Add a new etrace library for event tracing

BuildTools/Targets/EvoBuildTarget.lua

@@ -40,6 +40,7 @@ local EvoBuildTarget = {
 		"Runtime/Libraries/assertions.lua",
 		"Runtime/Libraries/bdd.lua",
 		"Runtime/Libraries/console.lua",
+		"Runtime/Libraries/etrace.lua",
 		"Runtime/Libraries/path.lua",
 		"Runtime/Libraries/transform.lua",
 		"Runtime/Libraries/uuid.lua",

Runtime/Libraries/etrace.lua

@@ -0,0 +1,180 @@
+local ipairs = ipairs
+local error = error
+local pairs = pairs
+local type = type
+
+local format = string.format
+local table_insert = table.insert
+
+local etrace = {
+	registeredEvents = {},
+	eventLog = {},
+}
+
+function etrace.reset()
+	etrace.registeredEvents = {}
+	etrace.eventLog = {}
+end
+
+function etrace.clear()
+	etrace.eventLog = {}
+end
+
+function etrace.list()
+	return etrace.registeredEvents
+end
+
+function etrace.register(event)
+	if type(event) == "table" then
+		for key, value in ipairs(event) do
+			etrace.register(value)
+		end
+
+		return
+	end
+
+	if event == nil then
+		event = tostring(nil)
+		error(format("Invalid event %s cannot be registered", event), 0)
+	end
+
+	if etrace.registeredEvents[event] ~= nil then
+		error(format("Known event %s cannot be registered again", event), 0)
+	end
+
+	etrace.registeredEvents[event] = false
+end
+
+function etrace.unregister(event)
+	if type(event) == "table" then
+		if #event == 0 then
+			for key, value in pairs(etrace.registeredEvents) do
+				etrace.registeredEvents[key] = nil
+			end
+		end
+
+		for key, value in ipairs(event) do
+			etrace.unregister(value)
+		end
+
+		return
+	end
+
+	if event == nil then
+		for key, value in pairs(etrace.registeredEvents) do
+			etrace.registeredEvents[key] = nil
+		end
+
+		return
+	end
+
+	if etrace.registeredEvents[event] == nil then
+		error(format("Unknown event %s cannot be unregistered", event), 0)
+	end
+
+	etrace.registeredEvents[event] = nil
+end
+
+function etrace.enable(event)
+	if event == nil then
+		for name, enabledFlag in pairs(etrace.registeredEvents) do
+			etrace.registeredEvents[name] = true
+		end
+
+		return
+	end
+
+	if type(event) == "table" then
+		for key, value in ipairs(event) do
+			etrace.enable(value)
+		end
+
+		return
+	end
+
+	if etrace.registeredEvents[event] == nil then
+		error(format("Cannot enable unknown event %s", event), 0)
+	end
+
+	etrace.registeredEvents[event] = true
+end
+
+function etrace.disable(event)
+	if event == nil then
+		for name, enabledFlag in pairs(etrace.registeredEvents) do
+			etrace.registeredEvents[name] = false
+		end
+
+		return
+	end
+
+	if type(event) == "table" then
+		for key, value in ipairs(event) do
+			etrace.disable(value)
+		end
+
+		return
+	end
+
+	if etrace.registeredEvents[event] == nil then
+		error(format("Cannot disable unknown event %s", event), 0)
+	end
+
+	etrace.registeredEvents[event] = false
+end
+
+function etrace.status(event)
+	return etrace.registeredEvents[event]
+end
+
+function etrace.create(event, payload)
+	if etrace.registeredEvents[event] == nil then
+		error(format("Cannot create entry for unknown event %s", event), 0)
+	end
+
+	if etrace.registeredEvents[event] == false then
+		return
+	end
+
+	local entry = {
+		name = event,
+		payload = payload or {},
+	}
+	table_insert(etrace.eventLog, entry)
+end
+
+local table_copy = table.copy
+
+function etrace.filter(event)
+	if event == nil or (type(event) == "table" and #event == 0) then
+		-- This may be modified if other events are created
+		return table_copy(etrace.eventLog)
+	end
+
+	local events = {}
+	local filteredEventLog = {}
+	if type(event) == "string" then
+		events = { [event] = true }
+	elseif type(event) == "table" then
+		for index, name in ipairs(event) do
+			-- Leave the array part intact since it's later discarded anyway
+			events[name] = true
+		end
+	end
+
+	for name, _ in pairs(events) do
+		if name ~= nil and etrace.registeredEvents[name] == nil then
+			error(format("Cannot filter event log for unknown event %s", name), 0)
+		end
+	end
+
+	for index, entry in pairs(etrace.eventLog) do
+		if events[entry.name] == true then
+			table_insert(filteredEventLog, entry)
+		end
+	end
+
+	return filteredEventLog
+end
+
+return etrace