Iterator Class

An Iterator is an object that allows to iterate over sequences. It implements next_iter and get_value to iterate and retrieve the value of the sequence it is associated with. For the standard S3 interface, see iter().

Author

Roman Pahl

Methods

Public methods

• Iterator$new()

• Iterator$begin()

• Iterator$get_value()

• Iterator$get_next()

• Iterator$has_next()

• Iterator$has_value()

• Iterator$length()

• Iterator$pos()

• Iterator$next_iter()

• Iterator$print()

• Iterator$reset_iter()

• Iterator$clone()

---

Method new()

Iterator constructor

Usage

Iterator$new(x, .subset = .subset2)

Arguments

x

object to iterate over

.subset

accessor function

Returns

invisibly returns the Iterator object

---

Method begin()

set iterator to the first element of the underlying sequence unless length of sequence is zero, in which case it will point to nothing.

Usage

Iterator$begin()

Returns

invisibly returns the Iterator object

---

Method get_value()

get value where the iterator points to

Usage

Iterator$get_value()

Returns

returns the value the Iterator is pointing at.

---

Method get_next()

get next value

Usage

Iterator$get_next()

Returns

increments the iterator and returns the value the Iterator is pointing to.

---

Method has_next()

check if iterator has more elements

Usage

Iterator$has_next()

Returns

TRUE if iterator has next element else FALSE

---

Method has_value()

check if iterator points at value

Usage

Iterator$has_value()

Returns

TRUE if iterator points at value otherwise FALSE

---

Method length()

iterator length

Usage

Iterator$length()

Returns

number of elements to iterate

---

Method pos()

get iterator position

Usage

Iterator$pos()

Returns

integer if iterator has next element else FALSE

---

Method next_iter()

increment iterator

Usage

Iterator$next_iter()

Returns

invisibly returns the Iterator object

---

Method print()

print method

Usage

Iterator$print()

---

Method reset_iter()

reset iterator to '0'

Usage

Iterator$reset_iter()

Returns

invisibly returns the Iterator object

---

Method clone()

The objects of this class are cloneable with this method.

Usage

Iterator$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

# Numeric Vector
v = 1:3
it = Iterator$new(v)
it
#> <Iterator> at position 0 / 3 

try(it$get_value())  # iterator does not point at a value
#> Error in it$get_value() : iterator does not point at a value

it$has_value()
#> [1] FALSE
it$has_next()
#> [1] TRUE
it$next_iter()
#> <Iterator> at position 1 / 3 
it$get_value()
#> [1] 1
it$get_next()
#> [1] 2
it$get_next()
#> [1] 3
it
#> <Iterator> at position 3 / 3 
it$has_next()
#> [1] FALSE
it$begin()
#> <Iterator> at position 1 / 3 
it$get_value()
#> [1] 1
it$reset_iter()
#> <Iterator> at position 0 / 3 

# Works by reference for Container
co = Container$new(1, 2, 3)
it = co$iter()
it$get_next()
#> [[1]]
#> [1] 1
#> 
co$discard(2)
#> [1, 3]
it
#> <Iterator> at position 1 / 2 
it$get_value()
#> [[1]]
#> [1] 1
#> 
co$discard(1)
#> [3]
it
#> <Iterator> at position 1 / 1 
it$get_value()
#> [[1]]
#> [1] 3
#> 
it$begin()
#> <Iterator> at position 1 / 1