Class: Sass::Util::SubsetMap

Inherits:
Object
  • Object
show all
Defined in:
.ruby-sass/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.

Examples:

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"]

Instance Method Summary (collapse)

Constructor Details

#initialize ⇒ SubsetMap

Creates a new, empty SubsetMap.



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# File '.ruby-sass/lib/sass/util/subset_map.rb', line 23

def initialize
  @hash = {}
  @vals = []
end

Constructor Details

#initialize ⇒ SubsetMap

Creates a new, empty SubsetMap.



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# File '.ruby-sass/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.

Parameters:

  • set (Set) —

    The set to use as the map key.

Returns:

  • (Array) —

    The array of all values associated with subsets of `set`, in insertion order.

See Also:



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# File '.ruby-sass/lib/sass/util/subset_map.rb', line 96

def [](set)
  get(set).map {|v, _| v}
end

#[]=(set, value) ⇒ Object

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`.

Parameters:

  • set (#to_set) —

    The set to use as the map key. May not be empty.

  • value (Object) —

    The value to associate with `set`.

Raises:

  • (ArgumentError) —

    If `set` is empty.



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# File '.ruby-sass/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

#each_value {|Object| ... } ⇒ Object

Iterates over each value in the subset map. Ignores keys completely. If multiple keys have the same value, this will return them multiple times.

Yields:

  • (Object) —

    Each value in the map.



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# File '.ruby-sass/lib/sass/util/subset_map.rb', line 104

def each_value
  @vals.each {|v| yield v}
end

#empty? ⇒ Boolean

Whether or not this SubsetMap has any key-value pairs.

Returns:

  • (Boolean) 


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# File '.ruby-sass/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 associations in the map. However, unless many keys in the map overlap with `set`, `m` will typically be much smaller.

Parameters:

  • set (Set) —

    The set to use as the map key.

Returns:

  • (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 Also:



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# File '.ruby-sass/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