Flex is backing up forever in the specific rule

Lavrentiy Ivanov <[email protected]> Fri, 17 Oct 2014 18:51:42 +0400
Newsgroups	gmane.comp.lex.flex.general
Message-ID	<[email protected]>
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My parser is for assembler, here is lex and bison files just in case

https://bitbucket.org/Pugnator/zcore/src/28c783d1f860c001faed2b44076d3fbc83b42c6f/src/macroasm/z80.lex?at=asm

https://bitbucket.org/Pugnator/zcore/src/28c783d1f860c001faed2b44076d3fbc83b42c6f/src/macroasm/asm.y?at=asm

in this example all works like a charm:

|nop
nop
nop
|

Here is debug output

|--accepting rule at line 154 ("nop")
--accepting rule at line 248 ("
")
--accepting rule at line 154 ("nop")
--accepting rule at line 248 ("
")
--accepting rule at line 154 ("nop")
--accepting rule at line 248 ("
")
--(end of buffer or a NUL)
--accepting rule at line 248 ("
")
--(end of buffer or a NUL)
--EOF (start condition 0)
|

The problem raise when I try to parse this code (rule is at line 255 in 
lex file)

|DEFB    '?'+$80
DEFM    "RN"
DEFB    'D'+$80
|

It backs up forever and looks like it can't reach newline (I have a rule 
for it). I generated backup file

http://pastebin.com/UW8zct3h

from flex, but can't understand how to use it in order to find the root 
cause.

|--accepting rule at line 255 ("DEFB")
--accepting rule at line 280 (" ")
--accepting rule at line 280 (" ")
--accepting rule at line 280 (" ")
--accepting rule at line 280 (" ")
--(end of buffer or a NUL)
--scanner backing up
--accepting rule at line 105 ("'?'")
--accepting rule at line 233 ("+")
--accepting rule at line 56 ("$80")
|


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    <div class="post-text" itemprop="text">
      <p>My parser is for assembler, here is lex and bison files just in
        case<br>
      </p>
      <p><a class="moz-txt-link-freetext" href="https://bitbucket.org/Pugnator/zcore/src/28c783d1f860c001faed2b44076d3fbc83b42c6f/src/macroasm/z80.lex?at=asm">https://bitbucket.org/Pugnator/zcore/src/28c783d1f860c001faed2b44076d3fbc83b42c6f/src/macroasm/z80.lex?at=asm</a><br>
      </p>
      <p><a class="moz-txt-link-freetext" href="https://bitbucket.org/Pugnator/zcore/src/28c783d1f860c001faed2b44076d3fbc83b42c6f/src/macroasm/asm.y?at=asm">https://bitbucket.org/Pugnator/zcore/src/28c783d1f860c001faed2b44076d3fbc83b42c6f/src/macroasm/asm.y?at=asm</a><br>
      </p>
      <p>in this example all works like a charm:</p>
      <pre><code>nop
nop
nop
</code></pre>
      <p>Here is debug output</p>
      <pre><code>--accepting rule at line 154 ("nop")
--accepting rule at line 248 ("
")
--accepting rule at line 154 ("nop")
--accepting rule at line 248 ("
")
--accepting rule at line 154 ("nop")
--accepting rule at line 248 ("
")
--(end of buffer or a NUL)
--accepting rule at line 248 ("
")
--(end of buffer or a NUL)
--EOF (start condition 0)
</code></pre>
      <p>The problem raise when I try to parse this code (rule is at
        line 255 in lex file)</p>
      <pre><code>DEFB    '?'+$80
DEFM    "RN"
DEFB    'D'+$80
</code></pre>
      <p>It backs up forever and looks like it can't reach newline (I
        have a rule for it).
        I generated backup file<br>
      </p>
      <p><a class="moz-txt-link-freetext" href="http://pastebin.com/UW8zct3h">http://pastebin.com/UW8zct3h</a></p>
      <p>from flex, but can't understand how to use it in order to find
        the root cause.</p>
      <pre><code>--accepting rule at line 255 ("DEFB")
--accepting rule at line 280 (" ")
--accepting rule at line 280 (" ")
--accepting rule at line 280 (" ")
--accepting rule at line 280 (" ")
--(end of buffer or a NUL)
--scanner backing up
--accepting rule at line 105 ("'?'")
--accepting rule at line 233 ("+")
--accepting rule at line 56 ("$80")
</code></pre>
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