safe_text 2.1.2 | Flutter package

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A high-performance Flutter package for filtering offensive language (profanity) and detecting phone numbers. Powered by the Aho-Corasick algorithm for O(N) single-pass scanning across 80+ languages and 55,000+ curated words.

Table of Contents #

Table of Contents
What's New in 2.0.0
Features
Installation
Quick Start
API Reference
Supported Languages
How it Works
Migrating from v1.x
Limitations
Contributing
Data Source
Authors
Contributors

What's New in 2.0.0 #

Aho-Corasick Algorithm — Near-instant multi-pattern search in O(N) complexity.
Up to 20x faster than the legacy regex-loop approach.
80+ languages — Full human-readable enum names (e.g., Language.hindi, Language.spanish).
Modular API — SafeTextFilter for profanity, PhoneNumberChecker for phone numbers.
Memory efficient — Single-pass string building via StringBuffer.
Leet-speak normalization — Catches bypasses like f@ck or b4d with zero extra overhead.

Features #

Scans thousands of bad words in a single pass of the input text.
Catches common character substitutions: @→a, 4→a, 3→e, 0→o, $→s, and more.
Detects phone numbers in digits, words, mixed formats, and multiplier words (e.g., "triple five").
Multiple masking strategies — full (******), partial (f**k), or custom replacement ([censored]).
Customizable — add your own words or exclude specific phrases.
Non-blocking — PhoneNumberChecker runs in a separate isolate via compute.
Works on Android, iOS, Web, macOS, Linux, and Windows.

Installation #

Add safe_text to your project using the Flutter CLI:

flutter pub add safe_text

Or manually add it to your pubspec.yaml:

dependencies:
  safe_text: ^2.1.2

Then run:

flutter pub get

Quick Start #

import 'package:safe_text/safe_text.dart';

void main() async {
  // Initialize once at app startup
  await SafeTextFilter.init(language: Language.english);

  // Filter profanity (full masking — default)
  final clean = SafeTextFilter.filterText(text: "What the f@ck!");
  print(clean); // "What the ****!"

  // Partial masking — keeps first & last characters for 4+ letter words
  final partial = SafeTextFilter.filterText(
    text: "What the f@ck!",
    strategy: const MaskStrategy.partial(),
  );
  print(partial); // "What the f**k!"

  // Custom replacement
  final custom = SafeTextFilter.filterText(
    text: "What the f@ck!",
    strategy: const MaskStrategy.custom(replacement: '[censored]'),
  );
  print(custom); // "What the [censored]!"

  // Check for bad words
  final hasBad = await SafeTextFilter.containsBadWord(text: "Some bad input");
  print(hasBad); // true or false

  // Detect phone numbers
  final hasPhone = await PhoneNumberChecker.containsPhoneNumber(
    text: "Call me at nine 7 eight 3 triple four",
  );
  print(hasPhone); // true
}

API Reference #

`SafeTextFilter.init` #

Must be called once before using filterText or containsBadWord. Builds the Aho-Corasick trie from the selected word list(s).

// Single language
await SafeTextFilter.init(language: Language.english);

// Custom combination
await SafeTextFilter.init(languages: [Language.english, Language.hindi, Language.spanish]);

// All 75+ languages
await SafeTextFilter.init(language: Language.all);

Parameter	Type	Default	Description
`language`	`Language?`	`Language.english`	A single language to load. Use `Language.all` to load every language. Ignored when `languages` is provided.
`languages`	`List<Language>?`	`null`	A custom list of languages. Takes precedence over `language`.

Note: If neither parameter is provided, the filter defaults to Language.english.

`SafeTextFilter.filterText` #

Synchronous. Returns the input text with matched bad words masked according to the chosen MaskStrategy.

// Full masking (default)
String result = SafeTextFilter.filterText(
  text: "Hello b4dass world!",
  extraWords: ["badterm"],      // optional: add custom words
  excludedWords: ["bass"],      // optional: never filter these
  useDefaultWords: true,        // use the built-in word list
);
// Result: "Hello ****** world!"

