import {

__String,

allKeysStartWithDot,

AmbientModuleDeclaration,

append,

arrayFrom,

changeFullExtension,

CharacterCodes,

combinePaths,

compareBooleans,

compareNumberOfDirectorySeparators,

comparePaths,

Comparison,

CompilerOptions,

concatenate,

containsIgnoredPath,

containsPath,

createGetCanonicalFileName,

Debug,

directorySeparator,

emptyArray,

endsWith,

ensurePathIsNonModuleName,

ensureTrailingDirectorySeparator,

every,

ExportAssignment,

Extension,

extensionFromPath,

extensionsNotSupportingExtensionlessResolution,

fileExtensionIsOneOf,

FileIncludeKind,

firstDefined,

flatMap,

flatten,

forEach,

forEachAncestorDirectoryStoppingAtGlobalCache,

FutureSourceFile,

getBaseFileName,

GetCanonicalFileName,

getConditions,

getDefaultResolutionModeForFileWorker,

getDirectoryPath,

getEmitModuleResolutionKind,

getModuleNameStringLiteralAt,

getModuleSpecifierEndingPreference,

getNodeModulePathParts,

getNormalizedAbsolutePath,

getOutputDeclarationFileNameWorker,

getOutputJSFileNameWorker,

getOwnKeys,

getPackageJsonTypesVersionsPaths,

getPackageNameFromTypesPackageName,

getPackageScopeForPath,

getPathsBasePath,

getRelativePathFromDirectory,

getRelativePathToDirectoryOrUrl,

getResolvePackageJsonExports,

getResolvePackageJsonImports,

getSourceFileOfModule,

getSupportedExtensions,

getTemporaryModuleResolutionState,

getTextOfIdentifierOrLiteral,

hasImplementationTSFileExtension,

hasJSFileExtension,

hasTSFileExtension,

hostGetCanonicalFileName,

hostUsesCaseSensitiveFileNames,

Identifier,

isAmbientModule,

isApplicableVersionedTypesKey,

isDeclarationFileName,

isExternalModuleAugmentation,

isExternalModuleNameRelative,

isFullSourceFile,

isMissingPackageJsonInfo,

isModuleBlock,

isModuleDeclaration,

isNonGlobalAmbientModule,

isPackageJsonInfo,

isRootedDiskPath,

isSourceFile,

isString,

JsxEmit,

map,

mapDefined,

MapLike,

matchPatternOrExact,

memoizeOne,

min,

ModuleDeclaration,

ModuleKind,

ModulePath,

ModuleResolutionHost,

ModuleResolutionKind,

ModuleSpecifierCache,

ModuleSpecifierEnding,

ModuleSpecifierOptions,

ModuleSpecifierResolutionHost,

NodeFlags,

NodeModulePathParts,

normalizePath,

PackageJsonPathFields,

pathContainsNodeModules,

pathIsBareSpecifier,

pathIsRelative,

PropertyAccessExpression,

removeExtension,

removeFileExtension,

removeSuffix,

removeTrailingDirectorySeparator,

replaceFirstStar,

ResolutionMode,

ResolvedModuleSpecifierInfo,

resolveModuleName,

resolvePath,

ScriptKind,

shouldAllowImportingTsExtension,

some,

SourceFile,

startsWith,

startsWithDirectory,

StringLiteral,

Symbol,

SymbolFlags,

toPath,

tryGetExtensionFromPath,

tryParseJson,

tryParsePatterns,

TypeChecker,

UserPreferences,

} from "./_namespaces/ts.js";

const stringToRegex = memoizeOne((pattern: string) => {

try {

let slash = pattern.indexOf("/");

if (slash !== 0) {

// No leading slash, treat as a pattern

return new RegExp(pattern);

}

const lastSlash = pattern.lastIndexOf("/");

if (slash === lastSlash) {

// Only one slash, treat as a pattern

return new RegExp(pattern);

}

while ((slash = pattern.indexOf("/", slash + 1)) !== lastSlash) {

if (pattern[slash - 1] !== "\\") {

// Unescaped middle slash, treat as a pattern

return new RegExp(pattern);

}

}

// Only case-insensitive and unicode flags make sense

const flags = pattern.substring(lastSlash + 1).replace(/[^iu]/g, "");

pattern = pattern.substring(1, lastSlash);

return new RegExp(pattern, flags);

}

catch {

return undefined;

}

});

// Used by importFixes, getEditsForFileRename, and declaration emit to synthesize import module specifiers.

/** @internal */

export const enum RelativePreference {

Relative,

NonRelative,

Shortest,

ExternalNonRelative,

}

/** @internal */

export interface ModuleSpecifierPreferences {

readonly relativePreference: RelativePreference;

/**

* @param syntaxImpliedNodeFormat Used when the import syntax implies ESM or CJS irrespective of the mode of the file.

*/

getAllowedEndingsInPreferredOrder(syntaxImpliedNodeFormat?: ResolutionMode): ModuleSpecifierEnding[];

readonly excludeRegexes?: readonly string[];

}

/** @internal */

export function getModuleSpecifierPreferences(

{ importModuleSpecifierPreference, importModuleSpecifierEnding, autoImportSpecifierExcludeRegexes }: UserPreferences,

host: Pick<ModuleSpecifierResolutionHost, "getDefaultResolutionModeForFile">,

compilerOptions: CompilerOptions,

importingSourceFile: Pick<SourceFile, "fileName" | "impliedNodeFormat">,

oldImportSpecifier?: string,

): ModuleSpecifierPreferences {

const filePreferredEnding = getPreferredEnding();

return {

excludeRegexes: autoImportSpecifierExcludeRegexes,

relativePreference: oldImportSpecifier !== undefined ? (isExternalModuleNameRelative(oldImportSpecifier) ?

