Rewinds the graph to the state tagged as ‘tag` @param [Object] tag the tag to rewind to @return [Void]
@return [Object] the requirement that led to a version of a possibility
with the given name being activated.
Requires the dependencies that the recently activated spec has @param [Object] activated_spec the specification that has just been
activated
@return [void]
Pushes a new {DependencyState} that encapsulates both existing and new requirements @param [Array] new_requirements @return [void]
@return [Array<Object>] all of the requirements that required
this vertex
@return [Array<Vertex>] the vertices of {#graph} that have an edge with
`self` as their {Edge#destination}
(see Gem::Resolver::Molinillo::ResolutionState#requirements)
(see Gem::Resolver::Molinillo::ResolutionState#requirement)
Processes the topmost available {RequirementState} on the stack @return [void]
Reset nil attributes to their default values to make the spec valid
Returns self
.
Same as Array#each
, but traverses self
in reverse order.
a = [ "a", "b", "c" ] a.reverse_each {|x| print x, " " }
produces:
c b a
Sorts self
in place using a set of keys generated by mapping the values in self
through the given block.
The result is not guaranteed to be stable. When two keys are equal, the order of the corresponding elements is unpredictable.
If no block is given, an Enumerator
is returned instead.
See also Enumerable#sort_by
.
When invoked with a block, yield all repeated permutations of length n
of the elements of the array, then return the array itself.
The implementation makes no guarantees about the order in which the repeated permutations are yielded.
If no block is given, an Enumerator
is returned instead.
Examples:
a = [1, 2] a.repeated_permutation(1).to_a #=> [[1], [2]] a.repeated_permutation(2).to_a #=> [[1,1],[1,2],[2,1],[2,2]] a.repeated_permutation(3).to_a #=> [[1,1,1],[1,1,2],[1,2,1],[1,2,2], # [2,1,1],[2,1,2],[2,2,1],[2,2,2]] a.repeated_permutation(0).to_a #=> [[]] # one permutation of length 0
When invoked with a block, yields all repeated combinations of length n
of elements from the array and then returns the array itself.
The implementation makes no guarantees about the order in which the repeated combinations are yielded.
If no block is given, an Enumerator
is returned instead.
Examples:
a = [1, 2, 3] a.repeated_combination(1).to_a #=> [[1], [2], [3]] a.repeated_combination(2).to_a #=> [[1,1],[1,2],[1,3],[2,2],[2,3],[3,3]] a.repeated_combination(3).to_a #=> [[1,1,1],[1,1,2],[1,1,3],[1,2,2],[1,2,3], # [1,3,3],[2,2,2],[2,2,3],[2,3,3],[3,3,3]] a.repeated_combination(4).to_a #=> [[1,1,1,1],[1,1,1,2],[1,1,1,3],[1,1,2,2],[1,1,2,3], # [1,1,3,3],[1,2,2,2],[1,2,2,3],[1,2,3,3],[1,3,3,3], # [2,2,2,2],[2,2,2,3],[2,2,3,3],[2,3,3,3],[3,3,3,3]] a.repeated_combination(0).to_a #=> [[]] # one combination of length 0
Creates a new Enumerator
which will enumerate by calling method
on obj
, passing args
if any.
If a block is given, it will be used to calculate the size of the enumerator without the need to iterate it (see Enumerator#size
).
str = "xyz" enum = str.enum_for(:each_byte) enum.each { |b| puts b } # => 120 # => 121 # => 122 # protect an array from being modified by some_method a = [1, 2, 3] some_method(a.to_enum)
It is typical to call to_enum
when defining methods for a generic Enumerable
, in case no block is passed.
Here is such an example, with parameter passing and a sizing block:
module Enumerable # a generic method to repeat the values of any enumerable def repeat(n) raise ArgumentError, "#{n} is negative!" if n < 0 unless block_given? return to_enum(__method__, n) do # __method__ is :repeat here sz = size # Call size and multiply by n... sz * n if sz # but return nil if size itself is nil end end each do |*val| n.times { yield *val } end end end %i[hello world].repeat(2) { |w| puts w } # => Prints 'hello', 'hello', 'world', 'world' enum = (1..14).repeat(3) # => returns an Enumerator when called without a block enum.first(4) # => [1, 1, 1, 2] enum.size # => 42