Re: Parse library
From: Justin Rogers (Justin_at_games4dotnet.com)
Date: 05/16/04
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Date: Sun, 16 May 2004 02:35:00 -0700
I won't add the IP change to the base code that I've already written, but you
can
special case the Value state code-path. Currently the Value state code-path
does:
Eat -> Assignment
Eat -> Value
Eat -> StatementTerminator
In order to enter this state we have to process an ID. As long as your period
isn't
a breaking character, then the IP address will come out as an identifier, if it
is not
placed within quotes (stringized). So you could have the following:
forwarders { 192.168.0.1; 192.168.0.2; }
Now, changes to the code-base would be that if assignment isn't found then look
for
the StatementTerminator immediately. Something like (not really something like,
probably
exactly like) the following.
} else {
Console.WriteLine("Executing Parser Loop: Processing Value
Start");
// Not starting a nesting? We must be a value;
string value = null;
int scanAssignment = ScanIgnoreWhitespace(TokenType.Assignment,
scanId + 1, typedTokens);
if ( scanAssignment > -1 ) {
// No longer an error here
Console.WriteLine("Executing Parser Loop: Scanned
Assignment");
int idOrString = ScanIdOrString(scanAssignment + 1,
typedTokens);
if ( idOrString == -1 ) {
// Error
break;
}
Console.WriteLine("Executing Parser Loop: Scanned ID Or
String");
int valueTerminator = -1;
value = string.Empty;
if ( typedTokens[idOrString].TokenType ==
TokenType.StringDelimiter ) {
Console.WriteLine("Executing Parser Loop: Building Value
>From String");
// We need to build a string now
valueTerminator = ScanString(idOrString + 1,
typedTokens);
if ( valueTerminator == -1 ) {
// Error
break;
}
for(int concat = idOrString + 1; concat <
valueTerminator; concat++) {
value += typedTokens[concat].Token.TokenData;
}
} else {
Console.WriteLine("Executing Parser Loop: Building Value
>From ID");
valueTerminator = idOrString;
value = typedTokens[valueTerminator].Token.TokenData;
}
Console.WriteLine("Executing Parser Loop: Our Value {0}",
value);
}
int endStatement =
ScanIgnoreWhitespace(TokenType.StatementTerminator, valueTerminator + 1,
typedTokens);
if ( endStatement == -1 ) {
// Error
break;
}
Console.WriteLine("Executing Parser Loop: Scanned End
Statement");
if ( value != null ) {
XmlAttribute nodeAttr = xDoc.CreateAttribute("Value");
nodeAttr.Value = value;
idNode.Attributes.SetNamedItem(nodeAttr);
}
i = endStatement;
}
The resulting XML would now be:
<forwarders><192.168.0.1 /><192.168.0.2 /></forwarders>
That isn't valid XML now though. You could use the XmlConvert.EncodeName method
in order to convert the value into a valid element name. That would happen back
where
we create the element and add it to the parent node. That would also mean your
code
that processes the XML file would need to realize it has to DecodeName on
elements
within <forwarders> sections, since they'll be encoded.
-- Justin Rogers DigiTec Web Consultants, LLC. Blog: http://weblogs.asp.net/justin_rogers "William Stacey [MVP]" <staceywREMOVE@mvps.org> wrote in message news:OrMe8byOEHA.3380@TK2MSFTNGP11.phx.gbl... > BTW. The html doco on bind (and src and binaries) are available at > www.ics.org. If you ever have any questions on bind or w2k dns, I will be > most happy to help or find an answer for you. Cheers! > > -- > William Stacey, MVP > > "Justin Rogers" <Justin@games4dotnet.com> wrote in message > news:uKeLrRyOEHA.3896@TK2MSFTNGP12.phx.gbl... > > I've gone the basic route. You can fine the article and full code for a > parse > > that does > > a pseudo-bind format. My format might support something like: > > > > bind { > > recursion = true; > > forwarders { > > 0 = "192.168.0.1"; 1 = "192.168.0.2"; > > } > > view1 { > > zone1 { > > name = "mydomain.com"; > > forwarders { > > 0 = "192.168.0.1"; 1 = "192.168.0.2"; > > } > > } > > } > > } > > > > Note, that I am going to finally implement the full bind configuration > format, > > not because I have > > to, but because I think it would be kind of cool. The result of my > compiler is > > an Xml file format, > > but you could easily evolve the compiler to spit out another format if you > > wished. I point out in > > the article that I do semantic processing in two places. If you wanted a > parser > > rather than a > > linked parser/compiler module, then there are some things that would have > to be > > changed to be > > more efficient to that form of program. With a parser module, you'd > expect some > > abstract output > > that you would then input to a compiler module that would create the final > view. > > I've