// Partial masking
String partial = SafeTextFilter.filterText(
  text: "Hello b4dass world!",
  strategy: const MaskStrategy.partial(),
);
// Result: "Hello b****s world!"

// Custom replacement
String custom = SafeTextFilter.filterText(
  text: "Hello b4dass world!",
  strategy: const MaskStrategy.custom(), // defaults to "[censored]"
);
// Result: "Hello [censored] world!"

Parameter	Type	Default	Description
`text`	`String`	required	The input string to process.
`extraWords`	`List<String>?`	`null`	Additional words to filter on top of (or instead of) the built-in list.
`excludedWords`	`List<String>?`	`null`	Words that must never be filtered, even if they appear in the list.
`useDefaultWords`	`bool`	`true`	Include the built-in language word list. Set to `false` to use only `extraWords`.
`strategy`	`MaskStrategy?`	`null` (defaults to `MaskStrategy.full()`)	Masking strategy. See Masking Strategies below.
`fullMode`	`bool`	`true`	Deprecated. Use `strategy` instead. `true` maps to `MaskStrategy.full()`, `false` maps to `MaskStrategy.partial()`.
`obscureSymbol`	`String`	`*`	Deprecated. Pass `obscureSymbol` via `MaskStrategy.full()` or `MaskStrategy.partial()` instead.

Precedence: When strategy is provided, it takes full precedence over the deprecated fullMode and obscureSymbol parameters. When strategy is omitted, fullMode: true maps to MaskStrategy.full(obscureSymbol: obscureSymbol) and fullMode: false maps to MaskStrategy.partial(obscureSymbol: obscureSymbol).

Masking Strategies

Strategy	Constructor	Output Example	Description
Full	`MaskStrategy.full(obscureSymbol: '*')`	`badass` → `******`	Replaces every character with the obscure symbol.
Partial	`MaskStrategy.partial(obscureSymbol: '*')`	`damn` → `dn`, `ass` → `a`	Keeps first character visible. For 4+ letter words, also keeps the last character.
Custom	`MaskStrategy.custom(replacement: '[censored]')`	`badass` → `[censored]`	Replaces the entire word with a fixed string.

Note: obscureSymbol must be exactly one character. This is enforced via assert in debug mode — a multi-character string will trigger an AssertionError during development.

`SafeTextFilter.containsBadWord` #

Asynchronous. Returns true if the text contains at least one filtered word.

bool hasBadWord = await SafeTextFilter.containsBadWord(
  text: "Don't be a pendejo",
  extraWords: ["badterm"],   // optional
  excludedWords: ["pend"],   // optional
  useDefaultWords: true,     // optional
);

Parameter	Type	Default	Description
`text`	`String`	required	The input string to check.
`extraWords`	`List<String>?`	`null`	Additional words to check against.
`excludedWords`	`List<String>?`	`null`	Words to ignore even if matched.
`useDefaultWords`	`bool`	`true`	Include the built-in word list in the check.

`PhoneNumberChecker.containsPhoneNumber` #

Asynchronous. Runs in a separate isolate via Flutter's compute function so it never blocks the UI thread.

Detects phone numbers expressed as:

Pure digits: 9783444
Word-based: nine seven eight three four four four
Mixed: 9 seven 8 3444
Multiplier words: nine seven eight three triple four

Supported multiplier words: double, triple, quadruple, quintuple, sextuple, septuple, octuple, nonuple, decuple.

bool hasPhone = await PhoneNumberChecker.containsPhoneNumber(
  text: "Call me at nine 7 eight 3 triple four",
  minLength: 7,   // minimum digit count to be considered a phone number
  maxLength: 15,  // maximum digit count
);

Parameter	Type	Default	Description
`text`	`String`	required	The input string to check.
`minLength`	`int`	`7`	Minimum number of digits for a valid phone number.
`maxLength`	`int`	`15`	Maximum number of digits for a valid phone number.

