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Re: URI Templates, percent-encoding, bnfs and working code

From: James M Snell <jasnell@gmail.com>
Date: Mon, 22 Oct 2007 09:26:44 -0700
Message-ID: <471CCF44.6060604@gmail.com>
To: Joe Gregorio <joe@bitworking.org>
CC: uri@w3.org

Joe and others,

Below is a first run at a complete ABNF covering URI and IRI templates.
This was adapted from the ABNF rules in RFC's 3986 and 3987.

- James

; =====================================================================
; A complete ABNF for URI and IRI Templates
; =====================================================================

wsp          =  *(%x20 / %x09)
sep          =  wsp ',' wsp

; =====================================================================
; Template Operators
; =====================================================================
PREFIX         = '<'
  ; prepend the value of arg to the replacement value of var
POSTFIX        = '>'
  ; append the value of arg to the replacement value of var
CONCAT         = ','
  ; substitute the concatenation of varname '=' value, join multiple
  ; vars with arg
LIST           = '&'
  ; treat var as a list, join multiple values with arg
POSITIVEINSERT = '?'
  ; insert arg if value of var is non-null or non-zero-length list
NEGATIVEINSERT = '!'
  ; insert arg if value of var is null or zero-length list

VARDELIM       = '|'

; =====================================================================
; URI Template Tokens
; =====================================================================
arg          = *(reserved / unreserved / pct-encoded)
varname      = *(ALPHA / DIGIT / "." / "_")
vardefault   = *(unreserved / pct-encoded)
var          = varname [ '=' vardefault ]
vars         = var [*(sep var)]
varnofefault = varname

identitytoken = var
operatortoken = ( POSTFIX        arg VARDELIM var )          /
                ( PREFIX         arg VARDELIM var )          /
                ( CONCAT         arg VARDELIM vars )         /
                ( LIST           arg VARDELIM varnodefault ) /
                ( POSITIVEINSERT arg VARDELIM varnodefault ) /
                ( NEGATIVEINSERT arg VARDELIM varnodefault )

token = identitytoken / operatortoken
value = *(unreserved / pct-encoded)
        ; replacement value for token

; =====================================================================
; IRI Template Tokens
; =====================================================================
iarg          = *(reserved / iunreserved / pct-encoded)
ivarname      = *(ALPHA / DIGIT / "." / "_" / ucschar)
ivardefault   = *(iunreserved / pct-encoded)
ivar          = ivarname [ '=' ivardefault ]
ivars         = ivar [*(sep ivar)]
ivarnofefault = ivarname

iidentitytoken = ivar
ioperatortoken = ( POSTFIX        iarg VARDELIM ivar )          /
                 ( PREFIX         iarg VARDELIM ivar )          /
                 ( CONCAT         iarg VARDELIM ivars )         /
                 ( LIST           iarg VARDELIM ivarnodefault ) /
                 ( POSITIVEINSERT iarg VARDELIM ivarnodefault ) /
                 ( NEGATIVEINSERT iarg VARDELIM ivarnodefault )

itoken = iidentitytoken / ioperatortoken
ivalue = *(iunreserved / pct-encoded)
         ; replacement value for itoken


; =====================================================================
; Full URI Template. Modified ABNF from RFC 3986
; =====================================================================
URI           = scheme ":" hier-part [ "?" query ] [ "#" fragment ]

hier-part     = "//" authority path-abempty
              / path-absolute
              / path-rootless
              / path-empty

URI-reference = URI / relative-ref

absolute-URI  = scheme ":" hier-part [ "?" query ]

relative-ref  = relative-part [ "?" query ] [ "#" fragment ]

relative-part = "//" authority path-abempty
              / path-absolute
              / path-noscheme
              / path-empty

scheme        = (ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )) / token

authority     = [ userinfo "@" ] host [ ":" port ]
userinfo      = *( unreserved / pct-encoded / sub-delims / ":" / token)
host          = IP-literal / IPv4address / reg-name / token
port          = *(DIGIT / token)

IP-literal    = "[" ( IPv6address / IPvFuture  ) "]"

IPvFuture     = "v" 1*HEXDIG "." 1*( unreserved / sub-delims / ":" )

