'use strict';
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const toposort = require('toposort');
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const _ = require('lodash');
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/**
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Sorts dependencies between chunks by their "parents" attribute.
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This function sorts chunks based on their dependencies with each other.
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The parent relation between chunks as generated by Webpack for each chunk
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is used to define a directed (and hopefully acyclic) graph, which is then
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topologically sorted in order to retrieve the correct order in which
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chunks need to be embedded into HTML. A directed edge in this graph is
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describing a "is parent of" relationship from a chunk to another (distinct)
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chunk. Thus topological sorting orders chunks from bottom-layer chunks to
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highest level chunks that use the lower-level chunks.
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@param {Array} chunks an array of chunks as generated by the html-webpack-plugin.
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- For webpack < 4, It is assumed that each entry contains at least the properties
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"id" (containing the chunk id) and "parents" (array containing the ids of the
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parent chunks).
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- For webpack 4+ the see the chunkGroups param for parent-child relationships
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@param {Array} chunks an array of ChunkGroups that has a getParents method.
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Each ChunkGroup contains a list of chunks in order.
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@return {Array} A topologically sorted version of the input chunks
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*/
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module.exports.dependency = (chunks, options, compilation) => {
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const chunkGroups = compilation.chunkGroups;
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if (!chunks) {
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return chunks;
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}
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// We build a map (chunk-id -> chunk) for faster access during graph building.
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const nodeMap = {};
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chunks.forEach(chunk => {
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nodeMap[chunk.id] = chunk;
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});
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// Next, we add an edge for each parent relationship into the graph
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let edges = [];
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if (chunkGroups) {
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// Add an edge for each parent (parent -> child)
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edges = chunkGroups.reduce((result, chunkGroup) => result.concat(
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Array.from(chunkGroup.parentsIterable, parentGroup => [parentGroup, chunkGroup])
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), []);
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const sortedGroups = toposort.array(chunkGroups, edges);
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// flatten chunkGroup into chunks
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const sortedChunks = sortedGroups
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.reduce((result, chunkGroup) => result.concat(chunkGroup.chunks), [])
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.map(chunk => // use the chunk from the list passed in, since it may be a filtered list
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nodeMap[chunk.id])
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.filter((chunk, index, self) => {
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// make sure exists (ie excluded chunks not in nodeMap)
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const exists = !!chunk;
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// make sure we have a unique list
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const unique = self.indexOf(chunk) === index;
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return exists && unique;
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});
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return sortedChunks;
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} else {
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// before webpack 4 there was no chunkGroups
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chunks.forEach(chunk => {
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if (chunk.parents) {
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// Add an edge for each parent (parent -> child)
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chunk.parents.forEach(parentId => {
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// webpack2 chunk.parents are chunks instead of string id(s)
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const parentChunk = _.isObject(parentId) ? parentId : nodeMap[parentId];
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// If the parent chunk does not exist (e.g. because of an excluded chunk)
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// we ignore that parent
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if (parentChunk) {
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edges.push([parentChunk, chunk]);
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}
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});
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}
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});
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// We now perform a topological sorting on the input chunks and built edges
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return toposort.array(chunks, edges);
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}
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};
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/**
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* Sorts the chunks based on the chunk id.
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*
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* @param {Array} chunks the list of chunks to sort
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* @return {Array} The sorted list of chunks
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*/
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module.exports.id = chunks => chunks.sort(function orderEntryLast (a, b) {
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if (a.entry !== b.entry) {
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return b.entry ? 1 : -1;
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} else {
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return b.id - a.id;
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}
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});
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/**
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* Performs identity mapping (no-sort).
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* @param {Array} chunks the chunks to sort
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* @return {Array} The sorted chunks
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*/
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module.exports.none = chunks => chunks;
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/**
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* Sort manually by the chunks
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* @param {Array} chunks the chunks to sort
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* @return {Array} The sorted chunks
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*/
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module.exports.manual = (chunks, options) => {
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const specifyChunks = options.chunks;
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const chunksResult = [];
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let filterResult = [];
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if (Array.isArray(specifyChunks)) {
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for (var i = 0; i < specifyChunks.length; i++) {
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filterResult = chunks.filter(chunk => {
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if (chunk.names[0] && chunk.names[0] === specifyChunks[i]) {
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return true;
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}
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return false;
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});
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filterResult.length > 0 && chunksResult.push(filterResult[0]);
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}
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}
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return chunksResult;
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};
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/**
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* Defines the default sorter.
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*/
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module.exports.auto = module.exports.id;
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// In webpack 2 the ids have been flipped.
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// Therefore the id sort doesn't work the same way as it did for webpack 1
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// Luckily the dependency sort is working as expected
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if (Number(require('webpack/package.json').version.split('.')[0]) > 1) {
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module.exports.auto = module.exports.dependency;
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}
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