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Graph/regex-group-capture-state-leak

AntiPattern

Regex Captures Misleading

regex-group-capture-state-leak

Regex evaluation state and grouping semantics get reused across re-matches or nested selections, causing captured substrings and filtering logic to persist or expand unexpectedly. Misplaced quantifiers, alternations, and boundary assumptions then yield incorrect matches and wrong exclusions.

Node Details

Public graph metadata

Updated7/6/2026

Connections

30 linked nodes

MATCHESSolution

To allow for a case insensitive 'live' search — This allows for partial matching from the beginning of the string. Tension: you may need to further adapt the regular expression. Outcome: adapt the code as follows.

MATCHESSolution

Three layered filters, applied to every NER candidate (people, organizations, places):. Outcome: 16 new regression tests covering every observed false-positive bucket plus regression cases for real names. All 16 pass; total privacy package suite goes from 100 → 116 tests, all green.

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Tension: the trap is mixing default (stripping) mode with a post-parse policy check. Outcome: parse AFTER the guard.

MATCHESSolution

Do expression evaluations in a single line

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Strip placeholder underscores from the captured value before setting state/display (e.g., replace /_/g with an empty string in the onChange handler), or otherwise sanitize the masked output.

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Use regex extraction and cast matched numbers to NUMERIC for ordering

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source is MongoDB and target is Redshift. Tension: I am unable to get the correct query. Outcome: tried using the regex to remove the string part in the format1.

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Use string splitting for the space-delimited parts (split_part) and a regex to strip the surrounding square brackets from the bracketed token (regexp_replace).

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Fix the regex escaping in importOrder (e.g., use \.(css|scss) correctly within strings) and adjust rule order so the non-relative .css/.scss matcher is applied to those imports last (e.g., exclude/route .*\.(css|scss)$ after the broader patterns).

MATCHESSolution

`{TM_FILENAME_BASE/(^\\w)|-(\\w)/${1:/capitalize}${2:/capitalize}/g}` — vscode snippets documentation. Tension: The main difference is going to be in the regex to capture 2 different character groups. Outcome: with this we have two regex groupings, denoted by the ( ), that we can then reference.

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Rewrite the traversal to reduce the number of OR branches—e.g., filter using a single predicate by combining the pair fields and applying `within` (or otherwise restructure into a simpler condition such as building a set of allowed pairs).

MATCHESSolution

My current effort is `(?https://regex101.com/r/hccbUh/1 — For these strings, I want to grab everything between `foo` and `bar`. Tension: haven't found one that works. Outcome: Given this `(?https://regex101.com/r/IAQgB5/1.

MATCHESSolution

How can I avoid that and not match this `g`? — I want to keep the capturing group in case I have to match a string like `stringMyString`. Tension: I do need that `g` as group 1. Outcome: avoid that and not match this `g`.

MATCHESSolution

If you want to avoid that then you need a way to separate that initial line and capture its contents — The main issue to overcome here is that you are treating the first line of your CSV specially. Tension: its contents inform the processing of all the other lines. Outcome: here is where `filter()` comes in, and the fact that lambdas close over their context.

MATCHESSolution

String[] parts = test.split("((?<=\\))\\s*|(?<=\\d{1,}\\.\\d{2} (DR|CR)))"); — for (String test: tests){. Tension: You could add the case "... or split for any white space preceded by a parenthesis". Outcome: Your regex could be written like this:.

MATCHESSolution

Instead of splitting you could also match the parts that you want using an alternation — where the alternative starts with `\S` to start the match with a non whitespace character. Tension: to prevent matching empty strings. Outcome: \d+(?:\.\d+)?\h*[DC]R|\S.*?(?=\h*\d+(?:\.\d+)?\h*[DC]R).

MATCHESSolution

You are missing another position to split on, which is the space at the end of `(FEES) ` — Instead of using a capture group `(DR|CR)` you can use a character class `[DC]R`. Tension: you can assert a digit to the right. Outcome: you can use a character class `[DC]R` and in the lookbehind you don't have to match 1 or more digits `\d{1,}` but just matching a digit `\d` would also suffice.

MATCHESSolution

Use regex boundaries that split before CREATE and after END; when procedures end with END;

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Add state check before XInclude expansion at line 1445 — at line 1445. Outcome: This prevents XInclude expansion code from executing while the reader is in backtracking state.

MATCHESSolution

The assertion at line 447 (assert(p2 - newstr == newlen)) catches mismatches in debug mode but not release. — reencode_escapes() (lines 406-449): two-pass size calculation with int arithmetic. Tension: The two-pass algorithm uses char_needs_escaping() which is context-sensitive. Outcome: The function is invoked in url_parse() at line 753 with attacker-controlled URL input from HTTP redirects.

MATCHESSolution

Instead of "required/optional," define Pattern as "the specific recurring structure that appears across multiple manifestations.". Tension: Pattern is specific enough to be testable but abstract enough to apply to other problems. Outcome: Include a pattern _scoring_ rule: "Only include patterns that apply to at least 2–3 other similar problems in the dataset.".

MATCHESSolution

The fix (commit ed0c7c7e) defines allowed = "-_.!~*'();:&=+$," and scans each character — The fix (commit ed0c7c7e) defines allowed = "-_.!~*'();:&=+$," and scans each character. Tension: This correctly treats ';' as valid userinfo without treating it as a terminator. Outcome: Fix is always component-specific grammar validation, not a combined strpbrk over all component terminators.

MATCHESSolution

"Omit if uncertain" rules are interpreted as permission to skip — Models (especially in batch mode where they're trying to be efficient) treat optional node types as low-priority. Outcome: Models match format much more reliably than they follow abstract rules.

MATCHESSolution

false positives are cheap (dedup catches them), false negatives are expensive (lost knowledge) — Abstract types like Pattern need 3-4 shot examples in the prompt. Tension: When uncertain, extract it. Outcome: downstream dedup will handle false positives.

MATCHESSolution

Later code at lines 273-274 attempts to write to regarray->start[i] for i >= 1, causing overflow — In regexp.c lines 265-267 within match_regex. Tension: Only allocates 1 element. Outcome: regsize can reach 16 (when max_id is 15).

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Add validation to reject any path containing ../ sequences after tilde expansion — after tilde expansion. Outcome: implement proper path normalization that prevents traversal.

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the `satisfies never` pattern is slightly more explicit and surfaces better errors — for cross-module exhaustiveness that's actually reliable. Tension: surfaces better errors. Outcome: const _: never = event // will error when non-exhaustive.

MATCHESSolution

Switching to derive-from-[REDACTED]+[REDACTED] made the whole thing trivially correct. Tension: reconciling required diffing what should be a pure rebuild. Outcome: made the whole thing trivially correct.

MATCHESSolution

Three techniques applied together: — any enforcement module (DOM assertion, CSP checker, sanitizer) that must reference the same patterns its surrounding CI gate scans for. Tension: split the forbidden literal at any point that breaks the contiguous match without altering the runtime string value.

MATCHESSolution

Coerce the nullable property to a non-null sentinel before the string operation — NOT coalesce(n.extractionSource, '') STARTS WITH $prefix AND (trustedSource OR n.reinforcementCount > 0). Tension: `coalesce(null, '')` is '', `'' STARTS WITH 'quarantined:'` is FALSE, `NOT FALSE` is TRUE. Outcome: the guard behaves as intended for unstamped nodes.

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