Continue preparation of function evaluation

Function table is now populated and FunctionDescriptor is no more an inner class
of FunctionTable.

BTW fixed few warnings

src/language/ASTSymbolTableBuilder.cpp

@@ -29,6 +29,10 @@ ASTSymbolTableBuilder::buildSymbolTable(ASTNode& n, std::shared_ptr<SymbolTable>
     for (auto& child : n.children) {
       this->buildSymbolTable(*child, local_symbol_table);
     }
+
+    size_t function_id             = symbol_table->functionTable()->add(FunctionDescriptor{});
+    i_symbol->attributes().value() = function_id;
+
   } else {
     n.m_symbol_table = symbol_table;
     if (n.has_content()) {

src/language/FunctionTable.hpp

@@ -12,22 +12,25 @@
 
 #include <iostream>
 
-class FunctionTable
-{
 class FunctionDescriptor
 {
   std::unique_ptr<ASTNode> m_domain_mapping_node;
   std::unique_ptr<ASTNode> m_expression_node;
 
  public:
-    FunctionDescriptor& operator=(const FunctionDescriptor&) = default;
   FunctionDescriptor& operator=(FunctionDescriptor&&) = default;
 
+  FunctionDescriptor(std::unique_ptr<ASTNode>&& domain_mapping_node, std::unique_ptr<ASTNode>&& expression_node)
+    : m_domain_mapping_node(std::move(domain_mapping_node)), m_expression_node(std::move(expression_node))
+  {}
+
   FunctionDescriptor(FunctionDescriptor&&) = default;
   FunctionDescriptor()                     = default;
   ~FunctionDescriptor()                    = default;
 };
 
+class FunctionTable
+{
  private:
   std::vector<FunctionDescriptor> m_function_descriptor_list;
 

src/language/SymbolTable.hpp

@@ -70,6 +70,9 @@ class SymbolTable
     friend std::ostream&
     operator<<(std::ostream& os, const Attributes& attributes)
     {
+      if (attributes.m_data_type == ASTNodeDataType::function_t) {
+        os << "function_id:";
+      }
       std::visit(
         [&](const auto& value) {
           using T = std::decay_t<decltype(value)>;
@@ -124,7 +127,6 @@ class SymbolTable
 
     Symbol(const Symbol&) = default;
     Symbol(Symbol&&)      = default;
-    Symbol()              = default;
     ~Symbol()             = default;
   };
 
@@ -134,6 +136,12 @@ class SymbolTable
   std::shared_ptr<FunctionTable> m_function_table;
 
  public:
+  auto
+  functionTable() const
+  {
+    return m_function_table;
+  }
+
   friend std::ostream&
   operator<<(std::ostream& os, const SymbolTable& symbol_table)
   {