webpack/lib/optimize/MangleExportsPlugin.js

132 lines
3.4 KiB
JavaScript

/*
MIT License http://www.opensource.org/licenses/mit-license.php
Author Tobias Koppers @sokra
*/
"use strict";
const { UsageState } = require("../ModuleGraph");
const {
numberToIdentifier,
NUMBER_OF_IDENTIFIER_START_CHARS,
NUMBER_OF_IDENTIFIER_CONTINUATION_CHARS
} = require("../Template");
const { assignDeterministicIds } = require("../ids/IdHelpers");
const {
concatComparators,
compareSelect,
compareStringsNumeric
} = require("../util/comparators");
/** @typedef {import("../Compiler")} Compiler */
/** @typedef {import("../ModuleGraph").ExportsInfo} ExportsInfo */
const OBJECT = [];
const ARRAY = [];
/**
* @param {ExportsInfo} exportsInfo exports info
* @param {boolean} canBeArray can be exports info point to an array
* @returns {boolean} mangle is possible
*/
const canMangle = (exportsInfo, canBeArray) => {
if (exportsInfo.otherExportsInfo.used !== UsageState.Unused) return false;
let hasSomethingToMangle = false;
const empty = canBeArray ? ARRAY : OBJECT;
for (const exportInfo of exportsInfo.exports) {
if (exportInfo.name in empty) {
return false;
}
if (exportInfo.canMangle === true) {
hasSomethingToMangle = true;
}
}
return hasSomethingToMangle;
};
const comparator = concatComparators(
// Sort used before unused fields
compareSelect(
e => e.used !== false,
(a, b) => (a === b ? 0 : a ? -1 : 1)
),
// Sort by name
compareSelect(e => e.name, compareStringsNumeric)
);
/**
* @param {ExportsInfo} exportsInfo exports info
* @param {boolean} canBeArray can be exports info point to an array
* @returns {void}
*/
const mangleExportsInfo = (exportsInfo, canBeArray) => {
if (!canMangle(exportsInfo, canBeArray)) return;
const usedNames = new Set();
const mangleableExports = [];
// Don't rename 1-2 char exports or exports that can't be mangled
for (const exportInfo of exportsInfo.ownedExports) {
const name = exportInfo.name;
if (exportInfo.usedName === null) {
if (
exportInfo.canMangle !== true ||
(name.length === 1 && /^[a-zA-Z0-9_$]/.test(name)) ||
(name.length === 2 && /^[a-zA-Z_$][a-zA-Z0-9_$]|^[1-9][0-9]/.test(name))
) {
exportInfo.usedName = name;
usedNames.add(name);
} else {
mangleableExports.push(exportInfo);
}
}
if (
exportInfo.exportsInfoOwned &&
(exportInfo.used === UsageState.OnlyPropertiesUsed ||
exportInfo.used === UsageState.Unused)
) {
mangleExportsInfo(exportInfo.exportsInfo, true);
}
}
assignDeterministicIds(
mangleableExports,
e => e.name,
comparator,
(e, id) => {
const name = numberToIdentifier(id);
const size = usedNames.size;
usedNames.add(name);
if (size === usedNames.size) return false;
e.usedName = name;
return true;
},
[
NUMBER_OF_IDENTIFIER_START_CHARS,
NUMBER_OF_IDENTIFIER_START_CHARS * NUMBER_OF_IDENTIFIER_CONTINUATION_CHARS
],
NUMBER_OF_IDENTIFIER_CONTINUATION_CHARS,
usedNames.size
);
};
class MangleExportsPlugin {
/**
* @param {Compiler} compiler webpack compiler
* @returns {void}
*/
apply(compiler) {
compiler.hooks.compilation.tap("MangleExportsPlugin", compilation => {
const moduleGraph = compilation.moduleGraph;
compilation.hooks.optimizeCodeGeneration.tap(
"MangleExportsPlugin",
modules => {
for (const module of modules) {
const exportsInfo = moduleGraph.getExportsInfo(module);
mangleExportsInfo(exportsInfo, false);
}
}
);
});
}
}
module.exports = MangleExportsPlugin;