Added safe operators, if/while with assignement, method stubs

README.md

@@ -20,6 +20,8 @@ end
 let a = {
 	hey = true,
 
+	child = nil,
+
 	method = :(foo, thing) -- short function declaration, with self
 		@hey = thing(foo) -- @ as an alias for self
 	end,
@@ -33,6 +35,13 @@ a:method(42, (foo)
 	return "something " .. foo
 end)
 
+local fn = a:method -- bundles an object and method in a function
+fn(42, (foo)
+	return "something" .. foo
+end)
+
+a.child?:method?() -- safe navigation operator
+
 local odd = [ -- table comprehension
 	for i=1, 10 do
 		if i%2 == 0 then
@@ -48,6 +57,12 @@ local a = if condition then "one" else "two" end -- statement as expressions
 
 print("Hello %s":format("world")) -- methods calls on strings (and tables) litterals without enclosing parentheses
 
+if f, err = io.open("data") then -- if condition with assignements
+	thing.process(f)
+else
+	error("can't open data: "..err)
+end
+
 ````
 
 **Current status**: Candran is heavily used in several of my personal projects and works as expected.
@@ -97,7 +112,7 @@ All theses operators can also be put right of the assigment operator, in which c
 
 Right and left operator can be used at the same time.
 
-**Please note** that the Lua code `a=-1` will be compiled into `a = 1 - a` and not `a = -1`! Write spaced code: `a = -1` works as expected.
+**Please note** that the code `a=-1` will be compiled into `a = -1` and not `a = a - 1`, like in pure Lua. If you want the latter, spacing is required between the `=-` and the expression: `a=- 1`. Yes, this is also valid Lua code, but as far as I'm aware, nobody write code like this; people who really like spacing would write `a= - 1` or `a = - 1`, and Candran will read both of those as it is expected in pure Lua. This is the only incompatibility between Candran and pure Lua.
 
 ##### Default function parameters
 ```lua
@@ -230,6 +245,68 @@ Values returned by the function will be inserted in the generated table in the o
 
 The table generation function also have access to the `self` variable (and its alias `@`), which is the table which is being created, so you can set any of the table's field.
 
+##### Safe navigation operators
+```lua
+a = nil
+print(a?.b) -- nil
+
+a = {b=true}
+print(a?.b) -- true
+
+-- So instead of typing
+if object and object.child and object.child.isGreen then
+	-- stuff
+end
+-- you can type
+if object?.child?.isGreen then
+	-- stuff
+end
+
+-- The ?. operator does not break the whole chain; make sure to use the operator on each index.
+print(a?.undefined.field) -- a?.undefined returns nil, so this throws a "attempt to index a nil value"
+
+-- Other safe navigator operators behave similarly:
+print(a:method) -- nil if a is nil, other normal behaviour
+print(a["key"]) -- nil if a is nil, other normal behaviour
+print(a?()) -- nil if a is nil, other normal behaviour
+```
+
+Some operators can be prefixed by a `?` to turn into a safe version of the operator: if the base value if `nil`, the normal behaviour of the operator will be skipped and nil will be returned; otherwise, the operator run as usual. Is available safe dot index `?.`, safe array index `?[...]`, safe method stub `?:` and safe function call `?(...)`.
+
+##### If and while with assignement in the condition
+```lua
+if f, err = io.open("somefile") then -- condition if verified if f is a truthy value (not nil or false)
+	-- do something with f
+	f:close()
+elseif f2, err2 = io.open("anotherfile") then -- same behaviour on elseif
+	print("could not open somefile:", err) -- f and err stay in scope for the rest of the if-elseif-else block
+	-- do something with f2
+	f2:close()
+else
+	print("could not open somefile:", err)
+	print("could not open anotherfile:", err2)
+end
+-- f, err, f2 and err2 are now out of scope
+
+if (value = list[index = 2]) and yes = true then -- several assignements can be performed, anywhere in the expression; index is defined before value, yes is defined after these two. The condition is verified if both value and yes are thruthy.
+	print(index, value)
+end
+
+-- When used in a while, the expression is evaluated at each iteration.
+while line = io.read() do
+	print(line)
+end
+
+-- The assignement have the same priority as regular assignements, i.e., the lowest.
+if a = 1 and 2 then -- will be read as a = (1 and 2)
+elseif (a = 1) and 2 then -- will be read as (a = 1) and 2
+end
+```
+
+Assignements can be used in the condition of if, elseif and while statements. Several variables can be assigned; only the first will be tested in the condition, for each assignement. The assigned variables will be in scope the duration of the block; for if statements, they will also be in scope for the following elseif(s) and else.
+
+For while statements, the assigned expression will be reevaluated at each iteration.
+
 ##### Suffixable string and table litterals
 ```lua
 "some text":upper() -- "SOME TEXT". Same as ("some text"):upper() in Lua.
@@ -246,6 +323,27 @@ String litterals, table litterals, and comprehensions can be suffixed with `:` m
 
 **Please note**, that "normal" functions calls have priority over this syntax, in order to maintain Lua compatibility.
 
+##### Method stubs
+```lua
+object = {
+	value = 25,
+	method = function(self, str)
+		print(str, self.value)
+	end
+}
+
+stub = object:method
+
+object.method = error -- stub stores the method as it was when stub was defined
+object = nil -- also stores the object
+
+print(stub("hello")) -- hello	25
+```
+
+Create a closure function which bundles the variable and its method; when called it will call the method on the variable, without requiring to pass the variable as a first argument.
+
+The closure stores the value of the variable and method when created.
+
 ##### Statement expressions
 ```lua
 a = if false then

candran.can

@@ -86,7 +86,7 @@ function candran.preprocess(input, options={})
 	-- @tparam modpath string module path
 	-- @tparam margs table preprocessor options to use when preprocessessing the module
 	env.import = function(modpath, margs={})
-		local filepath = assert(util.search(modpath), "No module named \""..modpath.."\"")
+		local filepath = assert(util.search(modpath, {"can", "lua"}), "No module named \""..modpath.."\"")
 
 		-- open module file
 		local f = io.open(filepath)

compiler/lua51.can

@@ -1,3 +1,5 @@
+targetName = "Lua 5.1"
+
 states.continue = {} -- when in a loop that use continue
 
 CONTINUE_START = ()
@@ -19,12 +21,9 @@ tags.Break = ()
 	end
 end
 
-tags.Goto = ()
+-- Unsuported features
-	error("Lua 5.1 does not support the goto keyword")
+tags.Goto = nil
-end
+tags.Label = nil
-tags.Label = ()
-	error("Lua 5.1 does not support labels")
-end
 
 #local patch = output
 #output = ""

compiler/lua53.can

@@ -1,3 +1,5 @@
+local targetName = "Lua 5.3"
+
 return function(code, ast, options)
 	--- Line mapping
 	local lastInputPos = 1 -- last token position in the input code
@@ -9,7 +11,7 @@ return function(code, ast, options)
 	local indentLevel = 0
 	-- Returns a newline.
 	local function newline()
-		local r = options.newline .. string.rep(options.indentation, indentLevel)
+		local r = options.newline..string.rep(options.indentation, indentLevel)
 		if options.mapLines then
 			local sub = code:sub(lastInputPos)
 			local source, line = sub:sub(1, sub:find("\n")):match("%-%- (.-)%:(%d+)\n")
@@ -25,7 +27,7 @@ return function(code, ast, options)
 
 			prevLinePos = lastInputPos
 
-			r = " -- " .. lastSource .. ":" .. lastLine .. r
+			r = " -- "..lastSource..":"..lastLine..r
 		end
 		return r
 	end
@@ -46,7 +48,7 @@ return function(code, ast, options)
 	-- Add the module "mod" to the list of modules to require, and load its field "field" (or the whole module if nil) into the variable "name".
 	local function addRequire(mod, name, field)
 		if not required[mod] then
-			requireStr ..= "local " .. options.variablePrefix .. name .. (" = require(%q)"):format(mod) .. (field and "."..field or "") .. options.newline
+			requireStr ..= "local "..options.variablePrefix..name..(" = require(%q)"):format(mod)..(field and "."..field or "")..options.newline
 			required[mod] = true
 		end
 	end
@@ -54,12 +56,13 @@ return function(code, ast, options)
 	--- Variable management
 	-- Returns the prefixed variable name.
 	local function var(name)
-		return options.variablePrefix .. name
+		return options.variablePrefix..name
 	end
 
