Class `Collection`

Collection empowers table: unicity, sort and type-protection of datas (elements).

Type-protection

At creation time, you declare what type of elements is accepted: number, string or table.
This ensure that all added elements must respect that else error is raised.

As table are the root of any object/class, you can store almost everything in a Collection. tables can't be compared eachother so thoses Collections can't be uniquified nor sorted, contains and value comparison is not possible neither.

Differences between table and Collection

Better than long explanations, here are code/algorithm that demonstrate the differences.

Action	table	Collection	Notes
Creation	`t = {}`	`c = Collection:new(elementType, sortFunction)`	where `elementType` is `"number"`, `"string"` or `"table"`
Add	`tinsert(t, data)`	`c:add(data)`	In the same table, you can insert numbers, strings and others types. Collection avoid this: more restrictive, less bugs.
Add a set of data	for i=1,getn(datas) do tinsert(t, datas[i]) end	`c:addAll(anotherCollection)`
Read	`print(t[2])`	`print(c:get(2))`	With Collection, the data is guaranteed to have the type you want.
Remove data at index 2	`tremove(t, 2)`	`c:removeAt(2)`
Remove first "banana"	for i=1,getn(t) do if t[i]=="banana" then tremove(t, i) break end end	`c:remove("banana")`
Remove all "bananas"	Loop backward, move efficient for i=getn(t),1,-1 do if t[i]=="banana" then tremove(t, i) end end	`c:removeAll("bananas")`
Get size	`getn(t)`	`c:size()`
Replace at index 2	`t[2] = "apple"`	`c:replaceAt(2, "apple")`
Sort	`sort(t, sortFunction)`	Nothing to do	Datas are sorted at insertion, if Collection is created with a sorting function
Does it contain "apricot"?	Sort if needed, and loop untile "apricot" or a greater data is found or loop the whole table untile "apricot" is found or end is reached	`c:contains("apricot")`
Don't add "banana" if already in table	Loop. if no "banana" found then insert. local found = false for i=1,getn(t) do if t[i]=="banana" then found=true; break; end end if found==false then tinsert(t, "banana") end	Nothing to do	At creation time, Collection may be a "set", i.e. a Collection of unique datas
Get index of "apple"	Sort if needed loop until first "apple" found or end reached	`c:indexOf("apple")`
Get the first / last data	Sort if needed `t[1]` or `t[getn(t)]`	`c:first()` or `c:last()`
Get greatest/least data	Sort and return `t[1]` / `t[getn(t)]` Or loop thought all data to find greatest / least	`c:last()` / `c:first()`	for sorted Collection only
Get all data before/after (or including) "banana"	Sort if needed Loop until "banana" is found Add previous/next datas to a table and return it.	`c:head("banana", inclusive)` or `c:tail("banana", inclusive)` where inclusive is a boolean.
Browse	`for i=1,getn(t) do print(t[i]) end` Backward browsing: `for i=getn(t),1,-1 do...`	c:iterator() while c:hasNext() do print(c:next()) end Backward browsing: `c:reverseIterator()`

As you can notice, very simple operation are easier to write using table, but complex ones are really more friendly using Collection.
Collection should save you time, make your script more maintainables, and reduce errors because of type-protection of inserted datas.

Note on performance: Collection is backed on native Lua table. It's fast, but just a little bit less than working with tables.
If you are really concerned by CPU and memory optimization and perform a lot of simple operation on many tables, you may prefer table to Collection.
If you are concerned by easy-to-read code and ready-to-use functions, Collection is for you.

For example, Collection is usless for building a large table of digital waveform (44100 numbers per second of sound).

