feat: Added defer keyword

alinalihassan · May 18, 2022 · c1e8e92 · c1e8e92
1 parent b80c074
commit c1e8e92
Show file tree

Hide file tree

Showing 3 changed files with 14 additions and 6 deletions.
diff --git a/src/liblesma/Backend/Codegen.cpp b/src/liblesma/Backend/Codegen.cpp
@@ -441,7 +441,7 @@ void Codegen::visit(FuncDecl *node) {
     FunctionType *FT = FunctionType::get(visit(node->getReturnType()), paramTypes, false);
     Function *F = Function::Create(FT, linkage, name, *TheModule);
 
-    //    deferStack.push({});
+    deferStack.push({});
 
     BasicBlock *BB = BasicBlock::Create(*TheContext, "entry", F);
     Builder->SetInsertPoint(BB);
@@ -459,8 +459,12 @@ void Codegen::visit(FuncDecl *node) {
     }
     visit(node->getBody());
 
-    //    auto instrs = deferStack.top();
-    //    deferStack.pop();
+    auto instrs = deferStack.top();
+    deferStack.pop();
+
+    if (!isReturn)
+        for (auto inst: instrs)
+            visit(inst);
 
     if (visit(node->getReturnType()) == Builder->getVoidTy() && !isReturn)
         Builder->CreateRetVoid();
@@ -606,6 +610,10 @@ void Codegen::visit(Return *node) {
     if (Builder->GetInsertBlock()->getParent() == TopLevelFunc)
         throw CodegenError(node->getSpan(), "Return statements are not allowed at top-level");
 
+    // Execute all defered statements
+    for (auto inst: deferStack.top())
+        visit(inst);
+
     isReturn = true;
     if (node->getValue() == nullptr)
         Builder->CreateRetVoid();
@@ -614,7 +622,7 @@ void Codegen::visit(Return *node) {
 }
 
 void Codegen::visit(Defer *node) {
-    throw CodegenError(node->getSpan(), "Defer functionality unimplemented!");
+    deferStack.top().push_back(node->getStatement());
 }
 
 void Codegen::visit(ExpressionStatement *node) {

diff --git a/src/liblesma/Backend/Codegen.h b/src/liblesma/Backend/Codegen.h
@@ -44,7 +44,7 @@ namespace lesma {
 
         std::stack<llvm::BasicBlock *> breakBlocks;
         std::stack<llvm::BasicBlock *> continueBlocks;
-        std::stack<std::vector<llvm::Value *>> deferStack;
+        std::stack<std::vector<Statement *>> deferStack;
 
         std::vector<std::string> ObjectFiles;
         llvm::Function *TopLevelFunc;

diff --git a/src/liblesma/Frontend/Lexer.cpp b/src/liblesma/Frontend/Lexer.cpp
@@ -370,7 +370,7 @@ Token *Lexer::AddIdentifierToken() {
 
     auto tok = AddToken(Token::GetIdentifierType(std::string(begin_loc.getPointer(), loc.getPointer()), GetLastToken()));
 
-    // If it's an 'else if' multiword keyword, remove the last token (which is an 'else' in this case)
+    // If it's a multi-word keyword, remove the last token
     if (tok->type == TokenType::ELSE_IF || tok->type == TokenType::IS_NOT)
         tokens.pop_back();