[css-content] Fix syntaxes according to CSS Values and Units grammar

[lahmatiy]

Comments for https://drafts.csswg.org/css-content/

<content-list>

• leader() should be surrounded by angle brackets instead of quotes

  [ <string> | contents | <image> | <quote> | <target> | 'leader()' ]+
->
  [ <string> | contents | <image> | <quote> | <target> | <leader()> ]+

leader( <leader-type> )

• Incorrect definition:
  • functions are declaring as <function()>
  • arguments are usually omitting -> <leader-type> should be omitted or declared aside
• A space before closing parenthesis is missing
• No semicolon at the end

  <leader-type> = leader( dotted | solid | space | <string>);
->
  <leader()> = leader( dotted | solid | space | <string> )
or
  <leader()> = leader( <leader-type> )
  <leader-type> = dotted | solid | space | <string> 

<target>

• All functions should be surrounded by angle brackets
• Square brackets aren't needed

  <target> = [ target-counter() | target-counters() | target-text() ]
->
  <target> = <target-counter()> | <target-counters()> | <target-text()>

<target-counter()>

• Angle brackets are missing in syntax reference
• Last group can be omitted since comma are implicitly omissible

  target-counter() = target-counter( [ <string> | <url> ] , <custom-ident> [ , <counter-style> ]? )
->
  <target-counter()> = target-counter( [ <string> | <url> ] , <custom-ident> , <counter-style>? )

<target-counters()>

• Angle brackets are missing in syntax reference
• Missed s in function's name
• Last group can be omitted since comma are implicitly omissible

  target-counters() = target-counter(  [ <string> | <url> ] , <custom-ident> , <string> [ , <counter-style> ]? )
->
  <target-counters()> = target-counters(  [ <string> | <url> ] , <custom-ident> , <string> , <counter-style>? )

<target-text()>

• Angle brackets are missing in syntax reference
• Last group can be omitted since comma are implicitly omissible
• A space is missing between first-letter and ]

  target-text() = target-text( [ <string> | <url> ] [ , [ content | before | after | first-letter] ]? )
->
  <target-text()> = target-text( [ <string> | <url> ] , [ content | before | after | first-letter ]? )

<string()>

• Angle brackets in syntax reference are missing

  string() = string( <custom-ident> , [ first | start | last | first-except ]? )
->
  <string()> = string( <custom-ident> , [ first | start | last | first-except ]? )

<content()>

• Angle brackets in syntax reference are missing
• Wrong multiplier ? is used since argument is required
• A space is missing between [ and text

  content() = content( [text | before | after | first-letter | marker ]? )
->
  <content()> = content( [ text | before | after | first-letter | marker ] )

05/15/2017 Updated to version of 15 May 2017

[SebastianZ]

  [ <image> ',' ]* [ normal | none | <content-list> ] [/ <string> ]?
->
  [ <image> , ]* [ normal | none | <content-list> ] [/ <string> ]?

This may actually be replaced by

<image># [ normal | none | <content-list> ] [/ <string> ]?

Sebastian

[SebastianZ]

  target-text() = target-text( [ <string> | <url> ] [ , [ content | before | after | first-letter] ]? )
->
  <target-text()> = target-text( [ <string> | <url> ] [, [ content | before | after | first-letter] ]? )

Also, a space is missing between first-letter and ].

Sebastian

[lahmatiy]

@SebastianZ

This may actually be replaced by

<image># [ normal | none | <content-list> ] [/ <string> ]?

No, it can't:

• # means one or more times but original syntax allows image list to be omitted, i.e. zero or more times should be used
• original syntax says that <image> list should be followed by comma, in your variant the comma after the list is prohibited

Also, a space is missing between first-letter and ].

You're right. Thank you.

[SebastianZ]

@SebastianZ

This may actually be replaced by

<image># [ normal | none | <content-list> ] [/ <string> ]?

No, it can't:

• means one or more times but original syntax allows image list to be omitted, i.e. zero or more times should be used

• original syntax says that list should be followed by comma, in your variant the comma after the list is prohibited

You're right. So, forget what I just wrote.

Sebastian

[SebastianZ]

• No details or references about document-url, but looks like it's a keyword and therefore shouldn't be quoted

For reference, I've filed issue #706 asking to define document-url.

Sebastian

[lahmatiy]

Fixed by #1381