250 lines
11 KiB
Plaintext
250 lines
11 KiB
Plaintext
"use strict";
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var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
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if (k2 === undefined) k2 = k;
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var desc = Object.getOwnPropertyDescriptor(m, k);
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if (!desc || ("get" in desc ? !m.__esModule : desc.writable || desc.configurable)) {
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desc = { enumerable: true, get: function() { return m[k]; } };
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}
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Object.defineProperty(o, k2, desc);
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}) : (function(o, m, k, k2) {
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if (k2 === undefined) k2 = k;
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o[k2] = m[k];
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}));
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var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
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Object.defineProperty(o, "default", { enumerable: true, value: v });
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}) : function(o, v) {
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o["default"] = v;
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});
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var __importStar = (this && this.__importStar) || function (mod) {
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if (mod && mod.__esModule) return mod;
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var result = {};
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if (mod != null) for (var k in mod) if (k !== "default" && Object.prototype.hasOwnProperty.call(mod, k)) __createBinding(result, mod, k);
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__setModuleDefault(result, mod);
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return result;
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};
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Object.defineProperty(exports, "__esModule", { value: true });
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const eslint_utils_1 = require("@typescript-eslint/utils/eslint-utils");
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const tsutils = __importStar(require("ts-api-utils"));
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const ts = __importStar(require("typescript"));
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const util_1 = require("../util");
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exports.default = (0, util_1.createRule)({
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name: 'switch-exhaustiveness-check',
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meta: {
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type: 'suggestion',
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docs: {
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description: 'Require switch-case statements to be exhaustive',
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requiresTypeChecking: true,
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},
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hasSuggestions: true,
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schema: [
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{
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type: 'object',
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properties: {
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allowDefaultCaseForExhaustiveSwitch: {
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description: `If 'true', allow 'default' cases on switch statements with exhaustive cases.`,
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type: 'boolean',
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},
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requireDefaultForNonUnion: {
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description: `If 'true', require a 'default' clause for switches on non-union types.`,
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type: 'boolean',
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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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switchIsNotExhaustive: 'Switch is not exhaustive. Cases not matched: {{missingBranches}}',
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dangerousDefaultCase: 'The switch statement is exhaustive, so the default case is unnecessary.',
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addMissingCases: 'Add branches for missing cases.',
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},
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},
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defaultOptions: [
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{
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allowDefaultCaseForExhaustiveSwitch: true,
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requireDefaultForNonUnion: false,
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},
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],
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create(context, [{ allowDefaultCaseForExhaustiveSwitch, requireDefaultForNonUnion }]) {
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const sourceCode = (0, eslint_utils_1.getSourceCode)(context);
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const services = (0, util_1.getParserServices)(context);
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const checker = services.program.getTypeChecker();
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const compilerOptions = services.program.getCompilerOptions();
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function getSwitchMetadata(node) {
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const defaultCase = node.cases.find(switchCase => switchCase.test == null);
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const discriminantType = (0, util_1.getConstrainedTypeAtLocation)(services, node.discriminant);
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const symbolName = discriminantType.getSymbol()?.escapedName;
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const containsNonLiteralType = doesTypeContainNonLiteralType(discriminantType);
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if (!discriminantType.isUnion()) {
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return {
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symbolName,
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missingBranchTypes: [],
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defaultCase,
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isUnion: false,
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containsNonLiteralType,
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};
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}
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const caseTypes = new Set();
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for (const switchCase of node.cases) {
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// If the `test` property of the switch case is `null`, then we are on a
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// `default` case.
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if (switchCase.test == null) {
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continue;
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}
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const caseType = (0, util_1.getConstrainedTypeAtLocation)(services, switchCase.test);
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caseTypes.add(caseType);
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}
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const unionTypes = tsutils.unionTypeParts(discriminantType);
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const missingBranchTypes = unionTypes.filter(unionType => !caseTypes.has(unionType));
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return {
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symbolName,
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missingBranchTypes,
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defaultCase,
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isUnion: true,
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containsNonLiteralType,
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};
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}
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/**
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* For example:
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*
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* - `"foo" | "bar"` is a type with all literal types.
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* - `"foo" | number` is a type that contains non-literal types.
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*
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* Default cases are never superfluous in switches with non-literal types.
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*/
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function doesTypeContainNonLiteralType(type) {
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const types = tsutils.unionTypeParts(type);
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return types.some(type => !isFlagSet(type.getFlags(), ts.TypeFlags.Literal | ts.TypeFlags.Undefined | ts.TypeFlags.Null));
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}
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function checkSwitchExhaustive(node, switchMetadata) {
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const { missingBranchTypes, symbolName, defaultCase } = switchMetadata;
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// We only trigger the rule if a `default` case does not exist, since that
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// would disqualify the switch statement from having cases that exactly
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// match the members of a union.
