Repo created

libs/base/visitor.hpp

@@ -0,0 +1,63 @@
+#pragma once
+
+#include <sstream>
+#include <string>
+
+class DebugPrintVisitor
+{
+public:
+  DebugPrintVisitor(std::string const & name) : m_name(name) {}
+
+  template <typename T>
+  void operator()(T const & t, char const * name = nullptr)
+  {
+    if (!m_empty)
+      m_os << ", ";
+    m_empty = false;
+
+    if (name)
+      m_os << name << ": ";
+    m_os << DebugPrint(t);
+  }
+
+  // This override is implemented to support deserialization with optional values
+  // which could be declared by DECLARE_VISITOR_AND_DEBUG_PRINT macro.
+  // Because of this class is used just for serialize structures into strings,
+  // the second parameter is used for method signature compatibility only.
+  template <typename T>
+  void operator()(T const & t, T const &, char const * name = nullptr)
+  {
+    operator()(t, name);
+  }
+
+  std::string ToString() const { return m_name + " [" + m_os.str() + "]"; }
+
+private:
+  std::string m_name;
+  bool m_empty = true;
+  std::ostringstream m_os;
+};
+
+#define DECLARE_VISITOR(...)          \
+  template <typename Visitor>         \
+  void Visit(Visitor & visitor)       \
+  {                                   \
+    __VA_ARGS__;                      \
+  }                                   \
+  template <typename Visitor>         \
+  void Visit(Visitor & visitor) const \
+  {                                   \
+    __VA_ARGS__;                      \
+  }
+
+#define DECLARE_DEBUG_PRINT(className)               \
+  friend std::string DebugPrint(className const & c) \
+  {                                                  \
+    DebugPrintVisitor visitor(#className);           \
+    c.Visit(visitor);                                \
+    return visitor.ToString();                       \
+  }
+
+#define DECLARE_VISITOR_AND_DEBUG_PRINT(className, ...) \
+  DECLARE_VISITOR(__VA_ARGS__)                          \
+  DECLARE_DEBUG_PRINT(className)