webpack
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Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.
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JavaScript
/*
MIT License http://www.opensource.org/licenses/mit-license.php
Author Tobias Koppers @sokra
*/
"use strict";
// Simulations show these probabilities for a single change
// 93.1% that one group is invalidated
// 4.8% that two groups are invalidated
// 1.1% that 3 groups are invalidated
// 0.1% that 4 or more groups are invalidated
//
// And these for removing/adding 10 lexically adjacent files
// 64.5% that one group is invalidated
// 24.8% that two groups are invalidated
// 7.8% that 3 groups are invalidated
// 2.7% that 4 or more groups are invalidated
//
// And these for removing/adding 3 random files
// 0% that one group is invalidated
// 3.7% that two groups are invalidated
// 80.8% that 3 groups are invalidated
// 12.3% that 4 groups are invalidated
// 3.2% that 5 or more groups are invalidated
/**
*
* @param {string} a key
* @param {string} b key
* @returns {number} the similarity as number
*/
const similarity = (a, b) => {
const l = Math.min(a.length, b.length);
let dist = 0;
for (let i = 0; i < l; i++) {
const ca = a.charCodeAt(i);
const cb = b.charCodeAt(i);
dist += Math.max(0, 10 - Math.abs(ca - cb));
}
return dist;
};
/**
* @param {string} a key
* @param {string} b key
* @param {Set<string>} usedNames set of already used names
* @returns {string} the common part and a single char for the difference
*/
const getName = (a, b, usedNames) => {
const l = Math.min(a.length, b.length);
let i = 0;
while (i < l) {
if (a.charCodeAt(i) !== b.charCodeAt(i)) {
i++;
break;
}
i++;
}
while (i < l) {
const name = a.slice(0, i);
const lowerName = name.toLowerCase();
if (!usedNames.has(lowerName)) {
usedNames.add(lowerName);
return name;
}
i++;
}
// names always contain a hash, so this is always unique
// we don't need to check usedNames nor add it
return a;
};
/**
* @param {Record<string, number>} total total size
* @param {Record<string, number>} size single size
* @returns {void}
*/
const addSizeTo = (total, size) => {
for (const key of Object.keys(size)) {
total[key] = (total[key] || 0) + size[key];
}
};
/**
* @param {Record<string, number>} total total size
* @param {Record<string, number>} size single size
* @returns {void}
*/
const subtractSizeFrom = (total, size) => {
for (const key of Object.keys(size)) {
total[key] -= size[key];
}
};
/**
* @param {Iterable<Node>} nodes some nodes
* @returns {Record<string, number>} total size
*/
const sumSize = nodes => {
const sum = Object.create(null);
for (const node of nodes) {
addSizeTo(sum, node.size);
}
return sum;
};
const isTooBig = (size, maxSize) => {
for (const key of Object.keys(size)) {
const s = size[key];
if (s === 0) continue;
const maxSizeValue = maxSize[key];
if (typeof maxSizeValue === "number") {
if (s > maxSizeValue) return true;
}
}
return false;
};
const isTooSmall = (size, minSize) => {
for (const key of Object.keys(size)) {
const s = size[key];
if (s === 0) continue;
const minSizeValue = minSize[key];
if (typeof minSizeValue === "number") {
if (s < minSizeValue) return true;
}
}
return false;
};
const getTooSmallTypes = (size, minSize) => {
const types = new Set();
for (const key of Object.keys(size)) {
const s = size[key];
if (s === 0) continue;
const minSizeValue = minSize[key];
if (typeof minSizeValue === "number") {
if (s < minSizeValue) types.add(key);
}
}
return types;
};
const getNumberOfMatchingSizeTypes = (size, types) => {
let i = 0;
for (const key of Object.keys(size)) {
if (size[key] !== 0 && types.has(key)) i++;
}
return i;
};
const selectiveSizeSum = (size, types) => {
let sum = 0;
for (const key of Object.keys(size)) {
if (size[key] !== 0 && types.has(key)) sum += size[key];
}
return sum;
};
/**
* @template T
*/
class Node {
/**
* @param {T} item item
* @param {string} key key
* @param {Record<string, number>} size size
*/
constructor(item, key, size) {
this.item = item;
this.key = key;
this.size = size;
}
}
/**
* @template T
*/
class Group {
/**
* @param {Node<T>[]} nodes nodes
* @param {number[]} similarities similarities between the nodes (length = nodes.length - 1)
