# `PiiCatalog.ScanError`
[🔗](https://github.com/signalvaultio/pii_catalog/blob/v0.1.0/lib/pii_catalog/scan_error.ex#L1)

Raised by `PiiCatalog.scan/2` and `PiiCatalog.find/2` when the regex
engine stops before it has scanned the whole text, for example when a
pattern reaches the engine's match limit (`:match_limit`) on a crafted
input.

The scan reports no result for that text rather than the matches found
before the engine stopped: a text that was not fully scanned is not
reported as holding no identifier. What to do with the text, such as
refusing it or redacting it whole, is the caller's choice.

The catalog's tests run its patterns on crafted inputs that make regexes
backtrack, such as a keyword followed by thousands of spaces; a pattern
of your own can still reach the limit.

  * `patterns` – the names of the patterns that were being scanned. For
    the shared pass (see `PiiCatalog.Scanner`) these are all the patterns
    in it.
  * `reason` – the error the regex engine returned, such as
    `:match_limit` or `:match_limit_recursion`.

# `t`

```elixir
@type t() :: %PiiCatalog.ScanError{
  __exception__: true,
  patterns: [atom()],
  reason: term()
}
```

# `message`

```elixir
@spec message(t()) :: String.t()
```

The error as a sentence, naming the patterns and the engine's reason.

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*Consult [api-reference.md](api-reference.md) for complete listing*