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import * as path from "path";
import * as Filesystem from "./filesystem";
import * as MappingEntry from "./mapping-entry";
import * as TryPath from "./try-path";
/**
* Function that can match a path
*/
export interface MatchPath {
(
requestedModule: string,
readJson?: Filesystem.ReadJsonSync,
fileExists?: (name: string) => boolean,
extensions?: ReadonlyArray<string>
): string | undefined;
}
/**
* Creates a function that can resolve paths according to tsconfig paths property.
* @param absoluteBaseUrl Absolute version of baseUrl as specified in tsconfig.
* @param paths The paths as specified in tsconfig.
* @param mainFields A list of package.json field names to try when resolving module files.
* @param addMatchAll Add a match-all "*" rule if none is present
* @returns a function that can resolve paths.
*/
export function createMatchPath(
absoluteBaseUrl: string,
paths: { [key: string]: Array<string> },
mainFields: string[] = ["main"],
addMatchAll: boolean = true
): MatchPath {
const absolutePaths = MappingEntry.getAbsoluteMappingEntries(
absoluteBaseUrl,
paths,
addMatchAll
);
return (
requestedModule: string,
readJson?: Filesystem.ReadJsonSync,
fileExists?: Filesystem.FileExistsSync,
extensions?: Array<string>
) =>
matchFromAbsolutePaths(
absolutePaths,
requestedModule,
readJson,
fileExists,
extensions,
mainFields
);
}
/**
* Finds a path from tsconfig that matches a module load request.
* @param absolutePathMappings The paths to try as specified in tsconfig but resolved to absolute form.
* @param requestedModule The required module name.
* @param readJson Function that can read json from a path (useful for testing).
* @param fileExists Function that checks for existence of a file at a path (useful for testing).
* @param extensions File extensions to probe for (useful for testing).
* @param mainFields A list of package.json field names to try when resolving module files.
* @returns the found path, or undefined if no path was found.
*/
export function matchFromAbsolutePaths(
absolutePathMappings: ReadonlyArray<MappingEntry.MappingEntry>,
requestedModule: string,
readJson: Filesystem.ReadJsonSync = Filesystem.readJsonFromDiskSync,
fileExists: Filesystem.FileExistsSync = Filesystem.fileExistsSync,
extensions: Array<string> = Object.keys(require.extensions),
mainFields: string[] = ["main"]
): string | undefined {
const tryPaths = TryPath.getPathsToTry(
extensions,
absolutePathMappings,
requestedModule
);
if (!tryPaths) {
return undefined;
}
return findFirstExistingPath(tryPaths, readJson, fileExists, mainFields);
}
function findFirstExistingMainFieldMappedFile(
packageJson: Filesystem.PackageJson,
mainFields: string[],
packageJsonPath: string,
fileExists: Filesystem.FileExistsSync
): string | undefined {
for (let index = 0; index < mainFields.length; index++) {
const mainFieldName = mainFields[index];
const candidateMapping = packageJson[mainFieldName];
if (candidateMapping && typeof candidateMapping === "string") {
const candidateFilePath = path.join(
path.dirname(packageJsonPath),
candidateMapping
);
if (fileExists(candidateFilePath)) {
return candidateFilePath;
}
}
}
return undefined;
}
function findFirstExistingPath(
tryPaths: ReadonlyArray<TryPath.TryPath>,
readJson: Filesystem.ReadJsonSync = Filesystem.readJsonFromDiskSync,
fileExists: Filesystem.FileExistsSync,
mainFields: string[] = ["main"]
): string | undefined {
for (const tryPath of tryPaths) {
if (
tryPath.type === "file" ||
tryPath.type === "extension" ||
tryPath.type === "index"
) {
if (fileExists(tryPath.path)) {
return TryPath.getStrippedPath(tryPath);
}
} else if (tryPath.type === "package") {
const packageJson: Filesystem.PackageJson = readJson(tryPath.path);
if (packageJson) {
const mainFieldMappedFile = findFirstExistingMainFieldMappedFile(
packageJson,
mainFields,
tryPath.path,
fileExists
);
if (mainFieldMappedFile) {
return mainFieldMappedFile;
}
}
} else {
TryPath.exhaustiveTypeException(tryPath.type);
}
}
return undefined;
}