* @param {Record<string, number>=} size size of the group
*/
constructor(nodes, similarities, size) {
this.nodes = nodes;
this.similarities = similarities;
this.size = size || sumSize(nodes);
/** @type {string} */
this.key = undefined;
}
/**
* @param {function(Node): boolean} filter filter function
* @returns {Node[]} removed nodes
*/
popNodes(filter) {
const newNodes = [];
const newSimilarities = [];
const resultNodes = [];
let lastNode;
for (let i = 0; i < this.nodes.length; i++) {
const node = this.nodes[i];
if (filter(node)) {
resultNodes.push(node);
} else {
if (newNodes.length > 0) {
newSimilarities.push(
lastNode === this.nodes[i - 1]
? this.similarities[i - 1]
: similarity(lastNode.key, node.key)
);
}
newNodes.push(node);
lastNode = node;
}
}
if (resultNodes.length === this.nodes.length) return undefined;
this.nodes = newNodes;
this.similarities = newSimilarities;
this.size = sumSize(newNodes);
return resultNodes;
}
}
/**
* @param {Iterable<Node>} nodes nodes
* @returns {number[]} similarities
*/
const getSimilarities = nodes => {
// calculate similarities between lexically adjacent nodes
/** @type {number[]} */
const similarities = [];
let last = undefined;
for (const node of nodes) {
if (last !== undefined) {
similarities.push(similarity(last.key, node.key));
}
last = node;
}
return similarities;
};
/**
* @template T
* @typedef {Object} GroupedItems<T>
* @property {string} key
* @property {T[]} items
* @property {Record<string, number>} size
*/
/**
* @template T
* @typedef {Object} Options
* @property {Record<string, number>} maxSize maximum size of a group
* @property {Record<string, number>} minSize minimum size of a group (preferred over maximum size)
* @property {Iterable<T>} items a list of items
* @property {function(T): Record<string, number>} getSize function to get size of an item
* @property {function(T): string} getKey function to get the key of an item
*/
/**
* @template T
* @param {Options<T>} options options object
* @returns {GroupedItems<T>[]} grouped items
*/
module.exports = ({ maxSize, minSize, items, getSize, getKey }) => {
/** @type {Group<T>[]} */
const result = [];
const nodes = Array.from(
items,
item => new Node(item, getKey(item), getSize(item))
);
/** @type {Node<T>[]} */
const initialNodes = [];
// lexically ordering of keys
nodes.sort((a, b) => {
if (a.key < b.key) return -1;
if (a.key > b.key) return 1;
return 0;
});
// return nodes bigger than maxSize directly as group
// But make sure that minSize is not violated
for (const node of nodes) {
if (isTooBig(node.size, maxSize) && !isTooSmall(node.size, minSize)) {
result.push(new Group([node], []));
} else {
initialNodes.push(node);
}
}
if (initialNodes.length > 0) {
const initialGroup = new Group(initialNodes, getSimilarities(initialNodes));
const removeProblematicNodes = (group, consideredSize = group.size) => {
const problemTypes = getTooSmallTypes(consideredSize, minSize);
if (problemTypes.size > 0) {
// We hit an edge case where the working set is already smaller than minSize
// We merge problematic nodes with the smallest result node to keep minSize intact
const problemNodes = group.popNodes(
n => getNumberOfMatchingSizeTypes(n.size, problemTypes) > 0
);
if (problemNodes === undefined) return false;
// Only merge it with result nodes that have the problematic size type
const possibleResultGroups = result.filter(
n => getNumberOfMatchingSizeTypes(n.size, problemTypes) > 0
);
if (possibleResultGroups.length > 0) {
const bestGroup = possibleResultGroups.reduce((min, group) => {
const minMatches = getNumberOfMatchingSizeTypes(min, problemTypes);
const groupMatches = getNumberOfMatchingSizeTypes(
group,
problemTypes
);
if (minMatches !== groupMatches)
return minMatches < groupMatches ? group : min;
if (
selectiveSizeSum(min.size, problemTypes) >
selectiveSizeSum(group.size, problemTypes)
)
return group;
return min;
});
for (const node of problemNodes) bestGroup.nodes.push(node);
bestGroup.nodes.sort((a, b) => {
if (a.key < b.key) return -1;
if (a.key > b.key) return 1;
return 0;
});
} else {
// There are no other nodes with the same size types
// We create a new group and have to accept that it's smaller than minSize
result.push(new Group(problemNodes, null));
}
return true;