IPv6address   =                            6( h16 ":" ) ls32
              /                       "::" 5( h16 ":" ) ls32
              / [               h16 ] "::" 4( h16 ":" ) ls32
              / [ *1( h16 ":" ) h16 ] "::" 3( h16 ":" ) ls32
              / [ *2( h16 ":" ) h16 ] "::" 2( h16 ":" ) ls32
              / [ *3( h16 ":" ) h16 ] "::"    h16 ":"   ls32
              / [ *4( h16 ":" ) h16 ] "::"              ls32
              / [ *5( h16 ":" ) h16 ] "::"              h16
              / [ *6( h16 ":" ) h16 ] "::"

h16           = 1*4HEXDIG
ls32          = ( h16 ":" h16 ) / IPv4address
IPv4address   = dec-octet "." dec-octet "." dec-octet "." dec-octet

dec-octet     = DIGIT                 ; 0-9
              / %x31-39 DIGIT         ; 10-99
              / "1" 2DIGIT            ; 100-199
              / "2" %x30-34 DIGIT     ; 200-249
              / "25" %x30-35          ; 250-255

reg-name      = *( unreserved / pct-encoded / sub-delims / token)

path          = path-abempty    ; begins with "/" or is empty
              / path-absolute   ; begins with "/" but not "//"
              / path-noscheme   ; begins with a non-colon segment
              / path-rootless   ; begins with a segment
              / path-empty      ; zero characters

path-abempty  = *( "/" segment )
path-absolute = "/" [ segment-nz *( "/" segment ) ]
path-noscheme = segment-nz-nc *( "/" segment )
path-rootless = segment-nz *( "/" segment )
path-empty    = 0<pchar>

segment       = *(pchar / token)
segment-nz    = 1*(pchar / token)
segment-nz-nc = 1*( unreserved / pct-encoded / sub-delims / "@" / token)
                 ; non-zero-length segment without any colon ":"

pchar         = unreserved / pct-encoded / sub-delims / ":" / "@"

query         = *( pchar / "/" / "?" / token)

fragment      = *( pchar / "/" / "?" / token)

pct-encoded   = "%" HEXDIG HEXDIG

unreserved    = ALPHA / DIGIT / "-" / "." / "_" / "~"
reserved      = gen-delims / sub-delims
gen-delims    = ":" / "/" / "?" / "#" / "[" / "]" / "@"
sub-delims    = "!" / "$" / "&" / "'" / "(" / ")"
              / "*" / "+" / "," / ";" / "="

; =====================================================================
; Full IRI Template. Modified ABNF from RFC 3987
; =====================================================================
IRI           = scheme ":" ihier-part [ "?" iquery ] [ "#" ifragment ]

ihier-part     = "//" iauthority ipath-abempty
               / ipath-absolute
               / ipath-rootless
               / ipath-empty

IRI-reference  = IRI / irelative-ref

absolute-IRI   = scheme ":" ihier-part [ "?" iquery ]

irelative-ref  = irelative-part [ "?" iquery ] [ "#" ifragment ]

irelative-part = "//" iauthority ipath-abempty
               / ipath-absolute
               / ipath-noscheme
               / ipath-empty

iauthority     = [ iuserinfo "@" ] ihost [ ":" port ]
iuserinfo      = *( iunreserved / pct-encoded / sub-delims / ":" / itoken)
ihost          = IP-literal / IPv4address / ireg-name / itoken

ireg-name      = *( iunreserved / pct-encoded / sub-delims / itoken)

ipath          = ipath-abempty   ; begins with "/" or is empty
               / ipath-absolute  ; begins with "/" but not "//"
               / ipath-noscheme  ; begins with a non-colon segment
               / ipath-rootless  ; begins with a segment
               / ipath-empty     ; zero characters

ipath-abempty  = *( "/" isegment )
ipath-absolute = "/" [ isegment-nz *( "/" isegment ) ]
ipath-noscheme = isegment-nz-nc *( "/" isegment )
ipath-rootless = isegment-nz *( "/" isegment )
ipath-empty    = 0<ipchar>

isegment       = *(ipchar / itoken)
isegment-nz    = 1*(ipchar / itoken)
isegment-nz-nc = 1*( iunreserved / pct-encoded / sub-delims / "@" / itoken)
               ; non-zero-length segment without any colon ":"

ipchar         = iunreserved / pct-encoded / sub-delims / ":" / "@"

iquery         = *( ipchar / iprivate / "/" / "?" / itoken)

ifragment      = *( ipchar / "/" / "?" / itoken)

iunreserved    = ALPHA / DIGIT / "-" / "." / "_" / "~" / ucschar

ucschar        = %xA0-D7FF / %xF900-FDCF / %xFDF0-FFEF
               / %x10000-1FFFD / %x20000-2FFFD / %x30000-3FFFD
               / %x40000-4FFFD / %x50000-5FFFD / %x60000-6FFFD
               / %x70000-7FFFD / %x80000-8FFFD / %x90000-9FFFD
               / %xA0000-AFFFD / %xB0000-BFFFD / %xC0000-CFFFD
               / %xD0000-DFFFD / %xE1000-EFFFD

iprivate       = %xE000-F8FF / %xF0000-FFFFD / %x100000-10FFFD
Received on Monday, 22 October 2007 16:26:59 GMT

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