 	--- AST traversal helpers
-	local loop = { "While", "Repeat", "Fornum", "Forin" } -- loops tags
+	local loop = { "While", "Repeat", "Fornum", "Forin", "WhileExpr", "RepeatExpr", "FornumExpr", "ForinExpr" } -- loops tags (can contain continue)
-	local func = { "Function", "TableCompr", "DoExpr", "WhileExpr", "RepeatExpr", "IfExpr", "FornumExpr", "ForinExpr" } -- function scope tags
+	local func = { "Function", "TableCompr", "DoExpr", "WhileExpr", "RepeatExpr", "IfExpr", "FornumExpr", "ForinExpr" } -- function scope tags (can contain push)
+
 	-- Returns the first node or subnode from the list "list" which tag is in the list "tags", or nil if there were none.
 	-- Won't recursively follow nodes which have a tag in "nofollow".
 	local function any(list, tags, nofollow={})
@@ -85,6 +88,50 @@ return function(code, ast, options)
 		return nil
 	end
 
+	-- Like any, but returns a list of every node found.
+	-- Order: in the order of the list, from the deepest to the nearest
+	local function search(list, tags, nofollow={})
+		local tagsCheck = {}
+		for _, tag in ipairs(tags) do
+			tagsCheck[tag] = true
+		end
+		local nofollowCheck = {}
+		for _, tag in ipairs(nofollow) do
+			nofollowCheck[tag] = true
+		end
+		local found = {}
+		for _, node in ipairs(list) do
+			if type(node) == "table" then
+				if not nofollowCheck[node.tag] then
+					for _, n in ipairs(search(node, tags, nofollow)) do
+						table.insert(found, n)
+					end
+				end
+				if tagsCheck[node.tag] then
+					table.insert(found, node)
+				end
+			end
+		end
+		return found
+	end
+
+	-- Returns true if the all the nodes in list have their type in tags.
+	local function all(list, tags)
+		for _, node in ipairs(list) do
+			local ok = false
+			for _, tag in ipairs(tags) do
+				if node.tag == tag then
+					ok = true
+					break
+				end
+			end
+			if not ok then
+				return false
+			end
+		end
+		return true
+	end
+
 	--- State stacks
 	-- Used for context-sensitive syntax.
 	local states = {
@@ -117,16 +164,16 @@ return function(code, ast, options)
 
 	--- Lua function calls writer
 	local UNPACK = (list, i, j) -- table.unpack
-		return "table.unpack(" .. list .. (i and (", " .. i .. (j and (", " .. j) or "")) or "") .. ")"
+		return "table.unpack("..list..(i and (", "..i..(j and (", "..j) or "")) or "")..")"
 	end
 	local APPEND = (t, toAppend) -- append values "toAppend" (multiple values possible) to t
-		return "do" .. indent() .. "local a = table.pack(" .. toAppend .. ")" .. newline() .. "table.move(a, 1, a.n, #" .. t .. "+1, " .. t .. ")" .. unindent() .. "end"
+		return "do"..indent().."local a = table.pack("..toAppend..")"..newline().."table.move(a, 1, a.n, #"..t.."+1, "..t..")"..unindent().."end"
 	end
 	local CONTINUE_START = () -- at the start of loops using continue
-		return "do" .. indent()
+		return "do"..indent()
 	end
 	local CONTINUE_STOP = () -- at the start of loops using continue
-		return unindent() .. "end" .. newline() .. "::" .. var("continue") .. "::"
+		return unindent().."end"..newline().."::"..var"continue".."::"
 	end
 
 	--- Tag constructors
@@ -140,16 +187,16 @@ return function(code, ast, options)
 			end
 			local r = ""
 			if hasPush then
-				r ..= push("push", var("push")) .. "local " .. var("push") .. " = {}" .. newline()
+				r ..= push("push", var"push").."local "..var"push".." = {}"..newline()
 			end
 			for i=1, #t-1, 1 do
-				r ..= lua(t[i]) .. newline()
+				r ..= lua(t[i])..newline()
 			end
 			if t[#t] then
 				r ..= lua(t[#t])
 			end
 			if hasPush and (t[#t] and t[#t].tag ~= "Return") then -- add return only if needed
-				r ..= newline() .. "return " .. UNPACK(var("push")) .. pop("push")
+				r ..= newline().."return "..UNPACK(var"push")..pop("push")
 			end
 			return r
 		end,
@@ -158,81 +205,122 @@ return function(code, ast, options)
 
