sub-.priority_queue: Indexing for Priority Queues

In Immutables: Fast and Functional Data Structures

Indexing for Priority Queues

Description

Name-based indexing is supported for reads only. Positional indexing and all replacement indexing are intentionally blocked to preserve queue-first UX.

Usage

## S3 method for class 'priority_queue'
x[i, ...]

## S3 method for class 'priority_queue'
x[[i, ...]]

## S3 replacement method for class 'priority_queue'
x[i] <- value

## S3 replacement method for class 'priority_queue'
x[[i]] <- value

## S3 method for class 'priority_queue'
x$name

## S3 replacement method for class 'priority_queue'
x$name <- value

Arguments

x	A priority_queue.
i	Index input. For reads, must be a character name (scalar for [[).
...	Unused.
value	Replacement value (unsupported).
name	Element name (for $ and ⁠$<-⁠).

Details

priority_queue supports name-based read indexing only.

• [: character vector of names, returns a priority_queue subset.

• [[ and $: scalar name, return the payload value.

• Positional indexing and all replacement indexing forms are unsupported.

Value

For $/[[/[: queue payload values or queue subsets by name. Replacement forms always error.

Examples

q <- priority_queue(a = "task-a", b = "task-b", priorities = c(2, 1))

q["a"]
q[["b"]]
q$b

try(q[1])
try(q$a <- "updated")

Immutables documentation built on April 29, 2026, 1:06 a.m.