RE: [Gm2] TextIO.ReadRestLine includes EOL char in string result

[Breeden, Thomas (tmb)]

> From: address@hidden [On Behalf Of SiTex Graphics]

> Not entirely sure this is a bug, but TextIO.ReadRestLine includes the
> EOL char in the string result.  The XDS and Stonybrook implementations
> do not.

It is a bug; ReadRestLine() should not read the EOL or past it.
Verified by pulling out my trusty ISO/IEC 1014-1 document.

ReadRestLine() will return "allRight" if it finds some text before an EOL or 
EOF,
so long as it does not find too much text for the parameter, in which case it 
will
return "outOfRange" (and the excess chars are discarded).

Either way, you need to call SkipLine() to get past the EOL char, which returns 
"allRight",
unless you are positioned past the last EOL char in the file in which case it 
returns
"endOfInput".

ReadRestLine(), however will return "endOfLine" if the line was blank with an 
EOL at the end.
You still have to call SkipLine() to get past that EOL char.

ReadRestLine() will instead return "endOfInput" if you are positioned beyond 
the last EOL char.

At one point I got tired of my mistake prone attempts to rewrite the code for 
reading a file line by line
via TextIO and write the following module  whose procedures return only 
"allRight" or "endOfInput".
It hides all the SkipLines() and necessity for multiple tests on return codes:

--------------------------------------------------------------------------------------------------------------------------------------
    DEFINITION MODULE TextIOHelper;  
   ...
    PROCEDURE ReadNextLine(cid:ChanId; VAR OneLine:ARRAY OF CHAR):ReadResults;
    PROCEDURE ReadNextNonBlankLine(cid:ChanId; VAR OneLine:ARRAY OF CHAR; VAR 
NumSkipped:CARDINAL):ReadResults;

    PROCEDURE dReadNextLine(cid:ChanId; VAR dOneLine:DynStr):ReadResults;
         (* dOneLine must exist or .str be NIL *)
    PROCEDURE dReadNextNonBlankLine(cid:ChanId; VAR dOneLine:DynStr; VAR 
NumSkipped:CARDINAL):ReadResults;

   (*    ReadNextLine  - silently truncates any line that won't fit in the 
OneLine parameter
                     - never returns endOfLine. For empty line returns allRight 
with empty OneLine
                     - endOfInput is returned only on the call AFTER the one 
that returned the
                       last line allRight.

          dReadNextLine - reallocates dOneLine to be larger if necessary.
   *)
--------------------------------------------------------------------------------------------------------------------------------------
 

regards,

Tom
tmb"virginia.edu