Fwd: ABNF

Sharing this thread with the TC list.

Markus

---------- Forwarded message ----------
From: Markus Sabadello <>
Date: Tue, Nov 18, 2014 at 10:28 AM
Subject: Re: ABNF
To: =Drummond Reed <>
Cc: Joseph Boyle <>, "Le Van Gong, Hubert" <>

I spent some time trying to add support for aParse and APG again in XDI2, based on this ABNF.
I think it basically works, but I would suggest the following changes:

1. Add a rule for the statement separator:

STMT = "/"

2. Rename the current rule "arc-address" to "context-arc-address", add new rule "arc-address", and add new rule "literal-arc-address":

arc-address            = context-arc-address / literal-arc-address

context-arc-address     = peer-root / inner-root / entity-singleton / entity-collection / entity-member /
                         attr-singleton / attr-collection / attr-member

literal-arc-address    = "&"

3. Then use the above new/changed rules appropriately

E.g. the "literal-statement" rule would then change from
literal-statement      = rooted-address "/&/" json-value
to
literal-statement      = rooted-address STMT literal-arc-address STMT json-value

This is all just for clarity, doesn't change the syntax itself.
I'm attaching my version of the ABNF with the above proposed changes.

Markus

On Tue, Nov 18, 2014 at 7:19 AM, =Drummond Reed <> wrote:

Joseph,

Thank you for extending this all the way through. I finally got a chance to look this over at a high level, and it looks pretty clean. Obviously it needs review at a much lower and more detailed level, as you have been doing in putting it together and testing it, but I won't be able to do that until at least Thursday and more likely next week.

The question of changing nesting order or switching symbols is obviously a very big one—I'm loathe to make any changes to syntax at this point unless there is an overwhelming good reason—but as you work through it, lay out your case.

Markus, I think we should schedule at least a report on this progress for this Friday's TC call (given that we won't be having one next week).

Thanks,

=Drummond  

On Sun, Nov 16, 2014 at 4:52 PM, Joseph Boyle <> wrote:

This is not complete, but I wanted to keep you up on progress, and give Markus and Hubert a sample grammar that generates successfully with http://www.coasttocoastresearch.com/interactiveapg

Some problems with interaction between successive lines (e.g. when object ends with &) so best to test one XDI statement at a time.

Extra whitespace / blanklines are not provided for.

Literal statements use /&/ not old form &/&/

The following are workarounds added for features that are not working:

xdi-name-char is relaxed to include “:” because xdi-uuid is failing to match (an example in isolation works, not sure where bad interaction is)

Relaxed constraint that attribute collection with no attribute member can’t be used for literal because greedy matching is breaking it

Drummond: the part in red reflects our work this last week on which combinations are allowable, if you want to check. There’s some extra complexity in order to get the brackets in the nesting order we currently specify - I’d like to consider the best order, and also whether to switch {} and ||.

xdi-statements         = xdi-statement *( ENDLINE xdi-statement ) *ENDLINE

xdi-statement          = contextual-statement / relational-statement / literal-statement

contextual-statement   = peer-root-context / inner-root-context / entity-part-context / entity-member-context

                         attr-part-context / attr-member-context

relational-statement   = rooted-address "/" common-address "/" xdi-address

literal-statement      = rooted-address "/&/" json-value

peer-root-context      = *peer-root "//" peer-root

inner-root-context     = root-address "//" inner-root

entity-part-context    = root-address *entity-part "//" ( entity-singleton / entity-collection )

entity-member-context  = root-address *entity-part entity-collection "//" entity-member

attr-part-context      = rooted-address "//" ( attr-singleton / attr-collection )

attr-member-context    = rooted-address attr-collection "//" attr-member

xdi-address            = literal-address / rooted-address

rooted-address         = root-address common-address

root-address           = *peer-root *inner-root

common-address         = entity-address attr-address

entity-address         = *entity-part

attr-address           = *attr-part

literal-address        = rooted-address attr-unit "&"

arc-address            = peer-root / inner-root / entity-singleton / entity-collection / entity-member /

