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