Regular Expressions

The regex module provides pattern matching using POSIX extended regular expressions.

Importing

import regex

Functions

match

Check if a pattern matches the entire string.

Syntax: call regex.match with string, pattern

Returns: true if the pattern matches the entire string, false otherwise

Example:

import regex

set matches to call regex.match with "hello", "h.*o"  # Returns true
set no_match to call regex.match with "world", "h.*o"  # Returns false

search

Find the first match of a pattern in a string.

Syntax: call regex.search with string, pattern

Returns: The first matched substring, or null if no match is found

Example:

import regex

set result to call regex.search with "hello world", "world"  # Returns "world"
set result2 to call regex.search with "hello world", "xyz"   # Returns null

findall

Find all matches of a pattern in a string.

Syntax: call regex.findall with string, pattern

Returns: A list of all matched substrings (empty list if no matches)

Example:

import regex

set matches to call regex.findall with "cat, bat, sat", "[a-z]at"
# Returns ["cat", "bat", "sat"]

set numbers to call regex.findall with "abc123def456ghi789", "[0-9]+"
# Returns ["123", "456", "789"]

Pattern Syntax

The regex module uses POSIX Extended Regular Expression syntax. Common patterns:

. - Matches any character
* - Zero or more of the preceding element
+ - One or more of the preceding element
? - Zero or one of the preceding element
[abc] - Matches any character in the brackets
[a-z] - Matches any character in the range
^ - Start of string
$ - End of string
\d - Digit (in some regex flavors, but POSIX uses [0-9])

Examples

Email Validation

import regex

function is_valid_email with email:
    set pattern to "^[a-z]+@[a-z]+\\.[a-z]+$"
    return call regex.match with email, pattern

set email1 to "user@example.com"
set email2 to "invalid-email"

print call is_valid_email with email1  # Prints: true
print call is_valid_email with email2  # Prints: false

Extracting Patterns

import regex

set text to "Contact: alice@example.com or bob@test.org"
set pattern to "[a-z]+@[a-z]+\\.[a-z]+"
set emails to call regex.findall with text, pattern

print emails  # Prints: ["alice@example.com", "bob@test.org"]

Phone Number Validation

import regex

function validate_phone with phone:
    set pattern to "^[0-9]{3}-[0-9]{3}-[0-9]{4}$"
    return call regex.match with phone, pattern

set phone1 to "123-456-7890"
set phone2 to "invalid"

print call validate_phone with phone1  # Prints: true
print call validate_phone with phone2  # Prints: false

Finding Words

import regex

set text to "The cat sat on the mat"
set pattern to "[a-z]at"
set matches to call regex.findall with text, pattern

print matches  # Prints: ["cat", "sat", "mat"]

Error Handling

Invalid regex patterns will raise a RuntimeError:

import regex

try:
    set result to call regex.match with "test", "[invalid"
    print result
catch error:
    print f"Invalid regex pattern: {error}"

Regular Expressions

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