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67 lines
2.3 KiB
67 lines
2.3 KiB
3 years ago
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# OrderedMap
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Persistent data structure representing an ordered mapping from strings
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to values, with some convenient update methods.
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This is not an efficient data structure for large maps, just a minimal
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helper for cleanly creating and managing small maps in a way that
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makes their key order explicit and easy to think about.
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License: MIT
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## Reference
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The exported value from this module is the class `OrderedMap`,
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instances of which represent a mapping from strings to arbitrary
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values.
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**`OrderedMap.from`**`(value: ?Object | OrderedMap) → OrderedMap`
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Return a map with the given content. If null, create an empty map. If
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given an ordered map, return that map itself. If given an object,
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create a map from the object's properties.
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### Methods
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Instances of `OrderedMap` have the following methods and properties:
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**`get`**`(key: string) → ?any`
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Retrieve the value stored under `key`, or return undefined when
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no such key exists.
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**`update`**`(key: string, value: any, newKey: ?string) → OrderedMap`
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Create a new map by replacing the value of `key` with a new
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value, or adding a binding to the end of the map. If `newKey` is
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given, the key of the binding will be replaced with that key.
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**`remove`**`(key: string) → OrderedMap`
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Return a map with the given key removed, if it existed.
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**`addToStart`**`(key: string, value: any) → OrderedMap`
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Add a new key to the start of the map.
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**`addToEnd`**`(key: string, value: any) → OrderedMap`
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Add a new key to the end of the map.
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**`addBefore`**`(place: string, key: value: string, value: any) → OrderedMap`
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Add a key after the given key. If `place` is not found, the new
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key is added to the end.
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**`forEach`**`(f: (key: string, value: any))`
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Call the given function for each key/value pair in the map, in
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order.
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**`prepend`**`(map: Object | OrderedMap) → OrderedMap`
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Create a new map by prepending the keys in this map that don't
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appear in `map` before the keys in `map`.
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**`append`**`(map: Object | OrderedMap) → OrderedMap`
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Create a new map by appending the keys in this map that don't
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appear in `map` after the keys in `map`.
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**`subtract`**`(map: Object | OrderedMap) → OrderedMap`
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Create a map containing all the keys in this map that don't
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appear in `map`.
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**`size`**`: number`
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The amount of keys in this map.
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