 		-- Do{ stat* }
 		Do = (t)
-			return "do" .. indent() .. lua(t, "Block") .. unindent() .. "end"
+			return "do"..indent()..lua(t, "Block")..unindent().."end"
 		end,
 		-- Set{ {lhs+} (opid? = opid?)? {expr+} }
 		Set = (t)
 			if #t == 2 then
-				return lua(t[1], "_lhs") .. " = " .. lua(t[2], "_lhs")
+				return lua(t[1], "_lhs").." = "..lua(t[2], "_lhs")
 			elseif #t == 3 then
-				return lua(t[1], "_lhs") .. " = " .. lua(t[3], "_lhs")
+				return lua(t[1], "_lhs").." = "..lua(t[3], "_lhs")
 			elseif #t == 4 then
 				if t[3] == "=" then
-					local r = lua(t[1], "_lhs") .. " = " .. lua({ t[2], t[1][1], { tag = "Paren", t[4][1] } }, "Op")
+					local r = lua(t[1], "_lhs").." = "..lua({ t[2], t[1][1], { tag = "Paren", t[4][1] } }, "Op")
 					for i=2, math.min(#t[4], #t[1]), 1 do
-						r ..= ", " .. lua({ t[2], t[1][i], { tag = "Paren", t[4][i] } }, "Op")
+						r ..= ", "..lua({ t[2], t[1][i], { tag = "Paren", t[4][i] } }, "Op")
 					end
 					return r
 				else
-					local r = lua(t[1], "_lhs") .. " = " .. lua({ t[3], { tag = "Paren", t[4][1] }, t[1][1] }, "Op")
+					local r = lua(t[1], "_lhs").." = "..lua({ t[3], { tag = "Paren", t[4][1] }, t[1][1] }, "Op")
 					for i=2, math.min(#t[4], #t[1]), 1 do
-						r ..= ", " .. lua({ t[3], { tag = "Paren", t[4][i] }, t[1][i] }, "Op")
+						r ..= ", "..lua({ t[3], { tag = "Paren", t[4][i] }, t[1][i] }, "Op")
 					end
 					return r
 				end
 			else -- You are mad.
-				local r = lua(t[1], "_lhs") .. " = " .. lua({ t[2], t[1][1], { tag = "Op", t[4], { tag = "Paren", t[5][1] }, t[1][1] } }, "Op")
+				local r = lua(t[1], "_lhs").." = "..lua({ t[2], t[1][1], { tag = "Op", t[4], { tag = "Paren", t[5][1] }, t[1][1] } }, "Op")
 				for i=2, math.min(#t[5], #t[1]), 1 do
-					r ..= ", " .. lua({ t[2], t[1][i], { tag = "Op", t[4], { tag = "Paren", t[5][i] }, t[1][i] } }, "Op")
+					r ..= ", "..lua({ t[2], t[1][i], { tag = "Op", t[4], { tag = "Paren", t[5][i] }, t[1][i] } }, "Op")
 				end
 				return r
 			end
 		end,
 		-- While{ expr block }
 		While = (t)
+			local r = ""
 			local hasContinue = any(t[2], { "Continue" }, loop)
-			local r = "while " .. lua(t[1]) .. " do" .. indent()
+			local lets = search({ t[1] }, { "LetExpr" })
+			if #lets > 0 then
+				r ..= "do"..indent()
+				for _, l in ipairs(lets) do
+					r ..= lua(l, "Let")..newline()
+				end
+			end
+			r ..= "while "..lua(t[1]).." do"..indent()
+			if #lets > 0 then
+				r ..= "do"..indent()
+			end
 			if hasContinue then
 				r ..= CONTINUE_START()
 			end
-			r .. = lua(t[2])
+			r ..= lua(t[2])
 			if hasContinue then
 				r ..= CONTINUE_STOP()
 			end
-			r ..= unindent() .. "end"
+			r ..= unindent().."end"
+			if #lets > 0 then
+				for _, l in ipairs(lets) do
+					r ..= newline()..lua(l, "Set")
+				end
+				r ..= unindent().."end"..unindent().."end"
+			end
 			return r
 		end,
 		-- Repeat{ block expr }
 		Repeat = (t)
 			local hasContinue = any(t[1], { "Continue" }, loop)
-			local r = "repeat" .. indent()
+			local r = "repeat"..indent()
 			if hasContinue then
 				r ..= CONTINUE_START()
 			end
-			r .. = lua(t[1])
+			r ..= lua(t[1])
 			if hasContinue then
 				r ..= CONTINUE_STOP()
 			end
-			r ..= unindent() .. "until " .. lua(t[2])
+			r ..= unindent().."until "..lua(t[2])
 			return r
 		end,
-		-- If{ (expr block)+ block? }
+		-- If{ (lexpr block)+ block? }
 		If = (t)
-			local r = "if " .. lua(t[1]) .. " then" .. indent() .. lua(t[2]) .. unindent()
+			local r = ""
+			local toClose = 0 -- blocks that need to be closed at the end of the if
+			local lets = search({ t[1] }, { "LetExpr" })
+			if #lets > 0 then
+				r ..= "do"..indent()
+				toClose += 1
+				for _, l in ipairs(lets) do
+					r ..= lua(l, "Let")..newline()
+				end
+			end
+			r ..= "if "..lua(t[1]).." then"..indent()..lua(t[2])..unindent()
 			for i=3, #t-1, 2 do
-				r ..= "elseif " .. lua(t[i]) .. " then" .. indent() .. lua(t[i+1]) .. unindent()
+				lets = search({ t[i] }, { "LetExpr" })
+				if #lets > 0 then
+					r ..= "else"..indent()
+					toClose += 1
+					for _, l in ipairs(lets) do
+						r ..= lua(l, "Let")..newline()
+					end
+				else
+					r ..= "else"
+				end
+				r ..= "if "..lua(t[i]).." then"..indent()..lua(t[i+1])..unindent()
 			end
 			if #t % 2 == 1 then
-				r ..= "else" .. indent() .. lua(t[#t]) .. unindent()
+				r ..= "else"..indent()..lua(t[#t])..unindent()
 			end
-			return r .. "end"
+			r ..= "end"
+			for i=1, toClose do
+				r ..= unindent().."end"
+			end
+			return r
 		end,
 		-- Fornum{ ident expr expr expr? block }
 		Fornum = (t)
-			local r = "for " .. lua(t[1]) .. " = " .. lua(t[2]) .. ", " .. lua(t[3])
+			local r = "for "..lua(t[1]).." = "..lua(t[2])..", "..lua(t[3])
 			if #t == 5 then
 				local hasContinue = any(t[5], { "Continue" }, loop)
-				r ..= ", " .. lua(t[4]) .. " do" .. indent()
+				r ..= ", "..lua(t[4]).." do"..indent()
 				if hasContinue then
 					r ..= CONTINUE_START()
 				end
@@ -240,10 +328,10 @@ return function(code, ast, options)
 				if hasContinue then
 					r ..= CONTINUE_STOP()
 				end
-				return r .. unindent() .. "end"
+				return r..unindent().."end"
 			else
 				local hasContinue = any(t[4], { "Continue" }, loop)
-				r ..= " do" .. indent()
+				r ..= " do"..indent()
 				if hasContinue then
 					r ..= CONTINUE_START()
 				end
@@ -251,13 +339,13 @@ return function(code, ast, options)
 				if hasContinue then
 					r ..= CONTINUE_STOP()
 				end
-				return r .. unindent() .. "end"
+				return r..unindent().."end"
 			end
 		end,
 		-- Forin{ {ident+} {expr+} block }
 		Forin = (t)
 			local hasContinue = any(t[3], { "Continue" }, loop)
-			local r = "for " .. lua(t[1], "_lhs") .. " in " .. lua(t[2], "_lhs") .. " do" .. indent()
+			local r = "for "..lua(t[1], "_lhs").." in "..lua(t[2], "_lhs").." do"..indent()
 			if hasContinue then
 				r ..= CONTINUE_START()
 			end
@@ -265,7 +353,7 @@ return function(code, ast, options)
 			if hasContinue then
 				r ..= CONTINUE_STOP()
 			end
-			return r .. unindent() .. "end"
+			return r..unindent().."end"
 		end,
 		-- Local{ {ident+} {expr+}? }
 		Local = (t)
@@ -278,12 +366,12 @@ return function(code, ast, options)
 		-- Let{ {ident+} {expr+}? }
 		Let = (t)
 			local nameList = lua(t[1], "_lhs")
-			local r = "local " .. nameList
+			local r = "local "..nameList
 			if t[2][1] then
-				if any(t[2], { "Function", "Table", "Paren" }) then -- predeclaration doesn't matter otherwise
+				if all(t[2], { "Nil", "Dots", "Boolean", "Number", "String" }) then -- predeclaration doesn't matter here
-					r ..= newline() .. nameList .. " = " .. lua(t[2], "_lhs")
+					r ..= " = "..lua(t[2], "_lhs")
 				else
-					r ..= " = " .. lua(t[2], "_lhs")
+					r ..= newline()..nameList.." = "..lua(t[2], "_lhs")
 				end
 			end
 			return r
@@ -294,11 +382,11 @@ return function(code, ast, options)
 		end,
 		-- Goto{ <string> }
 		Goto = (t)
-			return "goto " .. lua(t, "Id")
+			return "goto "..lua(t, "Id")
 		end,
 		-- Label{ <string> }
 		Label = (t)
-			return "::" .. lua(t, "Id") .. "::"
+			return "::"..lua(t, "Id").."::"
 		end,
 		-- Return{ <expr*> }
 		Return = (t)
@@ -306,9 +394,9 @@ return function(code, ast, options)
 			if push then
 				local r = ""
 				for _, val in ipairs(t) do
-					r ..= push .. "[#" .. push .. "+1] = " .. lua(val) .. newline()
+					r ..= push.."[#"..push.."+1] = "..lua(val)..newline()
 				end
-				return r .. "return " .. UNPACK(push)
+				return r.."return "..UNPACK(push)
 			else
 				return "return "..lua(t, "_lhs")
 			end
@@ -318,13 +406,13 @@ return function(code, ast, options)
 			local var = assert(peek("push"), "no context given for push")
 			r = ""
 			for i=1, #t-1, 1 do
-				r ..= var .. "[#" .. var .. "+1] = " .. lua(t[i]) .. newline()
+				r ..= var.."[#"..var.."+1] = "..lua(t[i])..newline()
 			end
 			if t[#t] then
-				if t[#t].tag == "Call" or t[#t].tag == "Invoke" then
+				if t[#t].tag == "Call" then
 					r ..= APPEND(var, lua(t[#t]))
 				else
-					r ..= var .. "[#" .. var .. "+1] = " .. lua(t[#t])
+					r ..= var.."[#"..var.."+1] = "..lua(t[#t])
 				end
 			end
 			return r
@@ -335,7 +423,7 @@ return function(code, ast, options)
 		end,
 		-- Continue
 		Continue = ()
-			return "goto " .. var("continue")
+			return "goto "..var"continue"
 		end,
 		-- apply (below)
 
