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-- SPDX-License-Identifier: Apache-2.0
-- SPDX-FileCopyrightText: 2025 Fundament Software SPC <https://fundament.software>
-- string.chars
-- intended usage: for i, c in mystring:chars() do ... end
-- instead of: for i = 1, #mystring do local c = mystring:sub(i, i) ... end
---@param state string
---@param control integer
---@return integer?
---@return string?
local function nextchar(state, control)
local i = control + 1
if i > #state then
return nil
else
return i, state:sub(i, i)
end
end
---@param s string
---@param start? integer
---@return function, string, integer
function string.chars(s, start)
if start == nil then
start = 0
else
start = start - 1
end
return nextchar, s, start
end
-- table.concat
-- in lua 5.2 and below, and luajit, stdlib table.concat ignores the __index
-- metamethod. unlike ipairs, there is no associated metamethod for
-- table.concat, so either we're careful to avoid table.concat on terms-gen
-- arrays (not happening), or we redefine the function.
-- lua 5.3 doesn't need this patch but it also doesn't hurt
---@param list (string|number)[]
---@param sep string?
---@param i integer?
---@param j integer?
---@return string
function table.concat(list, sep, i, j)
sep = sep or ""
i = i or 1
j = j or #list
if i > j then
return ""
end
local s = list[i]
for x = i + 1, j do
s = s .. sep .. list[x]
end
return s
end
-- if you're looking for table.pack/unpack, they aren't needed since we're
-- targetting lua 5.3, and luajit with lua 5.2 compat enabled, which already
-- supply them.
-- if you're looking for global unpack, stop using it!