RelativePreference.Relative :

RelativePreference.NonRelative) :

importModuleSpecifierPreference === "relative" ? RelativePreference.Relative :

importModuleSpecifierPreference === "non-relative" ? RelativePreference.NonRelative :

importModuleSpecifierPreference === "project-relative" ? RelativePreference.ExternalNonRelative :

RelativePreference.Shortest,

getAllowedEndingsInPreferredOrder: syntaxImpliedNodeFormat => {

const impliedNodeFormat = getDefaultResolutionModeForFile(importingSourceFile, host, compilerOptions);

const preferredEnding = syntaxImpliedNodeFormat !== impliedNodeFormat ? getPreferredEnding(syntaxImpliedNodeFormat) : filePreferredEnding;

const moduleResolution = getEmitModuleResolutionKind(compilerOptions);

if ((syntaxImpliedNodeFormat ?? impliedNodeFormat) === ModuleKind.ESNext && ModuleResolutionKind.Node16 <= moduleResolution && moduleResolution <= ModuleResolutionKind.NodeNext) {

if (shouldAllowImportingTsExtension(compilerOptions, importingSourceFile.fileName)) {

return [ModuleSpecifierEnding.TsExtension, ModuleSpecifierEnding.JsExtension];

}

return [ModuleSpecifierEnding.JsExtension];

}

if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic) {

return preferredEnding === ModuleSpecifierEnding.JsExtension

? [ModuleSpecifierEnding.JsExtension, ModuleSpecifierEnding.Index]

: [ModuleSpecifierEnding.Index, ModuleSpecifierEnding.JsExtension];

}

const allowImportingTsExtension = shouldAllowImportingTsExtension(compilerOptions, importingSourceFile.fileName);

switch (preferredEnding) {

case ModuleSpecifierEnding.JsExtension:

return allowImportingTsExtension

? [ModuleSpecifierEnding.JsExtension, ModuleSpecifierEnding.TsExtension, ModuleSpecifierEnding.Minimal, ModuleSpecifierEnding.Index]

: [ModuleSpecifierEnding.JsExtension, ModuleSpecifierEnding.Minimal, ModuleSpecifierEnding.Index];

case ModuleSpecifierEnding.TsExtension:

return [ModuleSpecifierEnding.TsExtension, ModuleSpecifierEnding.Minimal, ModuleSpecifierEnding.JsExtension, ModuleSpecifierEnding.Index];

case ModuleSpecifierEnding.Index:

return allowImportingTsExtension

? [ModuleSpecifierEnding.Index, ModuleSpecifierEnding.Minimal, ModuleSpecifierEnding.TsExtension, ModuleSpecifierEnding.JsExtension]

: [ModuleSpecifierEnding.Index, ModuleSpecifierEnding.Minimal, ModuleSpecifierEnding.JsExtension];

case ModuleSpecifierEnding.Minimal:

return allowImportingTsExtension

? [ModuleSpecifierEnding.Minimal, ModuleSpecifierEnding.Index, ModuleSpecifierEnding.TsExtension, ModuleSpecifierEnding.JsExtension]

: [ModuleSpecifierEnding.Minimal, ModuleSpecifierEnding.Index, ModuleSpecifierEnding.JsExtension];

default:

Debug.assertNever(preferredEnding);

}

},

};

function getPreferredEnding(resolutionMode?: ResolutionMode): ModuleSpecifierEnding {

if (oldImportSpecifier !== undefined) {

if (hasJSFileExtension(oldImportSpecifier)) return ModuleSpecifierEnding.JsExtension;

if (endsWith(oldImportSpecifier, "/index")) return ModuleSpecifierEnding.Index;

}

return getModuleSpecifierEndingPreference(

importModuleSpecifierEnding,

resolutionMode ?? getDefaultResolutionModeForFile(importingSourceFile, host, compilerOptions),

compilerOptions,

isFullSourceFile(importingSourceFile) ? importingSourceFile : undefined,

);

}

}

// `importingSourceFile` and `importingSourceFileName`? Why not just use `importingSourceFile.path`?

// Because when this is called by the file renamer, `importingSourceFile` is the file being renamed,

// while `importingSourceFileName` its *new* name. We need a source file just to get its

// `impliedNodeFormat` and to detect certain preferences from existing import module specifiers.

/** @internal */

export function updateModuleSpecifier(

compilerOptions: CompilerOptions,

importingSourceFile: SourceFile,

importingSourceFileName: string,

toFileName: string,

host: ModuleSpecifierResolutionHost,

oldImportSpecifier: string,

options: ModuleSpecifierOptions = {},

): string | undefined {

const res = getModuleSpecifierWorker(compilerOptions, importingSourceFile, importingSourceFileName, toFileName, host, getModuleSpecifierPreferences({}, host, compilerOptions, importingSourceFile, oldImportSpecifier), {}, options);

if (res === oldImportSpecifier) return undefined;

return res;

}

// `importingSourceFile` and `importingSourceFileName`? Why not just use `importingSourceFile.path`?

// Because when this is called by the declaration emitter, `importingSourceFile` is the implementation

// file, but `importingSourceFileName` and `toFileName` refer to declaration files (the former to the

// one currently being produced; the latter to the one being imported). We need an implementation file

// just to get its `impliedNodeFormat` and to detect certain preferences from existing import module

// specifiers.