simply linked > > these two steps into one because it is common and easy to do for small > > languages. > > > > http://weblogs.asp.net/justin_rogers/archive/2004/05/16/132744.aspx > > > > > > -- > > Justin Rogers > > DigiTec Web Consultants, LLC. > > Blog: http://weblogs.asp.net/justin_rogers > > > > "Daniel O'Connell [C# MVP]" <onyxkirx@--NOSPAM--comcast.net> wrote in > message > > news:%23UIehMyOEHA.3452@TK2MSFTNGP10.phx.gbl... > > > > > > "William Stacey [MVP]" <staceywREMOVE@mvps.org> wrote in message > > > news:uUhhptxOEHA.620@TK2MSFTNGP10.phx.gbl... > > > > Your the man! That is sweet. You gave me an idea. It might be > > > > interesting > > > > to use c# code style over the bind style. The bind is good and what I > was > > > > after, but the c# style would be a very cool twist and I am not tied > to > > > > the > > > > bind but for the common use of it. How could/should I define the same > > > > kind > > > > of config using c# style such as below and will this work? > > > > > > > > class BindConfig > > > > { > > > > bool recursion = true; > > > > IPAddress[] forwarders = {"192.168.0.1", "192.168.0.2"}; // not > sure > > > > here > > > > > > > > class View1 > > > > { > > > > class Zone1 > > > > { > > > > string name = "mydomain.com."; > > > > IPAddress[] forwarders = ... > > > > } > > > > } > > > > class View2 > > > > { > > > > // other zones. > > > > } > > > > } > > > > > > > > Not sure if this is better or not, but could be flexible. > > > If you are going to go this far, why not make it full blown syntax? > > > > > > config Bind > > > { > > > bool recursion = true; > > > IPAddress[] forwards = {192.168.0.1, 192.168.0.2}; > > > > > > view basicView > > > { > > > zone FooZone > > > { > > > string name = "mydomain.com"; > > > IPAddress[] forwarders = ... > > > } > > > } > > > > > > } > > > > > > or wahtever is specifica to your needs. Justins lexer is probably > flexible > > > enough to do this, although the parser would probably need a bit of work > for > > > type verification and the like. The flexibility is there, its just a > matter > > > of designing it and writing the parser. When you get into typing, c > style > > > strings, and the like the lexer and\or parser(depending on your design) > > > become a bit more complex, although not prohibitivly so. > > > > > > > Normally I don't need to be spoon fed, but this stuff is a bit new to > me. > > > > Very much appreciate your help and interest. > > > > > > > > -- > > > > William Stacey, MVP > > > > > > > > "Justin Rogers" <Justin@games4dotnet.com> wrote in message > > > > news:O66G$JxOEHA.1312@TK2MSFTNGP12.phx.gbl... > > > >> > Phew, that makes my lexer look bulky, ;)(536 lines so far). Granted > it > > > >> > supports several literal formats(string, integers and double right > > > >> > now). > > > >> > > > >> Yes, the lexer could be more advanced. Notice in a second post, I > took > > > >> out even more code bringing the 39 lines to only 30 (for the lexer), > but > > > >> added the necessary namespace imports and a test driver. > > > >> > > > >> http://weblogs.asp.net/justin_rogers/archive/2004/05/15/132693.aspx > > > >> > > > >> > Out of curiosity, what are you using for your parser? Are you using > a > > > > parser > > > >> > generator or just writing one by hand? I imagine I could wait for > you > > > >> > to > > > >> > post the article, but I am curious. > > > >> > > > >> I generally write my parser's by hand. It doesn't take much. I'm > not at > > > > the > > > >> machine with the parser on it right now so I can't tell you the > number of > > > > lines > > > >> to parse the Bind configuration file (thanks to William for pointing > out > > > > the > > > >> source of this configuration format), but it is relatively short, on > the > > > > order > > > >> of > > > >> only 100-150 with comments. There is some code to build the > XmlDocument > > > >> object (note this is not a straight parser, but rather a parser + > > > >> compiler > > > >> module > > > >> that compiles the Bind configuration file into XmlDocument). I'll > have > > > > the > > > >> article > > > >> up shortly. > > > >> > > > >> > > > >> -- > > > >> Justin Rogers > > > >> DigiTec Web Consultants, LLC. > > > >> Blog: http://weblogs.asp.net/justin_rogers > > > >> > > > >> > > > > > > > > > > > > > > >
- Next message: Sam: "Re: Writing a set extending ArrayList"
- Previous message: Justin Rogers: "Re: declare class of type...."
- In reply to: William Stacey [MVP]: "Re: Parse library"
- Next in thread: Ed Courtenay: "Re: Parse library"
- Messages sorted by: [ date ] [ thread ]
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