Summary

Return type	Function and summary
Collection	new(string elementType, bool unique, function sortFunction) Create a new Collection.
int	add(elementType element) Add `element` in the Collection.
int	addAll(anotherTable) Add all elements of a table or Collection in this Collection.
elementType	ceiling(elementType element) Returns the least element in this set greater than or equal to the given `element`, or `nil` if there is no such element.
	clear() Empty the Collection
bool	contains(elementType element) Does Collection already contains `element`?
bool	containsAll(anotherTable) Does this Collection contains all the elements of `anotherTable`?
	debug() Debug a structure of this Collection in console, only if `LOG_LEVEL = LOG_LEVEL_DEBUG`.
elementType	first() Returns the first (least in case of sorted Set) element of this Collection
elementType	floor(elementType element) Returns the greatest element in this set least than or equal to the given `element`, or `nil` if there is no such element.
	forEach(function fn) Apply transformation function `fn` to each element of this Collection.
elementType	get(number index) Returns the element at the specified index where `1 <= index <= size()`
bool	hasNext(string iteratorName) While iterating, is there a next element?
Collection	head(elementType element, bool inclusive) Returns a partial copy of this Collection, with elements less (or equal, if `inclusive = true`) than the given `element`.
elementType	higher(elementType element) Returns the least element in this set greater than to the given `element`, or nil if there is no such element.
int	indexOf(elementType element) Returns the index of the first occurrence of the specified `element` in this Collection, or `-1` if this Collection does not contain `element`.
bool	isEmpty() Is this Collection empty?
bool	isSet() Is this Collection a Set?
	iterator(string iteratorName) Starts or restarts an iterator on the Collection.
elementType	last() Returns the last (greatest if sorted) element in this set
int	lastIndexOf(elementType element) Returns the index of the last occurrence of the specified `element` in this Collection, or `-1` if this Collection does not contain the `element`.
elementType	lower(elementType element) Returns the greatest element in this set least than to the given `element`, or `nil` if there is no such element.
elementType	next(string iteratorName) While iterating, returns next element if `:hasNext()`, `nil` otherwise.
	print() Prints a debug structure of the Collection in console.
int	remove(elementType element) Removes the first element of this Collection that equals the given `element`.
int	removeAll(elements) Removes all elements of this Collection that: equals `elements` if it's a number or a string are contained in `elements`, if it's a table or Collection
elementType	removeAt(number index) Remove the element at the specified `index` and return deleted element
elementType	replaceAt(number idx, elementType newElement) Replace the element at the specified `index` by the given `newElement`, returns replaced element.
Collection	retainsAll(elements) Retains, in this Collection, only the elements that are contained in the specified `table`.
	reverseIterator(string iteratorName) Starts or restarts a reversed iterator on the Collection.
int	size() Returns the size of the Collection, the number of elements it contains.
Collection	sub(elementType from, bool fromInclusive, elementType to, bool toInclusive) Returns a partial copy of this Collection, with elements between `from` and `to`.
Collection	tail(elementType element, bool inclusive) Returns a partial copy of this Collection, with elements greater (or equal, if `inclusive = true`) than the given `element`.
table	toArray() Returns a Lua native table containing all elements of this Collection.

Methods

Collection:new(string elementType, bool unique, function sortFunction)

Create a new Collection.

Parameter	Type	Default	Description
elementType	string	"string"	`"number"`, `"string"` or `"table"`.
unique	bool	false	Are elements unique (as Java Set)? or not (as Java ArrayList)?
sortFunction	function	nil	if unique is `true`, sorting function can be provided, else elements stay in insertion order

Return: Collection: A new empty Collection
Error: if elementType is wrong

Collection:add(elementType element)

Add element in the Collection.

If Collection is a Set (unique values) and already contains element, nothing is added.

Parameter	Type	Default	Description
element	elementType

Return: int: Number of inserted element: 0 or 1.
Error: if type(element) doesn't match constructor elementType parameter

Collection:addAll(anotherTable)

Add all elements of a table or Collection in this Collection.

Parameter	Type	Default	Description
anotherTable			A table, `Collection:toArray()` or Collection

Return: int: The number of inserted elements
Errors: if anotherTable is not a table; if one of anotherTable type(element) doesn't match constructor elementType parameter

Collection:contains(elementType element)

Does Collection already contains element?

Equivalent of Collection:indexOf(element)~=-1

Parameter	Type	Default	Description
element	elementType

Return: bool: true, or nil (for false)
Errors: if type(element) doesn't match constructor elementType parameter; if elements of this Collection are not comparables

Collection:containsAll(anotherTable)

Does this Collection contains all the elements of anotherTable?

Parameter	Type	Default	Description
anotherTable			A table (native Lua table or `Collection:toArray()`) or a Collection

Return: bool: nil (for >false) if at least one element of anotherTable is missing in this Collection
Errors: if anotherTable contains one element which type doesn't match constructor elementType parameter; if elements of this Collection are not comparables

Collection:clear()

Empty the Collection

Collection:forEach(function fn)

Apply transformation function fn to each element of this Collection.

If this Collection is a Set, probable duplicate elements after transformation, only one will be kept. If this Collection is sorted, elements are sorted after the transformations.

