Split the more complicated WML tags into separate Lua files

data/lua/wml-flow.lua

@@ -0,0 +1,257 @@
+
+
+function wml_actions.command(cfg)
+	utils.handle_event_commands(cfg, "plain")
+end
+
+-- we can't create functions with names that are Lua keywords (eg if, while)
+-- instead, we store the following anonymous functions directly into
+-- the table, using the [] operator, rather than by using the point syntax
+
+wml_actions["if"] = function(cfg)
+	if not (helper.get_child(cfg, 'then') or helper.get_child(cfg, 'elseif') or helper.get_child(cfg, 'else')) then
+		helper.wml_error("[if] didn't find any [then], [elseif], or [else] children.")
+	end
+
+	if wesnoth.eval_conditional(cfg) then -- evaluate [if] tag
+		for then_child in helper.child_range(cfg, "then") do
+			local action = utils.handle_event_commands(then_child, "conditional")
+			if action ~= "none" then break end
+		end
+		return -- stop after executing [then] tags
+	end
+
+	for elseif_child in helper.child_range(cfg, "elseif") do
+		if wesnoth.eval_conditional(elseif_child) then -- we'll evaluate the [elseif] tags one by one
+			for then_tag in helper.child_range(elseif_child, "then") do
+				local action = utils.handle_event_commands(then_tag, "conditional")
+				if action ~= "none" then break end
+			end
+			return -- stop on first matched condition
+		end
+	end
+
+	-- no matched condition, try the [else] tags
+	for else_child in helper.child_range(cfg, "else") do
+		local action = utils.handle_event_commands(else_child, "conditional")
+		if action ~= "none" then break end
+	end
+end
+
+wml_actions["while"] = function( cfg )
+	if helper.child_count(cfg, "do") == 0 then
+		helper.wml_error "[while] does not contain any [do] tags"
+	end
+
+	-- execute [do] up to 65536 times
+	for i = 1, 65536 do
+		if wesnoth.eval_conditional( cfg ) then
+			for do_child in helper.child_range( cfg, "do" ) do
+				local action = utils.handle_event_commands(do_child, "loop")
+				if action == "break" then
+					utils.set_exiting("none")
+					return
+				elseif action == "continue" then
+					utils.set_exiting("none")
+					break
+				elseif action ~= "none" then
+					return
+				end
+			end
+		else return end
+	end
+end
+
+wml_actions["break"] = function(cfg)
+	utils.set_exiting("break")
+end
+
+wml_actions["return"] = function(cfg)
+	utils.set_exiting("return")
+end
+
+function wml_actions.continue(cfg)
+	utils.set_exiting("continue")
+end
+
+wesnoth.wml_actions["for"] = function(cfg)
+	if helper.child_count(cfg, "do") == 0 then
+		helper.wml_error "[for] does not contain any [do] tags"
+	end
+
+	local loop_lim = {}
+	local first
+	if cfg.array ~= nil then
+		if cfg.reverse then
+			first = wesnoth.get_variable(cfg.array .. ".length") - 1
+			loop_lim.last = 0
+			loop_lim.step = -1
+		else
+			first = 0
+			loop_lim.last = '$($' .. cfg.array .. ".length - 1)"
+			loop_lim.step = 1
+		end
+	else
+		-- Get a literal config to fetch end and step;
+		-- this done is to delay expansion of variables
+		local cfg_lit = helper.literal(cfg)
+		first = cfg.start or 0
+		loop_lim.last = cfg_lit["end"] or first
+		if cfg.step then loop_lim.step = cfg_lit.step end
+	end
+	loop_lim = wesnoth.tovconfig(loop_lim)
+	if loop_lim.step == 0 then -- Sanity check
+		helper.wml_error("[for] has a step of 0!")
