class Sass::Util::SubsetMap
A map from sets to values. A value is {#[]= set} by providing a set (the “set-set”) and a value, which is then recorded as corresponding to that set. Values are {#[] accessed} by providing a set (the “get-set”) and returning all values that correspond to set-sets that are subsets of the get-set.
SubsetMap preserves the order of values as they're inserted.
@example
ssm = SubsetMap.new ssm[Set[1, 2]] = "Foo" ssm[Set[2, 3]] = "Bar" ssm[Set[1, 2, 3]] = "Baz" ssm[Set[1, 2, 3]] #=> ["Foo", "Bar", "Baz"]
Public Class Methods
Creates a new, empty SubsetMap.
# File lib/sass/util/subset_map.rb, line 23 def initialize @hash = {} @vals = [] end
Public Instance Methods
Same as {#get}, but doesn't return the subsets of the argument for which values were found.
@param set [Set] The set to use as the map key. @return [Array] The array of all values
associated with subsets of `set`, in insertion order.
@see get
# File lib/sass/util/subset_map.rb, line 96 def [](set) get(set).map {|v, _| v} end
Associates a value with a set. When `set` or any of its supersets is accessed, `value` will be among the values returned.
Note that if the same `set` is passed to this method multiple times, all given `value`s will be associated with that `set`.
This runs in `O(n)` time, where `n` is the size of `set`.
@param set [#to_set] The set to use as the map key. May not be empty. @param value [Object] The value to associate with `set`. @raise [ArgumentError] If `set` is empty.
# File lib/sass/util/subset_map.rb, line 47 def []=(set, value) raise ArgumentError.new("SubsetMap keys may not be empty.") if set.empty? index = @vals.size @vals << value set.each do |k| @hash[k] ||= [] @hash[k] << [set, set.to_set, index] end end
Iterates over each value in the subset map. Ignores keys completely. If multiple keys have the same value, this will return them multiple times.
@yield [Object] Each value in the map.
# File lib/sass/util/subset_map.rb, line 104 def each_value @vals.each {|v| yield v} end
Whether or not this SubsetMap has any key-value pairs.
@return [Boolean]
# File lib/sass/util/subset_map.rb, line 31 def empty? @hash.empty? end
Returns all values associated with subsets of `set`.
In the worst case, this runs in `O(m*max(n, log m))` time, where `n` is the size of `set` and `m` is the number of associations in the map. However, unless many keys in the map overlap with `set`, `m` will typically be much smaller.
@param set [Set] The set to use as the map key. @return [Array<(Object, to_set)>] An array of pairs,
where the first value is the value associated with a subset of `set`, and the second value is that subset of `set` (or whatever `#to_set` object was used to set the value) This array is in insertion order.
@see []
# File lib/sass/util/subset_map.rb, line 73 def get(set) res = set.map do |k| subsets = @hash[k] next unless subsets subsets.map do |subenum, subset, index| next unless subset.subset?(set) [index, subenum] end end.flatten(1) res.compact! res.uniq! res.sort! res.map! {|i, s| [@vals[i], s]} res end