Add class plainstring.

It is a simple string class, which automatically manages its buffer, provides assignment, comparison and conversion to char const*.

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@4981 8aca7d54-2c30-db11-9de9-000461428c89

dataobj/loadsave.cc

@@ -10,6 +10,7 @@
 #include "../simversion.h"
 #include "../simmem.h"
 #include "../simdebug.h"
+#include "../utils/plainstring.h"
 #include "loadsave.h"
 
 #include "../utils/simstring.h"
@@ -775,6 +776,19 @@ void loadsave_t::rdwr_str(char* s, size_t const size)
 }
 
 
+void loadsave_t::rdwr_str(plainstring& s)
+{
+	if (is_loading()) {
+		char buf[1024];
+		rdwr_str(buf, lengthof(buf));
+		s = buf;
+	} else {
+		char const* tmp = s.c_str();
+		rdwr_str(tmp);
+	}
+}
+
+
 void loadsave_t::start_tag(const char *tag)
 {
 	if(  is_xml()  ) {

dataobj/loadsave.h

@@ -16,6 +16,8 @@
 
 #define INVALID_RDWR_ID (-1)
 
+class plainstring;
+
 /**
  * loadsave_t:
  *
@@ -106,6 +108,8 @@ class loadsave_t {
 	// s is a buf of size given
 	void rdwr_str(char* s, size_t size);
 
+	void rdwr_str(plainstring&);
+
 	// only meaningful for XML
 	void start_tag( const char *tag );
 	void end_tag( const char *tag );

utils/plainstring.h

@@ -0,0 +1,50 @@
+#ifndef PLAINSTRING_H
+#define PLAINSTRING_H
+
+#include <cstring>
+
+#include "../simtypes.h"
+
+
+class plainstring
+{
+	public:
+		plainstring() : str_() {}
+
+		plainstring(char const* const s) : str_(copy_string(s)) {}
+
+		~plainstring() { delete [] str_; }
+
+		plainstring& operator =(char const* const o)
+		{
+			char* const s = copy_string(o);
+			delete [] str_;
+			str_ = s;
+			return *this;
+		}
+
+		char const* c_str() const { return str_; }
+
+		operator char const*() const { return str_; }
+		operator char*()             { return str_; }
+
+		bool operator ==(char const* const o) const { return str_ && o ? std::strcmp(str_, o) == 0 : str_ == o; }
+		bool operator !=(char const* const o) const { return !(*this == o); }
+
+	private:
+		static char* copy_string(char const* const s)
+		{
+			if (s) {
+				size_t const n = std::strlen(s) + 1;
+				return static_cast<char*>(std::memcpy(new char[n], s, n));
+			} else {
+				return 0;
+			}
+		}
+
+		char* str_;
+};
+
+void free(plainstring const&) DELETED;
+
+#endif