source: trip-planner-front/node_modules/webpack/lib/optimize/EnsureChunkConditionsPlugin.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
*/

"use strict";

const { STAGE_BASIC } = require("../OptimizationStages");

/** @typedef {import("../Chunk")} Chunk */
/** @typedef {import("../ChunkGroup")} ChunkGroup */
/** @typedef {import("../Compiler")} Compiler */

class EnsureChunkConditionsPlugin {
        /**
         * Apply the plugin
         * @param {Compiler} compiler the compiler instance
         * @returns {void}
         */
        apply(compiler) {
                compiler.hooks.compilation.tap(
                        "EnsureChunkConditionsPlugin",
                        compilation => {
                                const handler = chunks => {
                                        const chunkGraph = compilation.chunkGraph;
                                        // These sets are hoisted here to save memory
                                        // They are cleared at the end of every loop
                                        /** @type {Set<Chunk>} */
                                        const sourceChunks = new Set();
                                        /** @type {Set<ChunkGroup>} */
                                        const chunkGroups = new Set();
                                        for (const module of compilation.modules) {
                                                for (const chunk of chunkGraph.getModuleChunksIterable(module)) {
                                                        if (!module.chunkCondition(chunk, compilation)) {
                                                                sourceChunks.add(chunk);
                                                                for (const group of chunk.groupsIterable) {
                                                                        chunkGroups.add(group);
                                                                }
                                                        }
                                                }
                                                if (sourceChunks.size === 0) continue;
                                                /** @type {Set<Chunk>} */
                                                const targetChunks = new Set();
                                                chunkGroupLoop: for (const chunkGroup of chunkGroups) {
                                                        // Can module be placed in a chunk of this group?
                                                        for (const chunk of chunkGroup.chunks) {
                                                                if (module.chunkCondition(chunk, compilation)) {
                                                                        targetChunks.add(chunk);
                                                                        continue chunkGroupLoop;
                                                                }
                                                        }
                                                        // We reached the entrypoint: fail
                                                        if (chunkGroup.isInitial()) {
                                                                throw new Error(
                                                                        "Cannot fullfil chunk condition of " + module.identifier()
                                                                );
                                                        }
                                                        // Try placing in all parents
                                                        for (const group of chunkGroup.parentsIterable) {
                                                                chunkGroups.add(group);
                                                        }
                                                }
                                                for (const sourceChunk of sourceChunks) {
                                                        chunkGraph.disconnectChunkAndModule(sourceChunk, module);
                                                }
                                                for (const targetChunk of targetChunks) {
                                                        chunkGraph.connectChunkAndModule(targetChunk, module);
                                                }
                                                sourceChunks.clear();
                                                chunkGroups.clear();
                                        }
                                };
                                compilation.hooks.optimizeChunks.tap(
                                        {
                                                name: "EnsureChunkConditionsPlugin",
                                                stage: STAGE_BASIC
                                        },
                                        handler
                                );
                        }
                );
        }
}
module.exports = EnsureChunkConditionsPlugin;