regexpp

import { parseRegExpLiteral, visitRegExpAST, RegExpValidator, RegExpParser, AST } from "regexpp"; // 1. Parse a regular expression literal and get its AST const literalSource = "/hello\s*(world)?/u"; const astLiteral = parseRegExpLiteral(literalSource); console.log("Parsed Literal (Pattern):", astLiteral.pattern.raw); console.log("Parsed Literal (Flags):", astLiteral.flags.raw); // 2. Parse a regular expression pattern directly const patternSource = "^([a-z]+)(\\d+)?$"; const parser = new RegExpParser({ ecmaVersion: 2021 }); // Specify ECMAScript version const astPattern = parser.parsePattern(patternSource, 0, patternSource.length, false); console.log("Parsed Pattern (raw):", astPattern.raw); // 3. Visit the AST to find specific nodes let capturingGroupsFound = 0; visitRegExpAST(astLiteral, { onCapturingGroupEnter(node: AST.CapturingGroup) { capturingGroupsFound++; console.log(` Found Capturing Group: ${node.name ?? '(unnamed)'} at [${node.start}, ${node.end}]`); }, onCharacterEnter(node: AST.Character) { if (node.value === 'o'.charCodeAt(0)) { console.log(` Found character 'o' at position ${node.start}`); } } }); console.log(`Total capturing groups in literal: ${capturingGroupsFound}`); // 4. Validate a regular expression (will throw on invalid input) try { new RegExpValidator().validateLiteral("/[a-z-\\s]/u"); // Valid new RegExpValidator().validateLiteral("/[b-a]/"); // Invalid range } catch (e: any) { console.error("Validation Error (expected for '[b-a]'):", e.message); }