namespace isc {
namespace dns {
+/// \brief Tokenizer for parsing DNS master files.
+///
+/// The \c MasterLexer class provides tokenize interfaces for parsing DNS
+/// master files. It understands some special rules of master files as
+/// defined in RFC 1035, such as comments, character escaping, or multi-line
+/// data, and provides the user application with the actual data in a
+/// more convenient form such as a std::string object.
+///
+/// In order to support the $INCLUDE notation, this class is designed to be
+/// able to operate on multiple files or input streams in the nested way.
+/// The \c open() and \c close() methods correspond to the push and pop
+/// operations.
+///
+/// While this class is public, it is less likely to be used by normal
+/// applications; it's mainly expected to be used within this library,
+/// specifically by the \c MasterLoader class and \c Rdata implementation
+/// classes.
class MasterLexer {
public:
class Token; // we define it separately for better readability
+ /// \brief The constructor.
+ ///
+ /// \throw std::bad_alloc Internal resource allocation fails (rare case).
MasterLexer();
+
+ /// \brief The destructor.
+ ///
+ /// It internally closes any remaining input sources.
~MasterLexer();
+
+ /// \brief Open a file and make it the current input source of MasterLexer.
+ ///
+ /// The opened file can be explicitly closed by the \c close() method;
+ /// if \c close() is not called within the lifetime of the \c MasterLexer,
+ /// it will be closed in the destructor.
+ ///
+ /// \throw InvalidParameter filename is NULL
+ /// \throw some_other The specified cannot be opened
+ /// \param filename A non NULL string specifying a master file
void open(const char* filename);
+
+ /// \brief Make the given stream the current input source of MasterLexer.
+ ///
+ /// The caller still holds the ownership of the passed stream; it's the
+ /// caller's responsibility to keep it valid as long as it's used in
+ /// \c MasterLexer or to release any resource for the stream after that.
+ /// The caller can explicitly tell \c MasterLexer to stop using the
+ /// stream by calling the \c close() method.
+ ///
+ /// \param input An input stream object that produces textual
+ /// representation of DNS RRs.
void open(std::istream& input);
+
+ /// \brief Close the most recently opened input source (file or stream).
+ ///
+ /// If it's a file, the opened file will be literally closed.
+ /// If it's a stream, \c MasterLexer will simply release the reference to
+ /// the stream; the caller can assume it will be never used in
+ /// \c MasterLexer thereafter.
+ ///
+ /// This method must not be called when there is no opened source for
+ /// \c MasterLexer. This method is otherwise exception free.
+ ///
+ /// \throw isc::InvalidOperation Called with no opened source.
void close();
+
+ /// \brief Return a name of the current input source name.
+ ///
+ /// If it's a file, it will be the C string given at the corresponding
+ /// \c open() call, that is, its file name. If it's a stream, it will
+ /// be formatted as "stream-%p" where %p is hex representation of the
+ /// address of the stream object.
+ ///
+ /// If there is no opened source at the time of the call, this method
+ /// returns an empty string.
+ ///
+ /// \throw std::bad_alloc Resource allocation failed for string
+ /// construction (rare case)
+ ///
+ /// \return A string representation of the current source (see the
+ /// description)
std::string getSourceName() const;
+
+ /// \brief Return the input source line number.
+ ///
+ /// If there is an opened source, the return value will be a non-0
+ /// integer indicating the line number of the current source where
+ /// the \c MasterLexer is currently working. The expected usage of
+ /// this value is to print a helpful error message when parsing fails
+ /// by specifically identifying the position of the error.
+ ///
+ /// If there is no opened source at the time of the call, this method
+ /// returns 0.
+ ///
+ /// \throw None
+ ///
+ /// \return A string representation of the current source (see the
+ /// description)
size_t getSourceLine() const;
private: