Indexing for Priority Queues — sub-.priority

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

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

# S3 method for class 'priority_queue'
x$name

# S3 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 $<-).

Value

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

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.

Examples

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

q["a"]
#> Named priority_queue with 1 element.
#> Minimum priority: 2, Maximum priority: 2
#> 
#> Elements (by priority):
#> 
#> $a (priority 2)
#> [1] "task-a"
#> 
q[["b"]]
#> [1] "task-b"
q$b
#> [1] "task-b"

try(q[1])
#> Error in `[.priority_queue`(q, 1) : 
#>   `[.priority_queue` supports character name indexing only. Cast first with `as_flexseq()`.
try(q$a <- "updated")
#> Error in `$<-.priority_queue`(`*tmp*`, a, value = "updated") : 
#>   `$<-` is not supported for priority_queue. Cast first with `as_flexseq()`.