lib.ts

import { parse } from "https://deno.land/x/swc@0.2.1/mod.ts";
import { z } from "https://deno.land/x/zod@v3.16.1/mod.ts";

interface ASTRegex {
  type: "RegExpLiteral";
  pattern: string;
  flag?: string;
}

function regexToString(regex: unknown): ASTRegex {
  const schema = z.object({
    type: z.literal("RegExpLiteral"),
    pattern: z.string(),
    flag: z.string().optional(),
  });

  return schema.parse(regex);
}

function filterType(module: unknown): ASTRegex[] {
  const result: ASTRegex[] = [];
  for (const value of Object.values(module)) {
    if (value === null || value === undefined) {
      continue;
    } else if (
      typeof value === "object" && "type" in value &&
      value.type === "RegExpLiteral"
    ) {
      result.push(regexToString(value));
    } else if (typeof value === "object") {
      result.push(...filterType(value as Record<string, unknown>));
    } else if (Array.isArray(value)) {
      result.push(...filterType(value));
    } else {
      continue;
    }
  }

  return result;
}

export function getRegexes(source: string) {
  const ast = parse(source, {
    target: "es2019",
    syntax: "typescript",
    comments: false,
  });
  const regexes: ASTRegex[] = [];
  for (const node of ast.body) {
    regexes.push(...filterType(node));
  }
  return regexes;
}