Restore tags when resuming from a checkpoint; simply resuming code

README.md

@@ -237,7 +237,7 @@ Paragraphs always have the following variable defined in its namespace by defaul
 
 `👁️`: number, number of times the paragraph was reached or executed before
 
-* `#`: tag line. Can be followed by an [expression](#expressions); otherwise empty expression is assumed. The results of the [expression](#expressions) will be added to the tags send along with any event sent from its children. Can be nested.
+* `#`: tag line. Can be followed by an [expression](#expressions); otherwise nil expression is assumed. The results of the [expression](#expressions) will be added to the tags send along with any event sent from its children. Can be nested.
 
 ```
 # "color": "red"
@@ -279,7 +279,7 @@ And this is more text, in a different event.
 
 Every line can also be followed with decorators, which are appended at the end of the line and affect its behaviour.
 
-* `~`: expression decorator. Same as an expression line, behaving as if this line was it sole child. Typically used to conditionally execute line.
+* `~`: expression decorator. Same as an expression line, behaving as if this line was it sole child. Typically used to conditionally execute line. Does not affect following else-conditions.
 
 * `§`: paragraph decorator. Same as a paragraph line, behaving as if this line was it sole child.
 
@@ -559,6 +559,12 @@ Method style calling is also possible, like with functions.
 
 Paragraphs commit variables after a call.
 
+Please also be aware that when resuming from a paragraph, Anselme will try to restore the interpreter state as if the function was correctly executed from the start up to this paragraph. This includes:
+
+* if the paragraph is in a expression block, it will assume the expression was true (but will not re-evaluate it)
+* if the paragraph is in a choice block, it will assume this choice was selected (but will not re-evaluate any of the choices from the same choice group)
+* will try to re-add every tag from parent lines; this require Anselme to re-evaluate every tag line and decorator that's a parent of the paragraph in the function. Be careful if your tag expressions have side-effects.
+
 #### Operators
 
 Built-in operators:

interpreter/expression.lua

@@ -103,25 +103,7 @@ local function eval(state, exp)
 				if fn.value.type == "paragraph" or fn.value.paragraph then
 					local r, e
 					if fn.value.type == "paragraph" then
-						r, e = run_block(state, fn.value.child)
-						if e then return r, e end
-						state.variables[fn.value.namespace.."👁️"] = {
-							type = "number",
-							value = state.variables[fn.value.namespace.."👁️"].value + 1
-						}
-						state.variables[fn.value.parent_function.namespace.."🏁"] = {
-							type = "string",
-							value = fn.value.name
-						}
-						flush_state(state)
-						if r then
-							return r, e
-						-- resume function from paragraph
-						elseif not exp.explicit_call then
-							r, e = run(state, fn.value.parent_block, true, fn.value.parent_position+1)
-						else
-							r = { type = "nil", value = nil }
-						end
+						r, e = run(state, fn.value.child, not exp.explicit_call)
 					-- paragraph decorators: run single line or resume from it.
 					-- checkpoint & seen variables will be updated from the interpreter usual paragraph-reaching code.
