1 files changed, 96 insertions, 8 deletions

diff --git a/src/MoonP/moon_compiler.cpp b/src/MoonP/moon_compiler.cpp
index 73bbd60..11d4ed8 100644
--- a/src/MoonP/moon_compiler.cpp
+++ b/src/MoonP/moon_compiler.cpp
@@ -53,7 +53,7 @@ inline std::string s(std::string_view sv) {
         return std::string(sv);
 }
 
-const std::string_view version = "0.5.2"sv;
+const std::string_view version = "0.6.0"sv;
 const std::string_view extension = "mp"sv;
 
 class MoonCompilerImpl {
@@ -429,7 +429,7 @@ private:
                 return result;
         }
 
-        Value_t* singleValueFrom(ast_node* item) const {
+        unary_exp_t* singleUnaryExpFrom(ast_node* item) const {
                 Exp_t* exp = nullptr;
                 switch (item->getId()) {
                         case id<Exp_t>():
@@ -451,8 +451,8 @@ private:
                         }
                         case id<unary_exp_t>(): {
                                 auto unary = static_cast<unary_exp_t*>(item);
-                                if (unary->ops.empty() && unary->expos.size() == 1) {
-                                        return static_cast<Value_t*>(unary->expos.back());
+                                if (unary->expos.size() == 1) {
+                                        return unary;
                                 }
                                 return nullptr;
                         }
@@ -463,13 +463,21 @@ private:
                 BREAK_IF(!exp->opValues.empty());
                 BREAK_IF(exp->backcalls.size() != 1);
                 auto unary = static_cast<unary_exp_t*>(exp->backcalls.back());
-                BREAK_IF(!unary->ops.empty());
                 BREAK_IF(unary->expos.size() != 1);
-                return static_cast<Value_t*>(unary->expos.back());
+                return unary;
                 BLOCK_END
                 return nullptr;
         }
 
+        Value_t* singleValueFrom(ast_node* item) const {
+                if (auto unary = singleUnaryExpFrom(item)) {
+                        if (unary->ops.empty()) {
+                                return static_cast<Value_t*>(unary->expos.back());
+                        }
+                }
+                return nullptr;
+        }
+
         ast_ptr<false, Exp_t> newExp(Value_t* value, ast_node* x) {
                 auto unary = x->new_ptr<unary_exp_t>();
                 unary->expos.push_back(value);
@@ -522,6 +530,60 @@ private:
                 return stmts.empty() ? nullptr : static_cast<Statement_t*>(stmts.back());
         }
 
