Q: how to parse embedded sections in a different syntax

Hi,

In the ADL archetype syntax (see 
http://www.openehr.org/drafts/t_drafts.htm) there are certain times when 
a piece of a second syntax occurs within the first; it may be at any 
level of the block structure. Both syntaxes normally occur separately 
however. An example of embedded sections is visible in the attached 
archetype - the C_QUANTITY sections with <> delimiters are in the dADL 
syntax, inside the archetype definition, which is in the cADL syntax - a 
curly bracket syntax which expresses constraints.

I have two separate gobo-based parsers, one for each language. To deal 
with embedded sections of dADL inside cADL, I wrote rules in the cADL 
scanner which attempt to match to the end of the embedded block, call 
the dADL parser, then give the resulting object with a token 
representing it, to the cADL parse process currently executing. The 
problem is that it is nearly impossible to correctly match such inline 
sections properly within the cADL parser, due to the fact that dADL can 
contain strings whcih can contain any symbols. The proper way to do this 
would be something like, in the cADL scanner:

- match the initial few characters which indicate the beginning of an 
embedded dADL section
- initialise a dADL parser with the string from the cADL buffer at 
'position+1' to the end
- the dADL parser would scan to the end of the block, which would be 
somewhere further along in the buffer, and then finish, producing the 
desired object
- the cADL scanner would take the object, generate a token, and 
'fast-forward' the scanner to the position in the buffer where the dADL 
scanner left off, +1.

It appears to me that what is needed is a way to tell a scanner to act 
as if it had matched the next N characters, i.e. just to move up N 
positions, no questions asked.

can this be supported?

- thomas beale



-- 
___________________________________________________________________________________
CTO Ocean Informatics (http://www.OceanInformatics.biz)
Hon. Research Fellow, University College London

openEHR (http://www.openEHR.org)
Archetypes (http://www.oceaninformatics.biz/adl.html)
Community Informatics (http://www.deepthought.com.au/ci/rii/Output/mainTOC.html)


  ----------

archetype 	
	adl-test-SOME_TYPE.c_quantity.draft

concept 
	[at0000]

description
	author = <"Thomas Beale <t.beale-iKIwAYpEHG/[email protected]>">
	submission = <
		organisation = <"Ocean Informatics">
		date = <2003-06-10>
	>
	version = <"draft">
	status = <"draft">
	revision = <"1.1">
	description("en") = <
		purpose = <"Illustrates the use of inline dADL representing C_QUANTITY, including with no magnitude">
		use = <"">
		misuse = <"">
	>
	adl_version = <"1.2">
	rights = <"">


definition
	SOME_TYPE[at0000] matches {
		standard_quantity_attr matches {
			QUANTITY matches {
				property matches {"temperature"}
				unit matches {"C"}
				magnitude matches {|>= 4.0|}
			}
			QUANTITY matches {
				property matches {"temperature"}
				unit matches {"F"}
				magnitude matches {|>= 40.0|}
			}
		}
	
		clinical_quantity_attr_1 matches {
			C_QUANTITY <
				property = <"temperature">
				list(1) = <
					units = <"C">
					magnitude = <|>=4.0|>
				>
				list(2) = <
					units = <"F">
					magnitude = <|>=40.0|>
				>
			>
		}	

		clinical_quantity_attr_2 matches {
			C_QUANTITY <
				property = <"temperature">
				list(1) = <
					units = <"C">
				>
				list(2) = <
					units = <"F">
				>
			>
		}	

		clinical_quantity_attr_3 matches {
			C_QUANTITY <
			>
		}	

		clinical_quantity_attr_4 cardinality matches {0..*; ordered} matches {
			C_QUANTITY <
			>
			COUNT matches {
				magnitude matches {|>= 0|}
			}
		}

		clinical_quantity_attr_5 matches {
			COUNT matches {
				magnitude matches {|>= 0|}
			}
			C_QUANTITY <
			>
		}
	
	}

ontology 
	primary_language = <"en">
	languages_available = <"en", ...>

	term_definitions("en") = <
		items("at0000") = <text = <"root item">; 		description = <"xxxx">>
	>



[Non-text portions of this message have been removed]



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