291 lines
9.3 KiB
JavaScript
291 lines
9.3 KiB
JavaScript
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/**
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* @fileoverview Restrict usage of duplicate imports.
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* @author Simen Bekkhus
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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const NAMED_TYPES = ["ImportSpecifier", "ExportSpecifier"];
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const NAMESPACE_TYPES = [
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"ImportNamespaceSpecifier",
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"ExportNamespaceSpecifier"
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];
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/**
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* Check if an import/export type belongs to (ImportSpecifier|ExportSpecifier) or (ImportNamespaceSpecifier|ExportNamespaceSpecifier).
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* @param {string} importExportType An import/export type to check.
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* @param {string} type Can be "named" or "namespace"
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* @returns {boolean} True if import/export type belongs to (ImportSpecifier|ExportSpecifier) or (ImportNamespaceSpecifier|ExportNamespaceSpecifier) and false if it doesn't.
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*/
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function isImportExportSpecifier(importExportType, type) {
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const arrayToCheck = type === "named" ? NAMED_TYPES : NAMESPACE_TYPES;
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return arrayToCheck.includes(importExportType);
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}
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/**
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* Return the type of (import|export).
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* @param {ASTNode} node A node to get.
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* @returns {string} The type of the (import|export).
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*/
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function getImportExportType(node) {
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if (node.specifiers && node.specifiers.length > 0) {
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const nodeSpecifiers = node.specifiers;
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const index = nodeSpecifiers.findIndex(
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({ type }) =>
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isImportExportSpecifier(type, "named") ||
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isImportExportSpecifier(type, "namespace")
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);
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const i = index > -1 ? index : 0;
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return nodeSpecifiers[i].type;
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}
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if (node.type === "ExportAllDeclaration") {
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if (node.exported) {
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return "ExportNamespaceSpecifier";
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}
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return "ExportAll";
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}
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return "SideEffectImport";
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}
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/**
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* Returns a boolean indicates if two (import|export) can be merged
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* @param {ASTNode} node1 A node to check.
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* @param {ASTNode} node2 A node to check.
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* @returns {boolean} True if two (import|export) can be merged, false if they can't.
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*/
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function isImportExportCanBeMerged(node1, node2) {
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const importExportType1 = getImportExportType(node1);
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const importExportType2 = getImportExportType(node2);
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if (
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(importExportType1 === "ExportAll" &&
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importExportType2 !== "ExportAll" &&
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importExportType2 !== "SideEffectImport") ||
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(importExportType1 !== "ExportAll" &&
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importExportType1 !== "SideEffectImport" &&
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importExportType2 === "ExportAll")
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) {
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return false;
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}
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if (
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(isImportExportSpecifier(importExportType1, "namespace") &&
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isImportExportSpecifier(importExportType2, "named")) ||
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(isImportExportSpecifier(importExportType2, "namespace") &&
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isImportExportSpecifier(importExportType1, "named"))
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) {
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return false;
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}
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return true;
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}
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/**
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* Returns a boolean if we should report (import|export).
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* @param {ASTNode} node A node to be reported or not.
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* @param {[ASTNode]} previousNodes An array contains previous nodes of the module imported or exported.
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* @returns {boolean} True if the (import|export) should be reported.
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*/
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function shouldReportImportExport(node, previousNodes) {
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let i = 0;
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while (i < previousNodes.length) {
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if (isImportExportCanBeMerged(node, previousNodes[i])) {
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return true;
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}
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i++;
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}
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return false;
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}
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/**
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* Returns array contains only nodes with declarations types equal to type.
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* @param {[{node: ASTNode, declarationType: string}]} nodes An array contains objects, each object contains a node and a declaration type.
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* @param {string} type Declaration type.
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* @returns {[ASTNode]} An array contains only nodes with declarations types equal to type.
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*/
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function getNodesByDeclarationType(nodes, type) {
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return nodes
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.filter(({ declarationType }) => declarationType === type)
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.map(({ node }) => node);
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}
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/**
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* Returns the name of the module imported or re-exported.
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* @param {ASTNode} node A node to get.
