add metamethods checking.

5 files changed, 169 insertions, 67 deletions

diff --git a/spec/inputs/import.yue b/spec/inputs/import.yue
index af5545d..fe5caf5 100644
--- a/spec/inputs/import.yue
+++ b/spec/inputs/import.yue
@@ -64,8 +64,9 @@ do
         import "org.package.module" as function:func, if:ifVar
 
 do
-        import "m" as {<a>: b}
-        import "m" as {e: f, <a>: c}
+        import "m" as {<gc>: b}
+        import "m" as {:<index>}
+        import "m" as {e: f, <pairs>: c}
         import "m" as {c: d}
-        import "m" as {g, {<h>: i}}
+        import "m" as {g, {<close>: i}}
 
diff --git a/spec/outputs/destructure.lua b/spec/outputs/destructure.lua
index 8953a2a..cb0eb3f 100644
--- a/spec/outputs/destructure.lua
+++ b/spec/outputs/destructure.lua
@@ -288,28 +288,31 @@ do
                         end)
                 end
         end
-        local _obj_0 = tb
-        local mtx, y, zItem = getmetatable(_obj_0.x), _obj_0.y, _obj_0.z
-        if mtx == nil then
-                mtx = { }
-        end
-        local index = getmetatable(_obj_0).__index
-        if index == nil then
-                index = function()
-                        return nil
+        local mtx, y, zItem, index
+        do
+                local _obj_0 = tb
+                mtx, y, zItem = getmetatable(_obj_0.x), _obj_0.y, _obj_0.z
+                if mtx == nil then
+                        mtx = { }
+                end
+                index = getmetatable(_obj_0).__index
+                if index == nil then
+                        index = function()
+                                return nil
+                        end
                 end
         end
         do
                 local _tmp_0
                 do
-                        local _obj_1 = getmetatable(tb)
-                        _tmp_0 = _obj_1.func
+                        local _obj_0 = getmetatable(tb)
+                        _tmp_0 = _obj_0.func
                 end
                 if _tmp_0 == nil then
                         do
-                                local _obj_1 = item
-                                if _obj_1 ~= nil then
-                                        _tmp_0 = _obj_1.defVal
+                                local _obj_0 = item
+                                if _obj_0 ~= nil then
+                                        _tmp_0 = _obj_0.defVal
                                 end
                         end
                 end
@@ -455,9 +458,12 @@ do
         end
 end
 do
-        local _obj_0 = tb
-        local value = _obj_0[name]
-        local value_meta = getmetatable(_obj_0)[name]
+        local value, value_meta
+        do
+                local _obj_0 = tb
+                value = _obj_0[name]
+                value_meta = getmetatable(_obj_0)[name]
+        end
 end
 do
         local tostring, add
@@ -492,16 +498,15 @@ do
 end
 do
         local tb = { }
-        local _obj_0 = tb
         do
                 local _tmp_0 = c()
-                local v2 = _obj_0[_tmp_0]
+                local v2 = tb[_tmp_0]
         end
         local v1
         do
-                local _obj_1 = getmetatable(_obj_0)
+                local _obj_0 = getmetatable(tb)
                 local _tmp_1 = a + b
-                v1 = _obj_1[_tmp_1]
+                v1 = _obj_0[_tmp_1]
         end
 end
 do
@@ -575,16 +580,15 @@ do
                 local _tab_0 = type(_exp_0)
                 _tab_0 = "table" == _tab_0 or "userdata" == _tab_0
                 if _tab_0 then
-                        local _obj_0 = _exp_0
                         do
-                                local _obj_1 = _obj_0.c
-                                local _type_0 = type(_obj_1)
+                                local _obj_0 = _exp_0.c
+                                local _type_0 = type(_obj_0)
                                 if "table" == _type_0 or "userdata" == _type_0 then
                                         do
-                                                local _obj_2 = getmetatable(_obj_1)
-                                                local _type_1 = type(_obj_2)
+                                                local _obj_1 = getmetatable(_obj_0)
+                                                local _type_1 = type(_obj_1)
                                                 if "table" == _type_1 or "userdata" == _type_1 then
-                                                        meta_field = _obj_2["abc"]
+                                                        meta_field = _obj_1["abc"]