@@ -359,7 +447,7 @@ return function(code, ast, options)
 		end,
 		-- String{ <string> }
 		String = (t)
-			return ("%q"):format(t[1])
+			return "%q":format(t[1])
 		end,
 		-- Function{ { ( `ParPair{ Id expr } | `Id{ <string> } )* `Dots? } block }
 		_functionWithoutKeyword = (t)
@@ -369,7 +457,7 @@ return function(code, ast, options)
 				if t[1][1].tag == "ParPair" then
 					local id = lua(t[1][1][1])
 					indentLevel += 1
-					table.insert(decl, "if " .. id .. " == nil then " .. id .. " = " .. lua(t[1][1][2]) .. " end")
+					table.insert(decl, "if "..id.." == nil then "..id.." = "..lua(t[1][1][2]).." end")
 					indentLevel -= 1
 					r ..= id
 				else
@@ -379,66 +467,66 @@ return function(code, ast, options)
 					if t[1][i].tag == "ParPair" then
 						local id = lua(t[1][i][1])
 						indentLevel += 1
-						table.insert(decl, "if " .. id .. " == nil then " .. id .. " = " .. lua(t[1][i][2]) .. " end")
+						table.insert(decl, "if "..id.." == nil then "..id.." = "..lua(t[1][i][2]).." end")
 						indentLevel -= 1
 						r ..= ", " ..id
 					else
-						r ..= ", " .. lua(t[1][i])
+						r ..= ", "..lua(t[1][i])
 					end
 				end
 			end
-			r ..= ")" .. indent()
+			r ..= ")"..indent()
 			for _, d in ipairs(decl) do
-				r ..= d .. newline()
+				r ..= d..newline()
 			end
 			if t[2][#t[2]] and t[2][#t[2]].tag == "Push" then -- convert final push to return
 				t[2][#t[2]].tag = "Return"
 			end
 			local hasPush = any(t[2], { "Push" }, func)
 			if hasPush then
-				r ..= push("push", var("push")) .. "local " .. var("push") .. " = {}" .. newline()
+				r ..= push("push", var"push").."local "..var"push".." = {}"..newline()
 			else
-				push("push", false) -- no push here (make sure higher push don't affect us)
+				push("push", false) -- no push here (make sure higher push doesn't affect us)
 			end
 			r ..= lua(t[2])
 			if hasPush and (t[2][#t[2]] and t[2][#t[2]].tag ~= "Return") then -- add return only if needed
-				r ..= newline() .. "return " .. UNPACK(var("push"))
+				r ..= newline().."return "..UNPACK(var"push")
 			end
 			pop("push")
-			return r .. unindent() .. "end"
+			return r..unindent().."end"
 		end,
 		Function = (t)
-			return "function" .. lua(t, "_functionWithoutKeyword")
+			return "function"..lua(t, "_functionWithoutKeyword")
 		end,
 		-- Table{ ( `Pair{ expr expr } | expr )* }
 		Pair = (t)
-			return "[" .. lua(t[1]) .. "] = " .. lua(t[2])
+			return "["..lua(t[1]).."] = "..lua(t[2])
 		end,
 		Table = (t)
 			if #t == 0 then
 				return "{}"
 			elseif #t == 1 then
-				return "{ " .. lua(t, "_lhs") .. " }"
+				return "{ "..lua(t, "_lhs").." }"
 			else
-				return "{" .. indent() .. lua(t, "_lhs", nil, true) .. unindent() .. "}"
+				return "{"..indent()..lua(t, "_lhs", nil, true)..unindent().."}"
 			end
 		end,
 		-- TableCompr{ block }
 		TableCompr = (t)
-			return push("push", "self") .. "(function()" .. indent() .. "local self = {}" .. newline() .. lua(t[1]) .. newline() .. "return self" .. unindent() .. "end)()" .. pop("push")
+			return push("push", "self").."(function()"..indent().."local self = {}"..newline()..lua(t[1])..newline().."return self"..unindent().."end)()"..pop("push")
 		end,
 		-- Op{ opid expr expr? }
 		Op = (t)
 			local r
 			if #t == 2 then
 				if type(tags._opid[t[1]]) == "string" then
-					r = tags._opid[t[1]] .. " " .. lua(t[2])
+					r = tags._opid[t[1]].." "..lua(t[2])
 				else
 					r = tags._opid[t[1]](t[2])
 				end
 			else
 				if type(tags._opid[t[1]]) == "string" then
-					r = lua(t[2]) .. " " .. tags._opid[t[1]] .. " " .. lua(t[3])
+					r = lua(t[2]).." "..tags._opid[t[1]].." "..lua(t[3])
 				else
 					r = tags._opid[t[1]](t[2], t[3])
 				end
@@ -447,27 +535,51 @@ return function(code, ast, options)
 		end,
 		-- Paren{ expr }
 		Paren = (t)
-			return "(" .. lua(t[1]) .. ")"
+			return "("..lua(t[1])..")"
+		end,
+		-- MethodStub{ expr expr }
+		MethodStub = (t)
+			return "(function()"..indent() ..
+					"local "..var"object".." = "..lua(t[1])..newline()..
+					"local "..var"method".." = "..var"object".."."..lua(t[2], "Id")..newline() ..
+					"if "..var"method".." == nil then return nil end"..newline()..
+					"return function(...) return "..var"method".."("..var"object"..", ...) end"..unindent()..
+				"end)()"
+		end,
+		-- SafeMethodStub{ expr expr }
+		SafeMethodStub = (t)
+			return "(function()"..indent() ..
+					"local "..var"object".." = "..lua(t[1])..newline()..
+					"if "..var"object".." == nil then return nil end"..newline()..
+					"local "..var"method".." = "..var"object".."."..lua(t[2], "Id")..newline() ..
+					"if "..var"method".." == nil then return nil end"..newline()..
+					"return function(...) return "..var"method".."("..var"object"..", ...) end"..unindent()..
+				"end)()"
 		end,
 		-- statexpr (below)
 		-- apply (below)
 		-- lhs (below)
 