 					elseif exp.explicit_call then

interpreter/interpreter.lua

@@ -1,11 +1,12 @@
 local eval
-local truthy, flush_state, to_lua, eval_text
+local truthy, flush_state, to_lua, eval_text, escape
 
 local tags = {
+	--- push new tags on top of the stack, from Anselme values
 	push = function(self, state, val)
 		local new = {}
 		-- copy
-		local last = state.interpreter.tags[#state.interpreter.tags] or {}
+		local last = self:current(state)
 		for k,v in pairs(last) do new[k] = v end
 		-- merge with new values
 		if val.type ~= "list" then val = { type = "list", value = { val } } end
@@ -13,14 +14,27 @@ local tags = {
 		-- add
 		table.insert(state.interpreter.tags, new)
 	end,
+	--- same but do not merge with last stack item
+	push_lua_no_merge = function(self, state, val)
+		table.insert(state.interpreter.tags, val)
+	end,
+	-- pop tag table on top of the stack
 	pop = function(self, state)
 		table.remove(state.interpreter.tags)
 	end,
+	--- return current lua tags table
 	current = function(self, state)
 		return state.interpreter.tags[#state.interpreter.tags] or {}
 	end,
-	push_ignore_past = function(self, state, tags)
-		table.insert(state.interpreter.tags, tags)
+	--- returns length of tags stack
+	len = function(self, state)
+		return #state.interpreter.tags
+	end,
+	--- pop item until we reached desired stack length
+	trim = function(self, state, len)
+		while #state.interpreter.tags > len do
+			self:pop(state)
+		end
 	end
 }
 
@@ -94,13 +108,11 @@ local function run_line(state, line)
 			})
 			write_event(state, "choice", t)
 		elseif line.type == "tag" then
-			if line.expression then
-				local v, e = eval(state, line.expression)
-				if not v then return v, ("%s; at %s"):format(e, line.source) end
-				tags:push(state, v)
-			end
-			local v, e = run_block(state, line.child)
-			if line.expression then tags:pop(state) end
+			local v, e = eval(state, line.expression)
+			if not v then return v, ("%s; at %s"):format(e, line.source) end
+			tags:push(state, v)
+			v, e = run_block(state, line.child)
+			tags:pop(state)
 			if e then return v, e end
 			if v then return v end
 		elseif line.type == "return" then
@@ -127,7 +139,7 @@ local function run_line(state, line)
 					else
 						local choice = state.interpreter.choice_available[sel]
 						state.interpreter.choice_available = {}
-						tags:push_ignore_past(state, choice.tags)
+						tags:push_lua_no_merge(state, choice.tags)
 						local v, e = run_block(state, choice.block)
 						tags:pop(state)
 						if e then return v, e end
@@ -142,7 +154,7 @@ local function run_line(state, line)
 		if line.tag then
 			tags:pop(state)
 		end
-		-- paragraph decorator
+		-- paragraph decorator and line
 		if line.paragraph then
 			state.variables[line.namespace.."👁️"] = {
 				type = "number",
@@ -182,10 +194,31 @@ run_block = function(state, block, resume_from_there, i, j)
 		end
 		i = i + 1
 	end
+	-- if we are exiting a paragraph block, mark it as ran and update checkpoint
+	-- (when resuming from a checkpoint, execution is resumed from inside the paragraph, the line.paragraph 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.paragraph then
+		local parent_line = block.parent_line
+		state.variables[parent_line.namespace.."👁️"] = {
+			type = "number",
+			value = state.variables[parent_line.namespace.."👁️"].value + 1
+		}
+		-- don't update checkpoint if an already more precise checkpoint is set
+		-- (since we will go up the whole checkpoint hierarchy when resuming from a nested checkpoint)
+		local current_checkpoint = state.variables[parent_line.parent_function.namespace.."🏁"].value