                                                 end
                                         end
                                 end
@@ -593,19 +597,19 @@ do
                                 meta_field = "def"
                         end
                         do
-                                local _obj_1 = getmetatable(_obj_0)
+                                local _obj_0 = getmetatable(_exp_0)
                                 do
-                                        local _obj_2 = _obj_1[ [[any string]]]
-                                        local _type_0 = type(_obj_2)
+                                        local _obj_1 = _obj_0[ [[any string]]]
+                                        local _type_0 = type(_obj_1)
                                         if "table" == _type_0 or "userdata" == _type_0 then
-                                                abc = _obj_2.d
+                                                abc = _obj_1.d
                                         end
                                 end
                                 do
-                                        local _obj_2 = _obj_1['str']
-                                        local _type_0 = type(_obj_2)
+                                        local _obj_1 = _obj_0['str']
+                                        local _type_0 = type(_obj_1)
                                         if "table" == _type_0 or "userdata" == _type_0 then
-                                                def = _obj_2.e
+                                                def = _obj_1.e
                                         end
                                 end
                                 if abc == nil then
diff --git a/spec/outputs/import.lua b/spec/outputs/import.lua
index edb7c44..f8d6ef0 100644
--- a/spec/outputs/import.lua
+++ b/spec/outputs/import.lua
@@ -89,14 +89,18 @@ do
         end
 end
 do
-        local b = getmetatable(require("m")).__a
-        local _obj_0 = require("m")
-        local f = _obj_0.e
-        local c = getmetatable(_obj_0).__a
+        local b = getmetatable(require("m")).__gc
+        local index = getmetatable(require("m")).__index
+        local f, c
+        do
+                local _obj_0 = require("m")
+                f = _obj_0.e
+                c = getmetatable(_obj_0).__pairs
+        end
         local d = require("m").c
         local g, i
         do
-                local _obj_1 = require("m")
-                g, i = _obj_1[1], getmetatable(_obj_1[2]).__h
+                local _obj_0 = require("m")
+                g, i = _obj_0[1], getmetatable(_obj_0[2]).__close
         end
 end
diff --git a/spec/outputs/metatable.lua b/spec/outputs/metatable.lua
index 937136f..907a584 100644
--- a/spec/outputs/metatable.lua
+++ b/spec/outputs/metatable.lua
@@ -38,28 +38,29 @@ getmetatable(a).__add = function(x, y)
         return x + y
 end
 do
-        local _obj_0 = a
-        local new = _obj_0.new
+        local new = a.new
         local close, closeA
         do
-                local _obj_1 = getmetatable(_obj_0)
-                close, closeA = _obj_1.__close, _obj_1.__close
+                local _obj_0 = getmetatable(a)
+                close, closeA = _obj_0.__close, _obj_0.__close
         end
         print(new, close, closeA)
 end
 do
         local x, new, var, close, closeA, num, add, sub
-        local _obj_0, _obj_1
-        x, _obj_0, _obj_1 = 123, a.b.c, func()
-        new, var = _obj_0.new, _obj_0.var
-        do
-                local _obj_2 = getmetatable(_obj_0)
-                close, closeA = _obj_2.__close, _obj_2.__close
-        end
-        num = _obj_1.num
         do
-                local _obj_2 = getmetatable(_obj_1)
-                add, sub = _obj_2.__add, _obj_2.__sub
+                local _obj_0, _obj_1
+                x, _obj_0, _obj_1 = 123, a.b.c, func()
+                new, var = _obj_0.new, _obj_0.var
+                do
+                        local _obj_2 = getmetatable(_obj_0)
+                        close, closeA = _obj_2.__close, _obj_2.__close
+                end
+                num = _obj_1.num
+                do
+                        local _obj_2 = getmetatable(_obj_1)
+                        add, sub = _obj_2.__add, _obj_2.__sub
+                end
         end
 end
 setmetatable(a.b, { })
diff --git a/src/yuescript/yue_compiler.cpp b/src/yuescript/yue_compiler.cpp
index 0d674f8..42310b2 100644
--- a/src/yuescript/yue_compiler.cpp
+++ b/src/yuescript/yue_compiler.cpp
@@ -60,7 +60,18 @@ namespace yue {
 
 typedef std::list<std::string> str_list;
 
