65 lines
1.9 KiB
TypeScript
Executable file
65 lines
1.9 KiB
TypeScript
Executable file
import * as path from "path";
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export interface MappingEntry {
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readonly pattern: string;
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readonly paths: ReadonlyArray<string>;
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}
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export interface Paths {
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readonly [key: string]: ReadonlyArray<string>;
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}
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/**
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* Converts an absolute baseUrl and paths to an array of absolute mapping entries.
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* The array is sorted by longest prefix.
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* Having an array with entries allows us to keep a sorting order rather than
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* sort by keys each time we use the mappings.
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* @param absoluteBaseUrl
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* @param paths
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* @param addMatchAll
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*/
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export function getAbsoluteMappingEntries(
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absoluteBaseUrl: string,
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paths: Paths,
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addMatchAll: boolean
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): ReadonlyArray<MappingEntry> {
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// Resolve all paths to absolute form once here, and sort them by
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// longest prefix once here, this saves time on each request later.
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// We need to put them in an array to preserve the sorting order.
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const sortedKeys = sortByLongestPrefix(Object.keys(paths));
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const absolutePaths: Array<MappingEntry> = [];
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for (const key of sortedKeys) {
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absolutePaths.push({
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pattern: key,
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paths: paths[key].map((pathToResolve) =>
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path.join(absoluteBaseUrl, pathToResolve)
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),
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});
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}
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// If there is no match-all path specified in the paths section of tsconfig, then try to match
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// all paths relative to baseUrl, this is how typescript works.
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if (!paths["*"] && addMatchAll) {
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absolutePaths.push({
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pattern: "*",
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paths: [`${absoluteBaseUrl.replace(/\/$/, "")}/*`],
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});
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}
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return absolutePaths;
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}
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/**
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* Sort path patterns.
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* If a module name can be matched with multiple patterns then pattern with the longest prefix will be picked.
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*/
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function sortByLongestPrefix(arr: Array<string>): Array<string> {
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return arr
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.concat()
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.sort((a: string, b: string) => getPrefixLength(b) - getPrefixLength(a));
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}
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function getPrefixLength(pattern: string): number {
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const prefixLength = pattern.indexOf("*");
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return pattern.substr(0, prefixLength).length;
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}
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