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InnerGraphPlugin.js
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Thu, Feb 13, 18:55

InnerGraphPlugin.js
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/*
MIT License http://www.opensource.org/licenses/mit-license.php
Author Tobias Koppers @sokra
*/
"use strict";
const PureExpressionDependency = require("../dependencies/PureExpressionDependency");
const InnerGraph = require("./InnerGraph");
/** @typedef {import("estree").ClassDeclaration} ClassDeclarationNode */
/** @typedef {import("estree").ClassExpression} ClassExpressionNode */
/** @typedef {import("estree").Node} Node */
/** @typedef {import("estree").VariableDeclarator} VariableDeclaratorNode */
/** @typedef {import("../Compiler")} Compiler */
/** @typedef {import("../Dependency")} Dependency */
/** @typedef {import("../dependencies/HarmonyImportSpecifierDependency")} HarmonyImportSpecifierDependency */
/** @typedef {import("../javascript/JavascriptParser")} JavascriptParser */
/** @typedef {import("./InnerGraph").InnerGraph} InnerGraph */
/** @typedef {import("./InnerGraph").TopLevelSymbol} TopLevelSymbol */
const { topLevelSymbolTag } = InnerGraph;
class InnerGraphPlugin {
/**
* Apply the plugin
* @param {Compiler} compiler the compiler instance
* @returns {void}
*/
apply(compiler) {
compiler.hooks.compilation.tap(
"InnerGraphPlugin",
(compilation, { normalModuleFactory }) => {
const logger = compilation.getLogger("webpack.InnerGraphPlugin");
compilation.dependencyTemplates.set(
PureExpressionDependency,
new PureExpressionDependency.Template()
);
/**
* @param {JavascriptParser} parser the parser
* @param {Object} parserOptions options
* @returns {void}
*/
const handler = (parser, parserOptions) => {
const onUsageSuper = sup => {
InnerGraph.onUsage(parser.state, usedByExports => {
switch (usedByExports) {
case undefined:
case true:
return;
default: {
const dep = new PureExpressionDependency(sup.range);
dep.loc = sup.loc;
dep.usedByExports = usedByExports;
parser.state.module.addDependency(dep);
break;
}
}
});
};
parser.hooks.program.tap("InnerGraphPlugin", () => {
InnerGraph.enable(parser.state);
});
parser.hooks.finish.tap("InnerGraphPlugin", () => {
if (!InnerGraph.isEnabled(parser.state)) return;
logger.time("infer dependency usage");
InnerGraph.inferDependencyUsage(parser.state);
logger.timeAggregate("infer dependency usage");
});
// During prewalking the following datastructures are filled with
// nodes that have a TopLevelSymbol assigned and
// variables are tagged with the assigned TopLevelSymbol
// We differ 3 types of nodes:
// 1. full statements (export default, function declaration)
// 2. classes (class declaration, class expression)
// 3. variable declarators (const x = ...)
/** @type {WeakMap<Node, TopLevelSymbol>} */
const statementWithTopLevelSymbol = new WeakMap();
/** @type {WeakMap<Node, Node>} */
const statementPurePart = new WeakMap();
/** @type {WeakMap<ClassExpressionNode | ClassDeclarationNode, TopLevelSymbol>} */
const classWithTopLevelSymbol = new WeakMap();
/** @type {WeakMap<VariableDeclaratorNode, TopLevelSymbol>} */
const declWithTopLevelSymbol = new WeakMap();
/** @type {WeakSet<VariableDeclaratorNode>} */
const pureDeclarators = new WeakSet();
// The following hooks are used during prewalking:
parser.hooks.preStatement.tap("InnerGraphPlugin", statement => {
if (!InnerGraph.isEnabled(parser.state)) return;
if (parser.scope.topLevelScope === true) {
if (statement.type === "FunctionDeclaration") {
const name = statement.id ? statement.id.name : "*default*";
const fn = InnerGraph.tagTopLevelSymbol(parser, name);
statementWithTopLevelSymbol.set(statement, fn);
return true;
}
}
});
parser.hooks.blockPreStatement.tap("InnerGraphPlugin", statement => {
if (!InnerGraph.isEnabled(parser.state)) return;
if (parser.scope.topLevelScope === true) {
if (statement.type === "ClassDeclaration") {
const name = statement.id ? statement.id.name : "*default*";
const fn = InnerGraph.tagTopLevelSymbol(parser, name);
classWithTopLevelSymbol.set(statement, fn);
return true;
}
if (statement.type === "ExportDefaultDeclaration") {
const name = "*default*";
const fn = InnerGraph.tagTopLevelSymbol(parser, name);
const decl = statement.declaration;
if (
decl.type === "ClassExpression" ||
decl.type === "ClassDeclaration"
) {
classWithTopLevelSymbol.set(decl, fn);
} else if (parser.isPure(decl, statement.range[0])) {
statementWithTopLevelSymbol.set(statement, fn);
if (
!decl.type.endsWith("FunctionExpression") &&
!decl.type.endsWith("Declaration") &&
decl.type !== "Literal"
) {
statementPurePart.set(statement, decl);
}
}
}
}
});
parser.hooks.preDeclarator.tap(
"InnerGraphPlugin",
(decl, statement) => {
if (!InnerGraph.isEnabled(parser.state)) return;
if (
parser.scope.topLevelScope === true &&
decl.init &&
decl.id.type === "Identifier"
) {
const name = decl.id.name;
if (decl.init.type === "ClassExpression") {
const fn = InnerGraph.tagTopLevelSymbol(parser, name);
classWithTopLevelSymbol.set(decl.init, fn);
} else if (parser.isPure(decl.init, decl.id.range[1])) {
const fn = InnerGraph.tagTopLevelSymbol(parser, name);
declWithTopLevelSymbol.set(decl, fn);
if (
!decl.init.type.endsWith("FunctionExpression") &&
decl.init.type !== "Literal"
) {
pureDeclarators.add(decl);
}
return true;
}
}
}
);
// During real walking we set the TopLevelSymbol state to the assigned
// TopLevelSymbol by using the fill datastructures.