Supported Languages #

Pass any of these Language enum values to SafeTextFilter.init. Use Language.all to load every language simultaneously.

View all 82 supported languages

Enum	Language
`Language.afrikaans`	Afrikaans
`Language.amharic`	Amharic
`Language.arabic`	Arabic
`Language.azerbaijani`	Azerbaijani
`Language.belarusian`	Belarusian
`Language.bulgarian`	Bulgarian
`Language.catalan`	Catalan
`Language.cebuano`	Cebuano
`Language.czech`	Czech
`Language.welsh`	Welsh
`Language.danish`	Danish
`Language.german`	German
`Language.dzongkha`	Dzongkha
`Language.greek`	Greek
`Language.english`	English
`Language.esperanto`	Esperanto
`Language.spanish`	Spanish
`Language.estonian`	Estonian
`Language.basque`	Basque
`Language.persian`	Persian
`Language.finnish`	Finnish
`Language.filipino`	Filipino
`Language.french`	French
`Language.scottishGaelic`	Scottish Gaelic
`Language.galician`	Galician
`Language.hindi`	Hindi
`Language.croatian`	Croatian
`Language.hungarian`	Hungarian
`Language.armenian`	Armenian
`Language.indonesian`	Indonesian
`Language.icelandic`	Icelandic
`Language.italian`	Italian
`Language.japanese`	Japanese
`Language.kabyle`	Kabyle
`Language.kannada`	Kannada
`Language.khmer`	Khmer
`Language.korean`	Korean
`Language.latin`	Latin
`Language.lithuanian`	Lithuanian
`Language.latvian`	Latvian
`Language.maori`	Maori
`Language.macedonian`	Macedonian
`Language.malayalam`	Malayalam
`Language.mongolian`	Mongolian
`Language.marathi`	Marathi
`Language.malay`	Malay
`Language.maltese`	Maltese
`Language.burmese`	Burmese
`Language.dutch`	Dutch
`Language.norwegian`	Norwegian
`Language.norfuk`	Norfuk / Pitcairn
`Language.piapoco`	Piapoco
`Language.polish`	Polish
`Language.portuguese`	Portuguese
`Language.romanian`	Romanian
`Language.kriol`	Kriol
`Language.russian`	Russian
`Language.slovak`	Slovak
`Language.slovenian`	Slovenian
`Language.samoan`	Samoan
`Language.albanian`	Albanian
`Language.serbian`	Serbian
`Language.swedish`	Swedish
`Language.tamil`	Tamil
`Language.telugu`	Telugu
`Language.tetum`	Tetum
`Language.thai`	Thai
`Language.klingon`	Klingon
`Language.tongan`	Tongan
`Language.turkish`	Turkish
`Language.ukrainian`	Ukrainian
`Language.uzbek`	Uzbek
`Language.vietnamese`	Vietnamese
`Language.yiddish`	Yiddish
`Language.chinese`	Chinese
`Language.zulu`	Zulu
`Language.bengali`	Bengali
`Language.gujarati`	Gujarati
`Language.punjabi`	Punjabi
`Language.swahili`	Swahili
`Language.urdu`	Urdu
`Language.all`	All of the above

How it Works #

Legacy approach (v1.x): For each bad word in a list of 10,000+ words, run a separate regex scan over the entire input — O(W × N) where W is the word count.

v2.0.0 approach: The Aho-Corasick algorithm builds a Finite State Automaton (Trie) once from the entire word list. The engine then scans the input exactly once, matching all patterns simultaneously in O(N) time where N is the length of the text — regardless of how many words are in the list.

