File

util/jsonpointer.lua @ 13182:c48ae06e24d6

util.datamanager: Fix indexing first item if not at the very start If the first item does not start at position 0 then the index function produces a phantom first entry covering position zero until where the real first item starts. When using the index, this would make it either appear as the first item was missing or cause an off-by-one issue with remaining items.
author Kim Alvefur <zash@zash.se>
date Mon, 10 Jul 2023 17:19:05 +0200
parent 12781:22066b02887f
line wrap: on
line source

local m_type = math.type;

local function unescape_token(escaped_token)
	local unescaped = escaped_token:gsub("~1", "/"):gsub("~0", "~")
	return unescaped
end

local function resolve_json_pointer(ref, path)
	local ptr_len = #path + 1
	for part, pos in path:gmatch("/([^/]*)()") do
		local token = unescape_token(part)
		if not (type(ref) == "table") then
			return nil
		end
		local idx = next(ref)
		local new_ref

		if type(idx) == "string" then
			new_ref = ref[token]
		elseif m_type(idx) == "integer" then
			local i = tonumber(token)
			if token == "-" then
				i = #ref + 1
			end
			new_ref = ref[i + 1]
		else
			return nil, "invalid-table"
		end

		if pos == ptr_len then
			return new_ref
		elseif type(new_ref) == "table" then
			ref = new_ref
		elseif not (type(ref) == "table") then
			return nil, "invalid-path"
		end

	end
	return ref
end

return { resolve = resolve_json_pointer }