Refactored op<< for Metadatum, introduced std::string Metadatum::print(). Fixes #474.

src/exif.cpp

@@ -111,6 +111,11 @@ namespace Exiv2 {
         if (rhs.value_.get() != 0) value_ = rhs.value_->clone(); // deep copy
     }
 
+    std::ostream& Exifdatum::write(std::ostream& os) const
+    {
+        return ExifTags::printTag(os, tag(), ifdId(), value());
+    }
+
     const Value& Exifdatum::value() const
     {
         if (value_.get() == 0) throw Error(8);
@@ -1281,10 +1286,6 @@ namespace Exiv2 {
         makerNote->add(e);
     } // addToMakerNote
 
-    std::ostream& operator<<(std::ostream& os, const Exifdatum& md)
-    {
-        return ExifTags::printTag(os, md.tag(), md.ifdId(), md.value());
-    }
 }                                       // namespace Exiv2
 
 // *****************************************************************************

src/exif.hpp

@@ -66,7 +66,6 @@ namespace Exiv2 {
              an ExifKey and a Value and provides methods to manipulate these.
      */
     class Exifdatum : public Metadatum {
-        friend std::ostream& operator<<(std::ostream&, const Exifdatum&);
         template<typename T> friend Exifdatum& setValue(Exifdatum&, const T&);
     public:
         //! @name Creators
@@ -202,6 +201,7 @@ namespace Exiv2 {
         */
         long copy(byte* buf, ByteOrder byteOrder) const
             { return value_.get() == 0 ? 0 : value_->copy(buf, byteOrder); }
+        std::ostream& write(std::ostream& os) const;
         //! Return the type id of the value
         TypeId typeId() const
             { return value_.get() == 0 ? invalidTypeId : value_->typeId(); }
@@ -257,12 +257,6 @@ namespace Exiv2 {
 
     }; // class Exifdatum
 
-    /*!
-      @brief Output operator for Exifdatum types, prints the interpreted
-             tag value.
-     */
-    std::ostream& operator<<(std::ostream& os, const Exifdatum& md);
-
     /*!
       @brief Set the value of \em exifDatum to \em value. If the object already
              has a value, it is replaced. Otherwise a new ValueType\<T\> value

src/iptc.cpp

@@ -63,6 +63,11 @@ namespace Exiv2 {
     {
     }
 
+    std::ostream& Iptcdatum::write(std::ostream& os) const
+    {
+        return os << value();
+    }
+
     const Value& Iptcdatum::value() const
     {
         if (value_.get() == 0) throw Error(8);
@@ -323,11 +328,4 @@ namespace Exiv2 {
         return iptcMetadata_.erase(pos);
     }
 
-    // *************************************************************************
-    // free functions
-    std::ostream& operator<<(std::ostream& os, const Iptcdatum& md)
-    {
-        return os << md.value();
-    }
-
 }                                       // namespace Exiv2

src/iptc.hpp

@@ -111,6 +111,7 @@ namespace Exiv2 {
         //@{
         long copy(byte* buf, ByteOrder byteOrder) const
             { return value_.get() == 0 ? 0 : value_->copy(buf, byteOrder); }
+        std::ostream& write(std::ostream& os) const;
         /*!
           @brief Return the key of the Iptcdatum. The key is of the form
                  '<b>Iptc</b>.recordName.datasetName'. Note however that the key
@@ -169,12 +170,6 @@ namespace Exiv2 {
 
