Struct NamedListBuilder 

pub struct NamedListBuilder {
    values: Preserved,
    names: Vec<String>,
}

A safe, owned builder for a named R list of mixed IntoR values.

One growing VECSXP holds the values and is rooted by a Preserved handle. Moving or dropping builders in any order is safe: no protect-stack entries are held by the builder, regardless of the number of values pushed. Construction, use and drop must take place on R’s main thread (!Send + !Sync).

Return the builder from a #[miniextendr] function to return a named list. To keep working with the finished value while R allocates (set a class, pass it to R code, read it back), consume it with into_list for a rooted BuiltList, or with into_data_frame for a rooted data frame. Empty results have names = character(0). There is no bare List finish.

let mut columns = NamedListBuilder::with_capacity(2);
columns.push("id", vec![1, 2, 3]);
columns.push("value", vec![0.5, 1.5, 2.5]);
columns.rename(1, "estimate");
let frame = columns.into_data_frame()?;

Fields

values: Preserved

names: Vec<String>

Implementations

impl NamedListBuilder

pub fn new() -> Self

Create an empty builder on R’s main thread.

pub fn with_capacity(n: usize) -> Self

Reserve space for n entries on R’s main thread.

pub fn push(&mut self, name: impl Into<String>, value: impl IntoR)

Convert and append a value, rooting it before any later allocation.

pub fn push_sexp(&mut self, name: impl Into<String>, sexp: SEXP)

Append an existing R value, retaining its attributes and identity.

The value must be live when passed in. A freshly allocated, unrooted value can be passed directly: even when growth is needed it is rooted before the allocation. The builder then keeps it alive independently of the caller’s roots.

pub fn rename(&mut self, index: usize, name: impl Into<String>)

Rename the entry at the zero-based index.

Panics if the index is outside 0..self.len().

pub fn names(&self) -> &[String]

Entry names in insertion order.

pub fn names_mut(&mut self) -> &mut [String]

Edit names without changing the number or order of values.

pub fn len(&self) -> usize

Number of entries pushed so far.

pub fn is_empty(&self) -> bool

Whether no entries have been pushed.

pub fn into_list(self) -> BuiltList

Finish as an owned, GC-rooted named list.

The BuiltList keeps the list reachable while it lives, so its attributes can be set and it can be handed to R code before it is returned.

pub fn into_data_frame(self) -> Result<BuiltDataFrame, DataFrameError>

Finish as an owned, GC-rooted data frame with compact row.names.

Returns DataFrameError::UnequalLengths naming every column whose length differs from the first. No recycling is performed. Zero columns produce a zero-row frame with names = character(0).

fn resize(&mut self, capacity: usize)

Reallocate, keeping both containers rooted until copying is complete.

fn finish(&mut self)

Trait Implementations

impl Default for NamedListBuilder

fn default() -> Self

Returns the “default value” for a type.

impl IntoR for NamedListBuilder

type Error = !

The error type for fallible conversions.

fn try_into_sexp(self) -> Result<SEXP, Self::Error>

Try to convert this value to an R SEXP.

unsafe fn try_into_sexp_unchecked(self) -> Result<SEXP, Self::Error>

Try to convert to SEXP without thread safety checks.

fn into_sexp(self) -> SEXP

where Self: Sized,

Convert this value to an R SEXP, panicking on error.

unsafe fn into_sexp_unchecked(self) -> SEXP

where Self: Sized,

Convert to SEXP without thread safety checks, panicking on error.

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