Module `string`

Overview

The string module has everything in the standard Lua string library, and some Tarantool extensions.

In this section we only discuss the additional functions that the Tarantool developers have added.

Below is a list of all additional string functions.

Name	Use
string.ljust()	Left-justify a string
string.rjust()	Right-justify a string
string.hex()	Get the hexadecimal value of a string
string.startswith()	Check if a string starts with a given substring
string.endswith()	Check if a string ends with a given substring
string.lstrip()	Remove spaces on the left of a string
string.rstrip()	Remove spaces on the right of a string
string.split()	Split a string into a table of strings
string.strip()	Remove spaces on the left and right of a string

string.ljust(input-string, width[, pad-character])

Return the string left-justified in a string of length width.

Parameters:	input-string (string) – the string to left-justify width (integer) – the width of the string after left-justifying pad-character (string) – a single character, default = 1 space
Return:	left-justified string (unchanged if width <= string length)
Rtype:	string

Example:

tarantool> string = require('string')
---
...
tarantool> string.ljust(' A', 5)
---
- ' A   '
...

string.rjust(input-string, width[, pad-character])

Return the string right-justified in a string of length width.

Parameters:	input-string (string) – the string to right-justify width (integer) – the width of the string after right-justifying pad-character (string) – a single character, default = 1 space
Return:	right-justified string (unchanged if width <= string length)
Rtype:	string

Example:

tarantool> string = require('string')
---
...
tarantool> string.rjust('', 5, 'X')
---
- 'XXXXX'
...

string.hex(input-string)

Return the hexadecimal value of the input string.

Parameters:	input-string (string) – the string to process
Return:	hexadecimal, 2 hex-digit characters for each input character
Rtype:	string

Example:

tarantool> string = require('string')
---
...
tarantool> string.hex('ABC ')
---
- '41424320'
...

string.startswith(input-string, start-string[, start-pos[, end-pos]])

Return True if input-string starts with start-string, otherwise return False.

Parameters:	input-string (string) – the string where `start-string` should be looked for start-string (string) – the string to look for start-pos (integer) – position: where to start looking within `input-string` end-pos (integer) – position: where to end looking within `input-string`
Return:	true or false
Rtype:	boolean

start-pos and end-pos may be negative, meaning the position should be calculated from the end of the string.

Example:

tarantool> string = require('string')
---
...
tarantool> string.startswith(' A', 'A', 2, 5)
---
- true
...

string.endswith(input-string, end-string[, start-pos[, end-pos]])

Return True if input-string ends with end-string, otherwise return False.

Parameters:	input-string (string) – the string where `end-string` should be looked for end-string (string) – the string to look for start-pos (integer) – position: where to start looking within `input-string` end-pos (integer) – position: where to end looking within `input-string`
Return:	true or false
Rtype:	boolean

start-pos and end-pos may be negative, meaning the position should be calculated from the end of the string.

Example:

tarantool> string = require('string')
---
...
tarantool> string.endswith('Baa', 'aa')
---
- true
...

string.lstrip(input-string)

Return the value of the input string, but without spaces on the left.

Parameters:	input-string (string) – the string to process
Return:	result after stripping spaces from input string
Rtype:	string

Example:

tarantool> string = require('string')
---
...
tarantool> string.lstrip(' ABC ')
---
- 'ABC '
...

string.rstrip(input-string)

Return the value of the input string, but without spaces on the right.

Parameters:	input-string (string) – the string to process
Return:	result after stripping spaces from input string
Rtype:	string

Example:

tarantool> string = require('string')
---
...
tarantool> string.rstrip(' ABC ')
---
- ' ABC'
...

string.split(input-string[, split-string[, max]])

Split input-string into one or more output strings in a table. The places to split are the places where split-string occurs.

Parameters:	input-string (string) – the string to split split-string (integer) – the string to find within `input-string`. Default = space. max (integer) – maximum number of delimiters to process counting from the beginning of the input string. Result will contain max + 1 parts maximum.
Return:	table of strings that were split from `input-string`
Rtype:	table

Example:

tarantool> string = require('string')
---
...
tarantool> string.split("A:B:C:D:F", ":", 2)
---
- - A
  - B
  - C:D:F
...

string.strip(input-string)

Return the value of the input string, but without spaces on the left or the right.

Parameters:	input-string (string) – the string to process
Return:	result after stripping spaces from input string
Rtype:	string

Example:

tarantool> string = require('string')
---
...
tarantool> string.strip(' ABC ')
---
- ABC
...