// In addition to tracking TopLevelSymbols, we sometimes need to
// add a PureExpressionDependency. This is needed to skip execution
// of pure expressions, even when they are not dropped due to
// minimizing. Otherwise symbols used there might not exist anymore
// as they are removed as unused by this optimization
// When we find a reference to a TopLevelSymbol, we register a
// TopLevelSymbol dependency from TopLevelSymbol in state to the
// referenced TopLevelSymbol. This way we get a graph of all
// TopLevelSymbols.
// The following hooks are called during walking:
parser.hooks.statement.tap("InnerGraphPlugin", statement => {
if (!InnerGraph.isEnabled(parser.state)) return;
if (parser.scope.topLevelScope === true) {
InnerGraph.setTopLevelSymbol(parser.state, undefined);
const fn = statementWithTopLevelSymbol.get(statement);
if (fn) {
InnerGraph.setTopLevelSymbol(parser.state, fn);
const purePart = statementPurePart.get(statement);
if (purePart) {
InnerGraph.onUsage(parser.state, usedByExports => {
switch (usedByExports) {
case undefined:
case true:
return;
default: {
const dep = new PureExpressionDependency(
purePart.range
);
dep.loc = statement.loc;
dep.usedByExports = usedByExports;
parser.state.module.addDependency(dep);
break;
}
}
});
}
}
}
});
parser.hooks.classExtendsExpression.tap(
"InnerGraphPlugin",
(expr, statement) => {
if (!InnerGraph.isEnabled(parser.state)) return;
if (parser.scope.topLevelScope === true) {
const fn = classWithTopLevelSymbol.get(statement);
if (
fn &&
parser.isPure(
expr,
statement.id ? statement.id.range[1] : statement.range[0]
)
) {
InnerGraph.setTopLevelSymbol(parser.state, fn);
onUsageSuper(expr);
}
}
}
);
parser.hooks.classBodyElement.tap(
"InnerGraphPlugin",
(element, statement) => {
if (!InnerGraph.isEnabled(parser.state)) return;
if (parser.scope.topLevelScope === true) {
const fn = classWithTopLevelSymbol.get(statement);
if (fn) {
if (element.type === "MethodDefinition") {
InnerGraph.setTopLevelSymbol(parser.state, fn);
} else if (
element.type === "ClassProperty" &&
!element.static
) {
// TODO add test case once acorn supports it
// Currently this is not parsable
InnerGraph.setTopLevelSymbol(parser.state, fn);
} else {
InnerGraph.setTopLevelSymbol(parser.state, undefined);
}
}
}
}
);
parser.hooks.declarator.tap("InnerGraphPlugin", (decl, statement) => {
if (!InnerGraph.isEnabled(parser.state)) return;
const fn = declWithTopLevelSymbol.get(decl);
if (fn) {
InnerGraph.setTopLevelSymbol(parser.state, fn);
if (pureDeclarators.has(decl)) {
if (decl.init.type === "ClassExpression") {
if (decl.init.superClass) {
onUsageSuper(decl.init.superClass);
}
} else {
InnerGraph.onUsage(parser.state, usedByExports => {
switch (usedByExports) {
case undefined:
case true:
return;
default: {
const dep = new PureExpressionDependency(
decl.init.range
);
dep.loc = decl.loc;
dep.usedByExports = usedByExports;
parser.state.module.addDependency(dep);
break;
}
}
});
}
}
parser.walkExpression(decl.init);
InnerGraph.setTopLevelSymbol(parser.state, undefined);
return true;
}
});
parser.hooks.expression
.for(topLevelSymbolTag)
.tap("InnerGraphPlugin", () => {
const topLevelSymbol = /** @type {TopLevelSymbol} */ (parser.currentTagData);
const currentTopLevelSymbol = InnerGraph.getTopLevelSymbol(
parser.state
);
InnerGraph.addUsage(
parser.state,
topLevelSymbol,
currentTopLevelSymbol || true
);
});
parser.hooks.assign
.for(topLevelSymbolTag)
.tap("InnerGraphPlugin", expr => {
if (!InnerGraph.isEnabled(parser.state)) return;
if (expr.operator === "=") return true;
});
};
normalModuleFactory.hooks.parser
.for("javascript/auto")
.tap("InnerGraphPlugin", handler);
normalModuleFactory.hooks.parser
.for("javascript/esm")
.tap("InnerGraphPlugin", handler);
compilation.hooks.finishModules.tap("InnerGraphPlugin", () => {
logger.timeAggregateEnd("infer dependency usage");
});
}
);
}
}
module.exports = InnerGraphPlugin;

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