[2375] Don't propagate exceptions from internal namespace

Move the ReadError exception into the MasterLexer. That way, it is in
public namespace, so people can expect to see it.

src/lib/dns/master_lexer.h

@@ -69,6 +69,14 @@ class State;
 class MasterLexer {
     friend class master_lexer_internal::State;
 public:
+    /// \brief Exception thrown when we fail to read from the input
+    /// stream or file.
+    struct ReadError : public Unexpected {
+        ReadError(const char* file, size_t line, const char* what) :
+            Unexpected(file, line, what)
+        {}
+    };
+
     class Token;       // we define it separately for better readability
 
     /// \brief Options for getNextToken.
@@ -198,9 +206,8 @@ public:
     /// \throw isc::InvalidOperation in case the source is not available. This
     ///     may mean the pushSource() has not been called yet, or that the
     ///     current source has been read past the end.
-    /// \throw isc::master_lexer_internal::InputSource::ReadError in case
-    ///     there's problem reading from the underlying source (eg. I/O error
-    ///     in the file on the disk).
+    /// \throw ReadError in case there's problem reading from the underlying
+    ///     source (eg. I/O error in the file on the disk).
     /// \throw std::bad_alloc in case allocation of some internal resources
     ///     or the token fail.
     Token getNextToken(Options options = NONE);

src/lib/dns/master_lexer_inputsource.cc

@@ -13,6 +13,7 @@
 // PERFORMANCE OF THIS SOFTWARE.
 
 #include <dns/master_lexer_inputsource.h>
+#include <dns/master_lexer.h>
 
 #include <cerrno>
 #include <cstring>
@@ -94,7 +95,7 @@ InputSource::getChar() {
         // This has to come after the .eof() check as some
         // implementations seem to check the eofbit also in .fail().
         if (input_.fail()) {
-            isc_throw(ReadError,
+            isc_throw(MasterLexer::ReadError,
                       "Error reading from the input stream: " << getName());
         }
         buffer_.push_back(c);

src/lib/dns/master_lexer_inputsource.h

@@ -56,14 +56,6 @@ public:
         {}
     };
 
-    /// \brief Exception thrown when we fail to read from the input
-    /// stream or file.
-    struct ReadError : public Unexpected {
-        ReadError(const char* file, size_t line, const char* what) :
-            Unexpected(file, line, what)
-        {}
-    };
-
     /// \brief Exception thrown when we fail to open the input file.
     struct OpenError : public Unexpected {
         OpenError(const char* file, size_t line, const char* what) :
@@ -124,8 +116,8 @@ public:
     /// \brief Returns a single character from the input source. If end
     /// of file is reached, \c END_OF_STREAM is returned.
     ///
-    /// \throws ReadError when reading from the input stream or file
-    /// fails.
+    /// \throws MasterLexer::ReadError when reading from the input stream or
+    /// file fails.
     int getChar();
 
     /// \brief Skips backward a single character in the input

src/lib/dns/master_lexer_state.h

@@ -69,7 +69,7 @@ public:
     /// tokenization session.  The lexer passes a reference to itself
     /// and options given in \c getNextToken().
     ///
-    /// \throw InputSource::ReadError Unexpected I/O error
+    /// \throw MasterLexer::ReadError Unexpected I/O error
     /// \throw std::bad_alloc Internal resource allocation failure
     ///
     /// \param lexer The lexer object that holds the main context.
@@ -85,7 +85,7 @@ public:
     /// start(), and keep called on the returned object until NULL is
     /// returned.  The call chain will form the complete state transition.
     ///
-    /// \throw InputSource::ReadError Unexpected I/O error
+    /// \throw MasterLexer::ReadError Unexpected I/O error
     /// \throw std::bad_alloc Internal resource allocation failure
     ///
     /// \param lexer The lexer object that holds the main context.