-const std::string_view version = "0.15.18"sv;
+static std::unordered_set<std::string> Metamethods = {
+        "add"s, "sub"s, "mul"s, "div"s, "mod"s,
+        "pow"s, "unm"s, "concat"s, "len"s, "eq"s,
+        "lt"s, "le"s, "index"s, "newindex"s, "call"s,
+        "gc"s, "mode"s, "tostring"s, "metatable"s, // Lua 5.1
+        "pairs"s, "ipairs"s, // Lua 5.2
+        "name"s, "idiv"s, "band"s, "bor"s, "bxor"s,
+        "bnot"s, "shl"s, "shr"s, // Lua 5.3 ipairs deprecated
+        "close"s // Lua 5.4
+};
+
+const std::string_view version = "0.15.19"sv;
 const std::string_view extension = "yue"sv;
 
 class YueCompilerImpl {
@@ -1089,6 +1100,46 @@ private:
                 return str;
         }
 
+        void checkMetamethod(const std::string& name, ast_node* x) {
+                if (Metamethods.find(name) == Metamethods.end()) {
+                        throw std::logic_error(_info.errorMessage("invalid metamethod name"sv, x));
+                }
+                int target = getLuaTarget(x);
+                switch (target) {
+                        case 501: goto metamethod51;
+                        case 502: goto metamethod52;
+                        case 503: {
+                                if (name == "ipairs"sv) {
+                                        throw std::logic_error(_info.errorMessage("metamethod is deprecated since Lua 5.3"sv, x));
+                                }
+                                goto metamethod53;
+                        }
+                        case 504: {
+                                if (name == "ipairs"sv) {
+                                        throw std::logic_error(_info.errorMessage("metamethod is not supported since Lua 5.4"sv, x));
+                                }
+                                goto metamethod54;
+                        }
+                }
+                metamethod51:
+                if (name == "pairs"sv || name == "ipairs"sv) {
+                        throw std::logic_error(_info.errorMessage("metamethod is not supported until Lua 5.2"sv, x));
+                }
+                metamethod52:
+                if (name == "name"sv || name == "idiv"sv ||
+                        name == "band"sv || name == "bor"sv ||
+                        name == "bxor"sv || name == "bnot"sv ||
+                        name == "shl"sv || name == "shr"sv) {
+                        throw std::logic_error(_info.errorMessage("metamethod is not supported until Lua 5.3"sv, x));
+                }
+                metamethod53:
+                if (name == "close"sv) {
+                        throw std::logic_error(_info.errorMessage("metamethod is not supported until Lua 5.4"sv, x));
+                }
+                metamethod54:
+                return;
+        }
+
         void transformStatement(Statement_t* statement, str_list& out) {
                 auto x = statement;
                 if (statement->appendix) {
@@ -1825,11 +1876,32 @@ private:
                 if (info.destructures.empty()) {
                         transformAssignmentCommon(assignment, out);
                 } else {
+                        auto x = assignment;
                         str_list temp;
+                        if (info.extraScope) {
+                                str_list defs;
+                                for (auto& destruct : info.destructures) {
+                                        for (auto& item : destruct.items) {
+                                                if (!item.targetVar.empty()) {
+                                                        if (!isDefined(item.targetVar)) {
+                                                                defs.push_back(item.targetVar);
+                                                        }
+                                                }
+                                        }
+                                }
+                                if (!defs.empty()) {
+                                        for (const auto& def : defs) {
+                                                checkConst(def, x);
+                                                addToScope(def);
+                                        }
+                                        temp.push_back(indent() + "local "s + join(defs, ", "sv) + nll(x));
+                                }
+                                temp.push_back(indent() + "do"s + nll(x));
+                                pushScope();
+                        }
                         if (info.assignment) {
                                 transformAssignmentCommon(info.assignment, temp);
                         }
-                        auto x = assignment;
                         for (auto& destruct : info.destructures) {
                                 std::list<std::pair<ast_ptr<true, Exp_t>, ast_ptr<true, Exp_t>>> leftPairs;
                                 bool extraScope = false;
@@ -1861,7 +1933,7 @@ private:
                                                                 }
                                                         }
                                                         if (!isNil) {
-                                                                auto stmt = toAst<Statement_t>(pair.targetVar + "=nil if "s + pair.targetVar + "==nil", pair.defVal);
+                                                                auto stmt = toAst<Statement_t>(pair.targetVar + "=nil if "s + pair.targetVar + "==nil"s, pair.defVal);
                                                                 auto defAssign = stmt->content.as<ExpListAssign_t>();
                                                                 auto assign = defAssign->action.as<Assign_t>();
                                                                 assign->values.clear();
@@ -2035,6 +2107,10 @@ private:
                                         temp.push_back(clearBuf());
                                 }
                         }
+                        if (info.extraScope) {
+                                popScope();
+                                temp.push_back(indent() + "end"s + nlr(x));
+                        }
                         out.push_back(join(temp));
                 }
         }
@@ -2247,6 +2323,7 @@ private:
                                         }
                                         auto mp = static_cast<meta_variable_pair_t*>(pair);
                                         auto name = _parser.toString(mp->name);
+                                        checkMetamethod(name, mp->name);
                                         _buf << "__"sv << name << ':' << name;
                                         auto newPairDef = toAst<normal_pair_def_t>(clearBuf(), pair);
                                         newPairDef->defVal.set(defVal);
@@ -2266,6 +2343,7 @@ private:
                                                 switch (mp->key->getId()) {
                                                         case id<Name_t>(): {
                                                                 auto key = _parser.toString(mp->key);
+                                                                checkMetamethod(key, mp->key);
                                                                 _buf << "__"sv << key;
                                                                 auto newKey = toAst<KeyName_t>(clearBuf(), mp->key);
                                                                 newPair->key.set(newKey);
@@ -2309,10 +2387,12 @@ private:
         struct DestructureInfo {
                 std::list<Destructure> destructures;
                 ast_ptr<false, ExpListAssign_t> assignment;
+                bool extraScope = false;
         };
 