Parameter	Type	Default	Description
fn	function		A function that accept an element as argument and must return two values: First is the new element value Second is a boolean, true to replace the value in the Collection, nil or false if no replacement to do.

Example

local c = Collection:new("string")
c:addAll({"apple", "banana", "kiwi"})
c:forEach(function(element) print(element.."s"); end)
--> apples, bananas, kiwis
c:forEach(function(element) return strupper(element), true; end)
--> all elements are now uppercase
c:forEach(function(element) print(element); end)
--> APPLE, BANANA, KIWI

Collection:get(number index)

Returns the element at the specified index where 1 <= index <= size()

Parameter	Type	Default	Description
index	number

Return: elementType: an element
Error: if index is out of bounds

Collection:indexOf(elementType element)

Returns the index of the first occurrence of the specified element in this Collection, or -1 if this Collection does not contain element.

Parameter	Type	Default	Description
element	elementType

Return

int: index between 1 and Collection:size(), or -1

Errors

if type(element) doesn't match constructor elementType parameter

if elements of this Collection are not comparables

See

Collection:lastIndexOf

Example

local c = Collection:new("string")
c:addAll({"apple", "banana", "apple", "kiwi"})
print(c:indexOf("apple")) --> 1
print(c:indexOf("cherry")) --> -1

Collection:isEmpty()

Is this Collection empty?

Return: bool: true if has no element at all, nil (for false) otherwise

Collection:isSet()

Is this Collection a Set?

A set is made of unique elements.

Return

bool: true, or nil (for false)

Example

Collection:new("string"):isSet() --> false
Collection:new("string", true):isSet() --> true

Collection:lastIndexOf(elementType element)

Returns the index of the last occurrence of the specified element in this Collection, or -1 if this Collection does not contain the element.

Parameter	Type	Default	Description
element	elementType

Return

int: index between 1 and Collection:size(), or -1

Errors

if type(element) doesn't match constructor elementType parameter

if elements of this Collection are not comparables

See

Collection:indexOf

Example

local c = Collection:new("string")
c:addAll({"apple", "banana", "apple", "kiwi"})
print(c:lastIndexOf("apple")) --> 3
print(c:lastIndexOf("cherry")) --> -1

Collection:remove(elementType element)

Removes the first element of this Collection that equals the given element.

Parameter	Type	Default	Description
element	elementType

Return: int: Number of element removed, 0 or 1
Errors: if type(element) doesn't match constructor elementType parameter; if elements of this Collection are not comparables

Collection:removeAll(elements)

Removes all elements of this Collection that:

equals elements if it's a number or a string
are contained in elements, if it's a table or Collection

Parameter	Type	Default	Description
elements			number, string, table or Collection

Return: int: Number of removals, between 0 and Collection:size()
Errors: if type(element) doesn't match constructor elementType parameter; if elements of this Collection are not comparables

Collection:removeAt(number index)

Remove the element at the specified index and return deleted element

Parameter	Type	Default	Description
index	number		1 <= index <= size()

Return: elementType: The removed element
Error: if index is out of bounds

Collection:replaceAt(number idx, elementType newElement)

Replace the element at the specified index by the given newElement, returns replaced element.

Parameter	Type	Default	Description
idx	number		`1 <= idx <= size()`
newElement	elementType

Return: elementType: the replaced element
Errors: if type(newElement) doesn't match constructor elementType parameter; if idx is out of bounds

Collection:retainsAll(elements)

Retains, in this Collection, only the elements that are contained in the specified table.

Parameter	Type	Default	Description
elements			List of elements to retain in this Collection, table (native or `Collection:toArray()`) or a Collection

Return

Collection: Collection of removed elements

Errors

if type(element) doesn't match constructor elementType parameter

if elements of this Collection are not comparables

Example

local c = Collection:new("number")
c:addAll({1,2,3,4,5,6,7,8,9,10})
local primes = Collection:new("number")
primes:addAll({1,2,3,5,7})
local c2 = c:retainAll(primes)
--> c now contains only primes 1, 2, 3, 5 and 7
--> c2 contains the removed elements: 4, 6, 8, 9 and 10.

Collection:size()

Returns the size of the Collection, the number of elements it contains.

Return: int: 0 or more

Collection:toArray()

Returns a Lua native table containing all elements of this Collection.

