Compiler: Implement if statements

Author: adazem009

src/dev/engine/compiler.cpp

@@ -39,6 +39,8 @@ std::shared_ptr<libscratchcpp::Block> Compiler::block() const
 std::shared_ptr<ExecutableCode> Compiler::compile(std::shared_ptr<Block> startBlock)
 {
     impl->builder = impl->builderFactory->create(startBlock->id());
+    impl->substackTree.clear();
+    impl->substackHit = false;
     impl->warp = false;
     impl->block = startBlock;
 
@@ -52,10 +54,13 @@ std::shared_ptr<ExecutableCode> Compiler::compile(std::shared_ptr<Block> startBl
             impl->unsupportedBlocks.insert(impl->block->opcode());
         }
 
-        if (substacks != impl->substackTree.size())
+        if (impl->substackHit) {
+            impl->substackHit = false;
             continue;
+        }
 
-        impl->block = impl->block->next();
+        if (impl->block)
+            impl->block = impl->block->next();
 
         if (!impl->block && !impl->substackTree.empty())
             impl->substackEnd();
@@ -100,18 +105,25 @@ void Compiler::addInput(const std::string &name)
 /*! Jumps to the given if substack. */
 void Compiler::moveToIf(std::shared_ptr<Block> substack)
 {
+    if (!substack)
+        return; // ignore empty if statements
+
+    impl->substackHit = true;
     impl->substackTree.push_back({ { impl->block, nullptr }, CompilerPrivate::SubstackType::IfStatement });
     impl->block = substack;
-
-    if (!impl->block)
-        impl->substackEnd();
+    impl->builder->beginIfStatement();
 }
 
 /*! Jumps to the given if/else substack. The second substack is used for the else branch. */
 void Compiler::moveToIfElse(std::shared_ptr<Block> substack1, std::shared_ptr<Block> substack2)
 {
+    if (!substack1 && !substack2)
+        return; // ignore empty if statements
+
+    impl->substackHit = true;
     impl->substackTree.push_back({ { impl->block, substack2 }, CompilerPrivate::SubstackType::IfStatement });
     impl->block = substack1;
+    impl->builder->beginIfStatement();
 
     if (!impl->block)
         impl->substackEnd();
@@ -120,6 +132,7 @@ void Compiler::moveToIfElse(std::shared_ptr<Block> substack1, std::shared_ptr<Bl
 /*! Jumps to the given loop substack. */
 void Compiler::moveToLoop(std::shared_ptr<Block> substack)
 {
+    impl->substackHit = true;
     impl->substackTree.push_back({ { impl->block, nullptr }, CompilerPrivate::SubstackType::Loop });
     impl->block = substack;
 

src/dev/engine/compiler_p.cpp

@@ -19,7 +19,7 @@ CompilerPrivate::CompilerPrivate(IEngine *engine, Target *target) :
 
 void CompilerPrivate::substackEnd()
 {
-    auto parent = substackTree.back();
+    auto &parent = substackTree.back();
 
     switch (parent.second) {
         case SubstackType::Loop:

src/dev/engine/compiler_p.h

@@ -32,6 +32,7 @@ struct CompilerPrivate
 
         std::shared_ptr<Block> block;
         std::vector<std::pair<std::pair<std::shared_ptr<Block>, std::shared_ptr<Block>>, SubstackType>> substackTree;
+        bool substackHit = false;
         bool warp = false;
 
         static inline ICodeBuilderFactory *builderFactory = nullptr;