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if (missingBranchTypes.length > 0 && defaultCase === undefined) {
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context.report({
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node: node.discriminant,
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messageId: 'switchIsNotExhaustive',
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data: {
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missingBranches: missingBranchTypes
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.map(missingType => tsutils.isTypeFlagSet(missingType, ts.TypeFlags.ESSymbolLike)
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? `typeof ${missingType.getSymbol()?.escapedName}`
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: checker.typeToString(missingType))
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.join(' | '),
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},
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suggest: [
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{
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messageId: 'addMissingCases',
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fix(fixer) {
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return fixSwitch(fixer, node, missingBranchTypes, symbolName?.toString());
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},
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},
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],
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});
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}
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}
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function fixSwitch(fixer, node, missingBranchTypes, // null means default branch
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symbolName) {
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const lastCase = node.cases.length > 0 ? node.cases[node.cases.length - 1] : null;
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const caseIndent = lastCase
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? ' '.repeat(lastCase.loc.start.column)
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: // If there are no cases, use indentation of the switch statement and
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// leave it to the user to format it correctly.
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' '.repeat(node.loc.start.column);
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const missingCases = [];
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for (const missingBranchType of missingBranchTypes) {
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if (missingBranchType == null) {
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missingCases.push(`default: { throw new Error('default case') }`);
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continue;
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}
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// While running this rule on the "checker.ts" file of TypeScript, the
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// the fix introduced a compiler error due to:
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//
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// ```ts
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// type __String = (string & {
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// __escapedIdentifier: void;
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// }) | (void & {
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// __escapedIdentifier: void;
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// }) | InternalSymbolName;
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// ```
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//
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// The following check fixes it.
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if (missingBranchType.isIntersection()) {
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continue;
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}
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const missingBranchName = missingBranchType.getSymbol()?.escapedName;
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let caseTest = checker.typeToString(missingBranchType);
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if (symbolName &&
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(missingBranchName || missingBranchName === '') &&
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(0, util_1.requiresQuoting)(missingBranchName.toString(), compilerOptions.target)) {
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const escapedBranchName = missingBranchName
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.replace(/'/g, "\\'")
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.replace(/\n/g, '\\n')
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.replace(/\r/g, '\\r');
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caseTest = `${symbolName}['${escapedBranchName}']`;
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}
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const errorMessage = `Not implemented yet: ${caseTest} case`;
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const escapedErrorMessage = errorMessage.replace(/'/g, "\\'");
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missingCases.push(`case ${caseTest}: { throw new Error('${escapedErrorMessage}') }`);
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}
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const fixString = missingCases
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.map(code => `${caseIndent}${code}`)
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.join('\n');
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if (lastCase) {
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return fixer.insertTextAfter(lastCase, `\n${fixString}`);
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}
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// There were no existing cases.
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const openingBrace = sourceCode.getTokenAfter(node.discriminant, util_1.isOpeningBraceToken);
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const closingBrace = sourceCode.getTokenAfter(node.discriminant, util_1.isClosingBraceToken);
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return fixer.replaceTextRange([openingBrace.range[0], closingBrace.range[1]], ['{', fixString, `${caseIndent}}`].join('\n'));
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}
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function checkSwitchUnnecessaryDefaultCase(switchMetadata) {
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if (allowDefaultCaseForExhaustiveSwitch) {
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return;
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}
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const { missingBranchTypes, defaultCase, containsNonLiteralType } = switchMetadata;
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if (missingBranchTypes.length === 0 &&
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defaultCase !== undefined &&
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!containsNonLiteralType) {
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context.report({
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node: defaultCase,
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messageId: 'dangerousDefaultCase',
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});
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}
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}
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function checkSwitchNoUnionDefaultCase(node, switchMetadata) {
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if (!requireDefaultForNonUnion) {
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return;
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}
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const { isUnion, defaultCase } = switchMetadata;
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if (!isUnion && defaultCase === undefined) {
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context.report({
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node: node.discriminant,
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messageId: 'switchIsNotExhaustive',
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data: {
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missingBranches: 'default',
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},
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suggest: [
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{
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messageId: 'addMissingCases',
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fix(fixer) {
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return fixSwitch(fixer, node, [null]);
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},
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},
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],
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});
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}
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}
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return {
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SwitchStatement(node) {
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const switchMetadata = getSwitchMetadata(node);
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checkSwitchExhaustive(node, switchMetadata);
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checkSwitchUnnecessaryDefaultCase(switchMetadata);
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checkSwitchNoUnionDefaultCase(node, switchMetadata);
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},
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};
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},
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});
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function isFlagSet(flags, flag) {
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return (flags & flag) !== 0;
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}
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//# sourceMappingURL=switch-exhaustiveness-check.js.map |