Def-eString

This Defold native extension implements functions for string manipulation in Lua scripts.

API

• estring.concat(...)

• Joins strings or numbers and returns the result.

• estring.trim(str)

• Removes leading and trailing whitespace from a string.

• estring.split(str, delimiter)

• Splits a string into parts using a specified delimiter and returns them in a table.

• estring.pad_start(str, padStr, targetLength)

• Pads the start of a string with a specified padding string to reach a target length.

• estring.pad_end(str, padStr, targetLength)

• Pads the end of a string with a specified padding string to reach a target length.

• estring.format_time(timeValue, formatType, delimiter)

• Formats a time value based on the provided format type, optionally using a specified delimiter.

• estring.format_number(number, precision, thousandsSeparator, decimalSeparator)

• Formats a number as a string with options for precision, thousands separator, and decimal separator.

Background

In Lua, strings are immutable. Every modification you make to a string value causes a new string object to be allocated.

Example:

local first = 'the '
local second = 'lazy '
local third = 'dog'
local sentence = first .. second .. third -- 'the lazy dog'
-- An intermediate string 'the lazy ' is allocated when first and second are joined

This library aims to avoid the creation of intermediate Lua strings by doing the work in C++ and only returning the final result to Lua.

local first = 'the '
local second = 'lazy '
local third = 'dog'
local sentence = estring.concat(first, second, third) -- 'the lazy dog'
-- No intermediate string is allocated

Installation

1. Edit game.project
2. Add dependency https://github.com/thinknathan/defold-estring/archive/main.zip for the current version
   • Or add a specific release

TypeScript Definitions

This extension includes types for use with TypeScript + Defold.

1. Install these types

yarn add git+https://[email protected]/thinknathan/defold-estring.git#^2.0.0 -D
# or
npm install git+https://[email protected]/thinknathan/defold-estring.git#^2.0.0 --save-dev

2. Add defold-estring to types in tsconfig.json

{
	"compilerOptions": {
		"types": [
+			"defold-estring",
		],
	}
}

3. Add node_modules/@types to typeRoots in tsconfig.json if it's not already there

{
	"compilerOptions": {
		"typeRoots": [
+			"node_modules/@types",
		],
	}
}

Usage

-- concat
-- Joins strings or numbers and returns the result.
local result_concat = estring.concat("Hello, ", "world", 123, "!")
print(result_concat) -- Output: Hello, world123!

-- trim
-- Removes leading and trailing whitespace from a string.
local result_trim = estring.trim("   This is a string with spaces   ")
print(result_trim) -- Output: This is a string with spaces

-- split
-- Splits a string into parts using a specified delimiter and returns them in a table.
local result_split = estring.split("apple,orange,banana", ",")
for i, value in ipairs(result_split) do
    print(i, value)
end
-- Output:
-- 1   apple
-- 2   orange
-- 3   banana

-- pad_start
-- Pads the start of a string with a specified padding string to reach a target length.
local result_pad_start = estring.pad_start("42", "0", 5)
print(result_pad_start) -- Output: 00042

-- pad_end
-- Pads the end of a string with a specified padding string to reach a target length.
local result_pad_end = estring.pad_end("42", "0", 5)
print(result_pad_end) -- Output: 42000

-- format_time
-- Formats a time value based on the provided format type, optionally using a specified delimiter.
local result_format_time = estring.format_time(os.time(), 2, "-")
print(result_format_time) -- Output: 12-45-30 PM
-- Parameters:
-- timeValue: (number or string) The time value to format. It can be either a numeric timestamp or a string representing a date and time.
-- formatType: (constant) Specifies the desired format type:
-- 	estring.FORMAT_12H: "h:mm AM/PM"
-- 	estring.FORMAT_12H_LEADING_ZERO: "hh:mm AM/PM"
-- 	estring.FORMAT_12H_LEADING_ZERO_WITH_SECONDS: "hh:mm:ss AM/PM"
-- 	estring.FORMAT_HH_MM_SS: "HH:mm:ss"
-- 	estring.FORMAT_HH_MM: "HH:mm"
-- 	estring.FORMAT_MM_SS: "mm:ss"
-- delimiter: (string, optional) The delimiter used in the formatted time. Default is ":".

-- format_number
-- Formats a number as a string with options for precision, thousands separator, and decimal separator.
local result_format_number = estring.format_number(1234567.89, 2, ",", ".")
print(result_format_number) -- Output: 1,234,567.89
-- Parameters:
-- numberValue: (number or string) The number to format.
-- precision: (integer, optional) The number of decimal places. Default is 0.
-- thousandsSeparator: (string, optional) The character used as a separator for thousands. Default is ",".
-- decimalSeparator: (string, optional) The character used as a decimal point. Default is ".".

Alternatives

DefString is a pure Lua implementation of string manipulation.