+		-- lexpr --
+		LetExpr = (t)
+			return lua(t[1][1])
+		end,
+
 		-- statexpr --
 		_statexpr = (t, stat)
 			local hasPush = any(t, { "Push" }, func)
-			local r = "(function()" .. indent()
+			local r = "(function()"..indent()
 			if hasPush then
-				r ..= push("push", var("push")) .. "local " .. var("push") .. " = {}" .. newline()
+				r ..= push("push", var"push").."local "..var"push".." = {}"..newline()
 			else
 				push("push", false) -- no push here (make sure higher push don't affect us)
 			end
 			r ..= lua(t, stat)
 			if hasPush then
-				r ..= newline() .. "return " .. UNPACK(var("push"))
+				r ..= newline().."return "..UNPACK(var"push")
 			end
 			pop("push")
-			r ..= unindent() .. "end)()"
+			r ..= unindent().."end)()"
 			return r
 		end,
 		-- DoExpr{ stat* }
@@ -509,18 +621,23 @@ return function(code, ast, options)
 		-- Call{ expr expr* }
 		Call = (t)
 			if t[1].tag == "String" or t[1].tag == "Table" then
-				return "("..lua(t[1]) .. ")(" .. lua(t, "_lhs", 2) .. ")"
+				return "("..lua(t[1])..")("..lua(t, "_lhs", 2)..")"
+			elseif t[1].tag == "MethodStub" then -- method call
+				if t[1][1].tag == "String" or t[1][1].tag == "Table" then
+					return "("..lua(t[1][1]).."):"..lua(t[1][2], "Id").."("..lua(t, "_lhs", 2)..")"
+				else
+					return lua(t[1][1])..":"..lua(t[1][2], "Id").."("..lua(t, "_lhs", 2)..")"
+				end
 			else
-				return lua(t[1]) .. "(" .. lua(t, "_lhs", 2) .. ")"
+				return lua(t[1]).."("..lua(t, "_lhs", 2)..")"
 			end
 		end,
-
+		-- SafeCall{ expr expr* }
-		-- Invoke{ expr `String{ <string> } expr* }
+		SafeCall = (t)
-		Invoke = (t)
+			if t[1].tag ~= "Id" then -- side effect possible, only evaluate each expr once (or already in a safe context)
-			if t[1].tag == "String" or t[1].tag == "Table" then
+				return lua(t, "SafeIndex")
-				return "("..lua(t[1]).."):"..lua(t[2], "Id").."("..lua(t, "_lhs", 3)..")"
+			else -- no side effects possible
-			else
+				return "("..lua(t[1]).." ~= nil and "..lua(t[1]).."("..lua(t, "_lhs", 2)..") or nil)"
-				return lua(t[1])..":"..lua(t[2], "Id").."("..lua(t, "_lhs", 3)..")"
 			end
 		end,
 
@@ -530,7 +647,7 @@ return function(code, ast, options)
 			if t[start] then
 				r = lua(t[start])
 				for i=start+1, #t, 1 do
-					r ..= "," .. (newlines and newline() or " ") .. lua(t[i])
+					r ..= ","..(newlines and newline() or " ")..lua(t[i])
 				end
 			else
 				r = ""
@@ -549,6 +666,29 @@ return function(code, ast, options)
 				return lua(t[1]).."["..lua(t[2]).."]"
 			end
 		end,
+		-- SafeIndex{ expr expr }
+		SafeIndex = (t)
+			if t[1].tag ~= "Id" then -- side effect possible, only evaluate each expr once (or already in a safe context)
+				local l = {} -- list of immediately chained safeindex, from deepest to nearest (to simply generated code)
+				while t.tag == "SafeIndex" or t.tag == "SafeCall" do
+					table.insert(l, 1, t)
+					t = t[1]
+				end
+				local r = "(function()"..indent().."local "..var"safe".." = "..lua(l[1][1])..newline() -- base expr
+				for _, e in ipairs(l) do
+					r ..= "if "..var"safe".." == nil then return nil end"..newline()
+					if e.tag == "SafeIndex" then
+						r ..= var"safe".." = "..var"safe".."["..lua(e[2]).."]"..newline()
+					else
+						r ..= var"safe".." = "..var"safe".."("..lua(e, "_lhs", 2)..")"..newline()
+					end
+				end
+				r ..= "return "..var"safe"..unindent().."end)()"
+				return r
+			else -- no side effects possible
+				return "("..lua(t[1]).." ~= nil and "..lua(t[1]).."["..lua(t[2]).."] or nil)"
+			end
+		end,
 
 		-- opid --
 		_opid = {
@@ -560,12 +700,12 @@ return function(code, ast, options)
 		}
 	}, {
 		__index = (self, key)
-			error("don't know how to compile a "..tostring(key).." to Lua 5.3")
+			error("don't know how to compile a "..tostring(key).." to "..targetName)
 		end
 	})
 
 	#placeholder("patch")
 
-	local code = lua(ast) .. newline()
+	local code = lua(ast)..newline()
-	return requireStr .. code
+	return requireStr..code
 end

compiler/luajit.can

@@ -1,3 +1,5 @@
+targetName = "luajit"
+
 UNPACK = (list, i, j)
 	return "unpack(" .. list .. (i and (", " .. i .. (j and (", " .. j) or "")) or "") .. ")"
 end

ideas.txt

@@ -8,7 +8,7 @@ To be implemented, theese need to:
 * be significantly useful compared to existing Candran/Lua code.
 * be useful without having to rewrite APIs specifically for Candran. Candran intends to make Lua easier, not supersede it.
 
-Example currently rejected ideas:
+Example rejected ideas:
 * Python-style function decorators (implemented in Candran 0.1.0):
     Useless 95% of the time because most Lua APIs applying something to a function are used like applySomething(someArg,func) instead of func=applySomething(someArg)(func).
     This could be adapted, but this will mean unecessary named functions in the environment and it will only works when the decorator returns the functions.
@@ -48,15 +48,6 @@ finally
     clean()
 end
 
-* Safe navigation operator
-local name = articles?[0].author?.name (?[] and ?. index opeators)
-or
-local zip = lottery.drawWinner?().address?.zipcode (expr? existence test suffix)
-
-if one is nil, returns nil
-
-See http://coffeescript.org/#existential-operator
-
 * static type checking
 local a = externalFunc() -- unknown
 if a == "hey" then
@@ -103,13 +94,3 @@ meh
 
 * Other potential inspiration
 https://www.ruby-lang.org/fr/
-
-* If with assignement
-if f = io.open("file") then
-    f:close()
-end
-
-f is in the if scope
-
-* Method self bundler
-obj:method -- returns (...) return method(obj, ...) end

lib/lua-parser/parser.lua

@@ -11,7 +11,7 @@ stat:
   | `Set{ {lhs+} (opid? = opid?)? {expr+} }   -- lhs1, lhs2... op=op e1, e2...
   | `While{ expr block }                      -- while e do b end
   | `Repeat{ block expr }                     -- repeat b until e
-  | `If{ (expr block)+ block? }               -- if e1 then b1 [elseif e2 then b2] ... [else bn] end
+  | `If{ (lexpr block)+ block? }              -- if e1 then b1 [elseif e2 then b2] ... [else bn] end
   | `Fornum{ ident expr expr expr? block }    -- for ident = e, e[, e] do b end
   | `Forin{ {ident+} {expr+} block }          -- for i1, i2... in e1, e2... do b end
   | `Local{ {ident+} {expr+}? }               -- local i1, i2... = e1, e2...
@@ -36,10 +36,17 @@ expr:
   | `Op{ opid expr expr? }
   | `Paren{ expr }       -- significant to cut multiple values returns
   | `TableCompr{ block }
+  | `MethodStub{ expr expr }
+  | `SafeMethodStub{ expr expr }
+  | `SafeIndex{ expr expr }
   | statexpr
   | apply
   | lhs
 
+lexpr:
+    `LetExpr{ {ident+} {expr+}? }
+  | every node from expr
+
 statexpr:
     `DoExpr{ stat* }
   | `WhileExpr{ expr block }                    -- while e do b end
@@ -50,7 +57,7 @@ statexpr:
 
 apply:
     `Call{ expr expr* }
-  | `Invoke{ expr `String{ <string> } expr* }
+  | `SafeCall{ expr expr* }
 
 lhs: `Id{ <string> } | `Index{ expr expr }
 
@@ -255,25 +262,32 @@ local function insertIndex (t, index)
   return { tag = "Index", pos = t.pos, [1] = t, [2] = index }
 end
 
-local function markMethod(t, method)
+local function markMethod (t, method)
   if method then
     return { tag = "Index", pos = t.pos, is_method = true, [1] = t, [2] = method }
   end
   return t
 end
 
