kmizu / mregex

Minimal Regex Matcher in Scala

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mregex

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A minimal regex matcher in Scala. This repository is mainly aimed at learning implementations of regular expressions.

Usage

Add the following lines to your build.sbt file:

libraryDependencies += "com.github.kmizu" %% "mregex" % "0.1.0"
import com.github.kmizu.mregex._

matches(pattern=”””ab”””,  string=“ab”) // true
matches(pattern=”””a|b”””, string=”a”) // true
matches(pattern=”””a|b”””, string=”c”) // false
matches(pattern=”””(a|b)*”””, string=”abbaab”) // true
matches(pattern=”””(a|b)*”””, string=”abaaac”) // false
matches(pattern=”””ab”””,  string=“ab”) // true
matches(pattern=”””a|b”””, string=”a”) // true
matches(pattern=”””a|b”””, string=”c”) // false
matches(pattern=”””(a|b)*”””, string=”abbaab”) // true
matches(pattern=”””(a|b)*”””, string=”abaaac”) // false

Syntax

Alphabet

a is regular expression. Note that a doesn't mean a itself but any character.

a
b
z
0
9

Choice

e1|e2 is regular expression where e1 and e2 are regular expressions:

a|b
a|b|c

Concatenation

e1e2 is regular expression where e1 and e2 are regular expressions:

ab
abc

Repetition (0 or more)

e* is regular expression where e is regular expression:

a*
(a|b)*

Repetition (1 ore more)

e+ is regular expression where e is regular expression:

a+
(a|b)+

Optional (0 ore 1)

e? is regular expression where e is regular expression:

a+
a(b)?c