+        Exp_t* lastExpFromAssign(ast_node* action) {
+                switch (action->getId()) {
+                        case id<Update_t>(): {
+                                auto update = static_cast<Update_t*>(action);
+                                return update->value;
+                        }
+                        case id<Assign_t>(): {
+                                auto assign = static_cast<Assign_t*>(action);
+                                return ast_cast<Exp_t>(assign->values.back());
+                        }
+                }
+                return nullptr;
+        }
+
+        Exp_t* lastExpFromStatement(Statement_t* stmt) {
+                if (!stmt->content) return nullptr;
+                switch (stmt->content->getId()) {
+                        case id<ExpListAssign_t>(): {
+                                auto expListAssign = static_cast<ExpListAssign_t*>(stmt->content.get());
+                                if (auto action = expListAssign->action.get()) {
+                                        return lastExpFromAssign(action);
+                                } else {
+                                        return static_cast<Exp_t*>(expListAssign->expList->exprs.back());
+                                }
+                        }
+                        case id<Export_t>(): {
+                                auto exportNode = static_cast<Export_t*>(stmt->content.get());
+                                if (auto action = exportNode->assign.get()) {
+                                        return lastExpFromAssign(action);
+                                } else {
+                                        switch (exportNode->target->getId()) {
+                                                case id<Exp_t>(): return exportNode->target.to<Exp_t>();
+                                                case id<ExpList_t>(): return static_cast<Exp_t*>(exportNode->target.to<ExpList_t>()->exprs.back());
+                                        }
+                                }
+                        }
+                        case id<Local_t>(): {
+                                if (auto localValues = static_cast<Local_t*>(stmt->content.get())->item.as<local_values_t>()) {
+                                        if (auto expList = localValues->valueList.as<ExpListLow_t>()) {
+                                                return static_cast<Exp_t*>(expList->exprs.back());
+                                        }
+                                }
+                        }
+                        case id<Global_t>(): {
+                                if (auto globalValues = static_cast<Global_t*>(stmt->content.get())->item.as<global_values_t>()) {
+                                        if (auto expList = globalValues->valueList.as<ExpListLow_t>()) {
+                                                return static_cast<Exp_t*>(expList->exprs.back());
+                                        }
+                                }
+                        }
+                }
+                return nullptr;
+        }
+
         template <class T>
         ast_ptr<false, T> toAst(std::string_view codes, ast_node* parent) {
                 auto res = _parser.parse<T>(s(codes));
@@ -812,6 +874,7 @@ private:
                         case id<Label_t>(): transformLabel(static_cast<Label_t*>(content), out); break;
                         case id<Goto_t>(): transformGoto(static_cast<Goto_t*>(content), out); break;
                         case id<LocalAttrib_t>(): transformLocalAttrib(static_cast<LocalAttrib_t*>(content), out); break;
+                        case id<BackcallBody_t>(): throw std::logic_error(_info.errorMessage("backcall chain must be following a value"sv, x)); break;
                         case id<ExpListAssign_t>(): {
                                 auto expListAssign = static_cast<ExpListAssign_t*>(content);
                                 if (expListAssign->action) {
@@ -1692,7 +1755,10 @@ private:
                         auto begin = values.begin(); begin++;
                         for (auto it = begin; it != values.end(); ++it) {
                                 auto unary = static_cast<unary_exp_t*>(*it);
-                                auto value = singleValueFrom(unary);
+                                auto value = static_cast<Value_t*>(singleUnaryExpFrom(unary) ? unary->expos.back() : nullptr);
+                                if (values.back() == *it && !unary->ops.empty() && usage == ExpUsage::Common) {
+                                        throw std::logic_error(_info.errorMessage("expression list is not supported here"sv, x));
+                                }
                                 if (!value) throw std::logic_error(_info.errorMessage("backcall operator must be followed by chain value"sv, *it));
                                 if (auto chainValue = value->item.as<ChainValue_t>()) {
                                         if (isChainValueCall(chainValue)) {
@@ -1936,7 +2002,29 @@ private:
                 for (auto it = nodes.begin(); it != nodes.end(); ++it) {
                         auto node = *it;
                         auto stmt = static_cast<Statement_t*>(node);
-                        if (auto backcall = stmt->content.as<Backcall_t>()) {
+                        if (auto backcallBody = stmt->content.as<BackcallBody_t>()) {
+                                auto x = stmt;
+                                bool cond = false;
+                                BLOCK_START
+                                BREAK_IF(it == nodes.begin());
+                                auto last = it; --last;
+                                auto lst = static_cast<Statement_t*>(*last);
+                                auto exp = lastExpFromStatement(lst);
+                                BREAK_IF(!exp);
+                                for (auto val : backcallBody->values.objects()) {
+                                        exp->backcalls.push_back(val);
+                                }
+                                cond = true;
+                                BLOCK_END
+                                if (!cond) throw std::logic_error(_info.errorMessage("backcall chain must be following a value"sv, x));
+                                stmt->content.set(nullptr);
+                                auto next = it; ++next;
+                                BLOCK_START
+                                BREAK_IF(next == nodes.end());
+                                BREAK_IF(!static_cast<Statement_t*>(*next)->content.as<BackcallBody_t>());
+                                throw std::logic_error(_info.errorMessage("indent mismatch in backcall chain"sv, *next));
+                                BLOCK_END
+                        } else if (auto backcall = stmt->content.as<Backcall_t>()) {
                                 auto x = *nodes.begin();
                                 auto newBlock = x->new_ptr<Block_t>();
                                 if (it != nodes.begin()) {