-local function makeIndexOrCall (t1, t2)
+local function makeSuffixedExpr (t1, t2)
-  if t2.tag == "Call" or t2.tag == "Invoke" then
+  if t2.tag == "Call" or t2.tag == "SafeCall" then
     local t = { tag = t2.tag, pos = t1.pos, [1] = t1 }
     for k, v in ipairs(t2) do
       table.insert(t, v)
     end
     return t
+  elseif t2.tag == "MethodStub" or t2.tag == "SafeMethodStub" then
+    return { tag = t2.tag, pos = t1.pos, [1] = t1, [2] = t2[1] }
+  elseif t2.tag == "SafeDotIndex" or t2.tag == "SafeArrayIndex" then
+    return { tag = "SafeIndex", pos = t1.pos, [1] = t1, [2] = t2[1] }
+  elseif t2.tag == "DotIndex" or t2.tag == "ArrayIndex" then
+    return { tag = "Index", pos = t1.pos, [1] = t1, [2] = t2[1] }
+  else
+    error("unexpected tag in suffixed expression")
   end
-  return { tag = "Index", pos = t1.pos, [1] = t1, [2] = t2[1] }
 end
 
-local function fixShortFunc(t)
+local function fixShortFunc (t)
     if t[1] == ":" then -- self method
         table.insert(t[2], 1, { tag = "Id", "self" })
         table.remove(t, 1)
@@ -283,12 +297,12 @@ local function fixShortFunc(t)
     return t
 end
 
-local function statToExpr(t) -- tag a StatExpr
+local function statToExpr (t) -- tag a StatExpr
     t.tag = t.tag .. "Expr"
     return t
 end
 
-local function fixStructure(t) -- fix the AST structure if needed
+local function fixStructure (t) -- fix the AST structure if needed
     local i = 1
     while i <= #t do
         if type(t[i]) == "table" then
@@ -309,7 +323,7 @@ local function fixStructure(t) -- fix the AST structure if needed
     return t
 end
 
-local function searchEndRec(block, isRecCall) -- recursively search potential "end" keyword wrongly consumed by a short anonymous function on stat end (yeah, too late to change the syntax to something easier to parse)
+local function searchEndRec (block, isRecCall) -- recursively search potential "end" keyword wrongly consumed by a short anonymous function on stat end (yeah, too late to change the syntax to something easier to parse)
     for i, stat in ipairs(block) do
         -- Non recursive statements
         if stat.tag == "Set" or stat.tag == "Push" or stat.tag == "Return" or stat.tag == "Local" or stat.tag == "Let" or stat.tag == "Localrec" then
@@ -404,7 +418,7 @@ local function searchEndRec(block, isRecCall) -- recursively search potential "e
     return nil
 end
 
-local function searchEnd(s, p, t) -- match time capture which try to restructure the AST to free an "end" for us
+local function searchEnd (s, p, t) -- match time capture which try to restructure the AST to free an "end" for us
     local r = searchEndRec(fixStructure(t))
     if not r then
         return false
@@ -412,7 +426,7 @@ local function searchEnd(s, p, t) -- match time capture which try to restructure
     return true, r
 end
 
-local function expectBlockOrSingleStatWithStartEnd(start, startLabel, stopLabel, canFollow) -- will try a SingleStat if start doesn't match
+local function expectBlockOrSingleStatWithStartEnd (start, startLabel, stopLabel, canFollow) -- will try a SingleStat if start doesn't match
     if canFollow then
         return (-start * V"SingleStatBlock" * canFollow^-1)
              + (expect(start, startLabel) * ((V"Block" * (canFollow + kw("end")))
@@ -424,16 +438,40 @@ local function expectBlockOrSingleStatWithStartEnd(start, startLabel, stopLabel,
     end
 end
 
-local function expectBlockWithEnd(label) -- can't work *optionnaly* with SingleStat unfortunatly
+local function expectBlockWithEnd (label) -- can't work *optionnaly* with SingleStat unfortunatly
     return (V"Block" * kw("end"))
          + (Cmt(V"Block", searchEnd) + throw(label))
 end
 
-local function maybeBlockWithEnd() -- same as above but don't error if it doesn't match
+local function maybeBlockWithEnd () -- same as above but don't error if it doesn't match
     return (V"BlockNoErr" * kw("end"))
          + Cmt(V"BlockNoErr", searchEnd)
 end
 
+local stacks = {
+  lexpr = {}
+}
+local function push (f)
+  return Cmt(P"", function()
+    table.insert(stacks[f], true)
+    return true
+  end)
+end
+local function pop (f)
+  return Cmt(P"", function()
+    table.remove(stacks[f])
+    return true
+  end)
+end
+local function when (f)
+  return Cmt(P"", function()
+    return #stacks[f] > 0
+  end)
+end
+local function set (f, patt) -- patt *must* succeed (or throw an error) to preserve stack integrity
+  return push(f) * patt * pop(f)
+end
+
 -- grammar
 local G = { V"Lua",
   Lua      = (V"Shebang"^-1 * V"Skip" * V"Block" * expect(P(-1), "Extra")) / fixStructure;
@@ -451,12 +489,12 @@ local G = { V"Lua",
   BlockNoErr      = tagC("Block", V"Stat"^0 * ((V"RetStat" + V"ImplicitPushStat") * sym(";")^-1)^-1); -- used to check if something a valid block without throwing an error
 
   IfStat      = tagC("If", V"IfPart");
-  IfPart      = kw("if") * expect(V"Expr", "ExprIf") * expectBlockOrSingleStatWithStartEnd(kw("then"), "ThenIf", "EndIf", V"ElseIfPart" + V"ElsePart");
+  IfPart      = kw("if") * set("lexpr", expect(V"Expr", "ExprIf")) * expectBlockOrSingleStatWithStartEnd(kw("then"), "ThenIf", "EndIf", V"ElseIfPart" + V"ElsePart");
-  ElseIfPart  = kw("elseif") * expect(V"Expr", "ExprEIf") * expectBlockOrSingleStatWithStartEnd(kw("then"), "ThenEIf", "EndIf", V"ElseIfPart" + V"ElsePart");
+  ElseIfPart  = kw("elseif") * set("lexpr", expect(V"Expr", "ExprEIf")) * expectBlockOrSingleStatWithStartEnd(kw("then"), "ThenEIf", "EndIf", V"ElseIfPart" + V"ElsePart");
   ElsePart    = kw("else") * expectBlockWithEnd("EndIf");
 
   DoStat      = kw("do") * expectBlockWithEnd("EndDo") / tagDo;
-  WhileStat   = tagC("While", kw("while") * expect(V"Expr", "ExprWhile") * V"WhileBody");
+  WhileStat   = tagC("While", kw("while") * set("lexpr", expect(V"Expr", "ExprWhile")) * V"WhileBody");
   WhileBody   = expectBlockOrSingleStatWithStartEnd(kw("do"), "DoWhile", "EndWhile");
   RepeatStat  = tagC("Repeat", kw("repeat") * V"Block" * expect(kw("until"), "UntilRep") * expect(V"Expr", "ExprRep"));
 
@@ -474,7 +512,7 @@ local G = { V"Lua",
   LetStat      = kw("let") * expect(V"LetAssign", "DefLet");
   LetAssign    = tagC("Let", V"NameList" * (sym("=") * expect(V"ExprList", "EListLAssign") + Ct(Cc())));
 
-  Assignment   = tagC("Set", V"VarList" * V"BinOp"^-1 * (P"=" / "=") * V"BinOp"^-1 * V"Skip" * expect(V"ExprList", "EListAssign"));
+  Assignment   = tagC("Set", V"VarList" * V"BinOp"^-1 * (P"=" / "=") * ((V"BinOp" - P"-") + #(P"-" * V"Space") * V"BinOp")^-1 * V"Skip" * expect(V"ExprList", "EListAssign"));
 