Return: table:

Collection:first()

Returns the first (least in case of sorted Set) element of this Collection

Return

elementType: An element, nil if Collection is empty

See

Collection:last

Example

local c = Collection:new("number")
c:addAll({2,4,6,1,3,5})
print(c:first()) --> 2
c = Collection:new("number", true, SORT_ASCENDING)
c:addAll({2,4,6,1,3,5})
print(c:first()) --> 1
c = Collection:new("number", true, SORT_DESCENDING)
c:addAll({2,4,6,1,3,5})
print(c:first()) --> 6

Collection:head(elementType element, bool inclusive)

Returns a partial copy of this Collection, with elements less (or equal, if inclusive = true) than the given element.

Parameter	Type	Default	Description
element	elementType
inclusive	bool	false	Include `element` in the result?

Return

Collection: A Collection with same properties, can be empty.

Errors

if type(element) doesn't match constructor elementType parameter

if elements of this Collection are not comparables

See

Collection:sub

Collection:tail

Example

local c = Collection:new("number")
c:addAll({1,2,3,5,7,11})
local h = c:head(5) -- or head(5, false)
--> h contains 1, 2 and 3
h = c:head(5, true)
--> h contains 1, 2, 3 and 5

Collection:last()

Returns the last (greatest if sorted) element in this set

Return

elementType: an element or nil if this Collection is empty

See

Collection:first

Example

local c = Collection:new("number")
c:addAll({1,3,5,7,2,4,6})
print(c:last()) --> 6
c = Collection:new("number", true, SORT_ASCENDING)
c:addAll({1,3,5,7,2,4,6})
print(c:last()) --> 7
c = Collection:new("number", true, SORT_DESCENDING)
c:addAll({1,3,5,7,2,4,6})
print(c:last()) --> 1

Collection:sub(elementType from, bool fromInclusive, elementType to, bool toInclusive)

Returns a partial copy of this Collection, with elements between from and to.

Parameter	Type	Default	Description
from	elementType
fromInclusive	bool	true	Include `from` in result?
to	elementType
toInclusive	bool	false	Include `to` in result ?

Return

Collection: A new Collection with same properties, can be empty

Errors

if from >= to

if type(from) or type(to) don't match constructor elementType parameter

if elements of this Collection are not comparables

See

Collection:head

Collection:tail

Example

local c = Collection:new("number")
c:addAll({1,2,3,5,7,11})
local s = c:sub(5, false, 9, false)
--> s contains 7
s = c:sub(5, true, 9, true)
--> s contains 5 and 7
s = c:sub(5, true, 11, false)
--> s contains 5 and 7
s = c:sub(5, true, 11, true)
--> s contains 5, 7 and 11

Collection:tail(elementType element, bool inclusive)

Returns a partial copy of this Collection, with elements greater (or equal, if inclusive = true) than the given element.

Parameter	Type	Default	Description
element	elementType
inclusive	bool	false	Include `element` in the result?

Return

Collection: A new Collection with same properties, can be empty

Errors

if type(element) doesn't match constructor elementType parameter

if elements of this Collection are not comparables

See

Example

local c = Collection:new("number")
c:addAll({1,2,3,5,7,11})
local t = c:tail(5) -- or tail(5, false)
--> t contains 7 and 11
t = c:tail(5, true)
--> t contains 5, 7 and 11

Collection:ceiling(elementType element)

Returns the least element in this set greater than or equal to the given element, or nil if there is no such element.

Parameter	Type	Default	Description
element	elementType

Return

elementType: Existing element or nil

Errors

if type(element) doesn't match constructor elementType parameter

if elements of this Collection are not comparables

See

Collection:floor

Collection:higher

Collection:lower

Example

local c = Collection:new("number")
c:addAll({1,2,3,5,7,11})
print(c:ceiling(3)) --> 3
print(c:ceiling(4)) --> 5
print(c:ceiling(14)) --> nil

Collection:floor(elementType element)

Returns the greatest element in this set least than or equal to the given element, or nil if there is no such element.

Parameter	Type	Default	Description
element	elementType

Return

elementType: An element or nil

Errors

if type(element) doesn't match constructor elementType parameter

if elements of this Collection are not comparables

See

Collection:ceiling

Collection:higher

Collection:lower

Example

local c = Collection:new("number")
c:addAll({1,2,3,5,7,11})
print(c:floor(0)) --> nil
print(c:floor(1)) --> 1
print(c:floor(4)) --> 3
print(c:floor(14)) --> 11

Collection:higher(elementType element)

Returns the least element in this set greater than to the given element, or nil if there is no such element.

