Module:TableTools/doc

This module includes a number of functions for dealing with Lua tables. It is a meta-module, meant to be called from other Lua modules, and should not be called directly from #invoke.

Loading the module

To use any of the functions, first you must load the module.

<source lang="lua"> local TableTools = require('Module:TableTools') </source>

isPositiveInteger

<source lang="lua"> TableTools.isPositiveInteger(value) </source>

Returns true if value is a positive integer, and false if not. Although it doesn't operate on tables, it is included here as it is useful for determining whether a given table key is in the array part or the hash part of a table.

isNan

<source lang="lua"> TableTools.isNan(value) </source>

Returns true if the given number is a NaN value, and false if not. Although it doesn't operate on tables, it is included here as it is useful for determining whether a value can be a valid table key. (Lua will generate an error if a NaN value is used as a table key.)

removeDuplicates

<source lang="lua"> TableTools.removeDuplicates(t) </source>

Removes duplicate values from an array. This function is only designed to work with standard arrays: keys that are not positive integers are ignored, and the function's behaviour is undefined if the array contains any nil values before the final element. (For arrays containing nil values, you can use compressSparseArray first.) The function tries to preserve the order of the array: the earliest non-unique value is kept, and all subsequent duplicate values are removed. For example, for the table {5, 4, 4, 3, 4, 2, 2, 1} removeDuplicates will return {5, 4, 3, 2, 1}

numKeys

<source lang="lua"> TableTools.numKeys(t) </source>

Takes a table t and returns an array containing the numbers of any positive integer keys that have non-nil values, sorted in numerical order. For example, for the table {1, nil, 2, 3, foo = 'bar'}, numKeys will return {1, 3, 4}.

affixNums

<source lang="lua"> TableTools.affixNums(t, prefix, suffix) </source>

Takes a table t and returns an array containing the numbers of keys with the optional prefix prefix and the optional suffix suffix. For example, for the table {a1 = 'foo', a3 = 'bar', a6 = 'baz'} and the prefix 'a', affixNums will return {1, 3, 6}.

compressSparseArray

<source lang="lua"> TableTools.compressSparseArray(t) </source>

Takes an array t with one or more nil values, and removes the nil values while preserving the order, so that the array can be safely traversed with ipairs. Any keys that are not positive integers are removed. For example, for the table {1, nil, foo = 'bar', 3, 2}, compressSparseArray will return {1, 3, 2}.

sparseIpairs

<source lang="lua"> TableTools.sparseIpairs(t) </source>

This is an iterator function for traversing a sparse array t. It is similar to ipairs, but will continue to iterate until the highest numerical key, whereas ipairs may stop after the first nil value. Any keys that are not positive integers are ignored.

Usually sparseIpairs is used in a generic for loop.

<source lang="lua"> for i, v in TableTools.sparseIpairs(t) do

  -- code block

end </source>

Note that sparseIpairs uses the pairs function in its implementation. Although some table keys appear to be ignored, all table keys are accessed when it is run.

union

<source lang="lua"> TableTools.union(t1, t2, ...) </source>

Returns the union of the key/value pairs of n tables. If any of the tables contain different values for the same table key, the table value is converted to an array holding all of the different values. For example, for the tables {foo = "foo", bar = "bar"} and {foo = "foo", bar = "baz", qux = "qux"}, union will return {foo = "foo", bar = {"bar", "baz"}, qux = "qux"}.

valueUnion

<source lang="lua"> TableTools.valueUnion(t1, t2, ...) </source>

Returns the union of the values of n tables, as an array. For example, for the tables {1, 3, 4, 5, foo = 7} and {2, bar = 3, 5, 6}, valueUnion will return {1, 2, 3, 4, 5, 6, 7}.

intersection

<source lang="lua"> TableTools.intersection(t1, t2, ...) </source>

Returns the intersection of the key/value pairs of n tables. Both the key and the value must match to be included in the resulting table. For example, for the tables {foo = "foo", bar = "bar"} and {foo = "foo", bar = "baz", qux = "qux"}, intersection will return {foo = "foo"}.

valueIntersection

<source lang="lua"> TableTools.valueIntersection(t1, t2, ...) </source>

Returns the intersection of the values of n tables, as an array. For example, for the tables {1, 3, 4, 5, foo = 7} and {2, bar = 3, 5, 6}, valueIntersection will return {3, 5}.

complement

<source lang="lua"> TableTools.complement(t1, t2, ..., tn) </source>

Returns the relative complement of t1, t2, ..., in tn. The complement is of key/value pairs. This is equivalent to all the key/value pairs that are in tn but are not in any of t1, t2, ... tn-1. For example, for the tables {foo = "foo", bar = "bar", baz = "baz"} and {foo = "foo", bar = "baz", qux = "qux"}, complement would return {bar = "baz", qux = "qux"}. An error is raised if the function receives less than two tables as arguments.

size

<source lang="lua"> TableTools.size(t) </source>

Finds the size of a key/value pair table. For example, for the table {foo = 'foo', bar = 'bar'}, size will return 2. The function will also work on arrays, but for arrays it is more efficient to use the # operator. Note that to find the table size, this function uses the pairs function to iterate through all of the table keys.