   FuncStat    = tagC("Set", kw("function") * expect(V"FuncName", "FuncName") * V"FuncBody") / fixFuncStat;
   FuncName    = Cf(V"Id" * (sym(".") * expect(V"StrId", "NameFunc1"))^0, insertIndex)
@@ -520,35 +558,39 @@ local G = { V"Lua",
   UnaryExpr   = V"UnaryOp" * expect(V"UnaryExpr", "UnaryExpr") / unaryOp
               + V"PowExpr";
   PowExpr     = V"SimpleExpr" * (V"PowOp" * expect(V"UnaryExpr", "PowExpr"))^-1 / binaryOp;
-
+  SimpleExpr  = tagC("Number", V"Number")
-  SimpleExpr = tagC("Number", V"Number")
+              + tagC("Nil", kw("nil"))
-             + tagC("Nil", kw("nil"))
+              + tagC("Boolean", kw("false") * Cc(false))
-             + tagC("Boolean", kw("false") * Cc(false))
+              + tagC("Boolean", kw("true") * Cc(true))
-             + tagC("Boolean", kw("true") * Cc(true))
+              + tagC("Dots", sym("..."))
-             + tagC("Dots", sym("..."))
+              + V"FuncDef"
-             + V"FuncDef"
+              + (when("lexpr") * tagC("LetExpr", V"NameList" * sym("=") * -sym("=") * expect(V"ExprList", "EListLAssign")))
-             + V"ShortFuncDef"
+              + V"ShortFuncDef"
-             + V"SuffixedExpr"
+              + V"SuffixedExpr"
-             + V"StatExpr";
+              + V"StatExpr";
 
   StatExpr = (V"IfStat" + V"DoStat" + V"WhileStat" + V"RepeatStat" + V"ForStat") / statToExpr;
 
-  FuncCall  = Cmt(V"SuffixedExpr", function(s, i, exp) return exp.tag == "Call" or exp.tag == "Invoke", exp end);
+  FuncCall  = Cmt(V"SuffixedExpr", function(s, i, exp) return exp.tag == "Call" or exp.tag == "SafeCall", exp end);
   VarExpr   = Cmt(V"SuffixedExpr", function(s, i, exp) return exp.tag == "Id" or exp.tag == "Index", exp end);
 
-  SuffixedExpr      = Cf(V"PrimaryExpr" * (V"Index" + V"Invoke" + V"Call")^0
+  SuffixedExpr      = Cf(V"PrimaryExpr" * (V"Index" + V"MethodStub" + V"Call")^0
-                       + V"NoCallPrimaryExpr" * -V"Call" * (V"Index" + V"Invoke" + V"Call")^0
+                    + V"NoCallPrimaryExpr" * -V"Call" * (V"Index" + V"MethodStub" + V"Call")^0
-                       + V"NoCallPrimaryExpr", makeIndexOrCall);
+                    + V"NoCallPrimaryExpr", makeSuffixedExpr);
   PrimaryExpr       = V"SelfId" * (V"SelfCall" + V"SelfIndex")
                     + V"Id"
                     + tagC("Paren", sym("(") * expect(V"Expr", "ExprParen") * expect(sym(")"), "CParenExpr"));
   NoCallPrimaryExpr = tagC("String", V"String") + V"Table" + V"TableCompr";
   Index             = tagC("DotIndex", sym("." * -P".") * expect(V"StrId", "NameIndex"))
-                    + tagC("ArrayIndex", sym("[" * -P(S"=[")) * expect(V"Expr", "ExprIndex") * expect(sym("]"), "CBracketIndex"));
+                    + tagC("ArrayIndex", sym("[" * -P(S"=[")) * expect(V"Expr", "ExprIndex") * expect(sym("]"), "CBracketIndex"))
-  Call              = tagC("Call", V"FuncArgs");
+                    + tagC("SafeDotIndex", sym("?." * -P".") * expect(V"StrId", "NameIndex"))
-  Invoke            = tagC("Invoke", Cg(sym(":" * -P":") * expect(V"StrId", "NameMeth") * expect(V"FuncArgs", "MethArgs")));
+                    + tagC("SafeArrayIndex", sym("?[" * -P(S"=[")) * expect(V"Expr", "ExprIndex") * expect(sym("]"), "CBracketIndex"));
+  MethodStub        = tagC("MethodStub", sym(":" * -P":") * expect(V"StrId", "NameMeth"))
+                    + tagC("SafeMethodStub", sym("?:" * -P":") * expect(V"StrId", "NameMeth"));
+  Call              = tagC("Call", V"FuncArgs")
+                    + tagC("SafeCall", P"?" * V"FuncArgs");
+  SelfCall          = tagC("MethodStub", V"StrId") * V"Call";
   SelfIndex         = tagC("DotIndex", V"StrId");
-  SelfCall          = tagC("Invoke", Cg(V"StrId" * V"FuncArgs"));
 
   FuncDef   = (kw("function") * V"FuncBody");
   FuncArgs  = sym("(") * commaSep(V"Expr", "ArgList")^-1 * expect(sym(")"), "CParenArgs")

lib/lua-parser/validator.lua

@@ -158,16 +158,6 @@ local function traverse_call (env, call)
   return true
 end
 
-local function traverse_invoke (env, invoke)
-  local status, msg = traverse_exp(env, invoke[1])
-  if not status then return status, msg end
-  for i=3, #invoke do
-    status, msg = traverse_exp(env, invoke[i])
-    if not status then return status, msg end
-  end
-  return true
-end
-
 local function traverse_assignment (env, stm)
   local status, msg = traverse_varlist(env, stm[1])
   if not status then return status, msg end
@@ -238,6 +228,18 @@ local function traverse_goto (env, stm)
   return true
 end
 
+local function traverse_let (env, stm)
+  local status, msg = traverse_explist(env, stm[2])
+  if not status then return status, msg end
+  return true
+end
+
+local function traverse_letrec (env, stm)
+  local status, msg = traverse_exp(env, stm[2][1])
+  if not status then return status, msg end
+  return true
+end
+
 local function traverse_if (env, stm)
   local len = #stm
   if len % 2 == 0 then
@@ -266,18 +268,6 @@ local function traverse_label (env, stm)
   return true
 end
 
-local function traverse_let (env, stm)
-  local status, msg = traverse_explist(env, stm[2])
-  if not status then return status, msg end
-  return true
-end
-
-local function traverse_letrec (env, stm)
-  local status, msg = traverse_exp(env, stm[2][1])
-  if not status then return status, msg end
-  return true
-end
-
 local function traverse_repeat (env, stm)
   begin_loop(env)
   local status, msg = traverse_block(env, stm[1])
@@ -327,6 +317,22 @@ function traverse_varlist (env, varlist)
   return true
 end
 