Parameter	Type	Default	Description
element	elementType

Return

elementType: existing element or nil

Errors

if type(element) doesn't match constructor elementType parameter

if elements of this Collection are not comparables

See

Collection:ceiling

Collection:floor

Collection:lower

Example

local c = Collection:new("number")
c:addAll({1,2,3,5,7,11})
print(c:higher(4)) --> 5
print(c:higher(5)) --> 7
print(c:higher(11)) --> nil

Collection:lower(elementType element)

Returns the greatest element in this set least than to the given element, or nil if there is no such element.

Parameter	Type	Default	Description
element	elementType

Return

elementType: existing element or nil

Errors

if type(element) doesn't match constructor elementType parameter

if elements of this Collection are not comparables

See

Collection:ceiling

Collection:floor

Collection:higher

Example

local c = Collection:new("number")
c:addAll({1,2,3,5,7,11})
print(c:lower(4)) --> 3
print(c:higher(3)) --> 2
print(c:higher(1)) --> nil

Collection:iterator(string iteratorName)

Starts or restarts an iterator on the Collection.

An iterator is a convenient way to browse the Collection from first to last element with :hasNext() and :next() methods.
You can provide an iteratorName to run multiple iterators simultaneously, else the result would be hazardous.

Parameter	Type	Default	Description
iteratorName	string	nil

See: Collection:hasNext; Collection:next; Collection:reverseIterator

Collection:reverseIterator(string iteratorName)

Starts or restarts a reversed iterator on the Collection.

A reverse iterator is a convenient way to browse the Collection from last to first element with :hasNext() and :next() methods.
You can provide an iteratorName to run multiple iterators simultaneously, else the result would be hazardous.

Parameter	Type	Default	Description
iteratorName	string	nil

See: Collection:hasNext; Collection:next; Collection:iterator

Collection:hasNext(string iteratorName)

While iterating, is there a next element?

You can provide an iteratorName to run multiple iterators simultaneously, else the result would be hazardous.

Parameter	Type	Default	Description
iteratorName	string	nil

Return: bool: nil (for false) if end of Collection is reached, true if there are still some element to iterate
See: Collection:next; Collection:iterator; Collection:reverseIterator

Collection:next(string iteratorName)

While iterating, returns next element if :hasNext(), nil otherwise.

You can provide an iteratorName to run multiple iterators simultaneously, else the result would be hazardous.

Parameter	Type	Default	Description
iteratorName	string	nil

Return: elementType: An element or nil
See: Collection:hasNext; Collection:iterator; Collection:reverseIterator

Collection:print()

Prints a debug structure of the Collection in console.

if you want it prints only if LOG_LEVEL = LOG_LEVEL_DEBUG, use Collection:debug() instead.

See: Collection:debug; LOG_LEVEL

Collection:debug()

Debug a structure of this Collection in console, only if LOG_LEVEL = LOG_LEVEL_DEBUG.

See: Collection:print; LOG_LEVEL

Class Collection

Type-protection

Differences between table and Collection

Summary

Methods

Collection:new(string elementType, bool unique, function sortFunction)

Collection:add(elementType element)

Collection:addAll(anotherTable)

Collection:contains(elementType element)

Collection:containsAll(anotherTable)

Collection:clear()

Collection:forEach(function fn)

Collection:get(number index)

Collection:indexOf(elementType element)

Collection:isEmpty()

Collection:isSet()

Collection:lastIndexOf(elementType element)

Collection:remove(elementType element)

Collection:removeAll(elements)

Collection:removeAt(number index)

Collection:replaceAt(number idx, elementType newElement)

Collection:retainsAll(elements)

Collection:size()

Collection:toArray()

Collection:first()

Collection:head(elementType element, bool inclusive)

Collection:last()

Collection:sub(elementType from, bool fromInclusive, elementType to, bool toInclusive)

Collection:tail(elementType element, bool inclusive)

Collection:ceiling(elementType element)

Collection:floor(elementType element)

Collection:higher(elementType element)

Collection:lower(elementType element)

Collection:iterator(string iteratorName)

Collection:reverseIterator(string iteratorName)

Collection:hasNext(string iteratorName)

Collection:next(string iteratorName)

Collection:print()

Collection:debug()

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References

Class `Collection`