proglib/lib/drawing/convert/route.js

Многофункциональная библиотека

const conversions = require('./conversions');

function buildGraph() {
	const graph = {};
	// https://jsperf.com/object-keys-vs-for-in-with-closure/3
	const models = Object.keys(conversions);

	for (let len = models.length, i = 0; i < len; i++) {
		graph[models[i]] = {
			// http://jsperf.com/1-vs-infinity
			distance: -1,
			parent: null
		};
	}

	return graph;
}

// https://en.wikipedia.org/wiki/Breadth-first_search
function deriveBFS(fromModel) {
	const graph = buildGraph();
	const queue = [fromModel];

	graph[fromModel].distance = 0;

	while (queue.length) {
		const current = queue.pop();
		const adjacents = Object.keys(conversions[current]);

		for (let len = adjacents.length, i = 0; i < len; i++) {
			const adjacent = adjacents[i];
			const node = graph[adjacent];

			if (node.distance === -1) {
				node.distance = graph[current].distance + 1;
				node.parent = current;
				queue.unshift(adjacent);
			}
		}
	}

	return graph;
}

function link(from, to) {
	return function (args) {
		return to(from(args));
	};
}

function wrapConversion(toModel, graph) {
	const path = [graph[toModel].parent, toModel];
	let fn = conversions[graph[toModel].parent][toModel];

	let cur = graph[toModel].parent;
	while (graph[cur].parent) {
		path.unshift(graph[cur].parent);
		fn = link(conversions[graph[cur].parent][cur], fn);
		cur = graph[cur].parent;
	}

	fn.conversion = path;
	return fn;
}

module.exports = function (fromModel) {
	const graph = deriveBFS(fromModel);
	const conversion = {};

	const models = Object.keys(graph);
	for (let len = models.length, i = 0; i < len; i++) {
		const toModel = models[i];
		const node = graph[toModel];

		if (node.parent === null) {
			continue;
		}

		conversion[toModel] = wrapConversion(toModel, graph);
	}

	return conversion;
};