Class: Sass::Util::SubsetMap
- Inherits:
-
Object
- Object
- Sass::Util::SubsetMap
- Defined in:
- lib/sass/util/subset_map.rb
Overview
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.
Instance Method Summary collapse
-
#[](set) ⇒ Array
Same as #get, but doesn't return the subsets of the argument for which values were found.
-
#[]=(set, value)
Associates a value with a set.
-
#empty? ⇒ Boolean
Whether or not this SubsetMap has any key-value pairs.
-
#get(set) ⇒ Array<(Object, #to_set)>
Returns all values associated with subsets of
set
. -
#initialize ⇒ SubsetMap
constructor
Creates a new, empty SubsetMap.
Constructor Details
#initialize ⇒ SubsetMap
Creates a new, empty SubsetMap.
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# File 'lib/sass/util/subset_map.rb', line 23
def initialize
@hash = {}
@vals = []
end
|
Instance Method Details
#[](set) ⇒ Array
Same as #get, but doesn't return the subsets of the argument for which values were found.
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# File 'lib/sass/util/subset_map.rb', line 96
def [](set)
get(set).map {|v, _| v}
end
|
#[]=(set, value)
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
.
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# 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
|
#empty? ⇒ Boolean
Whether or not this SubsetMap has any key-value pairs.
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# File 'lib/sass/util/subset_map.rb', line 31
def empty?
@hash.empty?
end
|
#get(set) ⇒ Array<(Object, #to_set)>
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 assocations in the map.
However, unless many keys in the map overlap with set
,
m
will typically be much smaller.
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# File 'lib/sass/util/subset_map.rb', line 73
def get(set)
res = set.map do |k|
next unless subsets = @hash[k]
subsets.map do |subenum, subset, index|
next unless subset.subset?(set)
[index, subenum]
end
end
res = Sass::Util.flatten(res, 1)
res.compact!
res.uniq!
res.sort!
res.map! {|i, s| [@vals[i], s]}
return res
end
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