+	end
+	if (first < loop_lim.last and loop_lim.step <= 0) or (first > loop_lim.last and loop_lim.step >= 0) then
+		-- Sanity check: If they specify something like start,end,step=1,4,-1
+		-- then we do nothing
+		return
+	end
+	local i_var = cfg.variable or "i"
+	local save_i = utils.start_var_scope(i_var)
+	wesnoth.set_variable(i_var, first)
+	local function loop_condition()
+		local sentinel = loop_lim.last
+		if loop_lim.step then
+			sentinel = sentinel + loop_lim.step
+		elseif loop_lim.last < first then
+			sentinel = sentinel - 1
+		else
+			sentinel = sentinel + 1
+		end
+		if loop_lim.step > 0 then
+			return wesnoth.get_variable(i_var) < sentinel
+		else
+			return wesnoth.get_variable(i_var) > sentinel
+		end
+	end
+	while loop_condition() do
+		for do_child in helper.child_range( cfg, "do" ) do
+			local action = utils.handle_event_commands(do_child, "loop")
+			if action == "break" then
+				utils.set_exiting("none")
+				goto exit
+			elseif action == "continue" then
+				utils.set_exiting("none")
+				break
+			elseif action ~= "none" then
+				goto exit
+			end
+		end
+		wesnoth.set_variable(i_var, wesnoth.get_variable(i_var) + loop_lim.step)
+	end
+	::exit::
+	utils.end_var_scope(i_var, save_i)
+end
+
+wml_actions["repeat"] = function(cfg)
+	if helper.child_count(cfg, "do") == 0 then
+		helper.wml_error "[repeat] does not contain any [do] tags"
+	end
+
+	local times = cfg.times or 1
+	for i = 1, times do
+		for do_child in helper.child_range( cfg, "do" ) do
+			local action = utils.handle_event_commands(do_child, "loop")
+			if action == "break" then
+				utils.set_exiting("none")
+				return
+			elseif action == "continue" then
+				utils.set_exiting("none")
+				break
+			elseif action ~= "none" then
+				return
+			end
+		end
+	end
+end
+
+function wml_actions.foreach(cfg)
+	if helper.child_count(cfg, "do") == 0 then
+		helper.wml_error "[foreach] does not contain any [do] tags"
+	end
+
+	local array_name = cfg.variable or helper.wml_error "[foreach] missing required variable= attribute"
+	local array = helper.get_variable_array(array_name)
+	if #array == 0 then return end -- empty and scalars unwanted
+	local item_name = cfg.item_var or "this_item"
+	local this_item = utils.start_var_scope(item_name) -- if this_item is already set
+	local i_name = cfg.index_var or "i"
+	local i = utils.start_var_scope(i_name) -- if i is already set
+	local array_length = wesnoth.get_variable(array_name .. ".length")
+
+	for index, value in ipairs(array) do
+		-- Some protection against external modification
+		-- It's not perfect, though - it'd be nice if *any* change could be detected
+		if array_length ~= wesnoth.get_variable(array_name .. ".length") then
+			helper.wml_error("WML array length changed during [foreach] iteration")
+		end
+		wesnoth.set_variable(item_name, value)
+		-- set index variable
+		wesnoth.set_variable(i_name, index-1) -- here -1, because of WML array
+		-- perform actions
+		for do_child in helper.child_range(cfg, "do") do
+			local action = utils.handle_event_commands(do_child, "loop")
+			if action == "break" then
+				utils.set_exiting("none")
+				goto exit
+			elseif action == "continue" then
+				utils.set_exiting("none")
+				break
+			elseif action ~= "none" then
+				goto exit
+			end
+		end
+		-- set back the content, in case the author made some modifications
+		if not cfg.readonly then
+			array[index] = wesnoth.get_variable(item_name)
+		end
+	end
+	::exit::
+
+	-- house cleaning
+	utils.end_var_scope(item_name, this_item)
+	utils.end_var_scope(i_name, i)
+
+	--[[
+		This forces the readonly key to be taken literally.
+		
+		If readonly=yes, then this line guarantees that the array
+		is unchanged after the [foreach] loop ends.
+		
+		If readonly=no, then this line updates the array with any
+		changes the user has applied through the $this_item
+		variable (or whatever variable was given in item_var).
+		
+		Note that altering the array via indexing (with the index_var)
+		is not supported; any such changes will be reverted by this line.
+	]]
+	helper.set_variable_array(array_name, array)
+end
+
+function wml_actions.switch(cfg)
+	local var_value = wesnoth.get_variable(cfg.variable)
+	local found = false
+
+	-- Execute all the [case]s where the value matches.
+	for v in helper.child_range(cfg, "case") do
+		for w in utils.split(v.value) do
+			if w == tostring(var_value) then 
+				local action = utils.handle_event_commands(v, "switch")
+				found = true
+				if action ~= "none" then goto exit end
+				break
+			end
+		end
+	end
+	::exit::
+
+	-- Otherwise execute [else] statements.
+	if not found then
+		for v in helper.child_range(cfg, "else") do
+			local action = utils.handle_event_commands(v, "switch")
+			if action ~= "none" then break end
+		end
+	end
+end