+local function traverse_methodstub (env, var)
+  local status, msg = traverse_exp(env, var[1])
+  if not status then return status, msg end
+  status, msg = traverse_exp(env, var[2])
+  if not status then return status, msg end
+  return true
+end
+
+local function traverse_safeindex (env, var)
+  local status, msg = traverse_exp(env, var[1])
+  if not status then return status, msg end
+  status, msg = traverse_exp(env, var[2])
+  if not status then return status, msg end
+  return true
+end
+
 function traverse_exp (env, exp)
   local tag = exp.tag
   if tag == "Nil" or
@@ -344,15 +350,17 @@ function traverse_exp (env, exp)
     return traverse_op(env, exp)
   elseif tag == "Paren" then -- `Paren{ expr }
     return traverse_paren(env, exp)
-  elseif tag == "Call" then -- `Call{ expr expr* }
+  elseif tag == "Call" or tag == "SafeCall" then -- `(Safe)Call{ expr expr* }
     return traverse_call(env, exp)
-  elseif tag == "Invoke" then -- `Invoke{ expr `String{ <string> } expr* }
-    return traverse_invoke(env, exp)
   elseif tag == "Id" or -- `Id{ <string> }
          tag == "Index" then -- `Index{ expr expr }
     return traverse_var(env, exp)
+  elseif tag == "SafeIndex" then -- `SafeIndex{ expr expr }
+    return traverse_safeindex(env, exp)
   elseif tag == "TableCompr" then -- `TableCompr{ block }
     return traverse_tablecompr(env, exp)
+  elseif tag == "MethodStub" or tag == "SafeMethodStub" then -- `(Safe)MethodStub{ expr expr }
+    return traverse_methodstub(env, exp)
   elseif tag:match("Expr$") then -- `StatExpr{ ... }
     return traverse_statexpr(env, exp)
   else
@@ -399,8 +407,6 @@ function traverse_stm (env, stm)
     return traverse_break(env, stm)
   elseif tag == "Call" then -- `Call{ expr expr* }
     return traverse_call(env, stm)
-  elseif tag == "Invoke" then -- `Invoke{ expr `String{ <string> } expr* }
-    return traverse_invoke(env, stm)
   elseif tag == "Continue" then
     return traverse_continue(env, stm)
   elseif tag == "Push" then -- `Push{ <expr>* }

lib/util.can

@@ -1,6 +1,6 @@
 local util = {}
 
-function util.search(modpath, exts={"can", "lua"})
+function util.search(modpath, exts={})
 	for _, ext in ipairs(exts) do
 		for path in package.path:gmatch("[^;]+") do
 			local fpath = path:gsub("%.lua", "."..ext):gsub("%?", (modpath:gsub("%.", "/")))

test/test.lua

@@ -1,4 +1,8 @@
 local candran = dofile(arg[1] or "../candran.lua")
+candran.default.indentation = "\t"
+candran.default.mapLines = false
+
+local load = require("lib.util").load
 
 -- test helper
 local results = {} -- tests result
@@ -10,15 +14,17 @@ local function test(name, candranCode, expectedResult, options)
 	local success, code = pcall(candran.make, candranCode, options)
 	if not success then
 		self.result = "error"
-		self.message = "error while making code:\n"..code
+		self.message = "/!\\ error while making code:\n"..code
 		return
 	end
 
 	-- load code
-	local success, func = pcall(loadstring or load, code)
+	local env = {}
+	for k, v in pairs(_G) do env[k] = v end
+	local success, func = pcall(load, code, nil, env)
 	if not success then
 		self.result = "error"
-		self.message = "error while loading code:\n"..func
+		self.message = "/!\\ error while loading code:\n"..func.."\ngenerated code:\n"..code
 		return
 	end
 
@@ -26,14 +32,14 @@ local function test(name, candranCode, expectedResult, options)
 	local success, output = pcall(func)
 	if not success then
 		self.result = "error"
-		self.message = "error while running code:\n"..output
+		self.message = "/!\\ error while running code:\n"..output.."\ngenerated code:\n"..code
 		return
 	end
 
 	-- check result
 	if output ~= expectedResult then
 		self.result = "fail"
-		self.message = "invalid result from the code; it returned "..tostring(output).." instead of "..tostring(expectedResult)
+		self.message = "/!\\ invalid result from the code; it returned "..tostring(output).." instead of "..tostring(expectedResult).."; generated code:\n"..code
 		return
 	else
 		self.result = "success"
@@ -669,6 +675,154 @@ test("suffixable table comprehension array index", [[
 return [@len=3]["len"]
 ]], 3)
 
+-- let in condition expression
+test("let in while condition, evaluation each iteration", [[
+	local s = ""
+	local i = 0
+	while (a = i+2) and i < 3 do
+		s = s .. tostring(a)
+		i = i + 1
+		a = 0
+	end
+	return s
+]], "234")
+test("let in while condition, scope", [[
+	local s = ""
+	local i = 0
+	while (a = i+2) and i < 3 do
+		s = s .. tostring(a)
+		i = i + 1
+		a = 0
+	end
+	return a
+]], nil)
+test("several let in while condition, evaluation order", [[
+	local s = ""
+	local i = 0
+	while (a = (b=i+1)+1) and i < 3 do
+		assert(b==i+1)
+		s = s .. tostring(a)
+		i = i + 1
+		a = 0
+	end
+	return s
+]], "234")
+test("several let in while condition, only test the first", [[
+	local s = ""
+	local i = 0
+	while (a,b = false,i) and i < 3 do
+		s = s .. tostring(a)
+		i = i + 1
+	end
+	return s
+]], "")
+
+test("let in if condition", [[
+	if a = false then
+		error("condition was false")
+	elseif b = nil then
+		error("condition was nil")
+	elseif c = true then
+		return "ok"
+	elseif d = true then
+		error("should not be reachable")
+	end
+]], "ok")
+test("let in if condition, scope", [[
+	local r
+	if a = false then
+		error("condition was false")
+	elseif b = nil then
+		error("condition was nil")
+	elseif c = true then
+		assert(a == false)
+		assert(d == nil)
+		r = "ok"
+	elseif d = true then
+		error("should not be reachable")
+	end
+	assert(c == nil)
+	return r
+]], "ok")
+test("several let in if condition, only test the first", [[
+	if a = false then
+		error("condition was false")
+	elseif b = nil then
+		error("condition was nil")
+	elseif c, d = false, "ok" then
+		error("should have tested against c")
+	else
+		return d
+	end
+]], "ok")
+test("several let in if condition, evaluation order", [[
+	local t = { k = "ok" }
+	if a = t[b,c = "k", "l"] then
+		assert(c == "l")
+		assert(b == "k")
+		return a
+	end
+]], "ok")
+
+-- Method stub
+test("method stub, basic", [[
+	local t = { s = "ok", m = function(self) return self.s end }
+	local f = t:m
+	return f()
+]], "ok")
+test("method stub, store method", [[
+	local t = { s = "ok", m = function(self) return self.s end }
+	local f = t:m
+	t.m = function() return "not ok" end
+	return f()
+]], "ok")
+test("method stub, store object", [[
+	local t = { s = "ok", m = function(self) return self.s end }
+	local f = t:m
+	t = {}
+	return f()
+]], "ok")
+test("method stub, returns nil if method nil", [[
+	local t = { m = nil }
+	return t:m
+]], nil)
+
+-- Safe prefixes
+test("safe method stub, when nil", [[
+	return t?:m
+]], nil)
+test("safe method stub, when non-nil", [[
+	local t = { s = "ok", m = function(self) return self.s end }
+	return t?:m()
+]], "ok")
+
+test("safe call, when nil", [[
+	return f?()
+]], nil)
+test("safe call, when non nil", [[
+	f = function() return "ok" end
+	return f?()
+]], "ok")
+
+test("safe index, when nil", [[
+	return f?.l
+]], nil)
+test("safe index, when non nil", [[
+	f = { l = "ok" }
+	return f?.l
+]], "ok")
+
+test("safe prefixes, random chaining", [[
+	f = { l = { m = function(s) return s or "ok" end } }
+	assert(f?.l?.m() == "ok")
+	assert(f?.l?.o == nil)
+	assert(f?.l?.o?() == nil)
+	assert(f?.lo?.o?() == nil)
+	assert(f?.l?:m?() == f.l)
+	assert(f?.l:mo == nil)
+	assert(f.l?:o?() == nil)
+]])
+
 -- results
 local resultCounter = {}
 local testCounter = 0