112 lines
4.2 KiB
TypeScript
112 lines
4.2 KiB
TypeScript
import * as XRegExp from 'xregexp';
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// The `XRegExp` typings are not accurate.
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interface XRegExp extends RegExp {
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xregexp: { captureNames?: string[] };
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}
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export class FirebaseRedirectSource {
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regex = XRegExp(this.pattern) as XRegExp;
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namedGroups: string[] = [];
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private constructor(public pattern: string, public restNamedGroups: string[] = []) {
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const restNamedGroupsSet = new Set(restNamedGroups);
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pattern.replace(/\(\?<([^>]+)>/g, (_, name) => {
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if (!restNamedGroupsSet.has(name)) {
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this.namedGroups.push(name);
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}
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return '';
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});
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}
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static fromGlobPattern(glob: string): FirebaseRedirectSource {
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const dot = /\./g;
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const star = /\*/g;
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const doubleStar = /(^|\/)\*\*($|\/)/g; // e.g. a/**/b or **/b or a/** but not a**b
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const modifiedPatterns = /(.)\(([^)]+)\)/g; // e.g. `@(a|b)
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const restParam = /\/:([A-Za-z]+)\*/g; // e.g. `:rest*`
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const namedParam = /\/:([A-Za-z]+)/g; // e.g. `:api`
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const possiblyEmptyInitialSegments = /^\.🐷\//g; // e.g. `**/a` can also match `a`
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const possiblyEmptySegments = /\/\.🐷\//g; // e.g. `a/**/b` can also match `a/b`
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const willBeStar = /🐷/g; // e.g. `a**b` not matched by previous rule
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try {
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const restNamedGroups: string[] = [];
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const pattern = glob
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.replace(dot, '\\.')
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.replace(modifiedPatterns, replaceModifiedPattern)
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.replace(restParam, (_, param) => {
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// capture the rest of the string
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restNamedGroups.push(param);
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return `(?:/(?<${param}>.🐷))?`;
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})
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.replace(namedParam, `/(?<$1>[^/]+)`)
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.replace(doubleStar, '$1.🐷$2') // use the pig to avoid replacing ** in next rule
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.replace(star, '[^/]*') // match a single segment
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.replace(possiblyEmptyInitialSegments, '(?:.*)')// deal with **/ special cases
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.replace(possiblyEmptySegments, '(?:/|/.*/)') // deal with /**/ special cases
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.replace(willBeStar, '*'); // other ** matches
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return new FirebaseRedirectSource(`^${pattern}$`, restNamedGroups);
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} catch (err) {
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throw new Error(`Error in FirebaseRedirectSource: "${glob}" - ${err.message}`);
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}
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}
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static fromRegexPattern(regex: string): FirebaseRedirectSource {
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try {
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// NOTE:
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// Firebase redirect regexes use the [RE2 library](https://github.com/google/re2/wiki/Syntax),
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// which requires named capture groups to begin with `?P`. See
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// https://firebase.google.com/docs/hosting/full-config#capture-url-segments-for-redirects.
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if (/\(\?<[^>]+>/.test(regex)) {
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// Throw if the regex contains a non-RE2 named capture group.
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throw new Error(
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'The regular expression pattern contains a named capture group of the format ' +
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'`(?<name>...)`, which is not compatible with the RE2 library. Use `(?P<name>...)` ' +
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'instead.');
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}
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// Replace `(?P<...>` with just `(?<...>` to convert to `XRegExp`-compatible syntax for named
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// capture groups.
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return new FirebaseRedirectSource(regex.replace(/(\(\?)P(<[^>]+>)/g, '$1$2'));
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} catch (err) {
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throw new Error(`Error in FirebaseRedirectSource: "${regex}" - ${err.message}`);
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}
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}
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test(url: string): boolean {
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return XRegExp.test(url, this.regex);
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}
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match(url: string): { [key: string]: string } | undefined {
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const match = XRegExp.exec(url, this.regex) as ReturnType<typeof XRegExp.exec>;
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if (!match) {
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return undefined;
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}
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const result: { [key: string]: string } = {};
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const names = this.regex.xregexp.captureNames || [];
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names.forEach(name => result[name] = match.groups![name]);
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return result;
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}
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}
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function replaceModifiedPattern(_: string, modifier: string, pattern: string) {
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switch (modifier) {
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case '!':
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throw new Error(`"not" expansions are not supported: "${_}"`);
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case '?':
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case '+':
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return `(${pattern})${modifier}`;
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case '*':
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return `(${pattern})🐷`; // it will become a star
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case '@':
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return `(${pattern})`;
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default:
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throw new Error(`unknown expansion type: "${modifier}" in "${_}"`);
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}
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}
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