String Methods

CXL provides 24 built-in methods for string manipulation. All string methods return null when the receiver is null (null propagation).

Case conversion

upper()

Converts all characters to uppercase.

$ cxl eval -e 'emit result = "hello world".upper()'

{
  "result": "HELLO WORLD"
}

lower()

Converts all characters to lowercase.

$ cxl eval -e 'emit result = "Hello World".lower()'

{
  "result": "hello world"
}

Whitespace trimming

trim()

Removes leading and trailing whitespace.

$ cxl eval -e 'emit result = "  hello  ".trim()'

{
  "result": "hello"
}

trim_start()

Removes leading whitespace only.

$ cxl eval -e 'emit result = "  hello  ".trim_start()'

{
  "result": "hello  "
}

trim_end()

Removes trailing whitespace only.

$ cxl eval -e 'emit result = "  hello  ".trim_end()'

{
  "result": "  hello"
}

Substring testing

starts_with(prefix: String) -> Bool

Tests whether the string starts with the given prefix.

$ cxl eval -e 'emit result = "hello world".starts_with("hello")'

{
  "result": true
}

ends_with(suffix: String) -> Bool

Tests whether the string ends with the given suffix.

$ cxl eval -e 'emit result = "report.csv".ends_with(".csv")'

{
  "result": true
}

contains(substring: String) -> Bool

Tests whether the string contains the given substring.

$ cxl eval -e 'emit result = "hello world".contains("lo wo")'

{
  "result": true
}

Find and replace

replace(find: String, replacement: String) -> String

Replaces all occurrences of find with replacement.

$ cxl eval -e 'emit result = "foo-bar-baz".replace("-", "_")'

{
  "result": "foo_bar_baz"
}

Extraction

substring(start: Int [, length: Int]) -> String

Extracts a substring starting at start (0-based character index). If length is provided, takes at most that many characters. If omitted, takes all remaining characters.

$ cxl eval -e 'emit result = "hello world".substring(6)'

{
  "result": "world"
}

$ cxl eval -e 'emit result = "hello world".substring(0, 5)'

{
  "result": "hello"
}

left(n: Int) -> String

Returns the first n characters.

$ cxl eval -e 'emit result = "hello world".left(5)'

{
  "result": "hello"
}

right(n: Int) -> String

Returns the last n characters.

$ cxl eval -e 'emit result = "hello world".right(5)'

{
  "result": "world"
}

Padding

pad_left(width: Int [, char: String]) -> String

Left-pads the string to the given width. Default pad character is a space.

$ cxl eval -e 'emit result = "42".pad_left(5, "0")'

{
  "result": "00042"
}

$ cxl eval -e 'emit result = "hi".pad_left(6)'

{
  "result": "    hi"
}

pad_right(width: Int [, char: String]) -> String

Right-pads the string to the given width. Default pad character is a space.

$ cxl eval -e 'emit result = "hi".pad_right(6, ".")'

{
  "result": "hi...."
}

Repetition and reversal

repeat(n: Int) -> String

Repeats the string n times.

$ cxl eval -e 'emit result = "ab".repeat(3)'

{
  "result": "ababab"
}

reverse() -> String

Reverses the characters in the string.

$ cxl eval -e 'emit result = "hello".reverse()'

{
  "result": "olleh"
}

Length

length() -> Int

Returns the number of characters in the string. Also works on arrays, returning the number of elements.

$ cxl eval -e 'emit result = "hello".length()'

{
  "result": 5
}

Splitting and joining

split(delimiter: String) -> Array

Splits the string by the delimiter, returning an array of strings.

$ cxl eval -e 'emit result = "a,b,c".split(",")'

{
  "result": ["a", "b", "c"]
}

join(delimiter: String) -> String

Joins an array of values into a string with the given delimiter. The receiver must be an array.

$ cxl eval -e 'emit result = "a,b,c".split(",").join(" - ")'

{
  "result": "a - b - c"
}

Regex operations

matches(pattern: String) -> Bool

Tests whether the string fully matches the given regex pattern.

$ cxl eval -e 'emit result = "abc123".matches("^[a-z]+[0-9]+$")'

{
  "result": true
}

find(pattern: String) -> Bool

Tests whether the string contains a substring matching the given regex pattern (partial match).

$ cxl eval -e 'emit result = "hello world 42".find("[0-9]+")'

{
  "result": true
}

capture(pattern: String [, group: Int]) -> String

Extracts a capture group from the first regex match. Default group is 0 (the full match).

$ cxl eval -e 'emit result = "order-12345".capture("order-([0-9]+)", 1)'

{
  "result": "12345"
}

Formatting and concatenation

format(fmt: String) -> String

Formats the receiver value as a string.

$ cxl eval -e 'emit result = 42.format("")'

{
  "result": "42"
}

concat(args: String…) -> String

Concatenates the receiver with one or more string arguments. Null arguments are treated as empty strings.

$ cxl eval -e 'emit result = "hello".concat(" ", "world")'

{
  "result": "hello world"
}

This is variadic – it accepts any number of string arguments:

$ cxl eval -e 'emit result = "a".concat("b", "c", "d")'

{
  "result": "abcd"
}