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star files and Decision can match input such as [message #1828187]

Wed, 03 June 2020 12:34

gary s thompson

Messages: 92
Registered: July 2009

Member

Dear all

sorry some rather a newby, questions which I am sure has been answered many times before. I am trying to implement a parser for STAR files a scientific format, details below

I have the following code:

grammar uk.ac.ccpn.neftools.Star 
hidden(WS, SL_COMMENT) 

import "http://www.eclipse.org/emf/2002/Ecore" as ecore

generate star "http://www.ac.uk/ccpn/neftools/Star"

Star_file:
    blocks+=Data_block*;


terminal SL_COMMENT : '#' !('\n'|'\r')* ('\r'? '\n')?;

terminal WS         : (' '|'\t'|'\r'|'\n')+;

terminal ANY_OTHER: .;

terminal fragment NON_BLANK_CHAR:
	('!'..'^' | '\''..'~')	
;

terminal SAVE:
 	'save_'
;

terminal DATA_HEADING:
 	'data_' NON_BLANK_CHAR+
;  


terminal DATA_NAME:
	'_' NON_BLANK_CHAR+
;


terminal NON_QUOTED_TEXT_STRING:
	(!'_') (NON_BLANK_CHAR)+
;

Data_block:
    heading = DATA_HEADING (bodies+= Data_block_body)+
;

Data_block_body:
	data+=(Data)+ 
;

Data:
	name=DATA_NAME value=NON_QUOTED_TEXT_STRING
;

but have several problems

1. The most pressing

warning(200): ../uk.ac.ccpn.neftools/src-gen/uk/ac/ccpn/neftools/parser/antlr/internal/InternalStar.g:188:2: Decision can match input such as "RULE_DATA_NAME" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
warning(200): ../uk.ac.ccpn.neftools.ide/src-gen/uk/ac/ccpn/neftools/ide/contentassist/antlr/internal/InternalStar.g:125:42: Decision can match input such as "RULE_DATA_NAME RULE_NON_QUOTED_TEXT_STRING" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input

I have seen plenty of discussion of what the problem is here, and it appears that the tokenizer(?) is finding mutiple ways to tokenize my code (?) I have read that predicates can solve this but don't see quite where I have to change things

2. I don't seem to be allowed to have whitespace at the start of a file before a Data_block

3. I had to re define what IDs and strings are because they don't fit in with the syntax of the star file and especially the character ranges used and the definition of an INT, but I don't really folllow how an ID and a String are defined in common terminals

ID is defined as

terminal ID: '^'?('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'_'|'0'..'9')*;

and STRING as

terminal STRING:
'"' ( '\\' . /* 'b'|'t'|'n'|'f'|'r'|'u'|'"'|"'"|'\\' */ | !('\\'|'"') )* '"' |
"'" ( '\\' . /* 'b'|'t'|'n'|'f'|'r'|'u'|'"'|"'"|'\\' */ | !('\\'|"'") )* "'"

I can understand how id is defined its just text ranges with the first letter not being allowed to be a number, but string seems a bit baffling...

can someone explain and also is what I am doing the right approach
any help gratefully received

regards
Gary

nb I also checked things an antlrworks (image attached)

Attachment: The STAR File - Detailed Specifications - J Chem Inf Comput Sc 1994 34 505-508 - ci00019a005.pdf (page 3 of 4) 2020-06-03 13-21-06.png
(Size: 191.42KB, Downloaded 38 times)
Attachment: :Users:garythompson:Dropbox:git:neftools:uk.ac.ccp.png
(Size: 31.56KB, Downloaded 51 times)

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Re: star files and Decision can match input such as [message #1828209 is a reply to message #1828187]

Thu, 04 June 2020 06:11

Christian Dietrich

Messages: 14665
Registered: July 2009

Senior Member

Data_block:
heading = DATA_HEADING (bodies+= Data_block_body)+
;

Data_block_body:
data+=(Data)+
;

if you have two data. will these become two Data_block_body or two (bodies+= Data_block_body)+

Twitter : @chrdietrich
Blog : https://www.dietrich-it.de

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Re: star files and Decision can match input such as [message #1828215 is a reply to message #1828187]

Thu, 04 June 2020 08:56

gary s thompson

Messages: 92
Registered: July 2009

Member

Dear Christian

Thank you so much, I was barking up completely the wrong tree and this solves the problem. As you explained the original syntax from the original paper had a degenerate definition.

<data_block_body>              ::= (data | save_frame)+
<data>                         ::= data_name data_value | <data_loop>
<data_block>                   ::= <data_heading> <data_block_body>+
<data_name>                    ::= _<non_blank_char>+
<data_heading>                 ::= data_<non_blank_char>+
<save_frame>                   ::= <save_heading> <data>+

I now have

grammar uk.ac.ccpn.neftools.Star 
hidden(WS, SL_COMMENT) 

import "http://www.eclipse.org/emf/2002/Ecore" as ecore

generate star "http://www.ac.uk/ccpn/neftools/Star"

Star_file:
    blocks+=Data_block*;

terminal STRING:
			'"' ( '\\' . /* 'b'|'t'|'n'|'f'|'r'|'u'|'"'|"'"|'\\' */ | !('\\'|'"') )* '"' |
			"'" ( '\\' . /* 'b'|'t'|'n'|'f'|'r'|'u'|'"'|"'"|'\\' */ | !('\\'|"'") )* "'"
		;
terminal SL_COMMENT : '#' !('\n'|'\r')* ('\r'? '\n')?;

terminal WS         : (' '|'\t'|'\r'|'\n')+;

terminal ANY_OTHER: .;


//TODO: the range here isn't quite right it doesn't include '
terminal fragment NON_BLANK_CHAR:
	('!'..'^' | '\''..'~')	
;




terminal SAVE:
 	'save_'
;

terminal DATA_HEADING:
 	'data_' NON_BLANK_CHAR+
;  

terminal SAVE_HEADING:
	SAVE  NON_BLANK_CHAR+
; 

terminal DATA_NAME:
	'_' NON_BLANK_CHAR+
;

terminal NON_QUOTED_TEXT_STRING:
	(!'_') (NON_BLANK_CHAR)+
;



Data_block:
    heading = DATA_HEADING (bodies+= Data_block_body)+
;

Data_block_body:
	Data|Save_frame
;

Data:
	name=DATA_NAME value=NON_QUOTED_TEXT_STRING
;

Save_frame:
	heading=SAVE_HEADING (data+=Data)+ SAVE
;

and this works. So on to finding out that causes my no white space problem, which seems to be quite odd. I am allowed two spaces in front of a heading or a comment at the start of a file but not one!

regards
Gary

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