Lua Tables — Queries

If you have imported the module as

require 'lulu.table'

Then you have access to the following query methods:

Method	Brief Description
`table.size(tbl)`	Returns the number of top-level items in `tbl`. This works correctly for any Lua `table`.
`table.is_table(tbl)`	Returns `true` if a table is a Lua table.
`table.is_array(tbl)`	Returns `true` if a table is a Lua array.
`table.is_array_of(tbl, e_type)`	Returns `true` if`tbl` is a Lua array where all the elements are of the given type `e_type`.
`table.is_array_of_one_type(tbl)`	Returns `true` if`tbl` is a Lua array where all the elements are of the same type.
`table.is_array_of_numbers(tbl)`	Returns `true` if`tbl` is a Lua array where all the elements are numbers.
`table.is_array_of_strings(tbl)`	Returns `true` if`tbl` is a Lua array where all the elements are strings.
`table.metadata(tbl)`	Returns a metadata table about `tbl`.

A Lua array is a Lua table where the keys are consecutive integers starting at 1 with no gaps.

Metadata

The table.metadata(tbl) function returns a table of metadata about a table tbl.

The returned table, md, has a sub-table md[t] for each sub-table t encountered in tbl, including tbl itself.

The md[t] sub-table has the following fields:

Field	Description
`md[t].array`	Boolean that is `true` if `t` is a Lua array.
`md[t].size`	Number of elements in `t`.
`md[t].subs`	Number of proper sub-tables in `t`.
`md[t].refs`	Number of references to `t`. Greater than one if `t` is shared.

This metadata helps understand the structure of a table. The metadata function can handle tables that contain circular references.