/** @internal */

export function getModuleSpecifier(

compilerOptions: CompilerOptions,

importingSourceFile: SourceFile | FutureSourceFile,

importingSourceFileName: string,

toFileName: string,

host: ModuleSpecifierResolutionHost,

options: ModuleSpecifierOptions = {},

): string {

return getModuleSpecifierWorker(compilerOptions, importingSourceFile, importingSourceFileName, toFileName, host, getModuleSpecifierPreferences({}, host, compilerOptions, importingSourceFile), {}, options);

}

/** @internal */

export function getNodeModulesPackageName(

compilerOptions: CompilerOptions,

importingSourceFile: SourceFile | FutureSourceFile,

nodeModulesFileName: string,

host: ModuleSpecifierResolutionHost,

preferences: UserPreferences,

options: ModuleSpecifierOptions = {},

): string | undefined {

const info = getInfo(importingSourceFile.fileName, host);

const modulePaths = getAllModulePaths(info, nodeModulesFileName, host, preferences, compilerOptions, options);

return firstDefined(modulePaths, modulePath => tryGetModuleNameAsNodeModule(modulePath, info, importingSourceFile, host, compilerOptions, preferences, /*packageNameOnly*/ true, options.overrideImportMode));

}

function getModuleSpecifierWorker(

compilerOptions: CompilerOptions,

importingSourceFile: SourceFile | FutureSourceFile,

importingSourceFileName: string,

toFileName: string,

host: ModuleSpecifierResolutionHost,

preferences: ModuleSpecifierPreferences,

userPreferences: UserPreferences,

options: ModuleSpecifierOptions = {},

): string {

const info = getInfo(importingSourceFileName, host);

const modulePaths = getAllModulePaths(info, toFileName, host, userPreferences, compilerOptions, options);

return firstDefined(modulePaths, modulePath => tryGetModuleNameAsNodeModule(modulePath, info, importingSourceFile, host, compilerOptions, userPreferences, /*packageNameOnly*/ undefined, options.overrideImportMode)) ||

getLocalModuleSpecifier(toFileName, info, compilerOptions, host, options.overrideImportMode || getDefaultResolutionModeForFile(importingSourceFile, host, compilerOptions), preferences);

}

/** @internal */

export function tryGetModuleSpecifiersFromCache(

moduleSymbol: Symbol,

importingSourceFile: SourceFile | FutureSourceFile,

host: ModuleSpecifierResolutionHost,

userPreferences: UserPreferences,

options: ModuleSpecifierOptions = {},

): ModuleSpecifierResult | undefined {

const result = tryGetModuleSpecifiersFromCacheWorker(

moduleSymbol,

importingSourceFile,

host,

userPreferences,

options,

);

return result[1] && { kind: result[0], moduleSpecifiers: result[1], computedWithoutCache: false };

}

function tryGetModuleSpecifiersFromCacheWorker(

moduleSymbol: Symbol,

importingSourceFile: SourceFile | FutureSourceFile,

host: ModuleSpecifierResolutionHost,

userPreferences: UserPreferences,

options: ModuleSpecifierOptions = {},

): readonly [kind?: ModuleSpecifierResult["kind"], specifiers?: readonly string[], moduleFile?: SourceFile, modulePaths?: readonly ModulePath[], cache?: ModuleSpecifierCache] {

const moduleSourceFile = getSourceFileOfModule(moduleSymbol);

if (!moduleSourceFile) {

return emptyArray as [];

}

const cache = host.getModuleSpecifierCache?.();

const cached = cache?.get(importingSourceFile.path, moduleSourceFile.path, userPreferences, options);

return [cached?.kind, cached?.moduleSpecifiers, moduleSourceFile, cached?.modulePaths, cache];

}

/**

* Returns an import for each symlink and for the realpath.

*

* @internal

*/

export function getModuleSpecifiers(

moduleSymbol: Symbol,

checker: TypeChecker,

compilerOptions: CompilerOptions,

importingSourceFile: SourceFile,

host: ModuleSpecifierResolutionHost,

userPreferences: UserPreferences,

options: ModuleSpecifierOptions = {},

): readonly string[] {

return getModuleSpecifiersWithCacheInfo(

moduleSymbol,

checker,

compilerOptions,

importingSourceFile,

host,

userPreferences,

options,

/*forAutoImport*/ false,

).moduleSpecifiers;

}

/** @internal */

export interface ModuleSpecifierResult {

kind: ResolvedModuleSpecifierInfo["kind"];

moduleSpecifiers: readonly string[];

computedWithoutCache: boolean;

}

/** @internal */

export function getModuleSpecifiersWithCacheInfo(

moduleSymbol: Symbol,

checker: TypeChecker,

compilerOptions: CompilerOptions,

importingSourceFile: SourceFile | FutureSourceFile,

host: ModuleSpecifierResolutionHost,

userPreferences: UserPreferences,

options: ModuleSpecifierOptions | undefined = {},

forAutoImport: boolean,

): ModuleSpecifierResult {

let computedWithoutCache = false;

const ambient = tryGetModuleNameFromAmbientModule(moduleSymbol, checker);

if (ambient) {

return {

kind: "ambient",

moduleSpecifiers: !(forAutoImport && isExcludedByRegex(ambient, userPreferences.autoImportSpecifierExcludeRegexes)) ? [ambient] : emptyArray,

computedWithoutCache,

};

}

// eslint-disable-next-line prefer-const

let [kind, specifiers, moduleSourceFile, modulePaths, cache] = tryGetModuleSpecifiersFromCacheWorker(

moduleSymbol,

importingSourceFile,

host,

userPreferences,

options,

);

if (specifiers) return { kind, moduleSpecifiers: specifiers, computedWithoutCache };

if (!moduleSourceFile) return { kind: undefined, moduleSpecifiers: emptyArray, computedWithoutCache };

computedWithoutCache = true;

modulePaths ||= getAllModulePathsWorker(getInfo(importingSourceFile.fileName, host), moduleSourceFile.originalFileName, host, compilerOptions, options);

const result = computeModuleSpecifiers(

modulePaths,

compilerOptions,

importingSourceFile,

host,

userPreferences,

options,

forAutoImport,

);

cache?.set(importingSourceFile.path, moduleSourceFile.path, userPreferences, options, result.kind, modulePaths, result.moduleSpecifiers);

return result;