+		if not current_checkpoint:match("^"..escape(parent_line.name)) then
+			state.variables[parent_line.parent_function.namespace.."🏁"] = {
+				type = "string",
+				value = parent_line.name
+			}
+		end
+		flush_state(state)
+	end
 	-- go up hierarchy if asked to resume
 	-- will stop at function boundary
 	-- 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
 		local parent_line = block.parent_line
 		if parent_line.type == "choice" then
@@ -193,6 +226,9 @@ run_block = function(state, block, resume_from_there, i, j)
 		elseif parent_line.type == "condition" or parent_line.type == "else-condition" then
 			parent_line.parent_block.last_condition_success = true
 		end
+		if parent_line.type == "tag" or parent_line.tag then
+			tags:pop(state)
+		end
 		local v, e = run_block(state, parent_line.parent_block, resume_from_there, parent_line.parent_position+1)
 		if e then return v, e end
 		if v then return v, e end
@@ -203,8 +239,39 @@ end
 -- returns var in case of success
 -- return nil, err in case of error
 local function run(state, block, resume_from_there, i, j)
+	-- restore tags from parents when resuming
+	local tags_len = tags:len(state)
+	if resume_from_there then
+		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
+			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
+				table.insert(tags_to_add, v)
+			end
+			if parent_line.tag then
+				local v, e = eval(state, parent_line.tag)
+				if not v then return v, ("%s; in tag decorator at %s"):format(e, parent_line.source) end
+				table.insert(tags_to_add, v)
+			end
+			parent_line = parent_line.parent_block.parent_line
+		end
+		-- re-add tag in desceding order
+		for k=#tags_to_add, 1, -1 do
+			tags:push(state, tags_to_add[k])
+		end
+	end
 	-- run
 	local v, e = run_block(state, block, resume_from_there, i, j)
+	-- return to previous tag state
+	-- tag stack pop when resuming is done when exiting the tag block
+	-- stray elements may be left on the stack if there is a return before we exit all the tag block, so we trim them
+	if resume_from_there then
+		tags:trim(state, tags_len)
+	end
+	-- return
 	if e then return v, e end
 	if v then
 		return v
@@ -227,5 +294,6 @@ package.loaded[...] = interpreter
 eval = require((...):gsub("interpreter$", "expression"))
 local common = require((...):gsub("interpreter$", "common"))
 truthy, flush_state, to_lua, eval_text = common.truthy, common.flush_state, common.to_lua, common.eval_text
+escape = require((...):gsub("interpreter%.interpreter$", "parser.common")).escape
 
 return interpreter

parser/preparser.lua

@@ -307,7 +307,7 @@ local function parse_line(line, state, namespace)
 		if expr:match("[^%s]") then
 			r.expression = expr
 		else
-			r.expression = nil
+			r.expression = "()"
 		end
 	-- return
 	elseif l:match("^%@") then

test/tests/resume from nested paragraph.ans

@@ -0,0 +1,26 @@
+$ f
+	x
+	§ p
+		a
+
+		§ q
+			b
+
+		c
+
+	d
+
+From start:
+~ f
+
+From p checkpoint:
+~ f
+
+From q checkpoint:
+~ f
+
+From q checkpoint again:
+~ f
+
+Force p checkpoint:
+~ f.p()

test/tests/resume from nested paragraph.lua

@@ -0,0 +1,135 @@
+local _={}
+_[63]={}
+_[62]={}
+_[61]={}
+_[60]={}
+_[59]={}
+_[58]={}
+_[57]={}
+_[56]={}
+_[55]={}
+_[54]={}
+_[53]={}
+_[52]={}
+_[51]={}
+_[50]={}
+_[49]={}
+_[48]={}
+_[47]={}
+_[46]={}
+_[45]={tags=_[63],data="c"}
+_[44]={tags=_[62],data="a"}
+_[43]={tags=_[61],data="Force p checkpoint:"}
+_[42]={tags=_[60],data="d"}
+_[41]={tags=_[59],data="c"}
+_[40]={tags=_[58],data="b"}
+_[39]={tags=_[57],data="From q checkpoint again:"}
+_[38]={tags=_[56],data="d"}
+_[37]={tags=_[55],data="c"}
+_[36]={tags=_[54],data="b"}
+_[35]={tags=_[53],data="From q checkpoint:"}
