core/packages/regex-tester/js/script.js

// ==========================================
// Regex Tester — Browser Extension
// ==========================================
// Tests regular expressions against input strings.
// Registers the regex_test tool so the LLM can verify
// patterns instead of guessing.
// ==========================================

Extensions.register({
    id: 'regex-tester',

    async init(ctx) {
        const self = this;

        ctx.tools.handle('regex_test', async (args) => {
            return self._test(args.pattern, args.flags || '', args.inputs || []);
        });
    },

    _test(pattern, flags, inputs) {
        // Validate pattern
        let regex;
        try {
            regex = new RegExp(pattern, flags);
        } catch (e) {
            return {
                success: false,
                error: `Invalid regex: ${e.message}`,
                pattern,
                flags,
            };
        }

        const results = inputs.map(input => {
            // Reset lastIndex for global/sticky patterns
            regex.lastIndex = 0;

            const isGlobal = regex.global;
            const matches = [];

            if (isGlobal) {
                // Collect all matches for global flag
                let match;
                while ((match = regex.exec(input)) !== null) {
                    matches.push(this._formatMatch(match));
                    // Prevent infinite loops on zero-length matches
                    if (match[0].length === 0) regex.lastIndex++;
                }
            } else {
                const match = regex.exec(input);
                if (match) {
                    matches.push(this._formatMatch(match));
                }
            }

            return {
                input,
                matched: matches.length > 0,
                matchCount: matches.length,
                matches,
            };
        });

        const totalMatched = results.filter(r => r.matched).length;

        return {
            success: true,
            pattern,
            flags,
            summary: `${totalMatched}/${inputs.length} inputs matched`,
            results,
        };
    },

    _formatMatch(match) {
        const result = {
            fullMatch: match[0],
            index: match.index,
            length: match[0].length,
        };

        // Named groups (ES2018)
        if (match.groups) {
            result.namedGroups = {};
            for (const [name, value] of Object.entries(match.groups)) {
                result.namedGroups[name] = value;
            }
        }

        // Numbered capture groups
        if (match.length > 1) {
            result.groups = [];
            for (let i = 1; i < match.length; i++) {
                result.groups.push(match[i] !== undefined ? match[i] : null);
            }
        }

        return result;
    },

    destroy() {}
});