}

/** @internal */

export function getLocalModuleSpecifierBetweenFileNames(

importingFile: Pick<SourceFile, "fileName" | "impliedNodeFormat">,

targetFileName: string,

compilerOptions: CompilerOptions,

host: ModuleSpecifierResolutionHost,

preferences: UserPreferences,

options: ModuleSpecifierOptions = {},

): string {

const info = getInfo(importingFile.fileName, host);

const importMode = options.overrideImportMode ?? importingFile.impliedNodeFormat;

return getLocalModuleSpecifier(

targetFileName,

info,

compilerOptions,

host,

importMode,

getModuleSpecifierPreferences(preferences, host, compilerOptions, importingFile),

);

}

function computeModuleSpecifiers(

modulePaths: readonly ModulePath[],

compilerOptions: CompilerOptions,

importingSourceFile: SourceFile | FutureSourceFile,

host: ModuleSpecifierResolutionHost,

userPreferences: UserPreferences,

options: ModuleSpecifierOptions = {},

forAutoImport: boolean,

): ModuleSpecifierResult {

const info = getInfo(importingSourceFile.fileName, host);

const preferences = getModuleSpecifierPreferences(userPreferences, host, compilerOptions, importingSourceFile);

const existingSpecifier = isFullSourceFile(importingSourceFile) && forEach(modulePaths, modulePath =>

forEach(

host.getFileIncludeReasons().get(toPath(modulePath.path, host.getCurrentDirectory(), info.getCanonicalFileName)),

reason => {

if (reason.kind !== FileIncludeKind.Import || reason.file !== importingSourceFile.path) return undefined;

// If the candidate import mode doesn't match the mode we're generating for, don't consider it

// TODO: maybe useful to keep around as an alternative option for certain contexts where the mode is overridable

const existingMode = host.getModeForResolutionAtIndex(importingSourceFile, reason.index);

const targetMode = options.overrideImportMode ?? host.getDefaultResolutionModeForFile(importingSourceFile);

if (existingMode !== targetMode && existingMode !== undefined && targetMode !== undefined) {

return undefined;

}

const specifier = getModuleNameStringLiteralAt(importingSourceFile, reason.index).text;

// If the preference is for non relative and the module specifier is relative, ignore it

return preferences.relativePreference !== RelativePreference.NonRelative || !pathIsRelative(specifier) ?

specifier :

undefined;

},

));

if (existingSpecifier) {

return { kind: undefined, moduleSpecifiers: [existingSpecifier], computedWithoutCache: true };

}

const importedFileIsInNodeModules = some(modulePaths, p => p.isInNodeModules);

// Module specifier priority:

// 1. "Bare package specifiers" (e.g. "@foo/bar") resulting from a path through node_modules to a package.json's "types" entry

// 2. Specifiers generated using "paths" from tsconfig

// 3. Non-relative specfiers resulting from a path through node_modules (e.g. "@foo/bar/path/to/file")

// 4. Relative paths

let nodeModulesSpecifiers: string[] | undefined;

let pathsSpecifiers: string[] | undefined;

let redirectPathsSpecifiers: string[] | undefined;

let relativeSpecifiers: string[] | undefined;

for (const modulePath of modulePaths) {

const specifier = modulePath.isInNodeModules

? tryGetModuleNameAsNodeModule(modulePath, info, importingSourceFile, host, compilerOptions, userPreferences, /*packageNameOnly*/ undefined, options.overrideImportMode)

: undefined;

if (specifier && !(forAutoImport && isExcludedByRegex(specifier, preferences.excludeRegexes))) {

nodeModulesSpecifiers = append(nodeModulesSpecifiers, specifier);

if (modulePath.isRedirect) {

// If we got a specifier for a redirect, it was a bare package specifier (e.g. "@foo/bar",

// not "@foo/bar/path/to/file"). No other specifier will be this good, so stop looking.

return { kind: "node_modules", moduleSpecifiers: nodeModulesSpecifiers, computedWithoutCache: true };

}

}

const local = getLocalModuleSpecifier(

modulePath.path,

info,

compilerOptions,

host,

options.overrideImportMode || importingSourceFile.impliedNodeFormat,

preferences,

/*pathsOnly*/ modulePath.isRedirect || !!specifier,

);

if (!local || forAutoImport && isExcludedByRegex(local, preferences.excludeRegexes)) {

continue;

}

if (modulePath.isRedirect) {

redirectPathsSpecifiers = append(redirectPathsSpecifiers, local);

}

else if (pathIsBareSpecifier(local)) {

if (pathContainsNodeModules(local)) {

// We could be in this branch due to inappropriate use of `baseUrl`, not intentional `paths`

// usage. It's impossible to reason about where to prioritize baseUrl-generated module

// specifiers, but if they contain `/node_modules/`, they're going to trigger a portability

// error, so *at least* don't prioritize those.

relativeSpecifiers = append(relativeSpecifiers, local);

}

else {

pathsSpecifiers = append(pathsSpecifiers, local);

}

}

else if (forAutoImport || !importedFileIsInNodeModules || modulePath.isInNodeModules) {

// Why this extra conditional, not just an `else`? If some path to the file contained

// 'node_modules', but we can't create a non-relative specifier (e.g. "@foo/bar/path/to/file"),

// that means we had to go through a *sibling's* node_modules, not one we can access directly.

