packages/babel-core/src/config/pattern-to-regex.js
// @flow
import path from "path";
import escapeRegExp from "lodash/escapeRegExp";
const sep = `\\${path.sep}`;
const endSep = `(?:${sep}|$)`;
const substitution = `[^${sep}]+`;
const starPat = `(?:${substitution}${sep})`;
const starPatLast = `(?:${substitution}${endSep})`;
const starStarPat = `${starPat}*?`;
const starStarPatLast = `${starPat}*?${starPatLast}?`;
/**
* Implement basic pattern matching that will allow users to do the simple
* tests with * and **. If users want full complex pattern matching, then can
* always use regex matching, or function validation.
*/
export default function pathToPattern(
pattern: string,
dirname: string,
): RegExp {
const parts = path.resolve(dirname, pattern).split(path.sep);
return new RegExp(
[
"^",
...parts.map((part, i) => {
const last = i === parts.length - 1;
// ** matches 0 or more path parts.
if (part === "**") return last ? starStarPatLast : starStarPat;
// * matches 1 path part.
if (part === "*") return last ? starPatLast : starPat;
// *.ext matches a wildcard with an extension.
if (part.indexOf("*.") === 0) {
return (
substitution + escapeRegExp(part.slice(1)) + (last ? endSep : sep)
);
}
// Otherwise match the pattern text.
return escapeRegExp(part) + (last ? endSep : sep);
}),
].join(""),
);
}