                         attr-singleton / attr-collection / attr-member

peer-root              = "(" common-address ")"

inner-root             = "(" common-address "/" common-address ")"

entity-unit            = ( entity-collection entity-member ) / entity-singleton

entity-part            = ( entity-collection [ entity-member ] ) / entity-singleton

attr-unit              = ( attr-collection attr-member ) / attr-singleton

attr-part              = ( attr-collection [ attr-member ] ) / attr-singleton

entity-singleton     = authority-singleton / authority-variable / class-singleton / class-variable / class-definition 

authority-variable   = VARL authority-singleton VARR

class-variable       = VARL class-singleton VARR

class-definition     = DEFL class-singleton DEFL

authority-singleton  = person-singleton / legal-singleton / general-singleton

class-singleton      = unreserved-class / reserved-class

person-singleton     = "=" C-I name-scheme-xref

legal-singleton      = "+" C-I name-scheme-xref

general-singleton    = "*" C-I name-scheme-xref

unreserved-class     = "#" C-I name-scheme-xref

reserved-class       = "$" C-I xdi-name

entity-collection    = authority-collection / auth-var-coll / class-collection / class-var-coll

auth-var-coll        = VARL authority-collection VARR

class-var-coll       = VARL class-collection     VARR

authority-collection = person-collection    / legal-collection / general-collection

class-collection     = reserved-collection  / unreserved-collection

person-collection    = COLL              "=" COLR 

legal-collection     = COLL              "+" COLR 

general-collection   = COLL              "*" COLR 

reserved-collection  = COLL   reserved-class COLR

unreserved-collection= COLL unreserved-class COLR

entity-member        = member 

member               = ordered-member / unordered-member

ordered-member       = "@" C-I ( ( %x31-39 DIGIT ) / "0" )

unordered-member     = "!" name-scheme-xref

attr-singleton       = attr-class/ attr-var / attr-defn 

attr-collection      = attr-coll-nonvar / attr-coll-var

attr-coll-var        = VARL attr-coll-nonvar VARR

attr-var             = VARL attr-class  VARR

attr-coll-nonvar     = COLL attr-class  COLR

attr-defn            = DEFL attr-class  DEFR

attr-class           = ATTL C-I class-singleton ATTR

attr-member          = ATTL C-I  member ATTR 

COLL     = "[" 

COLR     = "]"

ATTL     = "<" 

ATTR     = ">" 

DEFL     = "|"

DEFR     = "|"

VARL     = "{" 

VARR     = "}"

C-I    = ""

name-scheme-xref     = xdi-name / xdi-scheme / xref

xref        = "(" ( common-address / xdi-iri / xdi-name ) ")"

xdi-scheme   =  xdi-sha-256 / xdi-sha-384 / xdi-sha-512 / xdi-uuid / xdi-ipv6

xdi-uuid     = ":uuid:"      8HEX "-" 4HEX "-" 4HEX "-" 4HEX "-" 12HEX

xdi-sha-256  = ":sha-256:"  64HEX 

xdi-sha-384  = ":sha-384:"  96HEX 

xdi-sha-512  = ":sha-512:" 128HEX 

xdi-ipv6     = ":ipv6:"      4HEX 7*( ":" 4HEX )  

xdi-name       = *xdi-name-char

xdi-name-char  = UPPER / LOWER / DIGIT / "-" / "." / "_" / ":" / %x80-EFFFD  

context-symbol = "!" / "*" / "=" / "#" / "+" / "$"

LOWER          = %x61-7A

UPPER          = %x41-5A

HEX            = DIGIT / %x61-66

DIGIT          = %x30-39

NZDIG          = %x31-39

QUOTE          = %x22

ENDLINE        = %x0D / %x0A / ( %x0D %x0A )

xdi-iri    = iri-scheme ":" *iri-body

iri-scheme = LOWER *( LOWER / DIGIT ) 

iri-body   = ( "(" iri-body ")" ) / *iri-char

iri-char   = xdi-name-char / context-symbol / iri-delim

iri-delim  = "/" / "?" / "#" / "[" / "]" / "'" / "," 

json-value  = json-object / json-array / json-string / json-number / "true" / "false" / "null"

json-object = "{" [ json-string ":" json-value *( "," json-string ":" json-value ) ] "}"

json-array  = "[" [                 json-value *( ","                 json-value ) ] "]"

json-string = QUOTE *( " " / "!" / %x23-5B  / %x5D-EFFFD / json-escape )    QUOTE

json-escape = "\"    ("\" / "/" / "b" / "f" / "n" / "r" / "t" / QUOTE / ( "u" 4HEX ) )

json-number = ( "0" / [ "-" ] noleading ) [ "." notrailing ] [ "E" [ "-" ] noleading ]

noleading   = %x31-39 *DIGIT

notrailing  = *DIGIT  %x31-39

Attachment:
xdi.2014-11-18.modified.abnf

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