// If some path to the file was in node_modules but another was not, this likely indicates that

// we have a monorepo structure with symlinks. In this case, the non-node_modules path is

// probably the realpath, e.g. "../bar/path/to/file", but a relative path to another package

// in a monorepo is probably not portable. So, the module specifier we actually go with will be

// the relative path through node_modules, so that the declaration emitter can produce a

// portability error. (See declarationEmitReexportedSymlinkReference3)

relativeSpecifiers = append(relativeSpecifiers, local);

}

}

return pathsSpecifiers?.length ? { kind: "paths", moduleSpecifiers: pathsSpecifiers, computedWithoutCache: true } :

redirectPathsSpecifiers?.length ? { kind: "redirect", moduleSpecifiers: redirectPathsSpecifiers, computedWithoutCache: true } :

nodeModulesSpecifiers?.length ? { kind: "node_modules", moduleSpecifiers: nodeModulesSpecifiers, computedWithoutCache: true } :

{ kind: "relative", moduleSpecifiers: relativeSpecifiers ?? emptyArray, computedWithoutCache: true };

}

function isExcludedByRegex(moduleSpecifier: string, excludeRegexes: readonly string[] | undefined): boolean {

return some(excludeRegexes, pattern => !!stringToRegex(pattern)?.test(moduleSpecifier));

}

interface Info {

readonly getCanonicalFileName: GetCanonicalFileName;

readonly importingSourceFileName: string;

readonly sourceDirectory: string;

readonly canonicalSourceDirectory: string;

}

// importingSourceFileName is separate because getEditsForFileRename may need to specify an updated path

function getInfo(importingSourceFileName: string, host: ModuleSpecifierResolutionHost): Info {

importingSourceFileName = getNormalizedAbsolutePath(importingSourceFileName, host.getCurrentDirectory());

const getCanonicalFileName = createGetCanonicalFileName(host.useCaseSensitiveFileNames ? host.useCaseSensitiveFileNames() : true);

const sourceDirectory = getDirectoryPath(importingSourceFileName);

return {

getCanonicalFileName,

importingSourceFileName,

sourceDirectory,

canonicalSourceDirectory: getCanonicalFileName(sourceDirectory),

};

}

function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOptions: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: ResolutionMode, preferences: ModuleSpecifierPreferences): string;

function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOptions: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: ResolutionMode, preferences: ModuleSpecifierPreferences, pathsOnly?: boolean): string | undefined;

function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOptions: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: ResolutionMode, { getAllowedEndingsInPreferredOrder: getAllowedEndingsInPrefererredOrder, relativePreference, excludeRegexes }: ModuleSpecifierPreferences, pathsOnly?: boolean): string | undefined {

const { baseUrl, paths, rootDirs } = compilerOptions;

if (pathsOnly && !paths) {

return undefined;

}

const { sourceDirectory, canonicalSourceDirectory, getCanonicalFileName } = info;

const allowedEndings = getAllowedEndingsInPrefererredOrder(importMode);

const relativePath = rootDirs && tryGetModuleNameFromRootDirs(rootDirs, moduleFileName, sourceDirectory, getCanonicalFileName, allowedEndings, compilerOptions) ||

processEnding(ensurePathIsNonModuleName(getRelativePathFromDirectory(sourceDirectory, moduleFileName, getCanonicalFileName)), allowedEndings, compilerOptions);

if (!baseUrl && !paths && !getResolvePackageJsonImports(compilerOptions) || relativePreference === RelativePreference.Relative) {

return pathsOnly ? undefined : relativePath;

}

const baseDirectory = getNormalizedAbsolutePath(getPathsBasePath(compilerOptions, host) || baseUrl!, host.getCurrentDirectory());

const relativeToBaseUrl = getRelativePathIfInSameVolume(moduleFileName, baseDirectory, getCanonicalFileName);

if (!relativeToBaseUrl) {

return pathsOnly ? undefined : relativePath;

}

const fromPackageJsonImports = pathsOnly

? undefined

: tryGetModuleNameFromPackageJsonImports(

moduleFileName,

sourceDirectory,

compilerOptions,

host,

importMode,

prefersTsExtension(allowedEndings),

);

const fromPaths = pathsOnly || fromPackageJsonImports === undefined ? paths && tryGetModuleNameFromPaths(relativeToBaseUrl, paths, allowedEndings, baseDirectory, getCanonicalFileName, host, compilerOptions) : undefined;

if (pathsOnly) {

return fromPaths;

}

const maybeNonRelative = fromPackageJsonImports ?? (fromPaths === undefined && baseUrl !== undefined ? processEnding(relativeToBaseUrl, allowedEndings, compilerOptions) : fromPaths);

if (!maybeNonRelative) {

return relativePath;

}

const relativeIsExcluded = isExcludedByRegex(relativePath, excludeRegexes);

const nonRelativeIsExcluded = isExcludedByRegex(maybeNonRelative, excludeRegexes);

if (!relativeIsExcluded && nonRelativeIsExcluded) {

return relativePath;

}

if (relativeIsExcluded && !nonRelativeIsExcluded) {

return maybeNonRelative;

}

if (relativePreference === RelativePreference.NonRelative && !pathIsRelative(maybeNonRelative)) {

return maybeNonRelative;

}

if (relativePreference === RelativePreference.ExternalNonRelative && !pathIsRelative(maybeNonRelative)) {

const projectDirectory = compilerOptions.configFilePath ?

toPath(getDirectoryPath(compilerOptions.configFilePath), host.getCurrentDirectory(), info.getCanonicalFileName) :

info.getCanonicalFileName(host.getCurrentDirectory());

const modulePath = toPath(moduleFileName, projectDirectory, getCanonicalFileName);

const sourceIsInternal = startsWith(canonicalSourceDirectory, projectDirectory);

const targetIsInternal = startsWith(modulePath, projectDirectory);

if (sourceIsInternal && !targetIsInternal || !sourceIsInternal && targetIsInternal) {

// 1. The import path crosses the boundary of the tsconfig.json-containing directory.

