Another constructor for FILE_LINE_READER which enables more consistent file...

Another constructor for FILE_LINE_READER which enables more consistent file open strategies, and only call setvbuf() when the file is at position 0

common/richio.cpp

@@ -89,6 +89,27 @@ void LINE_READER::expandCapacity( unsigned newsize )
 }
 
 
+FILE_LINE_READER::FILE_LINE_READER( const wxString& aFileName,
+            unsigned aStartingLineNumber,
+            unsigned aMaxLineLength ) throw( IO_ERROR ) :
+    LINE_READER( aMaxLineLength ),
+    iOwn( true )
+{
+    fp = wxFopen( aFileName, wxT( "rt" ) );
+    if( !fp )
+    {
+        wxString msg = wxString::Format(
+            _( "Unable to open filename '%s' for reading" ), aFileName.GetData() );
+        THROW_IO_ERROR( msg );
+    }
+
+    setvbuf( fp, NULL, _IOFBF, BUFSIZ * 8 );
+
+    source  = aFileName;
+    lineNum = aStartingLineNumber;
+}
+
+
 FILE_LINE_READER::FILE_LINE_READER( FILE* aFile, const wxString& aFileName,
                     bool doOwn,
                     unsigned aStartingLineNumber,
@@ -97,7 +118,7 @@ FILE_LINE_READER::FILE_LINE_READER( FILE* aFile, const wxString& aFileName,
     iOwn( doOwn ),
     fp( aFile )
 {
-    if( doOwn )
+    if( doOwn && ftell( aFile ) == 0L )
     {
         setvbuf( fp, NULL, _IOFBF, BUFSIZ * 8 );
     }

include/richio.h

@@ -308,6 +308,27 @@ protected:
 
 public:
 
+    /**
+     * Constructor FILE_LINE_READER
+     * takes @a aFileName and the size of the desired line buffer and opens
+     * the file and assumes the obligation to close it.
+     *
+     * @param aFileName is the name of the file to open and to use for error reporting purposes.
+     *
+     * @param aStartingLineNumber is the initial line number to report on error, and is
+     *  accessible here for the case where multiple DSNLEXERs are reading from the
+     *  same file in sequence, all from the same open file (with @a doOwn = false).
+     *  Internally it is incremented by one after each ReadLine(), so the first
+     *  reported line number will always be one greater than what is provided here.
+     *
+     * @param aMaxLineLength is the number of bytes to use in the line buffer.
+     *
+     * @throw IO_ERROR if @a aFileName cannot be opened.
+     */
+    FILE_LINE_READER( const wxString& aFileName,
+            unsigned aStartingLineNumber = 0,
+            unsigned aMaxLineLength = LINE_READER_LINE_DEFAULT_MAX ) throw( IO_ERROR );
+
     /**
      * Constructor FILE_LINE_READER
      * takes an open FILE and the size of the desired line buffer and takes