Illustration

Details

Extends the Subjevko rule from:

Subjevko = Prefix Opener Jevko Closer

to:

Subjevko = Prefix Opener Jevko Closer / Prefix Escaper Quoter HeredocTag Quoter Heredoc Quoter HeredocTag Quoter

where:

Quoter = "'"
HeredocTag = *<any codepoint except Quoter>
Heredoc = *<any code point>

additionally:

• the second instance of HeredocTag must be identical to the first
• and Heredoc must not contain the sequence:

Quoter HeredocTag Quoter

where HeredocTag is also identical to the first HeredocTag instance.

Examples of valid heredocs

Empty Heredoc with empty HeredocTag:

some prefix `''''

Empty Heredoc with HeredocTag = some tag

some prefix `'some tag''some tag'

Nonempty Heredoc with empty HeredocTag:

some prefix `''heredoc contents which contain []`]''

in this case Heredoc = heredoc contents which contain []`].

Examples of invalid heredocs

What looks like empty Heredoc with HeredocTag = some tag, but the second instance of HeredocTag (some other tag) does not match the first:

some prefix `'some tag''some other tag'

in this case 'some other tag' would actually be considered part of the Heredoc and the second instance would be considered missing.

What looks like empty Heredoc with HeredocTag = some tag, but the Heredoc contains the forbidden sequence 'some tag':

some prefix `'some tag'content which contains 'some tag' and continues until here'some tag'

in this case Heredoc = content which contains rather than content which contains 'some tag' and continues until here. The remainder of the example ( and continues until here'some tag') is actually a Suffix of the parent Jevko.

Alternatively, if this example was to continue further like this:

some prefix `'some tag'content which contains 'some tag' and continues until here'some tag'
another prefix [something else]

then the remainder is actually part of the Prefix of the next Subjevko, making the Prefix:

 and continues until here'some tag'
another prefix

rather than another prefix .