} else {
return false;
}
};
if (initialGroup.nodes.length > 0) {
const queue = [initialGroup];
while (queue.length) {
const group = queue.pop();
// only groups bigger than maxSize need to be splitted
if (!isTooBig(group.size, maxSize)) {
result.push(group);
continue;
}
// If the group is already too small
// we try to work only with the unproblematic nodes
if (removeProblematicNodes(group)) {
// This changed something, so we try this group again
queue.push(group);
continue;
}
// find unsplittable area from left and right
// going minSize from left and right
// at least one node need to be included otherwise we get stuck
let left = 1;
let leftSize = Object.create(null);
addSizeTo(leftSize, group.nodes[0].size);
while (left < group.nodes.length && isTooSmall(leftSize, minSize)) {
addSizeTo(leftSize, group.nodes[left].size);
left++;
}
let right = group.nodes.length - 2;
let rightSize = Object.create(null);
addSizeTo(rightSize, group.nodes[group.nodes.length - 1].size);
while (right >= 0 && isTooSmall(rightSize, minSize)) {
addSizeTo(rightSize, group.nodes[right].size);
right--;
}
// left v v right
// [ O O O ] O O O [ O O O ]
// ^^^^^^^^^ leftSize
// rightSize ^^^^^^^^^
// leftSize > minSize
// rightSize > minSize
// Perfect split: [ O O O ] [ O O O ]
// right === left - 1
if (left - 1 > right) {
// We try to remove some problematic nodes to "fix" that
let prevSize;
if (right < group.nodes.length - left) {
subtractSizeFrom(rightSize, group.nodes[right + 1].size);
prevSize = rightSize;
} else {
subtractSizeFrom(leftSize, group.nodes[left - 1].size);
prevSize = leftSize;
}
if (removeProblematicNodes(group, prevSize)) {
// This changed something, so we try this group again
queue.push(group);
continue;
}
// can't split group while holding minSize
// because minSize is preferred of maxSize we return
// the problematic nodes as result here even while it's too big
// To avoid this make sure maxSize > minSize * 3
result.push(group);
continue;
}
if (left <= right) {
// when there is a area between left and right
// we look for best split point
// we split at the minimum similarity
// here key space is separated the most
// But we also need to make sure to not create too small groups
let best = -1;
let bestSimilarity = Infinity;
let pos = left;
let rightSize = sumSize(group.nodes.slice(pos));
// pos v v right
// [ O O O ] O O O [ O O O ]
// ^^^^^^^^^ leftSize
// rightSize ^^^^^^^^^^^^^^^
while (pos <= right + 1) {
const similarity = group.similarities[pos - 1];
if (
similarity < bestSimilarity &&
!isTooSmall(leftSize, minSize) &&
!isTooSmall(rightSize, minSize)
) {
best = pos;
bestSimilarity = similarity;
}
addSizeTo(leftSize, group.nodes[pos].size);
subtractSizeFrom(rightSize, group.nodes[pos].size);
pos++;
}
if (best < 0) {
// This can't happen
// but if that assumption is wrong
// fallback to a big group
result.push(group);
continue;
}
left = best;
right = best - 1;
}
// create two new groups for left and right area
// and queue them up
const rightNodes = [group.nodes[right + 1]];
/** @type {number[]} */
const rightSimilarities = [];
for (let i = right + 2; i < group.nodes.length; i++) {
rightSimilarities.push(group.similarities[i - 1]);
rightNodes.push(group.nodes[i]);
}
queue.push(new Group(rightNodes, rightSimilarities));
const leftNodes = [group.nodes[0]];
/** @type {number[]} */
const leftSimilarities = [];
for (let i = 1; i < left; i++) {
leftSimilarities.push(group.similarities[i - 1]);
leftNodes.push(group.nodes[i]);
}
queue.push(new Group(leftNodes, leftSimilarities));
}
}
}
// lexically ordering
result.sort((a, b) => {
if (a.nodes[0].key < b.nodes[0].key) return -1;
if (a.nodes[0].key > b.nodes[0].key) return 1;
return 0;
});
// give every group a name
const usedNames = new Set();
for (let i = 0; i < result.length; i++) {
const group = result[i];
if (group.nodes.length === 1) {
group.key = group.nodes[0].key;
} else {
const first = group.nodes[0];
const last = group.nodes[group.nodes.length - 1];
const name = getName(first.key, last.key, usedNames);
group.key = name;
}
}
// return the results
return result.map(group => {
/** @type {GroupedItems} */
return {
key: group.key,
items: group.nodes.map(node => node.item),
size: group.size
};
});
};