lume

A collection of handy functions for Lua, geared towards game development.

Installation

The lume.lua file should be dropped into an existing project and required by it:

lume = require "lume"

Function reference

lume.clamp(x, min, max)

Returns the value x clamped between the values min and max

lume.round(x)

Rounds x to the nearest integer. Rounds away from zero if we're midway between two integers.

lume.sign(x)

Returns 1 if x is 0 or above, returns -1 when x is negative.

lume.lerp(a, b, amount)

Returns the linearly interpolated value between a and b, amount should be range of 0 - 1; if amount is outside of this range it is clamped.

lume.smooth(a, b, amount)

Similar to lume.lerp() but uses cosine interpolation instead of linear interpolation.

lume.pingpong(x)

Ping-pongs the value x between 0 and 1.

lume.distance(x1, y1, x2, y2)

Returns the distance between the two points.

lume.angle(x1, y2, x2, y2)

Returns the angle between the two points.

lume.random([a [, b]])

Returns a random number between a and b. If only a is supplied a number between 0 and a is returned. If no arguments are supplied a random number between 0 and 1 is returned.

lume.randomchoice(t)

Returns a random value from array t.

lume.shuffle(t)

Shuffles the values of array t in place, returns the array.

lume.array(...)

Iterates the supplied iterator and returns an array filled with the values.

lume.array(pairs({a = 1, b = 2})) -- Returns {"a", "b"}

lume.map(t, fn)

Applies the function fn to each value in table t and returns a new table with the resulting values.

lume.map({1, 2, 3}, function(x) return x * 2 end) -- Returns {2, 4, 6}

lume.all(t [, fn])

Returns true if all the values in t table are true. If a fn function is supplied it is called on each value, true is returned if all of the calls to fn return true.

lume.all({1, 2, 1}, function(x) return x == 1 end) -- Returns false

lume.any(t [, fn])

Returns true if any of the values in t table are true. If a fn function is supplied it is called on each value, true is returned if any of the calls to fn return true.

lume.any({1, 2, 1}, function(x) return x == 1 end) -- Returns true

lume.reduce(t, fn, first)

Applies fn on two arguments cumulative to the items of the array t, from left to right, so as to reduce the array to a single value. The accumulator is intialised to the first value.

lume.reduce({1, 2, 3}, function(a, b) return a + b end, 0) -- Returns 6

lume.set(t [, retainkeys])

Returns a copy of the t table with all the duplicate values removed. If retainkeys is true the table is not treated as an array and retains its original keys.

lume.set({2, 1, 2, "cat", "cat"}) -- Returns {1, 2, cat}

lume.filter(t, fn [, retainkeys])

Calls fn on each value of t table. Returns a new table with only the values where fn returned true. If retainkeys is true the table is not treated as an array and retains its original keys.

lume.filter({1, 2, 3, 4}, function(x) return x % 2 == 0 end) -- Returns {2, 4}

lume.merge(t, t2 [, retainkeys])

Merges all the values from the table t2 into t in place. If retainkeys is true the table is not treated as an array and retains its original keys; if t and t2 have a conflicting key, the value from t2 is used.

lume.merge({2, 3}, {4, 5}) -- Returns {2, 3, 4, 5}

lume.find(t, value)

Returns the index/key of value in t. Returns nil if that value does not exist in the table.

lume.find({"a", "b", "c"}, "b") -- Returns 2

lume.once(fn, ...)

Returns a wrapper function to fn which takes the supplied arguments. The wrapper function will call fn on the first call and do nothing on any subsequent calls.

local f = lume.once(print, "Hello")
f() -- Prints "Hello"
f() -- Does nothing

lume.slice(t [, i [, j]])

Mimics the behaviour of Lua's string.sub, but operates on an array rather than a string. Creates and returns a new array of the given slice.

lume.slice({"a", "b", "c", "d", "e"}, 2, 4) -- Returns {"b", "c", "d"}

lume.clone(t)

Returns a shallow copy of the table t.

lume.fn(fn, ...)

Creates a wrapper function around function fn, automatically inserting the arguments into fn which will persist every time the wrapper is called.

local f = lume.fn(print, "Hello")
f() -- Prints "Hello"

lume.time(fn, ...)

Inserts the arguments into function fn and calls it. Returns the time in seconds the function fn took to execute followed by fn's returned values.

lume.time(function(x) return x end, "hello") -- Returns 0, "hello"

lume.serialize(x)

Serializes the argument x into a string which can be loaded again using lume.deserialize(). Only booleans, numbers, tables and strings can be serialized. Circular references are not handled; all nested tables are serialized as unique tables.

lume.serialize({a = "test", b = {1, 2, 3}, false})
-- Returns "{[1]=false,["a"]="test",["b"]={[1]=1,[2]=2,[3]=3,},}"

lume.deserialize(str)

Deserializes a string created by lume.serialize() and returns the resulting value. This function should not be run on an untrusted string.

lume.deserialize("{1, 2, 3}") -- Returns {1, 2, 3}

lume.split(str [, sep])

Splits the string str into words and returns a table of the sub strings. If sep is provided the string will be split at any of the characters in sep instead of on whitespace.

lume.split("One two three") -- Returns {"One", "two", "three"}

lume.trim(str [, chars])

Trims the whitespace from the start and end of the string str and returns the new string. If a chars value is set the characters in chars are trimmed instead of whitespace.

lume.trim("  Hello  ") -- Returns "Hello"

lume.format(str, vars)

Returns a formatted string. The values of keys in the table vars can be inserted into the string by using the form "{key}" in str.

lume.format("Hello {a}, I hope {a} is {b}.", {a = "world", b = "well"})
-- Returns "Hello world, I hope world is well."

lume.dostring(str)

Executes the lua code inside str.

lume.dostring("print('Hello!')") -- Prints "Hello!"

lume.rgba(color)

Takes the 32bit integer color argument and returns 4 numbers, one for each channel, with a range of 0 - 255. Handy for using as the argument to LÖVE's setColor() function.

lume.rgba(0xFF304050) -- Returns 48, 64, 80, 255

License

This library is free software; you can redistribute it and/or modify it under the terms of the MIT license. See LICENSE for details.