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pragma
Joined: 28 May 2004
Posts: 607
Location: Washington, DC
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 Posted: Wed Aug 11, 2004 2:09 pm Post subject: Progress |
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Sometimes it feels like I'm developing this software in geologic time. For those of you who have been waiting for a release, it's been painful for me as well.
The most recent hangup has been working with the servlet parser, which is arguably the very heart-and-soul of DSP. In the spirit of the original design, it has been abstracted out the wazoo to allow for other parsers to be built on top of it. This is going to be a key feature, when DSP moves away from .ini files for application configs and focus on xml-based configurations instead. So I've taken my time to make sure that I back a good, solid design that won't cause trouble any time soon.
Ultimately the parser works with a set of tokens to search for, and "tags" that they correspond to. Each tag has several overridden methods that are used during different phases of parsing that particular tag, to generate and filter content as it is passed in by the parser. That content is in turn passed onto several named buckets that are used in a second-pass to generate the output file.
What sets this version apart from its predecessor is that tags can (now) define what its child tags are. In the case of a <dsp:code> tag, it only defines <[CDATA[...]]>, text and {inline code} expressions as being sensitive to the parser..
Furthermore, the design also supports XML-like tags, subtitutions and inline statements all within the same scope.
Overally the parser is pretty much done, and I'm moving through a test phase to make sure that its generating good output. I also have a whole suite of interesting Mango parsers that have fallen out of the design. The most notable of which is the StringSet parser; this is what makes the DSP parser tick.
The next steps are to revisit servlet compilation and the library cache, followed by meshing that, the parser and the custom mango engine together. [/i]
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kris
Joined: 27 Mar 2004
Posts: 1494
Location: South Pacific
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| Posted: Wed Aug 11, 2004 3:17 pm Post subject: |
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Woohoo!
Looking forward to trying it out. Those parsers sound useful too! Note that Stonecobra is working on an XML parser, and Chris S is apparently building a DOM-style API. |
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pragma
Joined: 28 May 2004
Posts: 607
Location: Washington, DC
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| Posted: Wed Aug 11, 2004 4:23 pm Post subject: |
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| kris wrote: | Woohoo!
Looking forward to trying it out. Those parsers sound useful too! Note that Stonecobra is working on an XML parser, and Chris S is apparently building a DOM-style API. |
Outstanding! We could use a good D-native XML parser, as DSP's parser isn't really up to the task. 
The DSP parser *could* handle true XML, but parsing XML-like tags is about all it has in common with an XML parser. Its really more of a compromise of several parser types, leaning more towards explicit parsing of known tokens rather than a freely formatted file.
Here's a crude BNF for how it sees an input file, so you can see what I'm talking about:
| Code: |
file ::= entities
entities ::= null | entity | entity entities
entity ::= tag | text-entity
text-entity ::= null | char | char text-entity
tag ::= start-token |
start-token attribute-text end-close-token |
start-token attribute-text close-token entities end-token
start-token ::= text-entity
close-token ::= text-entity
end-close-token ::= text-entity
end-token ::= text-entity
attribute-text ::= null | text-entity | attribute-list
attribute-list ::= attribute | attribute attribute-list
attribute ::= attribute-name "=" attribute-value
attribute-name ::= text-entity
attribute-value ::= "\'" text-entity "\'" | "\"" text-entity "\""
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At first glance it looks like an XML parser, until you look at the def for 'tag'. A tag is defined by one, two or three tokens where the text in between is treated rather arbitrarily. The parser needs to know all the start-tokens ahead of time, and treats everything else as plain text.
Ultimately I did this so people could use DSP to cut-across non-DSP tags if they didn't care about their scripts being XML-compliant:
| Code: | | <img src="<dsp:output>{getPath("images")}foo.jpg</dsp:output>"/> |
Kris,
I have DspServletContext loading application.ini on load, as sort of an .htaccess-like config that also sets the various parameters needed to compile DSP servlets. Perhaps this kind of feature might be better served in Mango itself, by a generic "application.xml" on a per-context basis....?
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kris
Joined: 27 Mar 2004
Posts: 1494
Location: South Pacific
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| Posted: Wed Aug 11, 2004 4:34 pm Post subject: |
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| pragma wrote: | | Kris, I have DspServletContext loading application.ini on load, as sort of an .htaccess-like config that also sets the various parameters needed to compile DSP servlets. Perhaps this kind of feature might be better served in Mango itself, by a generic "application.xml" on a per-context basis....? |
Absolutely it would. I've held off on doing that until the XML parser was available. When it's operational I'll add a Context method to accept some kind of "ini file" adaptor (so it's loosly coupled: XML or text; file or socket; etc). Does that sound like it would meet your needs?
- Kris |
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pragma
Joined: 28 May 2004
Posts: 607
Location: Washington, DC
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| Posted: Wed Aug 11, 2004 5:32 pm Post subject: |
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| kris wrote: | I've held off on doing that until the XML parser was available. When it's operational I'll add a Context method to accept some kind of "ini file" adaptor (so it's loosly coupled: XML or text; file or socket; etc). Does that sound like it would meet your needs?
- Kris |
That would work well. When you add that, I think it would be great to get a thread going over on the Mango board about a baseline application.xml format so we're all on the same page. 
- Eric
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kris
Joined: 27 Mar 2004
Posts: 1494
Location: South Pacific
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| Posted: Wed Aug 11, 2004 7:49 pm Post subject: |
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Sounds like a plan!
When the time is right, perhaps you'll submit the schema used by Dsp as the baseline format? |
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pragma
Joined: 28 May 2004
Posts: 607
Location: Washington, DC
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| Posted: Mon Aug 16, 2004 5:28 pm Post subject: |
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| kris wrote: | Sounds like a plan!
When the time is right, perhaps you'll submit the schema used by Dsp as the baseline format? |
NP. When I finally work the kinks out of this iteration, It'll be the first of many contributions to mango I have planned.
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