Struct NamedDataFrameListBuilder 

pub struct NamedDataFrameListBuilder {
    scope: ProtectScope,
    pairs: Vec<(String, SEXP)>,
}

Assemble a named list whose elements are DataFrames, without per-result OwnedProtect bookkeeping.

Why this is distinct from DataFrame::builder

DataFrame::builder and the serde SerdeRowBuilder both produce a single DataFrame. This builder produces a different shape — a named list of data.frames, e.g. list(results = df, error = df) — so it deliberately keeps its own name rather than folding into the DataFrame::builder vocabulary. Its inputs are DataFrames (from any producer: IntoDataFrame, the serde vec_to_dataframe, or GroupedDataFrame::frames); its output is a List.

Each push protects the input data.frame’s SEXP via an internal ProtectScope; build consumes the builder and emits a named list via List::from_raw_pairs. The scope drops at the end of build, releasing the per-input protects — by which point the children are reachable from the assembled list.

Example

let result = NamedDataFrameListBuilder::new()
    .push("results", oks.into_dataframe()?)
    .push("error",   errs.into_dataframe()?)
    .build();

Fields

scope: ProtectScope

pairs: Vec<(String, SEXP)>

Implementations

impl NamedDataFrameListBuilder

pub fn new() -> Self

Create an empty builder.

Safety (caller)

Must be called from the R main thread. The internal ProtectScope carries !Send + !Sync so the builder cannot be moved to another thread.

pub fn with_capacity(n: usize) -> Self

Create a builder pre-allocated for n entries.

Equivalent to new but avoids repeated re-allocations when the number of partitions is known up front.

pub fn push<S: Into<String>>(self, name: S, df: DataFrame) -> Self

Append a named data.frame. The input’s SEXP is protected internally for the lifetime of the builder.

pub fn len(&self) -> usize

Number of entries pushed so far.

pub fn is_empty(&self) -> bool

Whether no entries have been pushed yet.

pub fn build(self) -> List

Consume the builder and return the assembled named List.

The returned List’s SEXP is not separately protected on return — the caller takes responsibility for protection (typically by immediately handing it back to R via the .Call return path). This matches the contract of List::from_raw_pairs.

Trait Implementations

impl Default for NamedDataFrameListBuilder

fn default() -> Self

Returns the “default value” for a type.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 32 bytes