         DestructureInfo extractDestructureInfo(ExpListAssign_t* assignment, bool varDefOnly, bool optional) {
                 auto x = assignment;
+                bool extraScope = false;
                 std::list<Destructure> destructs;
                 if (!assignment->action.is<Assign_t>()) return {destructs, nullptr};
                 auto exprs = assignment->expList->exprs.objects();
@@ -2367,6 +2447,7 @@ private:
                                                         auto mvp = static_cast<meta_variable_pair_def_t*>(item);
                                                         auto mp = mvp->pair.get();
                                                         auto name = _parser.toString(mp->name);
+                                                        checkMetamethod(name, mp->name);
                                                         _buf << "__"sv << name << ':' << name;
                                                         auto newPairDef = toAst<normal_pair_def_t>(clearBuf(), item);
                                                         newPairDef->defVal.set(mvp->defVal);
@@ -2381,6 +2462,7 @@ private:
                                                                 switch (mp->key->getId()) {
                                                                         case id<Name_t>(): {
                                                                                 auto key = _parser.toString(mp->key);
+                                                                                checkMetamethod(key, mp->key);
                                                                                 _buf << "__"sv << key;
                                                                                 auto newKey = toAst<KeyName_t>(clearBuf(), mp->key);
                                                                                 newPair->key.set(newKey);
@@ -2406,6 +2488,7 @@ private:
                                                 case id<meta_variable_pair_t>(): {
                                                         auto mp = static_cast<meta_variable_pair_t*>(item);
                                                         auto name = _parser.toString(mp->name);
+                                                        checkMetamethod(name, mp->name);
                                                         _buf << "__"sv << name << ':' << name;
                                                         auto newPairDef = toAst<normal_pair_def_t>(clearBuf(), item);
                                                         subMetaDestruct->values.push_back(newPairDef);
@@ -2418,6 +2501,7 @@ private:
                                                                 switch (mp->key->getId()) {
                                                                         case id<Name_t>(): {
                                                                                 auto key = _parser.toString(mp->key);
+                                                                                checkMetamethod(key, mp->key);
                                                                                 _buf << "__"sv << key;
                                                                                 auto newKey = toAst<KeyName_t>(clearBuf(), mp->key);
                                                                                 newPair->key.set(newKey);
@@ -2462,12 +2546,16 @@ private:
                                 }
                                 valueItems.push_back(*j);
                                 if (!varDefOnly && !subDestruct->values.empty() && !subMetaDestruct->values.empty()) {
-                                        auto objVar = getUnusedName("_obj_"sv);
-                                        addToScope(objVar);
-                                        valueItems.pop_back();
-                                        valueItems.push_back(toAst<Exp_t>(objVar, *j));
-                                        exprs.push_back(valueItems.back());
-                                        values.push_back(*j);
+                                        auto var = singleVariableFrom(*j, false);
+                                        if (var.empty() || !isLocal(var)) {
+                                                auto objVar = getUnusedName("_obj_"sv);
+                                                addToScope(objVar);
+                                                valueItems.pop_back();
+                                                valueItems.push_back(toAst<Exp_t>(objVar, *j));
+                                                exprs.push_back(valueItems.back());
+                                                values.push_back(*j);
+                                                extraScope = true;
+                                        }
                                 }
                                 TableLit_t* tabs[] = {subDestruct.get(), subMetaDestruct.get()};
                                 for (auto tab : tabs) {
@@ -2573,7 +2661,7 @@ private:
                         }
                 }
                 popScope();
-                return {std::move(destructs), newAssignment};
+                return {std::move(destructs), newAssignment, extraScope};
         }
 
