The Strings package is an evolution of the work originally produced by Andrew Mezoni.

The purpose of the Strings package is to provide:

• a collection of useful String functions to complement the core String class.
• where viable, directly extend the String class with methods such as String.right, String.left...
• provide a safer environment when working with nullable Strings (String?)
• wrappers for each of the core String methods which are safe to use with a nullable String?.

A core objective of the Strings package is to never 'throw' or return an error but to make a best effort to process the passed data.

// passing null works too.
Strings.right(null, 4, pad: Pad.left);
 -> '    '

// pass a short string and we can pad it (or not).
Strings.right('one', 4, pad: Pad.left);
 -> ' one'

The Strings package also includes a number of methods exposed as extensions to the core Dart String class:

'a normal string'.right(4);
-> 'a no'

Literal boundaries

Remove a single literal prefix or suffix, or split once while keeping the separator and both sides:

Strings.removePrefix('Bearer token', 'Bearer '); // 'token'
'report.txt'.removeSuffix('.txt'); // 'report'
Strings.partition('key=value=rest', '='); // ['key', '=', 'value=rest']
'archive.tar.gz'.lastPartition('.'); // ['archive.tar', '.', 'gz']
Strings.removePrefix(null, 'prefix'); // ''

All four methods are available as nullable Strings static methods and as StringEx extensions on String. Null input is treated as ''. A null, empty or unmatched affix leaves the input unchanged. A null, empty or unmatched separator produces [text, '', ''] for partition and ['', '', text] for lastPartition. Partition results always contain three strings; joining them reconstructs the input.

Matching is literal, case-sensitive UTF-16 matching, with no regular expressions or Unicode normalization. Complete emoji and combining sequences work as delimiters. Supplying only part of a surrogate pair or grapheme can split that character, just as with Dart's native string search and substring methods.

These methods draw on Python's literal affix removal and partition operations. Unlike Python, empty separators are handled without throwing.

Counting, extraction and whitespace

Strings.countMatches('aaaaa', 'aa'); // 2 (non-overlapping)
'key=value=rest'.substringAfter('='); // 'value=rest'
'archive.tar.gz'.substringAfterLast('.'); // 'gz'
'archive.tar.gz'.substringBeforeLast('.'); // 'archive.tar'
Strings.normalizeSpace('  hello\t world  '); // 'hello world'
'one\r\ntwo\u2028three'.replaceLineEndings(); // 'one\ntwo\nthree'
'one\ntwo'.replaceLineEndings(replacement: ' | '); // 'one | two'

All six methods have nullable Strings statics and StringEx extensions on String. Null input is treated as ''. Search and extraction use literal, case-sensitive UTF-16 matching without normalization, as described above.

Method	Null, empty or missing search/separator
countMatches	0
substringAfter	''
substringAfterLast	''
substringBeforeLast	Original input (or '' for null)

normalizeSpace removes leading/trailing whitespace and collapses internal runs to one ASCII space. It uses the existing Strings.isWhitespaceRune set, including non-breaking spaces, U+180E and U+FEFF (BOM). Other text is preserved.

replaceLineEndings recognizes CRLF as one ending, plus CR, LF, NEL (U+0085), form feed (U+000C), line separator (U+2028) and paragraph separator (U+2029). Vertical tab is unchanged. Its default replacement is LF on every platform; null or empty replacement removes endings. Replacement text is literal and is not processed again. Other code units are preserved exactly.

The counting and extraction helpers draw on Apache Commons Lang, with empty separators treated consistently as absent. The newline set follows .NET's ReplaceLineEndings, using deterministic LF rather than a platform default.

See the full list

The Strings package incudes over 50 functions.

You can see the full list including examples at:

strings.onepub.dev

Contributing:

The strings package is hosted on github at: github.com/onepub-dev/strings

Contributions are welcomed.

Sponser

The strings package is sponsored by OnePub - the private Dart repository SaaS.

onepub.dev