Classes and groups

Character classes bracket allowed characters:

• Ranges: [a-z], [A-C].
• Negation: [^0-9] (any non-digit).
• Parentheses: ([A-C][^0-9])+ groups multi-token subpatterns under quantifiers.

Mental Model: Per-Character Predicates

• [A-C]: tests character code range $A \dots C$.
• [^0-9]: inverts membership predicate.
• (...)+: repeats the composite group.

Your Goal in this Stage

Support character classes (ranges, negation) and grouped quantifier subexpressions.

Input Format

{
  "op": "search",
  "pattern": "([A-C][^0-9])+",
  "text": "xxAbCz7"
}

Output Format

{
  "matched": true,
  "span": [2, 6]
}

Step-by-Step Implementation Guide

1. Parse bracket classes: Extract ranges and negation flag.
2. Parse parentheses groups: Treat inner sequence as composite atom.
3. Emit output: Print JSON object.

Acceptance Criteria

• ✅ Matches character classes and ranges.
• ✅ Inverts negated classes.
• ✅ Quantifies nested parenthesized groups.

Multiline examples are formatted for readability. Emit compact JSON without optional spaces, with properties in the order shown by the output examples, and a final newline. Keep logs off stdout. Tests compare exact text. Invalid inputs use stderr containing error, empty stdout, and exit 1. Valid inputs exit 0. Serialize integer results as JSON integers.