Add object type, dot operator can return function references

interpreter/common.lua

@@ -189,9 +189,8 @@ common = {
 	end,
 	--- returns true if a variable should be persisted on save
 	-- will exclude: undefined variables, variables in scoped functions, internal anselme variables
-	should_keep_variable = function(state, name)
-		local v = state.variables[name]
-		return v.type ~= "undefined argument" and v.type ~= "pending definition" and name:match("^"..identifier_pattern.."$") and not name:match("^anselme%.")
+	should_keep_variable = function(state, name, value)
+		return value.type ~= "undefined argument" and value.type ~= "pending definition" and name:match("^"..identifier_pattern.."$") and not name:match("^anselme%.")
 	end,
 	--- check truthyness of an anselme value
 	truthy = function(val)

interpreter/expression.lua

@@ -208,16 +208,10 @@ local function eval(state, exp)
 		local tried_function_error_messages = {}
 		local selected_variant = { depths = { assignment = nil }, variant = nil, args_to_set = nil }
 		for _, fn in ipairs(variants) do
-			-- checkpoint: no args, nothing to select on
-			if fn.type == "checkpoint" then
-				if not selected_variant.variant then
-					selected_variant.depths = {}
-					selected_variant.variant = fn
-				else
-					return nil, ("checkpoint call %q is ambigous; may be at least either:\n\t%s\n\t%s"):format(exp.called_name, fn.pretty_signature, selected_variant.variant.pretty_signature)
-				end
-			-- function
-			elseif fn.type == "function" then
+			if fn.type ~= "function" then
+				return nil, ("unknown function type %q"):format(fn.type)
+			-- functions
+			else
 				if not fn.assignment or exp.assignment then
 					local ok = true
 					-- get and set args
@@ -342,18 +336,20 @@ local function eval(state, exp)
 						end
 					end
 				end
-			else
-				return nil, ("unknown function type %q"):format(fn.type)
 			end
 		end
 		-- function successfully selected: run
 		if selected_variant.variant then
 			local fn = selected_variant.variant
-			if fn.type == "checkpoint" then
+			if fn.type ~= "function" then
+				return nil, ("unknown function type %q"):format(fn.type)
+			-- checkpoint: no args and resume execution
+			elseif fn.subtype == "checkpoint" then
 				local r, e = run(state, fn.child, not paren_call)
 				if not r then return r, e end
 				return r
-			elseif fn.type == "function" then
+			-- other functions
+			else
 				local ret
 				-- push scope
 				-- NOTE: if error happens between here and scope:pop, will leave the stack a mess
@@ -452,6 +448,28 @@ local function eval(state, exp)
 					type = "number",
 					value = seen.value + 1
 				})
+				-- for classes: build resulting object
+				if fn.subtype == "class" then
+					local object = {
+						type = "type",
+						value = {
+							{
+								type = "object",
+								value = {
+									class = fn.name,
+									attributes = {}
+								}
+							},
+							{
+								type = "function reference",
+								value = { fn.name }
+							}
+						}
+					}
+					if ret and ret.type == "nil" then
+						ret = object
+					end
+				end
 				-- pop scope
 				if fn.scoped then
 					scope:pop(state, fn)

interpreter/interpreter.lua

@@ -111,7 +111,7 @@ run_line = function(state, line)
 	elseif line.type == "flush_events" then
 		local v, e = events:flush(state)
 		if not v then return v, ("%s; in event flush at %s"):format(e, line.source) end
-	elseif line.type == "checkpoint" then
+	elseif line.type == "function" and line.subtype == "checkpoint" then
 		local reached, reachede = get_variable(state, line.namespace.."🏁")
 		if not reached then return nil, reachede end
 		set_variable(state, line.namespace.."🏁", {
@@ -150,9 +150,9 @@ run_block = function(state, block, resume_from_there, i, j)
 		i = i + 1
 	end
 	-- if we are exiting a checkpoint block, mark it as ran and update checkpoint
-	-- (when resuming from a checkpoint, execution is resumed from inside the checkpoint, the line.type=="checkpoint" check in run_line is never called)
+	-- (when resuming from a checkpoint, execution is resumed from inside the checkpoint, the line.subtype=="checkpoint" check in run_line is never called)
 	-- (and we want this to be done after executing the checkpoint block anyway)
-	if block.parent_line and block.parent_line.type == "checkpoint" then
+	if block.parent_line and block.parent_line.type == "function" and block.parent_line.subtype == "checkpoint" then
 		local parent_line = block.parent_line
 		local reached, reachede = get_variable(state, parent_line.namespace.."🏁")
 		if not reached then return nil, reachede end
@@ -183,7 +183,7 @@ run_block = function(state, block, resume_from_there, i, j)
 	-- if parent is a choice, will ignore choices that belong to the same block (like the whole block was executed naturally from a higher parent)
 	-- if parent if a condition, will mark it as a success (skipping following else-conditions) (for the same reasons as for choices)
 	-- if parent pushed a tag, will pop it (tags from parents are added to the stack in run())
-	if resume_from_there and block.parent_line and block.parent_line.type ~= "function" then
+	if resume_from_there and block.parent_line and not block.parent_line.resume_boundary then
 		local parent_line = block.parent_line
 		if parent_line.type == "choice" then
 			state.interpreter.skip_choices_until_flush = true
@@ -209,7 +209,7 @@ local function run(state, block, resume_from_there, i, j)
 		local tags_to_add = {}
 		-- go up in hierarchy in ascending order until function boundary
 		local parent_line = block.parent_line
-		while parent_line and parent_line.type ~= "function" do
+		while parent_line and not parent_line.resume_boundary do
 			if parent_line.type == "tag" then
 				local v, e = eval(state, parent_line.expression)
 				if not v then return v, ("%s; at %s"):format(e, parent_line.source) end