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- 'use strict';
- // ::- 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)
- };
- module.exports = OrderedMap;
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