         void transformAssignmentCommon(ExpListAssign_t* assignment, str_list& out) {
@@ -5513,6 +5601,7 @@ private:
                                                 throw std::logic_error(_info.errorMessage("too many metatable declarations"sv, mp->name));
                                         }
                                         auto name = _parser.toString(mp->name);
+                                        checkMetamethod(name, mp->name);
                                         _buf << "__"sv << name << ':' << name;
                                         auto newPair = toAst<normal_pair_t>(clearBuf(), item);
                                         metatable->pairs.push_back(newPair);
@@ -5529,6 +5618,7 @@ private:
                                                 switch (mp->key->getId()) {
                                                         case id<Name_t>(): {
                                                                 auto key = _parser.toString(mp->key);
+                                                                checkMetamethod(key, mp->key);
                                                                 _buf << "__"sv << key;
                                                                 auto newKey = toAst<KeyName_t>(clearBuf(), mp->key);
                                                                 newPair->key.set(newKey);
@@ -6739,6 +6829,7 @@ private:
                                 case id<meta_variable_pair_t>(): {
                                         auto mtPair = static_cast<meta_variable_pair_t*>(keyValue);
                                         auto nameStr = _parser.toString(mtPair->name);
+                                        checkMetamethod(nameStr, mtPair->name);
                                         ref.set(toAst<normal_pair_t>("__"s + nameStr + ':' + nameStr, keyValue));
                                         keyValue = ref.get();
                                         break;
@@ -6748,6 +6839,7 @@ private:
                                         auto normal_pair = keyValue->new_ptr<normal_pair_t>();
                                         if (auto name = mtPair->key.as<Name_t>()) {
                                                 auto nameStr = _parser.toString(name);
+                                                checkMetamethod(nameStr, name);
                                                 normal_pair->key.set(toAst<KeyName_t>("__"s + nameStr, keyValue));
                                         } else if (auto str = mtPair->key.as<String_t>()) {
                                                 normal_pair->key.set(newExp(str, str));