//

// src/

// tsconfig.json

// index.ts -------

// lib/ | (path crosses tsconfig.json)

// imported.ts <---

//

return maybeNonRelative;

}

const nearestTargetPackageJson = getNearestAncestorDirectoryWithPackageJson(host, getDirectoryPath(modulePath));

const nearestSourcePackageJson = getNearestAncestorDirectoryWithPackageJson(host, sourceDirectory);

const ignoreCase = !hostUsesCaseSensitiveFileNames(host);

if (!packageJsonPathsAreEqual(nearestTargetPackageJson, nearestSourcePackageJson, ignoreCase)) {

// 2. The importing and imported files are part of different packages.

//

// packages/a/

// package.json

// index.ts --------

// packages/b/ | (path crosses package.json)

// package.json |

// component.ts <---

//

return maybeNonRelative;

}

return relativePath;

}

// Prefer a relative import over a baseUrl import if it has fewer components.

return isPathRelativeToParent(maybeNonRelative) || countPathComponents(relativePath) < countPathComponents(maybeNonRelative) ? relativePath : maybeNonRelative;

}

function packageJsonPathsAreEqual(a: string | undefined, b: string | undefined, ignoreCase?: boolean) {

if (a === b) return true;

if (a === undefined || b === undefined) return false;

return comparePaths(a, b, ignoreCase) === Comparison.EqualTo;

}

/** @internal */

export function countPathComponents(path: string): number {

let count = 0;

for (let i = startsWith(path, "./") ? 2 : 0; i < path.length; i++) {

if (path.charCodeAt(i) === CharacterCodes.slash) count++;

}

return count;

}

function comparePathsByRedirectAndNumberOfDirectorySeparators(a: ModulePath, b: ModulePath) {

return compareBooleans(b.isRedirect, a.isRedirect) || compareNumberOfDirectorySeparators(a.path, b.path);

}

function getNearestAncestorDirectoryWithPackageJson(host: ModuleSpecifierResolutionHost, fileName: string) {

if (host.getNearestAncestorDirectoryWithPackageJson) {

return host.getNearestAncestorDirectoryWithPackageJson(fileName);

}

return forEachAncestorDirectoryStoppingAtGlobalCache(

host,

fileName,

directory =>

host.fileExists(combinePaths(directory, "package.json")) ?

directory :

undefined,

);

}

/** @internal */

export function forEachFileNameOfModule<T>(

importingFileName: string,

importedFileName: string,

host: ModuleSpecifierResolutionHost,

preferSymlinks: boolean,

cb: (fileName: string, isRedirect: boolean) => T | undefined,

): T | undefined {

const getCanonicalFileName = hostGetCanonicalFileName(host);

const cwd = host.getCurrentDirectory();

const referenceRedirect = host.isSourceOfProjectReferenceRedirect(importedFileName) ? host.getRedirectFromSourceFile(importedFileName)?.outputDts : undefined;

const importedPath = toPath(importedFileName, cwd, getCanonicalFileName);

const redirects = host.redirectTargetsMap.get(importedPath) || emptyArray;

const importedFileNames = [...(referenceRedirect ? [referenceRedirect] : emptyArray), importedFileName, ...redirects];

const targets = importedFileNames.map(f => getNormalizedAbsolutePath(f, cwd));

let shouldFilterIgnoredPaths = !every(targets, containsIgnoredPath);

if (!preferSymlinks) {

// Symlinks inside ignored paths are already filtered out of the symlink cache,

// so we only need to remove them from the realpath filenames.

const result = forEach(targets, p => !(shouldFilterIgnoredPaths && containsIgnoredPath(p)) && cb(p, referenceRedirect === p));

if (result) return result;

}

const symlinkedDirectories = host.getSymlinkCache?.().getSymlinkedDirectoriesByRealpath();

const fullImportedFileName = getNormalizedAbsolutePath(importedFileName, cwd);

const result = symlinkedDirectories && forEachAncestorDirectoryStoppingAtGlobalCache(

host,

getDirectoryPath(fullImportedFileName),

realPathDirectory => {

const symlinkDirectories = symlinkedDirectories.get(ensureTrailingDirectorySeparator(toPath(realPathDirectory, cwd, getCanonicalFileName)));

if (!symlinkDirectories) return undefined; // Continue to ancestor directory

// Don't want to a package to globally import from itself (importNameCodeFix_symlink_own_package.ts)

if (startsWithDirectory(importingFileName, realPathDirectory, getCanonicalFileName)) {

return false; // Stop search, each ancestor directory will also hit this condition

}

return forEach(targets, target => {

if (!startsWithDirectory(target, realPathDirectory, getCanonicalFileName)) {

return;

}

const relative = getRelativePathFromDirectory(realPathDirectory, target, getCanonicalFileName);

for (const symlinkDirectory of symlinkDirectories) {

const option = resolvePath(symlinkDirectory, relative);

const result = cb(option, target === referenceRedirect);

shouldFilterIgnoredPaths = true; // We found a non-ignored path in symlinks, so we can reject ignored-path realpaths

if (result) return result;

}

});

},

);

return result || (preferSymlinks

? forEach(targets, p => shouldFilterIgnoredPaths && containsIgnoredPath(p) ? undefined : cb(p, p === referenceRedirect))

: undefined);

}

/**

* Looks for existing imports that use symlinks to this module.

* Symlinks will be returned first so they are preferred over the real path.

