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					138 lines
				
				4.3 KiB
			
		
		
			
		
	
	
					138 lines
				
				4.3 KiB
			| 
											3 years ago
										 | // ::- Persistent data structure representing an ordered mapping from
 | ||
|  | // strings to values, with some convenient update methods.
 | ||
|  | function OrderedMap(content) { | ||
|  |   this.content = content; | ||
|  | } | ||
|  | 
 | ||
|  | OrderedMap.prototype = { | ||
|  |   constructor: OrderedMap, | ||
|  | 
 | ||
|  |   find: function(key) { | ||
|  |     for (var i = 0; i < this.content.length; i += 2) | ||
|  |       if (this.content[i] === key) return i | ||
|  |     return -1 | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: (string) → ?any
 | ||
|  |   // Retrieve the value stored under `key`, or return undefined when
 | ||
|  |   // no such key exists.
 | ||
|  |   get: function(key) { | ||
|  |     var found = this.find(key); | ||
|  |     return found == -1 ? undefined : this.content[found + 1] | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: (string, any, ?string) → OrderedMap
 | ||
|  |   // Create a new map by replacing the value of `key` with a new
 | ||
|  |   // value, or adding a binding to the end of the map. If `newKey` is
 | ||
|  |   // given, the key of the binding will be replaced with that key.
 | ||
|  |   update: function(key, value, newKey) { | ||
|  |     var self = newKey && newKey != key ? this.remove(newKey) : this; | ||
|  |     var found = self.find(key), content = self.content.slice(); | ||
|  |     if (found == -1) { | ||
|  |       content.push(newKey || key, value); | ||
|  |     } else { | ||
|  |       content[found + 1] = value; | ||
|  |       if (newKey) content[found] = newKey; | ||
|  |     } | ||
|  |     return new OrderedMap(content) | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: (string) → OrderedMap
 | ||
|  |   // Return a map with the given key removed, if it existed.
 | ||
|  |   remove: function(key) { | ||
|  |     var found = this.find(key); | ||
|  |     if (found == -1) return this | ||
|  |     var content = this.content.slice(); | ||
|  |     content.splice(found, 2); | ||
|  |     return new OrderedMap(content) | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: (string, any) → OrderedMap
 | ||
|  |   // Add a new key to the start of the map.
 | ||
|  |   addToStart: function(key, value) { | ||
|  |     return new OrderedMap([key, value].concat(this.remove(key).content)) | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: (string, any) → OrderedMap
 | ||
|  |   // Add a new key to the end of the map.
 | ||
|  |   addToEnd: function(key, value) { | ||
|  |     var content = this.remove(key).content.slice(); | ||
|  |     content.push(key, value); | ||
|  |     return new OrderedMap(content) | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: (string, string, any) → OrderedMap
 | ||
|  |   // Add a key after the given key. If `place` is not found, the new
 | ||
|  |   // key is added to the end.
 | ||
|  |   addBefore: function(place, key, value) { | ||
|  |     var without = this.remove(key), content = without.content.slice(); | ||
|  |     var found = without.find(place); | ||
|  |     content.splice(found == -1 ? content.length : found, 0, key, value); | ||
|  |     return new OrderedMap(content) | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: ((key: string, value: any))
 | ||
|  |   // Call the given function for each key/value pair in the map, in
 | ||
|  |   // order.
 | ||
|  |   forEach: function(f) { | ||
|  |     for (var i = 0; i < this.content.length; i += 2) | ||
|  |       f(this.content[i], this.content[i + 1]); | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: (union<Object, OrderedMap>) → OrderedMap
 | ||
|  |   // Create a new map by prepending the keys in this map that don't
 | ||
|  |   // appear in `map` before the keys in `map`.
 | ||
|  |   prepend: function(map) { | ||
|  |     map = OrderedMap.from(map); | ||
|  |     if (!map.size) return this | ||
|  |     return new OrderedMap(map.content.concat(this.subtract(map).content)) | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: (union<Object, OrderedMap>) → OrderedMap
 | ||
|  |   // Create a new map by appending the keys in this map that don't
 | ||
|  |   // appear in `map` after the keys in `map`.
 | ||
|  |   append: function(map) { | ||
|  |     map = OrderedMap.from(map); | ||
|  |     if (!map.size) return this | ||
|  |     return new OrderedMap(this.subtract(map).content.concat(map.content)) | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: (union<Object, OrderedMap>) → OrderedMap
 | ||
|  |   // Create a map containing all the keys in this map that don't
 | ||
|  |   // appear in `map`.
 | ||
|  |   subtract: function(map) { | ||
|  |     var result = this; | ||
|  |     map = OrderedMap.from(map); | ||
|  |     for (var i = 0; i < map.content.length; i += 2) | ||
|  |       result = result.remove(map.content[i]); | ||
|  |     return result | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: () → Object
 | ||
|  |   // Turn ordered map into a plain object.
 | ||
|  |   toObject: function() { | ||
|  |     var result = {}; | ||
|  |     this.forEach(function(key, value) { result[key] = value; }); | ||
|  |     return result | ||
|  |   }, | ||
|  | 
 | ||
|  |   // :: number
 | ||
|  |   // The amount of keys in this map.
 | ||
|  |   get size() { | ||
|  |     return this.content.length >> 1 | ||
|  |   } | ||
|  | }; | ||
|  | 
 | ||
|  | // :: (?union<Object, OrderedMap>) → OrderedMap
 | ||
|  | // Return a map with the given content. If null, create an empty
 | ||
|  | // map. If given an ordered map, return that map itself. If given an
 | ||
|  | // object, create a map from the object's properties.
 | ||
|  | OrderedMap.from = function(value) { | ||
|  |   if (value instanceof OrderedMap) return value | ||
|  |   var content = []; | ||
|  |   if (value) for (var prop in value) content.push(prop, value[prop]); | ||
|  |   return new OrderedMap(content) | ||
|  | }; | ||
|  | 
 | ||
|  | export default OrderedMap; |