[ragel-users] Ragel falls to infinite loop then actions are specified, and more questions about Ragel and ABNFGEN

[Александр Мартынов]

Hello Ragel-users,


I try to create XML parser using abnfgen tool (http://www.2p.cz/en/abnf_gen/),
which I was found in the "Links" section on Ragel page (http://www.complang.org/ragel/).

1) The main problem is that the Ragel falls to infinite loop, eats all available memory
and cause the system message:

"This application has requested the runtime to terminate it in unusual way.
Please contact the application support team for more information."

when I try to add entering, leavint and "all transitions" actions to some machine.

This machine defines the Xml comment.
In ABNFGEN source I wrote:

ANYCHAREXCEPTMINUS = %x01-2C / %x2C-FF
XmlCommentText = *( (ANYCHAREXCEPTMINUS) / ("-" ANYCHAREXCEPTMINUS) ) ; - "-->"
XmlComment = "<!--" XmlCommentText "-->"

which produces next Ragel code:

ANYCHAREXCEPTMINUS = 0x01..0x2c | 0x2c..0xff;
XmlCommentText = ( ANYCHAREXCEPTMINUS | ( "-" ANYCHAREXCEPTMINUS ) )*;
XmlComment = "<!--" XmlCommentText "-->";

The problem occurs when I try to add entering, leaving and "all transitions"
actions to XmlCommentText (or XmlComment) machine/statement:

XmlCommentText = ( ( ANYCHAREXCEPTMINUS | ( "-" ANYCHAREXCEPTMINUS ) )* ) >pfs_sax_parser_e_XmlCommentText %pfs_sax_parser_l_XmlCommentText $pfs_sax_parser_t_XmlCommentText;
XmlComment = "<!--" XmlCommentText "-->";

In this case the Ragel fails. What I need to do here?

2) Next question is about CData section, whis described in XML definition as:

[18] CDSect ::= CDStart CData CDEnd
[19] CDStart ::= '<![CDATA['
[20] CData ::= (Char* - (Char* ']]>' Char*))
[21] CDEnd ::= ']]>'

I can't understand, how to write BNF to ABNFGEN tool, or rule for Ragel both.

3) The XML Element definition contains itself, and if I wrote exact

XmlElement = XmlEmptyTag | ( XmlStartTag ( XmlCharData? ( ( XmlElement | XmlCommentOrPiOrCDataOrRef ) XmlCharData? )? ) XmlEndTag );

I got the message: graph lookup for 'XmlElement' failed.
I think I need to call submachine XmlElement, but I can't understand
how and where I must do it, and where I need to return from submachine

4) I was find that the Ragel generates invalid code, which can't be compiled with MSVC (but GCC can):

...
if ( p == eof )
{
if ( _abnf_reader_eof_trans[cs] > 0 ) {
_trans = _abnf_reader_eof_trans[cs] - 1;
goto _eof_trans;
}
const char *__acts = _abnf_reader_actions + _abnf_reader_eof_actions[cs]; /* !!! */
unsigned int __nacts = (unsigned int) *__acts++;
while ( __nacts-- > 0 ) {
switch ( *__acts++ ) {
case 5:
...

MSVC fails on line marked with "!!!" with message

error C2143: syntax error : missing ';' before 'const'

I think occurs because variable __acts defined not at the block start, but after if statement.
How this problem can be solved?




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