Minetest-WorldEditAdditions/worldeditadditions/utils/tables.lua

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--- Shallow clones a table.
-- @source http://lua-users.org/wiki/CopyTable
-- @param orig table The table to clone.
-- @return table The cloned table.
function worldeditadditions.shallowcopy(orig)
local orig_type = type(orig)
local copy
if orig_type == 'table' then
copy = {}
for orig_key, orig_value in pairs(orig) do
copy[orig_key] = orig_value
end
else -- number, string, boolean, etc
copy = orig
end
return copy
end
--- SHALLOW ONLY - applies the values in source to overwrite the equivalent keys in target.
-- Warning: This function mutates target!
-- @param source table The source to take values from
-- @param target table The target to write values to
function worldeditadditions.table_apply(source, target)
for key, value in pairs(source) do
target[key] = value
end
end
--- Polyfill for unpack / table.unpack.
-- Calls unpack when available, and looks for table.unpack if unpack() isn't
-- found.
-- This is needed because in Lua 5.1 it's the global unpack(), but in Lua 5.4
-- it's moved to table.unpack().
function worldeditadditions.table_unpack(tbl, offset, count)
if type(unpack) == "function" then
return unpack(tbl, offset, count)
else
return table.unpack(tbl, offset, count)
end
end
--- Returns only the last count items in a given numerical table-based list.
function worldeditadditions.table_get_last(tbl, count)
return {worldeditadditions.table_unpack(
tbl,
math.max(0, (#tbl) - (count - 1))
)}
end
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--- Returns the key value pairs in a table as a single string
-- @param tbl table input table
-- @param sep string key value seperator
-- @param new_line string key value pair delimiter
-- @return string concatenated table pairs
function worldeditadditions.table_tostring(tbl, sep, new_line)
if type(sep) ~= "string" then sep = ": " end
if type(new_line) ~= "string" then new_line = ", " end
local ret = {}
if type(tbl) ~= "table" then return "Error: input not table!" end
for key,value in pairs(tbl) do
ret:append(key)
ret:append(sep)
ret:append(value)
ret:append(new_line)
end
return ret:concat("")
end
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--- Executes the given function on every item in the given table.
-- Ignores return values that are nil and doesn't insert them into the table.
-- @param tbl table The table to operate on.
-- @param func function<any>:any|nil The function to execute on every item in the table.
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-- @returns table A new table containing the return values of the function.
function worldeditadditions.table_map(tbl, func)
local result = {}
for i,value in ipairs(tbl) do
local newval = func(value, i)
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if newval ~= nil then table.insert(result, newval) end
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end
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return result
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end
--- Filters the items in the given table using the given function.
-- The function is executed for each item in the list. If it returns true, the
-- item is kept. If it returns false, the item is discarded.
-- Arguments passed to the function: item, i
-- ...where item is the item to filter, and i is the index in the table the item
-- is located at.
-- @param tbl table The table of values to filter.
-- @param func function<any, number>:bool The filter function to execute - should return a boolean value indicating whether the item provided as the first argument should be kept
-- @returns table A new table containing the values that the given function returned true for.
function worldeditadditions.table_filter(tbl, func)
local result = {}
for i,value in ipairs(tbl) do
if func(value, i) then
table.insert(result, value)
end
end
return result
end
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--- Builds a new table with the elements of the given table appearing at most once.
-- @param tbl table The table of values to make unique.
-- @returns table A new table containing the values of the given table appearing at most once.
function worldeditadditions.table_unique(tbl)
local newtbl = {}
for i,value in ipairs(tbl) do
local seen = false
for j,seenvalue in ipairs(newtbl) do
if value == seenvalue then
seen = true
break
end
end
if not seen then
table.insert(newtbl, value)
end
end
return newtbl
end