Input text  ──► [Normalizer] ──► [Aho-Corasick FSA] ──► Match ranges ──► [StringBuffer] ──► Filtered text
                  (leet-speak)     (single O(N) pass)    (merged)         (single-pass)

Migrating from v1.x #

The original SafeText class is still available but marked @Deprecated. It internally delegates to the new classes. Migrate when ready:

v1.x	v2.0.0
`await SafeTextFilter.init(...)`	Required — call once at startup
`SafeText.filterText(text: ...)`	`SafeTextFilter.filterText(text: ...)`
`await SafeText.containsBadWord(text: ...)`	`await SafeTextFilter.containsBadWord(text: ...)`
`await SafeText.containsPhoneNumber(text: ...)`	`await PhoneNumberChecker.containsPhoneNumber(text: ...)`

Before:

// v1.x — no init required, but slow
bool bad = await SafeText.containsBadWord(text: "some input");

After:

// v2.0.0 — init once, then use anywhere
await SafeTextFilter.init(language: Language.english); // once, e.g. in main()
bool bad = await SafeTextFilter.containsBadWord(text: "some input");

Limitations #

SafeTextFilter.init must be called before use. Calling filterText or containsBadWord before init will fall back to a small built-in word list without the full multilingual dataset.
Phone number detection is English-word based. Words like "nine", "triple", etc. are English only — the detector does not parse written numbers in other languages.
False positives on technical terms. Short words in the filter list may match substrings of unrelated technical terms. Use excludedWords to suppress known false positives.
Language.all increases init time. Loading all 75+ language files is I/O-heavy. For most apps a targeted language list is faster.

Contributing #

Contributions are welcome! Please read CONTRIBUTING.md for the full guidelines. The short version:

Clone the repo and check out the develop branch.
Create a feature branch: git checkout -b feature/your-feature
Add tests for any new behaviour.
Run checks before submitting:
```
flutter analyze
flutter test
```
Open a pull request targeting develop. Ensure CI passes.

For major changes, please open an issue first to discuss the approach.

Data Source #

SafeText uses the List of Dirty, Naughty, Obscene, and Otherwise Bad Words dataset:

80+ dialects and languages
55,000+ curated words

We are grateful to the contributors of this dataset for providing a robust multilingual foundation.

Authors #

_{Ronit Rameja}

LinkedIn • Report an Issue • Discussions • Buy me a coffee

Contributors #

Thanks to everyone who has contributed to SafeText!

Made with contrib.rocks

safe_text 2.1.2
safe_text: ^2.1.2 copied to clipboard

Metadata

Table of Contents #

What's New in 2.0.0 #

Features #

Installation #

Quick Start #

API Reference #

`SafeTextFilter.init` #

`SafeTextFilter.filterText` #

Masking Strategies

`SafeTextFilter.containsBadWord` #

`PhoneNumberChecker.containsPhoneNumber` #

Supported Languages #

How it Works #

Migrating from v1.x #

Limitations #

Contributing #

Data Source #

Authors #

Contributors #

← Metadata

Documentation

Publisher

Weekly Downloads

Metadata

Topics

Funding

License

Dependencies

More

safe_text 2.1.2 safe_text: ^2.1.2 copied to clipboard

Metadata

Table of Contents #

What's New in 2.0.0 #

Features #

Installation #

Quick Start #

API Reference #

SafeTextFilter.init #

SafeTextFilter.filterText #

Masking Strategies

SafeTextFilter.containsBadWord #

PhoneNumberChecker.containsPhoneNumber #

Supported Languages #

How it Works #

Migrating from v1.x #

Limitations #

Contributing #

Data Source #

Authors #

Contributors #

← Metadata

Documentation

Publisher

Weekly Downloads

Metadata

Topics

Funding

License

Dependencies

More

safe_text 2.1.2
safe_text: ^2.1.2 copied to clipboard

`SafeTextFilter.init` #

`SafeTextFilter.filterText` #

`SafeTextFilter.containsBadWord` #

`PhoneNumberChecker.containsPhoneNumber` #