44 lines
1.9 KiB
Go
44 lines
1.9 KiB
Go
package set
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// Rules represents the operations that define membership for a Set.
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//
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// Each Set has a Rules instance, whose methods must satisfy the interface
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// contracts given below for any value that will be added to the set.
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type Rules interface {
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// Hash returns an int that somewhat-uniquely identifies the given value.
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//
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// A good hash function will minimize collisions for values that will be
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// added to the set, though collisions *are* permitted. Collisions will
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// simply reduce the efficiency of operations on the set.
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Hash(interface{}) int
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// Equivalent returns true if and only if the two values are considered
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// equivalent for the sake of set membership. Two values that are
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// equivalent cannot exist in the set at the same time, and if two
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// equivalent values are added it is undefined which one will be
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// returned when enumerating all of the set members.
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//
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// Two values that are equivalent *must* result in the same hash value,
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// though it is *not* required that two values with the same hash value
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// be equivalent.
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Equivalent(interface{}, interface{}) bool
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}
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// OrderedRules is an extension of Rules that can apply a partial order to
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// element values. When a set's Rules implements OrderedRules an iterator
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// over the set will return items in the order described by the rules.
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//
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// If the given order is not a total order (that is, some pairs of non-equivalent
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// elements do not have a defined order) then the resulting iteration order
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// is undefined but consistent for a particular version of cty. The exact
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// order in that case is not part of the contract and is subject to change
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// between versions.
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type OrderedRules interface {
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Rules
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// Less returns true if and only if the first argument should sort before
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// the second argument. If the second argument should sort before the first
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// or if there is no defined order for the values, return false.
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Less(interface{}, interface{}) bool
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}
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