BNF

aka Backus-Naur Form

Wikipedia / BNF

 

The purpose of this document is to show the BNF that HtmGem uses and the way it determines the line type and what information it fetches from. For this, it uses curly brackets to explicitely show what information it takes. In addition to this, the canonical form shows how it should be displayed.

 

———————————————————— ✀ ————————————————————

 

textgemini = *(link / preformat / heading / ulist / quoted / plain)

; Preformat toggle starts as 'false'.

 

plain = {[WSP] text} [WSP] end-of-line

; If preformat toggle is false, wrap text to the

; width of the display. Otherwise, do no wrapping.

; canonical form = {[WSP] text}

 

preformat = "```" [WSP] [{alt-text}] [WSP] end-of-line

; Preformat toggle set to opposite state:

; false goes to true

; true goes to false

; While in preformat toggle is true, link, heading,

; ulist and quoted lines are NOT interpreted, but

; displayed as is to the user.

; canonical form = ``` [SP {alt-text}]

 

link = '=>' [WSP] [{URI-reference}] [[WSP] {text}] end-of-line

; canonical form = '=>' SP {uri-reference} [SP {text}]

 

heading = '#' [WSP] [{text}] [WSP] end-of-line

/ '##' [WSP] {text} [WSP] end-of-line

/ '###' [WSP] {text} [WSP] end-of-line

; canonical form = ('#' / '##' / '###') [SP {text}]

 

ulist = '*' [WSP] {text} [WSP] end-of-line

; canonical form = '*' SP {text}

 

quoted = '>' [WSP] {text} [WSP] end-of-line

; canonical form = '>' SP {text}

 

alt-text = text

text = *UVCHAR

end-of-line = [CR] LF

 

UVCHAR = VCHAR / UTF8-2v / UTF8-3 / UTF8-4

UTF8-2v = %xC2 %xA0-BF UTF8-tail ; no C1 control set

/ %xC3-DF UTF8-tail

 

; CRLF from RFC-5234

; DIGIT from RFC-5234

; SP from RFC-5234

; VCHAR from RFC-5234

; OCTET from RFC-5234

; WSP from RFC-5234

;

; UTF8-3 from RFC-3629

; UTF8-4 from RFC-3629

; UTF8-tail from RFC-3629

 

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This BNF was taken from the working group and adapted to HtmGem's implementation.

Gitlab / Original ticket

 

Changes:

 

The white spaces that end a line are never used. See the definition of text in the BNF, which no longer contains SP.

 

Examples

 

=> links

 

Normal link

link = '=>' [WSP] [{URI-reference}] [[WSP] {text}] end-of-line

; canonical form = '=>' SP {uri-reference} [SP {text}]

 

Source: => foo.invalid text of the link

Data: '=>' {'foo.invalid'} {'text of the link'}

Canonical: => foo.invalid text of the link

Html: <a href="foo.invalid">text of the link</a>

 

Source: =>foo.invalid text of the link

Data: '=>' {'foo.invalid'} {'text of the link'}

Canonical: => foo.invalid text of the link

Html: <a href="foo.invalid">text of the link</a>

 

Source: => just_a_page

Data: '=>' {'just_a_page'} {}

Canonical: => just_a_page

Html: <a href="just_a_page">just_a_page</a>

 

Source: =>

Data: '=>' {''} {''}

Canonical: =>

Html: <a href="">&nbsp;</a>

 

# Headings

heading = '#' [WSP] [{text}] [WSP] end-of-line

(…)

; canonical form = ('#' / '##' / '###') [SP {text}]

 

Source: #title

Data: '#' {"title"}

Canonical: # title

 

Source: # title with two spaces between title and with

Data: '#' {"title with spaces"}

Canonical: # title with two spaces between title and with