*/

function getAllModulePaths(

info: Info,

importedFileName: string,

host: ModuleSpecifierResolutionHost,

preferences: UserPreferences,

compilerOptions: CompilerOptions,

options: ModuleSpecifierOptions = {},

) {

const importingFilePath = toPath(info.importingSourceFileName, host.getCurrentDirectory(), hostGetCanonicalFileName(host));

const importedFilePath = toPath(importedFileName, host.getCurrentDirectory(), hostGetCanonicalFileName(host));

const cache = host.getModuleSpecifierCache?.();

if (cache) {

const cached = cache.get(importingFilePath, importedFilePath, preferences, options);

if (cached?.modulePaths) return cached.modulePaths;

}

const modulePaths = getAllModulePathsWorker(info, importedFileName, host, compilerOptions, options);

if (cache) {

cache.setModulePaths(importingFilePath, importedFilePath, preferences, options, modulePaths);

}

return modulePaths;

}

const runtimeDependencyFields = ["dependencies", "peerDependencies", "optionalDependencies"] as const;

function getAllRuntimeDependencies(packageJson: PackageJsonPathFields) {

let result;

for (const field of runtimeDependencyFields) {

const deps = packageJson[field];

if (deps && typeof deps === "object") {

result = concatenate(result, getOwnKeys(deps));

}

}

return result;

}

function getAllModulePathsWorker(info: Info, importedFileName: string, host: ModuleSpecifierResolutionHost, compilerOptions: CompilerOptions, options: ModuleSpecifierOptions): readonly ModulePath[] {

const cache = host.getModuleResolutionCache?.();

const links = host.getSymlinkCache?.();

if (cache && links && host.readFile && !pathContainsNodeModules(info.importingSourceFileName)) {

Debug.type<ModuleResolutionHost>(host);

// Cache resolutions for all `dependencies` of the `package.json` context of the input file.

// This should populate all the relevant symlinks in the symlink cache, and most, if not all, of these resolutions

// should get (re)used.

const state = getTemporaryModuleResolutionState(cache.getPackageJsonInfoCache(), host, {});

const packageJson = getPackageScopeForPath(getDirectoryPath(info.importingSourceFileName), state);

if (packageJson) {

const toResolve = getAllRuntimeDependencies(packageJson.contents.packageJsonContent);

for (const depName of (toResolve || emptyArray)) {

const resolved = resolveModuleName(depName, combinePaths(packageJson.packageDirectory, "package.json"), compilerOptions, host, cache, /*redirectedReference*/ undefined, options.overrideImportMode);

links.setSymlinksFromResolution(resolved.resolvedModule);

}

}

}

const allFileNames = new Map<string, { path: string; isRedirect: boolean; isInNodeModules: boolean; }>();

let importedFileFromNodeModules = false;

forEachFileNameOfModule(

info.importingSourceFileName,

importedFileName,

host,

/*preferSymlinks*/ true,

(path, isRedirect) => {

const isInNodeModules = pathContainsNodeModules(path);

allFileNames.set(path, { path: info.getCanonicalFileName(path), isRedirect, isInNodeModules });

importedFileFromNodeModules = importedFileFromNodeModules || isInNodeModules;

// don't return value, so we collect everything

},

);

// Sort by paths closest to importing file Name directory

const sortedPaths: ModulePath[] = [];

for (

let directory = info.canonicalSourceDirectory;

allFileNames.size !== 0;

) {

const directoryStart = ensureTrailingDirectorySeparator(directory);

let pathsInDirectory: ModulePath[] | undefined;

allFileNames.forEach(({ path, isRedirect, isInNodeModules }, fileName) => {

if (startsWith(path, directoryStart)) {

(pathsInDirectory ||= []).push({ path: fileName, isRedirect, isInNodeModules });

allFileNames.delete(fileName);

}

});

if (pathsInDirectory) {

if (pathsInDirectory.length > 1) {

pathsInDirectory.sort(comparePathsByRedirectAndNumberOfDirectorySeparators);

}

sortedPaths.push(...pathsInDirectory);

}

const newDirectory = getDirectoryPath(directory);

if (newDirectory === directory) break;

directory = newDirectory;

}

if (allFileNames.size) {

const remainingPaths = arrayFrom(

allFileNames.entries(),

([fileName, { isRedirect, isInNodeModules }]): ModulePath => ({ path: fileName, isRedirect, isInNodeModules }),

);

if (remainingPaths.length > 1) remainingPaths.sort(comparePathsByRedirectAndNumberOfDirectorySeparators);

sortedPaths.push(...remainingPaths);

}

return sortedPaths;

}

function tryGetModuleNameFromAmbientModule(moduleSymbol: Symbol, checker: TypeChecker): string | undefined {

const decl = moduleSymbol.declarations?.find(

d => isNonGlobalAmbientModule(d) && (!isExternalModuleAugmentation(d) || !isExternalModuleNameRelative(getTextOfIdentifierOrLiteral(d.name))),

) as (ModuleDeclaration & { name: StringLiteral; }) | undefined;

if (decl) {

return decl.name.text;

}

// the module could be a namespace, which is export through "export=" from an ambient module.

/**

* declare module "m" {

* namespace ns {

* class c {}

* }

* export = ns;

* }

*/

// `import {c} from "m";` is valid, in which case, `moduleSymbol` is "ns", but the module name should be "m"

const ambientModuleDeclareCandidates = mapDefined(moduleSymbol.declarations, d => {

if (!isModuleDeclaration(d)) return;

const topNamespace = getTopNamespace(d);

if (

!(topNamespace?.parent?.parent

&& isModuleBlock(topNamespace.parent)

&& isAmbientModule(topNamespace.parent.parent)

&& isSourceFile(topNamespace.parent.parent.parent))

) return;

const exportAssignment = (topNamespace.parent.parent.symbol.exports?.get("export=" as __String)?.valueDeclaration as ExportAssignment)?.expression as PropertyAccessExpression | Identifier;

if (!exportAssignment) return;

const exportSymbol = checker.getSymbolAtLocation(exportAssignment);

if (!exportSymbol) return;

const originalExportSymbol = exportSymbol?.flags & SymbolFlags.Alias ? checker.getAliasedSymbol(exportSymbol) : exportSymbol;

if (originalExportSymbol === d.symbol) return topNamespace.parent.parent;

function getTopNamespace(namespaceDeclaration: ModuleDeclaration) {

while (namespaceDeclaration.flags & NodeFlags.NestedNamespace) {

namespaceDeclaration = namespaceDeclaration.parent as ModuleDeclaration;

