Handout

object/stringbuffer.h

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+/*! \file
+ *  \brief \ref Stringbuffer composes single characters into a buffer
+ */
+
+#pragma once
+#include "../types.h"
+
+/*! \brief The class Stringbuffer composes single characters into a longer text
+ * that can be processed on block.
+ *
+ *  To make Stringbuffer as versatile as possible, the class does make
+ *  assumptions about neither the underlying hardware, nor the meaning of
+ *  "processing". When flush() is called (i.e., either on explicit request or
+ *  once the buffer is full). To be hardware independent, flush() is to be
+ *  implemented by the derived classes.
+ *
+ *  \par Hints for Implementation
+ *  Use a buffer of fixed size for caching characters, which should be
+ *  accessible by derived classes.
+ *  Keep in mind that the derived implementation of flush() will need to know
+ *  about numbers of characters in the buffer.
+ *
+ *  \par Notes
+ *  Reason for the existence of this class is that generating longer texts is
+ *  often implemented by assembly of small fragments (such as single characters
+ *  or numbers).
+ *  However, writing such small fragments directly to (for example) screen is
+ *  quite inefficient (e.g., due to the use of IO ports, syscalls, or locks) and
+ *  can be improved drastically by delaying the output step until the assembly
+ *  is finished (or the buffer runs full).
+ */
+class Stringbuffer {
+  // Prevent copies and assignments
+  Stringbuffer(const Stringbuffer&) = delete;
+  Stringbuffer& operator=(const Stringbuffer&) = delete;
+
+  // All variables and methods are protected in this class,
+  // as the derived classes need direct access to be buffer,
+  // the constructor, the destructor, and the method put.
+  // flush() is to be implemented either way and may be redefined
+  // as public.
+
+ protected:
+  /*! \brief Constructor; Marks the buffer as empty
+   */
+  Stringbuffer() {}
+
+  /*! \brief Inserts a character into the buffer.
+   *
+   *  Once the buffer is full, a call to flush() will be issued and
+   *  thereby clearing the buffer.
+   *
+   *  \param c Char to be added
+   *
+   *  \todo(11) Implement
+   */
+  void put(char c);
+
+  /*! \brief Flush the buffer contents
+   *
+   *  This method is to be defined in derived classes, as only those know
+   *  how to print characters.
+   *  flush() is required to reset the position pos.
+   */
+  virtual void flush() = 0;
+
+ public:
+  /*! \brief Destructor (nothing to do here)
+   */
+  virtual ~Stringbuffer() {}
+};