
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Value::Error { .. } => return vec![item.clone()],
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other => {
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return vec![Value::error(
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ShellError::OnlySupportsThisInputType {
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exp_input_type: "record".into(),
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wrong_type: other.get_type().to_string(),
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dst_span: name_tag,
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src_span: other.span(),
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},
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name_tag,
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)];
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}
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};
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for (column_index, (column, value)) in val.into_iter().enumerate() {
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let column_requested = columns.iter().find(|c| c.into_string() == column);
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let need_flatten = { columns.is_empty() || column_requested.is_some() };
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let span = value.span();
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let s = item.span();
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for (column_index, (column, value)) in record.iter().enumerate() {
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let column_requested = columns.iter().find(|c| c.into_string() == *column);
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let need_flatten = { columns.is_empty() || column_requested.is_some() };
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let span = value.span();
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match value {
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Value::Record { val, .. } => {
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if need_flatten {
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val.iter().for_each(|(col, val)| {
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if out.contains_key(col) {
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out.insert(format!("{column}_{col}"), val.clone());
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} else {
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out.insert(col.to_string(), val.clone());
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}
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})
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} else if out.contains_key(column) {
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out.insert(format!("{column}_{column}"), value.clone());
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} else {
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out.insert(column.to_string(), value.clone());
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}
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}
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Value::List { vals, .. } if all && vals.iter().all(|f| f.as_record().is_ok()) => {
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if need_flatten && inner_table.is_some() {
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return vec![Value::error( ShellError::UnsupportedInput { msg: "can only flatten one inner list at a time. tried flattening more than one column with inner lists... but is flattened already".to_string(), input: "value originates from here".into(), msg_span: s, input_span: span }, span)
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];
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}
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// it's a table (a list of record, we can flatten inner record)
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let mut records = vec![];
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for v in vals {
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if let Ok(r) = v.as_record() {
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records.push(r)
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}
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}
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if need_flatten {
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let cols = records.iter().map(|r| r.cols.clone());
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let vals = records.iter().map(|r| r.vals.clone());
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inner_table = Some(TableInside::FlattenedRows {
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columns: cols.collect(),
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_span: &s,
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values: vals.collect(),
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parent_column_name: column,
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parent_column_index: column_index,
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});
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} else if out.contains_key(column) {
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out.insert(format!("{column}_{column}"), value.clone());
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} else {
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out.insert(column.to_string(), value.clone());
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}
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}
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Value::List { vals: values, .. } => {
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if need_flatten && inner_table.is_some() {
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return vec![Value::error( ShellError::UnsupportedInput { msg: "can only flatten one inner list at a time. tried flattening more than one column with inner lists... but is flattened already".to_string(), input: "value originates from here".into(), msg_span: s, input_span: span }, span)
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];
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}
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if !columns.is_empty() {
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let cell_path = column_requested.and_then(|x| match x.members.first() {
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Some(PathMember::String { val, span: _, .. }) => Some(val),
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_ => None,
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});
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if let Some(r) = cell_path {
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inner_table = Some(TableInside::Entries(
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r,
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&s,
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values.iter().collect::<Vec<_>>(),
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column_index,
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));
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} else {
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out.insert(column.to_string(), value.clone());
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}
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} else {
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inner_table = Some(TableInside::Entries(
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column,
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&s,
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values.iter().collect::<Vec<_>>(),
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column_index,
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));
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}
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}
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_ => {
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out.insert(column.to_string(), value.clone());
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}
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}
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}
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let mut expanded = vec![];
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match inner_table {
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Some(TableInside::Entries(column, _, entries, parent_column_index)) => {
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for entry in entries {
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let base = out.clone();
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let mut record = Record::new();
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let mut index = 0;
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for (col, val) in base.into_iter() {
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// meet the flattened column, push them to result record first
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// this can avoid output column order changed.
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if index == parent_column_index {
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record.push(column, entry.clone());
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}
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record.push(col, val);
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index += 1;
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}
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// the flattened column may be the last column in the original table.
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if index == parent_column_index {
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record.push(column, entry.clone());
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}
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expanded.push(Value::record(record, tag));
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}
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}
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Some(TableInside::FlattenedRows {
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columns,
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_span,
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values,
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parent_column_name,
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parent_column_index,
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}) => {
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for (inner_cols, inner_vals) in columns.into_iter().zip(values) {
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let base = out.clone();
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let mut record = Record::new();
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let mut index = 0;
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for (base_col, base_val) in base.into_iter() {
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// meet the flattened column, push them to result record first
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// this can avoid output column order changed.
