Standard library

regex

Module regex

matches
replace
replaceAll
replaceFirst
searchsearchAll
split

Groups

Match
PartMatch

Replacement

ballerina/regex

1.4.3

Deprecation Notice: This library is deprecated and will no longer be maintained or updated. Instead, it is recommended to use the ballerina/lang.regexp library for continued support and updates. For more information, see the new RegExp type example, RegExp operations example, and Regular expressions feature guide.

Overview

This module provides APIs for searching, splitting, and replacing the set of characters of a string. These APIs are using a regular expression as a String to perform these operations by finding the string matches.

Regular expressions, are notations for describing sets of character strings. If a particular string is in the set described by a regular expression, the regular expression matches that string.

For information on the operations, which you can perform with the regex module, see the below Functions.

Functions

matches

Isolated Function
function matches(string stringToMatch, string regex) returns boolean

Checks whether the given string matches the provided regex. Note that \\ is used as for escape sequence and \\\\ is used to insert a backslash character in the string or regular expression. The following special characters should be escaped in the regex definition. Special Characters: ., +, *, ?, ^, $, (, ), [, ], {, }

Copy
boolean isMatched = regex:matches("Ballerina is great", "Ba[a-z ]+");
Parameters
  • stringToMatch string - The string to match the regex
  • regex string - The regex to match the string
Return Type
  • boolean - true if the provided string matches the regex or else false

replace

Isolated Function
function replace(string originalString, string regex, Replacement replacement, int startIndex) returns string

Replaces the first substring that matches the given regex with the provided replacement string or string returned by the provided function. Note that \\ is used as for escape sequence and \\\\ is used to insert a backslash character in the string or regular expression. The following special characters should be escaped in the regex definition. Special Characters: ., +, *, ?, ^, $, (, ), [, ], {, }

Copy
string result = regex:replace("Ballerina is great", "\\s+", "_");
Parameters
  • originalString string - The original string to replace the first occurrence of the substring that matches the provided regex
  • regex string - The regex to match the first substring in the originalString to be replaced
  • replacement Replacement - The replacement string or a function to be invoked to create the new substring to be used to replace the first match to the given regex
  • startIndex int (default 0) - The starting index for the search
Return Type
  • string - The resultant string with the replaced substring

replaceAll

Isolated Function
function replaceAll(string originalString, string regex, Replacement replacement) returns string

Replaces each occurrence of the substrings, which match the provided regex from the given original string value with the provided replacement string. Note that \\ is used as for escape sequence and \\\\ is used to insert a backslash character in the string or regular expression. The following special characters should be escaped in the regex definition. Special Characters: ., +, *, ?, ^, $, (, ), [, ], {, }

Copy
string result = regex:replaceAll("Ballerina is great", "\\s+", "_");
Parameters
  • originalString string - The original string to replace the occurrences of the substrings that match the provided regex
  • regex string - The regex to match the substrings in the originalString , which is to be replaced
  • replacement Replacement - The replacement string or a function to be invoked to create the new substring to be used to replace the first match to the given regex
Return Type
  • string - The resultant string with the replaced substrings

replaceFirst

DeprecatedIsolated Function
function replaceFirst(string originalString, string regex, string replacement) returns string

Replaces the first substring that matches the given regex with the provided replacement string. Note that \\ is used as for escape sequence and \\\\ is used to insert a backslash character in the string or regular expression. The following special characters should be escaped in the regex definition. Special Characters: ., +, *, ?, ^, $, (, ), [, ], {, }

Copy
string result = regex:replaceFirst("Ballerina is great", "\\s+", "_");
Parameters
  • originalString string - The original string to replace the first occurrence of the substring that matches the provided regex
  • regex string - The regex to match the first substring in the originalString to be replaced
  • replacement string - The replacement string to replace the first substring, which matches the regex
Return Type
  • string - The resultant string with the replaced substring

    Deprecated

    This function will be removed in a later. Use replace instead.
Isolated Function
function search(string str, string regex, int startIndex) returns Match?

Returns the first substring in str that matches the regex. Note that \\ is used as for escape sequence and \\\\ is used to insert a backslash character in the string or regular expression. The following special characters should be escaped in the regex definition. Special Characters: ., +, *, ?, ^, $, (, ), [, ], {, }

Copy
regex:Match? result = regex:search("Betty Botter bought some butter but she said the butter’s bitter.",
                                   "\\b[bB].tt[a-z]*");
Parameters
  • str string - The string to be matched
  • regex string - The regex value
  • startIndex int (default 0) - The starting index for the search
Return Type
  • Match? - a Match record which holds the matched substring, or nil if there is no match

searchAll

Isolated Function
function searchAll(string str, string regex) returns Match[]

Returns all substrings in string that match the regex. Note that \\ is used as for escape sequence and \\\\ is used to insert a backslash character in the string or regular expression. The following special characters should be escaped in the regex definition. Special Characters: ., +, *, ?, ^, $, (, ), [, ], {, }

Copy
regex:Match[] result = regex:searchAll("Betty Botter bought some butter but she said the butter’s bitter.",
                                     "\\b[bB].tt[a-z]*");
Parameters
  • str string - The string to be matched
  • regex string - The regex value
Return Type
  • Match[] - An array of Match records

split

Isolated Function
function split(string receiver, string delimiter) returns string[]

Returns an array of strings by splitting a string using the provided regex as the delimiter. Note that \\ is used as for escape sequence and \\\\ is used to insert a backslash character in the string or regular expression. The following special characters should be escaped in the regex definition. Special Characters: ., +, *, ?, ^, $, (, ), [, ], {, }

Copy
string[] result = regex:split("Ballerina is great", " ");
Parameters
  • receiver string - The string to split
  • delimiter string - The delimiter is a regex, which splits the given string
Return Type
  • string[] - An array of strings containing the individual strings that are split

Object types

regex: Groups

Read Only

Abstract object representation to hold information about matched regex groups.

get

Isolated Function
function get(int index) returns PartMatch?
Parameters

Records

regex: Match

Closed record

Holds the results of a match against a regular expression. It contains the match boundaries, groups, and group boundaries.

Fields
  • groups Groups - Information about matched regex groups

regex: PartMatch

Closed record

Holds the matched substring and its position in the input string.

Fields
  • matched string - Matched substring
  • startIndex int - The start index of the match
  • endIndex int - The last index of the match

Types

regex: Replacement

ReplacerFunction|string

A type to be used to get a replacement string.

Other versions

1.4.3

1.4.21.4.11.4.01.3.2
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