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97 lines
2.2 KiB
97 lines
2.2 KiB
const conversions = require('./conversions');
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/*
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This function routes a model to all other models.
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all functions that are routed have a property `.conversion` attached
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to the returned synthetic function. This property is an array
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of strings, each with the steps in between the 'from' and 'to'
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color models (inclusive).
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conversions that are not possible simply are not included.
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*/
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function buildGraph() {
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const graph = {};
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// https://jsperf.com/object-keys-vs-for-in-with-closure/3
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const models = Object.keys(conversions);
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for (let len = models.length, i = 0; i < len; i++) {
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graph[models[i]] = {
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// http://jsperf.com/1-vs-infinity
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// micro-opt, but this is simple.
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distance: -1,
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parent: null
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};
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}
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return graph;
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}
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// https://en.wikipedia.org/wiki/Breadth-first_search
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function deriveBFS(fromModel) {
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const graph = buildGraph();
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const queue = [fromModel]; // Unshift -> queue -> pop
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graph[fromModel].distance = 0;
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while (queue.length) {
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const current = queue.pop();
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const adjacents = Object.keys(conversions[current]);
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for (let len = adjacents.length, i = 0; i < len; i++) {
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const adjacent = adjacents[i];
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const node = graph[adjacent];
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if (node.distance === -1) {
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node.distance = graph[current].distance + 1;
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node.parent = current;
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queue.unshift(adjacent);
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}
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}
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}
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return graph;
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}
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function link(from, to) {
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return function (args) {
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return to(from(args));
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};
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}
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function wrapConversion(toModel, graph) {
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const path = [graph[toModel].parent, toModel];
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let fn = conversions[graph[toModel].parent][toModel];
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let cur = graph[toModel].parent;
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while (graph[cur].parent) {
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path.unshift(graph[cur].parent);
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fn = link(conversions[graph[cur].parent][cur], fn);
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cur = graph[cur].parent;
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}
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fn.conversion = path;
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return fn;
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}
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module.exports = function (fromModel) {
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const graph = deriveBFS(fromModel);
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const conversion = {};
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const models = Object.keys(graph);
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for (let len = models.length, i = 0; i < len; i++) {
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const toModel = models[i];
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const node = graph[toModel];
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if (node.parent === null) {
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// No possible conversion, or this node is the source model.
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continue;
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}
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conversion[toModel] = wrapConversion(toModel, graph);
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}
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return conversion;
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};
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