Examples first
Require at least five valid and five invalid examples so the model does not infer the wrong pattern.
🤖 Regex prompt builder with test-case guardrails
Regex Generator Prompt Generator
By Omellody Editorial Team · Published · UpdatedUse this existing Omellody prompt utility to create a safer regex request with accepted examples, rejected examples, engine constraints, anchoring rules, Unicode notes, and backtracking risk checks. The builder runs locally in your browser and does not send project details to Omellody.
Interactive prompt builder
Replace the examples with sanitized project details. The generated prompt updates locally in your browser.
Act as a senior engineer and careful reviewer. Help me create a regular expression generation plan from the real context below.
Project context: {context}
Stack or tools: {stack}
Goal: {goal}
Constraints: {constraints}
Return these sections:
1. Direct recommendation with assumptions called out.
2. Inputs needed before acting and questions that block a reliable answer.
3. Decision table: option or hypothesis, evidence needed, risk, next action.
4. Step-by-step workflow with safe checks first.
5. Security, privacy, reliability, and maintainability review.
6. Tests, examples, or validation cases before merge or publication.
7. Rollback, escalation, and owner handoff plan.
8. Final checklist.
Rules: use only supplied facts, mark unknowns, avoid secrets or private data, do not invent undocumented behavior, and explain how to verify the result.
Copy-ready base prompt
Act as a senior engineer and careful reviewer. Help me create a regular expression generation plan from the real context below.
Project context: {context}
Stack or tools: {stack}
Goal: {goal}
Constraints: {constraints}
Return these sections:
1. Direct recommendation with assumptions called out.
2. Inputs needed before acting and questions that block a reliable answer.
3. Decision table: option or hypothesis, evidence needed, risk, next action.
4. Step-by-step workflow with safe checks first.
5. Security, privacy, reliability, and maintainability review.
6. Tests, examples, or validation cases before merge or publication.
7. Rollback, escalation, and owner handoff plan.
8. Final checklist.
Rules: use only supplied facts, mark unknowns, avoid secrets or private data, do not invent undocumented behavior, and explain how to verify the result.
Prompt formula and variables
Formula: Pattern goal + regex engine + accepted examples + rejected examples + anchoring/flags + safety constraints + test table.
| Variable | What to enter |
|---|---|
{context} | Add specific, sanitized context details. If unknown, write the assumption explicitly. |
{stack} | Add specific, sanitized stack details. If unknown, write the assumption explicitly. |
{goal} | Add specific, sanitized goal details. If unknown, write the assumption explicitly. |
{constraints} | Add specific, sanitized constraints details. If unknown, write the assumption explicitly. |
Engine specificity
Name JavaScript, Python, PCRE, RE2, PostgreSQL, or another engine because lookbehind, Unicode classes, and flags differ.
Safety review
Ask for backtracking risk, anchoring, maximum input length, escaping rules, and cases where parser code is safer than regex.
Output review table
| Check | Pass condition | Fix if weak |
|---|---|---|
| Grounding | The answer distinguishes facts, assumptions, and unknowns. | Add source snippets, example inputs, or explicit non-goals. |
| Safety | No secrets, customer data, account identifiers, or destructive commands are requested. | Sanitize examples and ask for read-only checks first. |
| Actionability | The plan includes concrete steps, owners, tests, and rollback or review criteria. | Request a checklist with evidence and stop conditions. |
| Verification | The output can be tested with unit cases, logs, traces, fixtures, or source-of-truth docs. | Add expected results and failure examples before using it. |
Source snapshot
| Item | Snapshot |
|---|---|
| Page type | Existing Omellody coding prompt utility refreshed in Red Mode for depth and internal discovery. |
| Demand signal | URL inventory on 2026-05-22 flagged this prompt-family page as thin with limited internal-link depth while traffic radar continued to show AI prompt generator demand. |
| Originality | Omellody-created formula, builder, review criteria, FAQ, source snapshot, and safety guidance. No external repository content copied. |
| Last reviewed | 2026-05-22 |
Related coding prompt tools
FAQ
What should a regex prompt include?
Include the target pattern, regex engine, valid examples, invalid examples, anchoring rules, flags, maximum input length, and security constraints.
Why do I need rejected examples?
Rejected examples prevent over-broad patterns that appear correct on one sample but accept unsafe or irrelevant input.
Can AI write production regex safely?
Treat it as a draft. Run unit tests, fuzz edge cases, and check backtracking behavior before production use.
When should I avoid regex?
Avoid regex for nested grammars, complex HTML parsing, high-risk security validation, or data that needs a real parser.