Skylib module containing common hash-set algorithms.
An empty set can be created using: `sets.make()`, or it can be created with some starting values
if you pass it an sequence: `sets.make([1, 2, 3])`. This returns a struct containing all of the
values as keys in a dictionary - this means that all passed in values must be hashable. The
values in the set can be retrieved using `sets.to_list(my_set)`.
An arbitrary object can be tested whether it is a set generated by `sets.make()` or not with the
`types.is_set()` method in types.bzl.
## sets.contains
sets.contains(a, e)
Checks for the existence of an element in a set.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| a | A set, as returned by `sets.make()`. | none |
| e | The element to look for. | none |
**RETURNS**
True if the element exists in the set, False if the element does not.
## sets.copy
sets.copy(s)
Creates a new set from another set.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| s | A set, as returned by `sets.make()`. | none |
**RETURNS**
A new set containing the same elements as `s`.
## sets.difference
sets.difference(a, b)
Returns the elements in `a` that are not in `b`.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| a | A set, as returned by `sets.make()`. | none |
| b | A set, as returned by `sets.make()`. | none |
**RETURNS**
A set containing the elements that are in `a` but not in `b`.
## sets.disjoint
sets.disjoint(a, b)
Returns whether two sets are disjoint.
Two sets are disjoint if they have no elements in common.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| a | A set, as returned by `sets.make()`. | none |
| b | A set, as returned by `sets.make()`. | none |
**RETURNS**
True if `a` and `b` are disjoint, False otherwise.
## sets.insert
sets.insert(s, e)
Inserts an element into the set.
Element must be hashable. This mutates the original set.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| s | A set, as returned by `sets.make()`. | none |
| e | The element to be inserted. | none |
**RETURNS**
The set `s` with `e` included.
## sets.intersection
sets.intersection(a, b)
Returns the intersection of two sets.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| a | A set, as returned by `sets.make()`. | none |
| b | A set, as returned by `sets.make()`. | none |
**RETURNS**
A set containing the elements that are in both `a` and `b`.
## sets.is_equal
sets.is_equal(a, b)
Returns whether two sets are equal.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| a | A set, as returned by `sets.make()`. | none |
| b | A set, as returned by `sets.make()`. | none |
**RETURNS**
True if `a` is equal to `b`, False otherwise.
## sets.is_subset
sets.is_subset(a, b)
Returns whether `a` is a subset of `b`.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| a | A set, as returned by `sets.make()`. | none |
| b | A set, as returned by `sets.make()`. | none |
**RETURNS**
True if `a` is a subset of `b`, False otherwise.
## sets.length
sets.length(s)
Returns the number of elements in a set.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| s | A set, as returned by `sets.make()`. | none |
**RETURNS**
An integer representing the number of elements in the set.
## sets.make
sets.make(elements)
Creates a new set.
All elements must be hashable.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| elements | Optional sequence to construct the set out of. | `None` |
**RETURNS**
A set containing the passed in values.
## sets.remove
sets.remove(s, e)
Removes an element from the set.
Element must be hashable. This mutates the original set.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| s | A set, as returned by `sets.make()`. | none |
| e | The element to be removed. | none |
**RETURNS**
The set `s` with `e` removed.
## sets.repr
sets.repr(s)
Returns a string value representing the set.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| s | A set, as returned by `sets.make()`. | none |
**RETURNS**
A string representing the set.
## sets.str
sets.str(s)
Returns a string value representing the set.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| s | A set, as returned by `sets.make()`. | none |
**RETURNS**
A string representing the set.
## sets.to_list
sets.to_list(s)
Creates a list from the values in the set.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| s | A set, as returned by `sets.make()`. | none |
**RETURNS**
A list of values inserted into the set.
## sets.union
sets.union(args)
Returns the union of several sets.
**PARAMETERS**
| Name | Description | Default Value |
| :------------- | :------------- | :------------- |
| args | An arbitrary number of sets. | none |
**RETURNS**
The set union of all sets in `*args`.