[Versa] ENBF (take 2)

[Michael Olson]

Changes:

* Simplified all of the different expressions (per Uche's suggestion)  
so it should be easier to read/follow/understand
   As a Note, I thought there would be a need to support different  
"expressions" at different locations but now I think otherwise.  The  
only cavet is that where there used to be
   a filter expression, now we need to document that expressions like ".  
< 18"  are short hand for (!x : $x = '.' < 18)
* Finished patterns, constants and the like
* Add keyword support to calling a function and anonymous function  
definitions

One thought I did have is where I use "query-expression" to show a  
nested expression, maybe this should be "query"  The difference being  
that query allows for a context reference.

I'll spend a bit of time today updating the bgen file to see if we are  
even close to parsable....



[1] versa-query ::= declaration-list? query

[2] declaration-list ::= declaration ';' declaration-list ?

[3] declaration ::= variable-declaration
                     | function-declaration
                     | prefix-declarion
                     | context-declaration


[4] variable-declaration ::= "@variable" variable-name '=' query

[5] function-declaration  ::= "@function" function-name '(' ( qname (  
',' qname ) * ) * ')' = query-expression

[6] prefix-declaration  ::= "@prefix" prefix '=' uriref

[7] context-declaration  ::= "@context" context-name '=' query

[8] query ::= context-reference? query-expression

[9] context-reference ::= '{' context-name '}'

[10] query-expression ::= '(' query-expression ')'
                         | query-expression slice_operator
                         | traversal
                         | filter
                         | function-call
                         | anonymous-function
                         | variable-reference
                         | operator-expression
                         | pattern
                         | DOT

[11] slice-operator ::= '[' (signed-number | (signed-number ':') | (':'  
signed-number) | (signed-number ':' signed-number)

[12] traversal ::= forward-traversal | backward-traversal

[13] filter ::= forward-filter | backward-filter

[14] forward-traversal ::= (query-expression "-" query-expression "->"  
query-expression)
                            | ( '[' '-' query-expression "->"  
query-expression ']' )

[15] forward-filter ::= (query-expression "|-" query-expression "->"  
query-expression)
                         | ( '[' "|-" query-expression "->"  
query-expression ']' )

[16] backward-traversal ::= (query-expression "<-" query-expression "-"  
query-expression)
                             | ( '[' query-expression "<-"  
query-expression "-" ']' )

[17] backward-filter ::= (query-expression "<-" query-expression "-|"  
query-expression )
                          | ( '[' query-expression "<-" query-expression  
"-|" ']' )


[18] function_call ::= function-name '(' argument-list ')'

[19] argument-list ::= fixed-argument-list? keyword-argument-list?

[20] fixed-argument-list ::= query-expression ( ',' query-expression )*

[21] keyword-argument-list ::= keyword-argument ( ',' keywrod-argument  
) *

[22] keyword-argument ::= keyword-argument-name '=' query-expression

[23] keyword-argument-name :: = qname

[24] operator-expression  ::= operator-expression? operator  
query-expression

[25] anonymous-function ::= '(!' anonymous-argument-definition-list ':'  
query-expression ')'

[26] anonymous-argument-defintion-list ::=  
anonymous-fixed-argument-definition-list?  
anonymous-keyword-argument-definition-list?

[27] anonymous-fixed-argument-definition-list ::=  
(anonymous-fixed-argument-definition ( ','  
anonymous-fixed-argument-definition ) * ) ?

[28] anonymous-fixed-argument-definition ::= qname

[29] anonymous-keyword-argument-definition-list ::=  
(anonymous-keyword-argument-definition ( ','  
anonymous-keyword-argument-definition ) * ) ?

[30] anonymous-keyword-argument-definition ::= keyword-argument-name  
'=' query-expresion

[31] pattern  ::= node-pattern | literal-pattern | wild-card

[32] node-pattern ::= uri-pattern | qname-pattern

[33] uri-pattern ::= uriref

[34] qname-pattern ::= qname
                        | '*:' localname
                        | prefix ':*'

[35] literal-pattern ::= string-constant
                          | literal-constant
                          | number-constant
                          | boolean-constant
                          | typed-literal-pattern
                          | language-literal-pattern

[36]  operator ::= '!'
                    | '<'
                    | '>'
                    | '<='
                    | '>='
                    | '='
                    | '!='
                    | '<>'
                    | 'and'
                    | '&'
                    | 'or'
                    | '|'
                    | 'not '
                    | 'union'
                    | 'intersection'
                    | '+'
                    | '-'
                    | '*'
                    | '\'
                    | '*'


[37] variable-reference ::= '$' variable-name

[38] variable-name ::= qname

[39] function-name ::= qname

[40] context-name ::= qname

#Strings must be escaped following section 4.6.2.1
[41] string-constant ::= single-line-string | multiline-string

[42] single-line-string ::= single-line-apos | single-line-quote

[43] single-line-apos ::= '\'' [\'\n]*'\''

[44] single-line-quote ::= '"' [\"\n]*'"'

[45] multi-line-string ::= '""".*'"""'

[46] literal-constant ::= typed-literal-constant |  
language-literal-constant

[47] typed-literal-constant ::= string '^^' uriref

[48] language-literal-constant ::= string '@' language

[49] number-constant ::= (signed-number ( (\.simple-number)? ) ('e'  
signed-number)?

[50] signed-number ::= [-+]?simple-number

[51] simple-number ::= [-+]?[0-9]+

[52] boolean-constant ::= 'true' | 'false'

[53] typed-literal-pattern ::= ('!') ? string '^^' ('!') ?  
(node_pattern | wild_card)
                                | wild_card '^^' ('!') ? uriref
                                | wild_card '^^' ('!') ? (node-pattern |  
wild-card)


[54] language-literal-pattern ::= string '@' wild-card
                                   | wild-card '@' ('!') ? language

[55] language ::= [a-z]+(-[a-z0-9]+)*


#qName, prefix and localname as defined here:  
http://www.w3.org/TR/2004/REC-xml-20040204


#uri references are escaped as per section 4.5
[56] uriref ::= '<'[\<]* '>'







------------------------------------------------------------------------ 
-----------------
Mike Olson                                                Principal  
Consultant
mike.olson at fourthought.com                +1 720 253 4662
Fourthought, Inc.                                       
http://Fourthought.com
PO Box 270590,                                       http://4Suite.org
Louisville, CO 80027-5009, USA
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