}

return namespaceDeclaration;

}

});

const ambientModuleDeclare = ambientModuleDeclareCandidates[0] as (AmbientModuleDeclaration & { name: StringLiteral; }) | undefined;

if (ambientModuleDeclare) {

return ambientModuleDeclare.name.text;

}

}

function tryGetModuleNameFromPaths(relativeToBaseUrl: string, paths: MapLike<readonly string[]>, allowedEndings: ModuleSpecifierEnding[], baseDirectory: string, getCanonicalFileName: GetCanonicalFileName, host: ModuleSpecifierResolutionHost, compilerOptions: CompilerOptions): string | undefined {

for (const key in paths) {

for (const patternText of paths[key]) {

const normalized = normalizePath(patternText);

const pattern = getRelativePathIfInSameVolume(normalized, baseDirectory, getCanonicalFileName) ?? normalized;

const indexOfStar = pattern.indexOf("*");

// In module resolution, if `pattern` itself has an extension, a file with that extension is looked up directly,

// meaning a '.ts' or '.d.ts' extension is allowed to resolve. This is distinct from the case where a '*' substitution

// causes a module specifier to have an extension, i.e. the extension comes from the module specifier in a JS/TS file

// and matches the '*'. For example:

//

// Module Specifier | Path Mapping (key: [pattern]) | Interpolation | Resolution Action

// ---------------------->------------------------------->--------------------->---------------------------------------------------------------

// import "@app/foo" -> "@app/*": ["./src/app/*.ts"] -> "./src/app/foo.ts" -> tryFile("./src/app/foo.ts") || [continue resolution algorithm]

// import "@app/foo.ts" -> "@app/*": ["./src/app/*"] -> "./src/app/foo.ts" -> [continue resolution algorithm]

//

// (https://github.com/microsoft/TypeScript/blob/ad4ded80e1d58f0bf36ac16bea71bc10d9f09895/src/compiler/moduleNameResolver.ts#L2509-L2516)

//

// The interpolation produced by both scenarios is identical, but only in the former, where the extension is encoded in

// the path mapping rather than in the module specifier, will we prioritize a file lookup on the interpolation result.

// (In fact, currently, the latter scenario will necessarily fail since no resolution mode recognizes '.ts' as a valid

// extension for a module specifier.)

//

// Here, this means we need to be careful about whether we generate a match from the target filename (typically with a

// .ts extension) or the possible relative module specifiers representing that file:

//

// Filename | Relative Module Specifier Candidates | Path Mapping | Filename Result | Module Specifier Results

// --------------------<----------------------------------------------<------------------------------<-------------------||----------------------------

// dist/haha.d.ts <- dist/haha, dist/haha.js <- "@app/*": ["./dist/*.d.ts"] <- @app/haha || (none)

// dist/haha.d.ts <- dist/haha, dist/haha.js <- "@app/*": ["./dist/*"] <- (none) || @app/haha, @app/haha.js

// dist/foo/index.d.ts <- dist/foo, dist/foo/index, dist/foo/index.js <- "@app/*": ["./dist/*.d.ts"] <- @app/foo/index || (none)

// dist/foo/index.d.ts <- dist/foo, dist/foo/index, dist/foo/index.js <- "@app/*": ["./dist/*"] <- (none) || @app/foo, @app/foo/index, @app/foo/index.js

// dist/wow.js.js <- dist/wow.js, dist/wow.js.js <- "@app/*": ["./dist/*.js"] <- @app/wow.js || @app/wow, @app/wow.js

//

// The "Filename Result" can be generated only if `pattern` has an extension. Care must be taken that the list of

// relative module specifiers to run the interpolation (a) is actually valid for the module resolution mode, (b) takes

// into account the existence of other files (e.g. 'dist/wow.js' cannot refer to 'dist/wow.js.js' if 'dist/wow.js'

// exists) and (c) that they are ordered by preference. The last row shows that the filename result and module

// specifier results are not mutually exclusive. Note that the filename result is a higher priority in module

// resolution, but as long criteria (b) above is met, I don't think its result needs to be the highest priority result

// in module specifier generation. I have included it last, as it's difficult to tell exactly where it should be

// sorted among the others for a particular value of `importModuleSpecifierEnding`.

const candidates: { ending: ModuleSpecifierEnding | undefined; value: string; }[] = allowedEndings.map(ending => ({

ending,

value: processEnding(relativeToBaseUrl, [ending], compilerOptions),

}));

if (tryGetExtensionFromPath(pattern)) {

candidates.push({ ending: undefined, value: relativeToBaseUrl });

}

if (indexOfStar !== -1) {

const prefix = pattern.substring(0, indexOfStar);

const suffix = pattern.substring(indexOfStar + 1);

for (const { ending, value } of candidates) {

if (

value.length >= prefix.length + suffix.length &&

startsWith(value, prefix) &&

endsWith(value, suffix) &&

validateEnding({ ending, value })

) {

const matchedStar = value.substring(prefix.length, value.length - suffix.length);

if (!pathIsRelative(matchedStar)) {

return replaceFirstStar(key, matchedStar);

}

}

}

}

else if (

some(candidates, c => c.ending !== ModuleSpecifierEnding.Minimal && pattern === c.value) ||

some(candidates, c => c.ending === ModuleSpecifierEnding.Minimal && pattern === c.value && validateEnding(c))

) {

return key;

}

}

}