Return the data element at the front of an rdeque

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Description

Simply returns the data element sitting at the front of the rdeque, leaving the rdeque alone.

Usage

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## S3 method for class 'rdeque'
peek_front(x, ...)

Arguments

x

rdeque to peek at.

...

additional arguments to be passed to or from methods (ignored).

Details

Runs in O(1) worst-case time.

Value

data element existing at the front of the rdeque.

See Also

without_front for removing the front element.

Examples

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d <- rdeque()
d <- insert_front(d, "a")
d <- insert_front(d, "b")
e <- peek_front(d)
print(e)
print(d)

## Assigning to the front data element with peek_front:
d <- rdeque()
d <- insert_front(d, data.frame(a = 1, b = 1))
d <- insert_front(d, data.frame(a = 1, b = 1))

peek_front(d)$a <- 100
print(d)

peek_front(d) <- data.frame(a = 100, b = 100)
print(d)

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