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CommonJsExportsParserPlugin.js
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Wed, Feb 19, 07:32

CommonJsExportsParserPlugin.js
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/*
MIT License http://www.opensource.org/licenses/mit-license.php
Author Tobias Koppers @sokra
*/
"use strict";
const RuntimeGlobals = require("../RuntimeGlobals");
const formatLocation = require("../formatLocation");
const { evaluateToString } = require("../javascript/JavascriptParserHelpers");
const propertyAccess = require("../util/propertyAccess");
const CommonJsExportRequireDependency = require("./CommonJsExportRequireDependency");
const CommonJsExportsDependency = require("./CommonJsExportsDependency");
const CommonJsSelfReferenceDependency = require("./CommonJsSelfReferenceDependency");
const DynamicExports = require("./DynamicExports");
const HarmonyExports = require("./HarmonyExports");
const ModuleDecoratorDependency = require("./ModuleDecoratorDependency");
/** @typedef {import("estree").Expression} ExpressionNode */
/** @typedef {import("../NormalModule")} NormalModule */
/** @typedef {import("../javascript/BasicEvaluatedExpression")} BasicEvaluatedExpression */
/** @typedef {import("../javascript/JavascriptParser")} JavascriptParser */
const getValueOfPropertyDescription = expr => {
if (expr.type !== "ObjectExpression") return;
for (const property of expr.properties) {
if (property.computed) continue;
const key = property.key;
if (key.type !== "Identifier" || key.name !== "value") continue;
return property.value;
}
};
const isTruthyLiteral = expr => {
switch (expr.type) {
case "Literal":
return !!expr.value;
case "UnaryExpression":
if (expr.operator === "!") return isFalsyLiteral(expr.argument);
}
return false;
};
const isFalsyLiteral = expr => {
switch (expr.type) {
case "Literal":
return !expr.value;
case "UnaryExpression":
if (expr.operator === "!") return isTruthyLiteral(expr.argument);
}
return false;
};
/**
* @param {JavascriptParser} parser the parser
* @param {ExpressionNode} expr expression
* @returns {{ argument: BasicEvaluatedExpression, ids: string[] } | undefined} parsed call
*/
const parseRequireCall = (parser, expr) => {
const ids = [];
while (expr.type === "MemberExpression") {
if (expr.object.type === "Super") return;
if (!expr.property) return;
const prop = expr.property;
if (expr.computed) {
if (prop.type !== "Literal") return;
ids.push(`${prop.value}`);
} else {
if (prop.type !== "Identifier") return;
ids.push(prop.name);
}
expr = expr.object;
}
if (expr.type !== "CallExpression" || expr.arguments.length !== 1) return;
const callee = expr.callee;
if (
callee.type !== "Identifier" ||
parser.getVariableInfo(callee.name) !== "require"
) {
return;
}
const arg = expr.arguments[0];
if (arg.type === "SpreadElement") return;
const argValue = parser.evaluateExpression(arg);
return { argument: argValue, ids: ids.reverse() };
};
class CommonJsExportsParserPlugin {
constructor(moduleGraph) {
this.moduleGraph = moduleGraph;
}
/**
* @param {JavascriptParser} parser the parser
*/
apply(parser) {
const enableStructuredExports = () => {
DynamicExports.enable(parser.state);
};
const checkNamespace = (topLevel, members, valueExpr) => {
if (!DynamicExports.isEnabled(parser.state)) return;
if (members.length > 0 && members[0] === "__esModule") {
if (valueExpr && isTruthyLiteral(valueExpr) && topLevel) {
DynamicExports.setFlagged(parser.state);
} else {
DynamicExports.setDynamic(parser.state);
}
}
};
const bailout = reason => {
DynamicExports.bailout(parser.state);
if (reason) bailoutHint(reason);
};
const bailoutHint = reason => {
this.moduleGraph
.getOptimizationBailout(parser.state.module)
.push(`CommonJS bailout: ${reason}`);
};
// metadata //
parser.hooks.evaluateTypeof
.for("module")
.tap("CommonJsExportsParserPlugin", evaluateToString("object"));
parser.hooks.evaluateTypeof
.for("exports")
.tap("CommonJsPlugin", evaluateToString("object"));
// exporting //
const handleAssignExport = (expr, base, members) => {
if (HarmonyExports.isEnabled(parser.state)) return;
// Handle reexporting
const requireCall = parseRequireCall(parser, expr.right);
if (
requireCall &&
requireCall.argument.isString() &&
(members.length === 0 || members[0] !== "__esModule")
) {
enableStructuredExports();
// It's possible to reexport __esModule, so we must convert to a dynamic module
if (members.length === 0) DynamicExports.setDynamic(parser.state);
const dep = new CommonJsExportRequireDependency(
expr.range,
null,
base,
members,
requireCall.argument.string,
requireCall.ids,
!parser.isStatementLevelExpression(expr)
);
dep.loc = expr.loc;
dep.optional = !!parser.scope.inTry;
parser.state.module.addDependency(dep);
return true;
}
if (members.length === 0) return;
enableStructuredExports();
const remainingMembers = members;
checkNamespace(
parser.statementPath.length === 1 &&
parser.isStatementLevelExpression(expr),
