glistix_stdlib

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.

Note that POSIX ERE syntax is used for the Nix target instead of PCRE.

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

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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

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

Constructors 

  • Options(case_insensitive: Bool, multi_line: Bool)

Regex

</> 
pub type Regex

Functions

check

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

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

Examples

let 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.

Warning

In the Nix target, you need to use the POSIX ERE syntax for regex, which differs from other Gleam targets. This means you will need to specify different regexes for different targets, if they aren’t compatible. For example, the usual escape sequences, such as \s and \w, do not exist in POSIX ERE syntax. Rather, you have to use character classes, such as [[:space:]] for \s or [[:alnum:]_] for \w.

Additionally, we currently cannot detect invalid regexes, so evaluation is aborted when the provided regex is invalid.

Examples

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

let options = Options(case_insensitive: True, multi_line: False)
let 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.

Warning

In the Nix target, you need to use the POSIX ERE syntax for regex, which differs from other Gleam targets. This means you will need to specify different regexes for different targets, if they aren’t compatible. For example, the usual escape sequences, such as \s and \w, do not exist in POSIX ERE syntax. Rather, you have to use character classes, such as [[:space:]] for \s or [[:alnum:]_] for \w.

Additionally, we currently cannot detect invalid regexes, so evaluation is aborted when the provided regex is invalid.

Examples

let 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

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