merge.priority_queue: Merge Two Priority Queues

In Immutables: Fast and Functional Data Structures

Merge Two Priority Queues

Description

Returns a new priority_queue containing every entry from both inputs, preserving each queue's internal insertion order (entries of x come first, then entries of y).

Usage

## S3 method for class 'priority_queue'
merge(x, y, ...)

Arguments

x	A priority_queue.
y	A priority_queue.
...	Unused.

Details

The cached .pq_min / .pq_max monoids recompute automatically on the merged tree, so peek_min() / peek_max() reflect the combined extremum immediately.

Both queues must share the same priority type and the same monoid set; mismatches error rather than being silently harmonized. Merging an empty queue with a non-empty queue returns the non-empty queue unchanged.

Both inputs are left unmodified.

Value

A new priority_queue of size length(x) + length(y).

Examples

a <- priority_queue("x", "y", priorities = c(5, 1))
b <- priority_queue("z", priorities = 3)
m <- merge(a, b)
peek_min(m)
length(m)

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