remainingMembers,
expr.right
);
const dep = new CommonJsExportsDependency(
expr.left.range,
null,
base,
remainingMembers
);
dep.loc = expr.loc;
parser.state.module.addDependency(dep);
parser.walkExpression(expr.right);
return true;
};
parser.hooks.assignMemberChain
.for("exports")
.tap("CommonJsExportsParserPlugin", (expr, members) => {
return handleAssignExport(expr, "exports", members);
});
parser.hooks.assignMemberChain
.for("this")
.tap("CommonJsExportsParserPlugin", (expr, members) => {
if (!parser.scope.topLevelScope) return;
return handleAssignExport(expr, "this", members);
});
parser.hooks.assignMemberChain
.for("module")
.tap("CommonJsExportsParserPlugin", (expr, members) => {
if (members[0] !== "exports") return;
return handleAssignExport(expr, "module.exports", members.slice(1));
});
parser.hooks.call
.for("Object.defineProperty")
.tap("CommonJsExportsParserPlugin", expression => {
const expr = /** @type {import("estree").CallExpression} */ (expression);
if (!parser.isStatementLevelExpression(expr)) return;
if (expr.arguments.length !== 3) return;
if (expr.arguments[0].type === "SpreadElement") return;
if (expr.arguments[1].type === "SpreadElement") return;
if (expr.arguments[2].type === "SpreadElement") return;
const exportsArg = parser.evaluateExpression(expr.arguments[0]);
if (!exportsArg || !exportsArg.isIdentifier()) return;
if (
exportsArg.identifier !== "exports" &&
exportsArg.identifier !== "module.exports" &&
(exportsArg.identifier !== "this" || !parser.scope.topLevelScope)
) {
return;
}
const propertyArg = parser.evaluateExpression(expr.arguments[1]);
if (!propertyArg) return;
const property = propertyArg.asString();
if (typeof property !== "string") return;
enableStructuredExports();
const descArg = expr.arguments[2];
checkNamespace(
parser.statementPath.length === 1,
[property],
getValueOfPropertyDescription(descArg)
);
const dep = new CommonJsExportsDependency(
expr.range,
expr.arguments[2].range,
`Object.defineProperty(${exportsArg.identifier})`,
[property]
);
dep.loc = expr.loc;
parser.state.module.addDependency(dep);
parser.walkExpression(expr.arguments[2]);
return true;
});
// Self reference //
const handleAccessExport = (expr, base, members, call = undefined) => {
if (HarmonyExports.isEnabled(parser.state)) return;
if (members.length === 0) {
bailout(`${base} is used directly at ${formatLocation(expr.loc)}`);
}
if (call && members.length === 1) {
bailoutHint(
`${base}${propertyAccess(
members
)}(...) prevents optimization as ${base} is passed as call context at ${formatLocation(
expr.loc
)}`
);
}
const dep = new CommonJsSelfReferenceDependency(
expr.range,
base,
members,
!!call
);
dep.loc = expr.loc;
parser.state.module.addDependency(dep);
if (call) {
parser.walkExpressions(call.arguments);
}
return true;
};
parser.hooks.callMemberChain
.for("exports")
.tap("CommonJsExportsParserPlugin", (expr, members) => {
return handleAccessExport(expr.callee, "exports", members, expr);
});
parser.hooks.expressionMemberChain
.for("exports")
.tap("CommonJsExportsParserPlugin", (expr, members) => {
return handleAccessExport(expr, "exports", members);
});
parser.hooks.expression
.for("exports")
.tap("CommonJsExportsParserPlugin", expr => {
return handleAccessExport(expr, "exports", []);
});
parser.hooks.callMemberChain
.for("module")
.tap("CommonJsExportsParserPlugin", (expr, members) => {
if (members[0] !== "exports") return;
return handleAccessExport(
expr.callee,
"module.exports",
members.slice(1),
expr
);
});
parser.hooks.expressionMemberChain
.for("module")
.tap("CommonJsExportsParserPlugin", (expr, members) => {
if (members[0] !== "exports") return;
return handleAccessExport(expr, "module.exports", members.slice(1));
});
parser.hooks.expression
.for("module.exports")
.tap("CommonJsExportsParserPlugin", expr => {
return handleAccessExport(expr, "module.exports", []);
});
parser.hooks.callMemberChain
.for("this")
.tap("CommonJsExportsParserPlugin", (expr, members) => {
if (!parser.scope.topLevelScope) return;
return handleAccessExport(expr.callee, "this", members, expr);
});
parser.hooks.expressionMemberChain
.for("this")
.tap("CommonJsExportsParserPlugin", (expr, members) => {
if (!parser.scope.topLevelScope) return;
return handleAccessExport(expr, "this", members);
});
parser.hooks.expression
.for("this")
.tap("CommonJsExportsParserPlugin", expr => {
if (!parser.scope.topLevelScope) return;
return handleAccessExport(expr, "this", []);
});
// Bailouts //
parser.hooks.expression.for("module").tap("CommonJsPlugin", expr => {
bailout();
const isHarmony = HarmonyExports.isEnabled(parser.state);
const dep = new ModuleDecoratorDependency(
isHarmony
? RuntimeGlobals.harmonyModuleDecorator
: RuntimeGlobals.nodeModuleDecorator,
!isHarmony
);
dep.loc = expr.loc;
parser.state.module.addDependency(dep);
return true;
});
}
}
module.exports = CommonJsExportsParserPlugin;

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