Philiprehberger.RegexBuilder

Fluent, readable regex construction — build patterns programmatically and compile to standard Regex objects.

Installation

dotnet add package Philiprehberger.RegexBuilder

Usage

using Philiprehberger.RegexBuilder;

var emailRegex = Pattern.Start()
    .Words()
    .Literal("@")
    .Words()
    .Literal(".")
    .Word().Times(2, 6)
    .Build();

bool isValid = emailRegex.IsMatch("user@example.com"); // true

Build a Pattern

using Philiprehberger.RegexBuilder;

var pattern = Pattern.StartOfLine()
    .Literal("Hello")
    .Whitespace()
    .Words()
    .EndOfLine()
    .Build();

bool match = pattern.IsMatch("Hello World"); // true

Character Classes

using Philiprehberger.RegexBuilder;

var hexColor = Pattern.Start()
    .Literal("#")
    .AnyOf("0123456789abcdefABCDEF").Times(6)
    .Build();

bool isHex = hexColor.IsMatch("#ff00cc"); // true

var noDigits = Pattern.Start()
    .NonDigit().OneOrMore()
    .Build();

bool alpha = noDigits.IsMatch("hello"); // true

Groups and Quantifiers

using Philiprehberger.RegexBuilder;

var datePattern = Pattern.Start()
    .CaptureGroup("year", b => b.Digit().Times(4))
    .Literal("-")
    .CaptureGroup("month", b => b.Digit().Times(2))
    .Literal("-")
    .CaptureGroup("day", b => b.Digit().Times(2))
    .Build();

var match = datePattern.Match("2026-03-21");
string year = match.Groups["year"].Value;  // "2026"
string month = match.Groups["month"].Value; // "03"

var timePattern = Pattern.Start()
    .NamedGroup("hour", b => b.Digit().Times(2))
    .Literal(":")
    .NamedGroup("minute", b => b.Digit().Times(2))
    .Build();

var time = timePattern.Match("14:30");
string hour = time.Groups["hour"].Value;   // "14"
string minute = time.Groups["minute"].Value; // "30"

var protocol = Pattern.Start()
    .Group(b => b.Literal("http").Group(b2 => b2.Literal("s")).Optional())
    .Literal("://")
    .Build();

bool matchesHttp = protocol.IsMatch("http://example.com");  // true
bool matchesHttps = protocol.IsMatch("https://example.com"); // true

API

Pattern

Method	Description
Start()	Begin building a new pattern
StartOfLine()	Begin with a start-of-line anchor (^)
EndOfLine()	Begin with an end-of-line anchor ($)

PatternBuilder

Method	Description
Literal(string text)	Match exact text (auto-escaped)
Digit()	Match a single digit (\d)
Digits()	Match one or more digits (\d+)
NonDigit()	Match a non-digit (\D)
Word()	Match a word character (\w)
Words()	Match one or more word characters (\w+)
NonWord()	Match a non-word character (\W)
Whitespace()	Match a whitespace character (\s)
NonWhitespace()	Match a non-whitespace character (\S)
Any()	Match any character (.)
AnyOf(string chars)	Match any character in the set
NoneOf(string chars)	Match any character not in the set
Times(int n)	Repeat previous element exactly n times
Times(int min, int max)	Repeat previous element between min and max times
Optional()	Make previous element optional (?)
OneOrMore()	Repeat previous element one or more times (+)
ZeroOrMore()	Repeat previous element zero or more times (*)
Group(Action<PatternBuilder> inner)	Non-capturing group
CaptureGroup(string name, Action<PatternBuilder> inner)	Named capturing group
NamedGroup(string name, Action<PatternBuilder> inner)	Named capturing group (alias for CaptureGroup)
Or(Action<PatternBuilder> alt)	Alternation with another pattern
StartOfLine()	Append start-of-line anchor (^)
EndOfLine()	Append end-of-line anchor ($)
Lazy()	Make previous quantifier lazy
Build(RegexOptions? options)	Compile to a Regex object
ToString()	Return the raw pattern string

Development

dotnet build src/Philiprehberger.RegexBuilder.csproj --configuration Release

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License

MIT