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* @returns {string} The name of the module, or empty string if no name.
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*/
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function getModule(node) {
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if (node && node.source && node.source.value) {
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return node.source.value.trim();
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}
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return "";
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}
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/**
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* Checks if the (import|export) can be merged with at least one import or one export, and reports if so.
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* @param {RuleContext} context The ESLint rule context object.
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* @param {ASTNode} node A node to get.
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* @param {Map} modules A Map object contains as a key a module name and as value an array contains objects, each object contains a node and a declaration type.
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* @param {string} declarationType A declaration type can be an import or export.
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* @param {boolean} includeExports Whether or not to check for exports in addition to imports.
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* @returns {void} No return value.
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*/
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function checkAndReport(
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context,
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node,
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modules,
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declarationType,
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includeExports
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) {
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const module = getModule(node);
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if (modules.has(module)) {
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const previousNodes = modules.get(module);
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const messagesIds = [];
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const importNodes = getNodesByDeclarationType(previousNodes, "import");
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let exportNodes;
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if (includeExports) {
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exportNodes = getNodesByDeclarationType(previousNodes, "export");
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}
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if (declarationType === "import") {
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if (shouldReportImportExport(node, importNodes)) {
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messagesIds.push("import");
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}
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if (includeExports) {
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if (shouldReportImportExport(node, exportNodes)) {
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messagesIds.push("importAs");
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}
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}
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} else if (declarationType === "export") {
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if (shouldReportImportExport(node, exportNodes)) {
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messagesIds.push("export");
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}
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if (shouldReportImportExport(node, importNodes)) {
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messagesIds.push("exportAs");
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}
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}
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messagesIds.forEach(messageId =>
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context.report({
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node,
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messageId,
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data: {
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module
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}
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}));
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}
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}
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/**
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* @callback nodeCallback
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* @param {ASTNode} node A node to handle.
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*/
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/**
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* Returns a function handling the (imports|exports) of a given file
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* @param {RuleContext} context The ESLint rule context object.
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* @param {Map} modules A Map object contains as a key a module name and as value an array contains objects, each object contains a node and a declaration type.
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* @param {string} declarationType A declaration type can be an import or export.
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* @param {boolean} includeExports Whether or not to check for exports in addition to imports.
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* @returns {nodeCallback} A function passed to ESLint to handle the statement.
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*/
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function handleImportsExports(
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context,
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modules,
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declarationType,
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includeExports
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) {
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return function(node) {
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const module = getModule(node);
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if (module) {
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checkAndReport(
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context,
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node,
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modules,
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declarationType,
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includeExports
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);
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const currentNode = { node, declarationType };
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let nodes = [currentNode];
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if (modules.has(module)) {
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const previousNodes = modules.get(module);
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nodes = [...previousNodes, currentNode];
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}
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modules.set(module, nodes);
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}
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};
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}
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/** @type {import('../shared/types').Rule} */
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module.exports = {
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meta: {
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type: "problem",
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docs: {
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description: "disallow duplicate module imports",
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recommended: false,
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url: "https://eslint.org/docs/rules/no-duplicate-imports"
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},
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schema: [
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{
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type: "object",
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properties: {
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includeExports: {
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type: "boolean",
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default: false
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}
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},
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additionalProperties: false
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}
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],
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messages: {
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import: "'{{module}}' import is duplicated.",
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importAs: "'{{module}}' import is duplicated as export.",
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export: "'{{module}}' export is duplicated.",
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exportAs: "'{{module}}' export is duplicated as import."
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}
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},
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create(context) {
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const includeExports = (context.options[0] || {}).includeExports,
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modules = new Map();
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const handlers = {
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ImportDeclaration: handleImportsExports(
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context,
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modules,
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"import",
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includeExports
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)
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};
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if (includeExports) {
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handlers.ExportNamedDeclaration = handleImportsExports(
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context,
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modules,
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"export",
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includeExports
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);
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handlers.ExportAllDeclaration = handleImportsExports(
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context,
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modules,
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"export",
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includeExports
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);
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}
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return handlers;
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}
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};
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