+_[34]={tags=_[52],data="d"}
+_[33]={tags=_[51],data="c"}
+_[32]={tags=_[50],data="a"}
+_[31]={tags=_[49],data="From p checkpoint:"}
+_[30]={tags=_[48],data="d"}
+_[29]={tags=_[47],data="x"}
+_[28]={tags=_[46],data="From start:"}
+_[27]={_[45]}
+_[26]={_[43],_[44]}
+_[25]={_[42]}
+_[24]={_[41]}
+_[23]={_[39],_[40]}
+_[22]={_[38]}
+_[21]={_[37]}
+_[20]={_[35],_[36]}
+_[19]={_[34]}
+_[18]={_[33]}
+_[17]={_[31],_[32]}
+_[16]={_[30]}
+_[15]={_[28],_[29]}
+_[14]={"return"}
+_[13]={"text",_[27]}
+_[12]={"text",_[26]}
+_[11]={"text",_[25]}
+_[10]={"text",_[24]}
+_[9]={"text",_[23]}
+_[8]={"text",_[22]}
+_[7]={"text",_[21]}
+_[6]={"text",_[20]}
+_[5]={"text",_[19]}
+_[4]={"text",_[18]}
+_[3]={"text",_[17]}
+_[2]={"text",_[16]}
+_[1]={"text",_[15]}
+return {_[1],_[2],_[3],_[4],_[5],_[6],_[7],_[8],_[9],_[10],_[11],_[12],_[13],_[14]}
+--[[
+{ "text", { {
+      data = "From start:",
+      tags = {}
+    }, {
+      data = "x",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "d",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "From p checkpoint:",
+      tags = {}
+    }, {
+      data = "a",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "c",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "d",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "From q checkpoint:",
+      tags = {}
+    }, {
+      data = "b",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "c",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "d",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "From q checkpoint again:",
+      tags = {}
+    }, {
+      data = "b",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "c",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "d",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "Force p checkpoint:",
+      tags = {}
+    }, {
+      data = "a",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "c",
+      tags = {}
+    } } }
+{ "return" }
+]]--

test/tests/resume from paragraph restore tags.ans

@@ -0,0 +1,16 @@
+$ f
+	# "a":"a"
+		a
+		~ 1 # "b":"b"
+			§ p
+				b # "c":"c"
+
+			c
+
+		d
+
+	e
+
+~ f
+
+~ f

test/tests/resume from paragraph restore tags.lua

@@ -0,0 +1,85 @@
+local _={}
+_[32]={}
+_[31]={a="a"}
+_[30]={a="a",b="b"}
+_[29]={a="a",c="c",b="b"}
+_[28]={}
+_[27]={a="a",b="b"}
+_[26]={a="a"}
+_[25]={tags=_[32],data="e"}
+_[24]={tags=_[31],data="d"}
+_[23]={tags=_[30],data="c"}
+_[22]={tags=_[29],data="b"}
+_[21]={tags=_[28],data="e"}
+_[20]={tags=_[26],data="d"}
+_[19]={tags=_[27],data="c"}
+_[18]={tags=_[26],data="a"}
+_[17]={_[25]}
+_[16]={_[24]}
+_[15]={_[23]}
+_[14]={_[22]}
+_[13]={_[21]}
+_[12]={_[20]}
+_[11]={_[19]}
+_[10]={_[18]}
+_[9]={"return"}
+_[8]={"text",_[17]}
+_[7]={"text",_[16]}
+_[6]={"text",_[15]}
+_[5]={"text",_[14]}
+_[4]={"text",_[13]}
+_[3]={"text",_[12]}
+_[2]={"text",_[11]}
+_[1]={"text",_[10]}
+return {_[1],_[2],_[3],_[4],_[5],_[6],_[7],_[8],_[9]}
+--[[
+{ "text", { {
+      data = "a",
+      tags = {
+        a = "a"
+      }
+    } } }
+{ "text", { {
+      data = "c",
+      tags = {
+        a = "a",
+        b = "b"
+      }
+    } } }
+{ "text", { {
+      data = "d",
+      tags = {
+        a = "a"
+      }
+    } } }
+{ "text", { {
+      data = "e",
+      tags = {}
+    } } }
+{ "text", { {
+      data = "b",
+      tags = {
+        a = "a",
+        b = "b",
+        c = "c"
+      }
+    } } }
+{ "text", { {
+      data = "c",
+      tags = {
+        a = "a",
+        b = "b"
+      }
+    } } }
+{ "text", { {
+      data = "d",
+      tags = {
+        a = "a"
+      }
+    } } }
+{ "text", { {
+      data = "e",
+      tags = {}
+    } } }
+{ "return" }
+]]--