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if index == parent_column_index {
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for (col, val) in inner_cols.iter().zip(inner_vals.iter()) {
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if record.contains(col) {
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record.push(format!("{parent_column_name}_{col}"), val.clone());
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match value {
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Value::Record { val, .. } => {
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if need_flatten {
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for (col, val) in val {
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if out.contains_key(&col) {
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out.insert(format!("{column}_{col}"), val);
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} else {
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record.push(col, val.clone());
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};
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out.insert(col, val);
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}
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}
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} else if out.contains_key(&column) {
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out.insert(format!("{column}_{column}"), Value::record(val, span));
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} else {
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out.insert(column, Value::record(val, span));
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}
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}
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Value::List { vals, .. } => {
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if need_flatten && inner_table.is_some() {
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return vec![Value::error(
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ShellError::UnsupportedInput {
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msg: "can only flatten one inner list at a time. tried flattening more than one column with inner lists... but is flattened already".into(),
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input: "value originates from here".into(),
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msg_span: tag,
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input_span: span
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},
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span,
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)];
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}
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record.push(base_col, base_val);
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index += 1;
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}
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if all && vals.iter().all(|f| f.as_record().is_ok()) {
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// it's a table (a list of record, we can flatten inner record)
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if need_flatten {
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let records = vals
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.into_iter()
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.filter_map(|v| {
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if let Value::Record { val, .. } = v {
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Some(val)
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} else {
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None
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}
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})
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.collect();
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// the flattened column may be the last column in the original table.
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if index == parent_column_index {
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for (col, val) in inner_cols.iter().zip(inner_vals.iter()) {
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if record.contains(col) {
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record.push(format!("{parent_column_name}_{col}"), val.clone());
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inner_table = Some(TableInside::FlattenedRows {
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records,
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parent_column_name: column,
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parent_column_index: column_index,
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});
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} else if out.contains_key(&column) {
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out.insert(format!("{column}_{column}"), Value::list(vals, span));
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} else {
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record.push(col, val.clone());
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out.insert(column, Value::list(vals, span));
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}
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} else if !columns.is_empty() {
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let cell_path =
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column_requested.and_then(|x| match x.members.first() {
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Some(PathMember::String { val, .. }) => Some(val),
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_ => None,
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});
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if let Some(r) = cell_path {
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inner_table =
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Some(TableInside::Entries(r.clone(), vals, column_index));
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} else {
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out.insert(column, Value::list(vals, span));
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}
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} else {
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inner_table = Some(TableInside::Entries(column, vals, column_index));
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}
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}
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expanded.push(Value::record(record, tag));
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_ => {
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out.insert(column, value);
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}
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}
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}
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None => {
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expanded.push(Value::record(out.into_iter().collect(), tag));
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let mut expanded = vec![];
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match inner_table {
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Some(TableInside::Entries(column, entries, parent_column_index)) => {
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for entry in entries {
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let base = out.clone();
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let mut record = Record::new();
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let mut index = 0;
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for (col, val) in base.into_iter() {
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// meet the flattened column, push them to result record first
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// this can avoid output column order changed.
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if index == parent_column_index {
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record.push(column.clone(), entry.clone());
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}
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record.push(col, val);
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index += 1;
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}
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// the flattened column may be the last column in the original table.
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if index == parent_column_index {
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record.push(column.clone(), entry);
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}
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expanded.push(Value::record(record, tag));
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}
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}
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Some(TableInside::FlattenedRows {
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records,
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parent_column_name,
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parent_column_index,
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}) => {
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for inner_record in records {
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let base = out.clone();
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let mut record = Record::new();
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let mut index = 0;
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for (base_col, base_val) in base {
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// meet the flattened column, push them to result record first
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// this can avoid output column order changed.
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if index == parent_column_index {
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for (col, val) in &inner_record {
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if record.contains(col) {
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record.push(
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format!("{parent_column_name}_{col}"),
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val.clone(),
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);
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} else {
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record.push(col, val.clone());
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};
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}
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}
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record.push(base_col, base_val);
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index += 1;
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}
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// the flattened column may be the last column in the original table.
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if index == parent_column_index {
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for (col, val) in inner_record {
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if record.contains(&col) {
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record.push(format!("{parent_column_name}_{col}"), val);
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} else {
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record.push(col, val);
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}
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}
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}
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expanded.push(Value::record(record, tag));
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}
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}
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None => {
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expanded.push(Value::record(out.into_iter().collect(), tag));
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}
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}
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expanded
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}
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expanded
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} else if item.as_list().is_ok() {
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if let Value::List { vals, .. } = item {
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vals.to_vec()
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} else {
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vec![]
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}
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} else {
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vec![item.clone()]
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Value::List { vals, .. } => vals,
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item => vec![item],
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}
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}
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