gleam_stdlib - v0.28.0

gleam/regex

This module contains regular expression matching functions for strings. The matching algorithms of the library are based on the PCRE library, but not all of the PCRE library is interfaced and some parts of the library go beyond what PCRE offers. Currently PCRE version 8.40 (release date 2017-01-11) is used.

Types

CompileError

</>

When a regular expression fails to compile:

pub type CompileError {
  CompileError(error: String, byte_index: Int)
}

Constructors 

  • CompileError(error: String, byte_index: Int)

    Arguments

    • error

      The problem encountered that caused the compilation to fail

    • byte_index

      The byte index into the string to where the problem was found This value may not be correct in JavaScript environments.

Match

</>

The details about a particular match:

pub type Match {
  Match(content: String, submatches: List(Option(String)))
}

Constructors 

  • Match(content: String, submatches: List(Option(String)))

    Arguments

    • content

      The full string of the match.

    • submatches

      A Regex can have subpatterns, sup-parts that are in parentheses.

Options

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The problem encountered that caused the compilation to fail The byte index into the string to where the problem was found This value may not be correct in JavaScript environments.

pub type Options {
  Options(case_insensitive: Bool, multi_line: Bool)
}

Constructors 

  • Options(case_insensitive: Bool, multi_line: Bool)

Regex

</> 
pub external type Regex

Functions

check

</> 
pub fn check(with regex: Regex, content content: String) -> Bool

Returns a boolean indicating whether there was a match or not.

Examples

> assert Ok(re) = from_string("^f.o.?")
> check(with: re, content: "foo")
True

> check(with: re, content: "boo")
False

compile

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pub fn compile(pattern: String, with options: Options) -> Result(
  Regex,
  CompileError,
)

Creates a Regex with some additional options.

Examples

> let options = Options(case_insensitive: False, multi_line: True)
> assert Ok(re) = compile("^[0-9]", with: options)
> check(re, "abc\n123")
True

> let options = Options(case_insensitive: True, multi_line: False)
> assert Ok(re) = compile("[A-Z]", with: options)
> check(re, "abc123")
True

from_string

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pub fn from_string(pattern: String) -> Result(Regex, CompileError)

Creates a new Regex.

Examples

> assert Ok(re) = from_string("[0-9]")
> check(re, "abc123")
True

> check(re, "abcxyz")
False

> from_string("[0-9")
Error(
  CompileError(
    error: "missing terminating ] for character class",
    byte_index: 4
  )
)

scan

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pub fn scan(with regex: Regex, content string: String) -> List(
  Match,
)

Collects all matches of the regular expression.

Examples

> let assert Ok(re) = from_string("[oi]n a (\\w+)")
> scan(with: re, content: "I am on a boat in a lake.")
[
  Match(
    content: "on a boat",
    submatches: [Some("boat")]
  ),
  Match(
    content: "in a lake",
    submatches: [Some("lake")]
  )
]

> let assert Ok(re) = regex.from_string("([+|\\-])?(\\d+)(\\w+)?")
> scan(with: re, content: "-36")
[
  Match(
    content: "-36",
    submatches: [Some("-"), Some("36")]
  )
]

> scan(with: re, content: "36")
[
  Match(
    content: "36",
    submatches: [None, Some("36")]
  )
]

> let assert Ok(re) = regex.from_string("var\\s*(\\w+)\\s*(int|string)?\\s*=\\s*(.*)")
> scan(with: re, content: "var age = 32")
[
  Match(
    content: "var age = 32",
    submatches: [Some("age"), None, Some("32")]
  )
]

> let assert Ok(re) = regex.from_string("let (\\w+) = (\\w+)")
> scan(with: re, content: "let age = 32")
[
  Match(
    content: "let age = 32",
    submatches: [Some("age"), Some("32")]
  )
]

> scan(with: re, content: "const age = 32")
[]

split

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pub fn split(with regex: Regex, content string: String) -> List(
  String,
)

Splits a string.

Examples

> assert Ok(re) = from_string(" *, *")
> split(with: re, content: "foo,32, 4, 9  ,0")
["foo", "32", "4", "9", "0"]
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