Add ASTNodeDeclarationCleaner

This removes declaration instructions. These instructions have been used to
build symbol tables are then useless in the AST.

Other instructions could probably be removed but it is future work and probably
not crucial optimization.

src/language/ASTNodeDeclarationCleaner.cpp

+#include <ASTNodeDeclarationCleaner.hpp>
+
+#include <PEGGrammar.hpp>
+#include <PugsAssert.hpp>
+
+#include <stack>
+
+void
+ASTNodeDeclarationCleaner::_removeDeclarationNode(ASTNode& n)
+{
+  std::stack<size_t> declaration_ids;
+  for (size_t i_child = 0; i_child < n.children.size(); ++i_child) {
+    if (n.children[i_child]->is<language::declaration>()) {
+      declaration_ids.push(i_child);
+    }
+  }
+
+  while (declaration_ids.size() > 0) {
+    size_t i_removed = declaration_ids.top();
+    declaration_ids.pop();
+    for (size_t i = i_removed; i + 1 < n.children.size(); ++i) {
+      n.children[i] = std::move(n.children[i + 1]);
+    }
+    n.children.pop_back();
+  }
+
+  for (auto& child : n.children) {
+    this->_removeDeclarationNode(*child);
+  }
+}
+
+ASTNodeDeclarationCleaner::ASTNodeDeclarationCleaner(ASTNode& n)
+{
+  Assert(n.is_root());
+  this->_removeDeclarationNode(n);
+}

src/language/ASTNodeDeclarationCleaner.hpp

+#ifndef AST_NODE_DECLARATION_CLEANER_HPP
+#define AST_NODE_DECLARATION_CLEANER_HPP
+
+#include <ASTNode.hpp>
+
+class ASTNodeDeclarationCleaner
+{
+ private:
+  void _removeDeclarationNode(ASTNode& node);
+
+ public:
+  ASTNodeDeclarationCleaner(ASTNode& root_node);
+};
+
+#endif   // AST_NODE_DECLARATION_CLEANER_HPP

src/language/CMakeLists.txt

@@ -13,6 +13,7 @@ add_library(
   ASTNodeDataTypeBuilder.cpp
   ASTNodeDataTypeChecker.cpp
   ASTNodeDeclarationToAffectationConverter.cpp
+  ASTNodeDeclarationCleaner.cpp
   ASTNodeExpressionBuilder.cpp
   ASTNodeIncDecExpressionBuilder.cpp
   ASTNodeJumpPlacementChecker.cpp

src/language/PugsParser.cpp

@@ -29,6 +29,7 @@
 #include <ASTSymbolInitializationChecker.hpp>
 #include <ASTSymbolTableBuilder.hpp>
 
+#include <ASTNodeDeclarationCleaner.hpp>
 #include <ASTNodeDeclarationToAffectationConverter.hpp>
 
 #include <ASTDotPrinter.hpp>
@@ -72,6 +73,7 @@ parser(const std::string& filename)
 
     // optimizations
     ASTNodeDeclarationToAffectationConverter{*root_node};
+    ASTNodeDeclarationCleaner{*root_node};
 
     language::build_node_type(*root_node);