     }; // class Iptcdatum
 
-    /*!
-      @brief Output operator for Iptcdatum types, printing the interpreted
-             tag value.
-     */
-    std::ostream& operator<<(std::ostream& os, const Iptcdatum& md);
-
     //! Container type to hold all metadata
     typedef std::vector<Iptcdatum> IptcMetadata;
 

src/metadatum.cpp

@@ -70,17 +70,11 @@ namespace Exiv2 {
         return *this;
     }
 
-    std::ostream& operator<<(std::ostream& os, const Metadatum& md)
+    std::string Metadatum::print() const
     {
-        os << "0x" << std::setw(4) << std::setfill('0') << std::right
-                  << std::hex << md.tag() << " "
-                  << std::setw(40) << std::setfill(' ') << std::left
-                  << md.key() << " "
-                  << std::setw(9) << std::setfill(' ') << std::left
-                  << md.typeName() << " "
-                  << std::dec << md.value()
-                  << "\n";
-        return os;
+        std::ostringstream os;
+        write(os);
+        return os.str();
     }
 
     bool cmpMetadataByTag(const Metadatum& lhs, const Metadatum& rhs)

src/metadatum.hpp

@@ -154,6 +154,12 @@ namespace Exiv2 {
 
         //! @name Accessors
         //@{
+        /*!
+          @brief Write the interpreted value to a string.
+
+          Implemented in terms of std::ostream& write(std::ostream& os).
+         */
+        std::string print() const;
         /*!
           @brief Write value to a data buffer and return the number
                  of bytes written.
@@ -166,6 +172,17 @@ namespace Exiv2 {
           @return Number of characters written.
         */
         virtual long copy(byte* buf, ByteOrder byteOrder) const =0;
+        /*!
+          @brief Write the interpreted value to an output stream, return
+                 the stream.
+
+          You do not usually have to use this function; it is used for the
+          implementation of the output operator for %Metadatum,
+          operator<<(std::ostream &os, const Metadatum &md). See also
+          std::string print() const, which prints the interpreted value
+          to a string.
+         */
+        virtual std::ostream& write(std::ostream& os) const =0;
         /*!
           @brief Return the key of the metadatum. The key is of the form
                  'familyName.ifdItem.tagName'. Note however that the key
@@ -280,12 +297,15 @@ namespace Exiv2 {
 
     }; // class FindMetadatumByTag
 
-
     /*!
-      @brief Output operator for Metadatum types, printing the interpreted
+      @brief Output operator for Metadatum types, writing the interpreted
              tag value.
      */
-    std::ostream& operator<<(std::ostream& os, const Metadatum& md);
+    inline std::ostream& operator<<(std::ostream& os, const Metadatum& md)
+    {
+        return md.write(os);
+    }
+
     /*!
       @brief Compare two metadata by tag. Return true if the tag of metadatum
              lhs is less than that of rhs.

src/xmp.cpp

@@ -246,6 +246,11 @@ namespace Exiv2 {
         return 0;
     }
 
+    std::ostream& Xmpdatum::write(std::ostream& os) const
+    {
+        return XmpProperties::printProperty(os, key(), value());
+    }
+
     Xmpdatum& Xmpdatum::operator=(const std::string& value)
     {
         setValue(value);
@@ -665,14 +670,6 @@ namespace Exiv2 {
     } // XmpParser::encode
 #endif // !EXV_HAVE_XMP_TOOLKIT
 
-    // *************************************************************************
-    // free functions
-
-    std::ostream& operator<<(std::ostream& os, const Xmpdatum& md)
-    {
-        return XmpProperties::printProperty(os, md.key(), md.value());
-    }
-
 }                                       // namespace Exiv2
 
 // *****************************************************************************

src/xmp.hpp

@@ -120,6 +120,7 @@ namespace Exiv2 {
         //@{
         //! Not implemented. Calling this method will raise an exception.
         long copy(byte* buf, ByteOrder byteOrder) const;
+        std::ostream& write(std::ostream& os) const;
         /*!
           @brief Return the key of the Xmpdatum. The key is of the form
                  '<b>Xmp</b>.prefix.property'. Note however that the
@@ -157,12 +158,6 @@ namespace Exiv2 {
 
     }; // class Xmpdatum
 
-    /*!
-      @brief Output operator for Xmpdatum types, printing the interpreted
-             tag value.
-     */
-    std::ostream& operator<<(std::ostream& os, const Xmpdatum& md);
-
     //! Container type to hold all metadata
     typedef std::vector<Xmpdatum> XmpMetadata;